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Overton K, Dempster T, Swearer SE, Morris RL, Barrett LT. Achieving conservation and restoration outcomes through ecologically beneficial aquaculture. Conserv Biol 2024; 38:e14065. [PMID: 36811200 DOI: 10.1111/cobi.14065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 06/18/2023]
Abstract
A range of conservation and restoration tools are needed to safeguard the structure and function of aquatic ecosystems. Aquaculture, the culturing of aquatic organisms, often contributes to the numerous stressors that aquatic ecosystems face, yet some aquaculture activities can also deliver ecological benefits. We reviewed the literature on aquaculture activities that may contribute to conservation and restoration outcomes, either by enhancing the persistence or recovery of one or more target species or by moving aquatic ecosystems toward a target state. We identified 12 ecologically beneficial outcomes achievable via aquaculture: species recovery, habitat restoration, habitat rehabilitation, habitat protection, bioremediation, assisted evolution, climate change mitigation, wild harvest replacement, coastal defense, removal of overabundant species, biological control, and ex situ conservation. This list may be expanded as new applications are discovered. Positive intentions do not guarantee positive ecological outcomes, so it is critical that potentially ecologically beneficial aquaculture activities be evaluated via clear and measurable indicators of success to reduce potential abuse by greenwashing. Unanimity on outcomes, indicators, and related terminology will bring the field of aquaculture-environment interactions into line with consensus standards in conservation and restoration ecology. Broad consensus will also aid the development of future certification schemes for ecologically beneficial aquaculture.
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Affiliation(s)
- Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
- National Centre for Coasts and Climate (NCCC), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
- Coastal and Estuarine Adaptation Lab, School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
- National Centre for Coasts and Climate (NCCC), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Stephen E Swearer
- National Centre for Coasts and Climate (NCCC), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Rebecca L Morris
- National Centre for Coasts and Climate (NCCC), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
- Coastal and Estuarine Adaptation Lab, School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
- National Centre for Coasts and Climate (NCCC), School of BioSciences, University of Melbourne, Melbourne, Victoria, Australia
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Coates A, Robinson NA, Dempster T, Johnsen I, Phillips BL. Evolutionary predictions for a parasite metapopulation: Modelling salmon louse resistance to pest controls in aquaculture. Evol Appl 2023; 16:1982-1998. [PMID: 38143899 PMCID: PMC10739098 DOI: 10.1111/eva.13618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 10/20/2023] [Accepted: 11/02/2023] [Indexed: 12/26/2023] Open
Abstract
Pests often evolve resistance to pest controls used in agriculture and aquaculture. The rate of pest adaptation is influenced by the type of control, the selective pressure it imposes, and the gene flow between farms. By understanding how these factors influence evolution at the metapopulation level, pest management strategies that prevent resistance from evolving can be developed. We developed a model for the metapopulation and evolutionary dynamics of the salmon louse (Lepeophtheirus salmonis), which is a major parasite affecting salmon aquaculture. Different management scenarios were simulated across a network of salmon farms covering half of Norway, and their effects on louse epidemiology and evolution were investigated. We compared louse controls that differed in how they were deployed through time (discrete vs. continuous), how they impacted the louse life cycle, and in their overall efficacy. We adjusted the strength of selection imposed by treatments, the dominance effect of the resistant allele, and the geographic location at which resistance originated. Continuously acting strategies (e.g., louse-resistant salmon) were generally more effective than discrete strategies at controlling lice, especially when they increased louse mortality during early developmental stages. However, effective strategies also risked imposing frequent and/or strong selection on lice, thus driving rapid adaptation. Resistant alleles were more likely to be lost through genetic drift when they were recessive, had a low-fitness advantage, or originated in low-farm-density areas. The north-flowing current along the Norwegian coastline dispersed resistant genes from south to north, and limited gene flow in the opposite direction. We demonstrate how evolutionary models can produce quantitative predictions over large spatial and temporal scales and for a range of pest control scenarios. Quantitative outputs can be translated into practical management decisions applied at a regional level to minimise the risk of resistance developing.
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Affiliation(s)
- Andrew Coates
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT), Queenscliff Marine Science CentreDeakin UniversityBurwoodVictoriaAustralia
| | - Nicholas A. Robinson
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT), Queenscliff Marine Science CentreDeakin UniversityBurwoodVictoriaAustralia
- Breeding and Genetics, NofimaÅsNorway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT), Queenscliff Marine Science CentreDeakin UniversityBurwoodVictoriaAustralia
| | | | - Ben L. Phillips
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
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Robinson NA, Robledo D, Sveen L, Daniels RR, Krasnov A, Coates A, Jin YH, Barrett LT, Lillehammer M, Kettunen AH, Phillips BL, Dempster T, Doeschl‐Wilson A, Samsing F, Difford G, Salisbury S, Gjerde B, Haugen J, Burgerhout E, Dagnachew BS, Kurian D, Fast MD, Rye M, Salazar M, Bron JE, Monaghan SJ, Jacq C, Birkett M, Browman HI, Skiftesvik AB, Fields DM, Selander E, Bui S, Sonesson A, Skugor S, Østbye TK, Houston RD. Applying genetic technologies to combat infectious diseases in aquaculture. Rev Aquac 2023; 15:491-535. [PMID: 38504717 PMCID: PMC10946606 DOI: 10.1111/raq.12733] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/24/2022] [Accepted: 08/16/2022] [Indexed: 03/21/2024]
Abstract
Disease and parasitism cause major welfare, environmental and economic concerns for global aquaculture. In this review, we examine the status and potential of technologies that exploit genetic variation in host resistance to tackle this problem. We argue that there is an urgent need to improve understanding of the genetic mechanisms involved, leading to the development of tools that can be applied to boost host resistance and reduce the disease burden. We draw on two pressing global disease problems as case studies-sea lice infestations in salmonids and white spot syndrome in shrimp. We review how the latest genetic technologies can be capitalised upon to determine the mechanisms underlying inter- and intra-species variation in pathogen/parasite resistance, and how the derived knowledge could be applied to boost disease resistance using selective breeding, gene editing and/or with targeted feed treatments and vaccines. Gene editing brings novel opportunities, but also implementation and dissemination challenges, and necessitates new protocols to integrate the technology into aquaculture breeding programmes. There is also an ongoing need to minimise risks of disease agents evolving to overcome genetic improvements to host resistance, and insights from epidemiological and evolutionary models of pathogen infestation in wild and cultured host populations are explored. Ethical issues around the different approaches for achieving genetic resistance are discussed. Application of genetic technologies and approaches has potential to improve fundamental knowledge of mechanisms affecting genetic resistance and provide effective pathways for implementation that could lead to more resistant aquaculture stocks, transforming global aquaculture.
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Affiliation(s)
- Nicholas A. Robinson
- Nofima ASTromsøNorway
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | - Rose Ruiz Daniels
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | - Andrew Coates
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Ye Hwa Jin
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Luke T. Barrett
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
- Institute of Marine Research, Matre Research StationMatredalNorway
| | | | | | - Ben L. Phillips
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Andrea Doeschl‐Wilson
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Francisca Samsing
- Sydney School of Veterinary ScienceThe University of SydneyCamdenAustralia
| | | | - Sarah Salisbury
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | | | | | | | - Dominic Kurian
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Mark D. Fast
- Atlantic Veterinary CollegeThe University of Prince Edward IslandCharlottetownPrince Edward IslandCanada
| | | | | | - James E. Bron
- Institute of AquacultureUniversity of StirlingStirlingScotlandUK
| | - Sean J. Monaghan
- Institute of AquacultureUniversity of StirlingStirlingScotlandUK
| | - Celeste Jacq
- Blue Analytics, Kong Christian Frederiks Plass 3BergenNorway
| | | | - Howard I. Browman
- Institute of Marine Research, Austevoll Research Station, Ecosystem Acoustics GroupTromsøNorway
| | - Anne Berit Skiftesvik
- Institute of Marine Research, Austevoll Research Station, Ecosystem Acoustics GroupTromsøNorway
| | | | - Erik Selander
- Department of Marine SciencesUniversity of GothenburgGothenburgSweden
| | - Samantha Bui
- Institute of Marine Research, Matre Research StationMatredalNorway
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Warren-Myers F, Hvas M, Vågseth T, Dempster T, Oppedal F. Sentinels in Salmon Aquaculture: Heart Rates Across Seasons and During Crowding Events. Front Physiol 2021; 12:755659. [PMID: 34899386 PMCID: PMC8662354 DOI: 10.3389/fphys.2021.755659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/28/2021] [Indexed: 11/20/2022] Open
Abstract
Advances in tag technology now make it possible to monitor the behavior of small groups of individual fish as bioindicators of population wellbeing in commercial aquaculture settings. For example, tags may detect unusual patterns in fish heart rate, which could serve as an early indicator of whether fish health or welfare is becoming compromised. Here, we investigated the use of commercially available heart rate biologgers implanted into 24 Atlantic salmon weighing 3.6 ± 0.8 kg (mean ± SD) to monitor fish over 5 months in a standard 12 m × 12 m square sea cage containing ∼6,000 conspecifics. Post tagging, fish established a diurnal heart rate rhythm within 24 h, which stabilized after 4 days. Whilst the registered tagged fish mortality over the trial period was 0%, only 75% of tagged fish were recaptured at harvest, resulting in an unexplained tag loss rate of 25%. After 5 months, tagged fish were approximately 20% lighter and 8% shorter, but of the similar condition when compared to untagged fish. Distinct diurnal heart rate patterns were observed and changed with seasonal day length of natural illumination. Fish exhibited lower heart rates at night [winter 39 ± 0.2 beats per min (bpm), spring 37 ± 0.2 bpm, summer 43 ± 0.3 bpm, mean ± SE] than during the day (winter 50 ± 0.3 bpm, spring 48 ± 0.2 bpm, summer 49 ± 0.2 bpm) with the difference between night and day heart rates near half during the summer (6 bpm) compared to winter and spring (both 11 bpm). When fish experienced moderate and severe crowding events in early summer, the highest hourly heart rates reached 60 ± 2.5 bpm and 72 ± 2.4 bpm, respectively, on the day of crowding. Here, if the negative sublethal effects on fish that carry tags (e.g., growth rate) can be substantially reduced, the ability to monitor diurnal heart rate patterns across seasons and detect changes during crowding events, and using heart rate biologgers could be a useful warning mechanism for detecting sudden changes in fish behavior in sea cages.
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Affiliation(s)
- Fletcher Warren-Myers
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Melbourne, VIC, Australia
| | - Malthe Hvas
- Institute of Marine Research, Animal Welfare Group, Matre, Norway
| | - Tone Vågseth
- Institute of Marine Research, Animal Welfare Group, Matre, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Melbourne, VIC, Australia
| | - Frode Oppedal
- Institute of Marine Research, Animal Welfare Group, Matre, Norway
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Adams LW, Morris RL, Hull RB, Dempster T, Strain EMA. Making marinas bivalve friendly for enhanced biodiversity outcomes. Mar Pollut Bull 2021; 169:112464. [PMID: 34087666 DOI: 10.1016/j.marpolbul.2021.112464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/30/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Natural coastlines are being replaced by artificial structures (pilings, pontoons, breakwaters), with negative environmental impacts, particularly in marinas. Ropes seeded with mussels (Mytilus galloprovincialis) were added to artificial structures in a marina, using aquaculture techniques, to reduce the colonisation of invasive taxa. After 6-months, droplines beneath pontoons had the highest seeded mussel survival and growth, richness of native and invasive taxa, and proportion of invasive to native taxa, compared with the other interventions. Mussel ropes on the intertidal structures (pilings and breakwaters) supported higher biomass of native taxa, whereas mussel ropes on subtidal structures (pontoons and breakwaters) had reduced biomass of invasive taxa, relative to the unseeded ropes. Droplines had the greater biomass of mussels, while mussel ropes placed under pontoons, and in subtidal gabion baskets limited the biomass but not the diversity of invasive species. Further study is required to determine whether these interventions can be upscaled to improve both the native biodiversity and functioning of marinas.
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Affiliation(s)
- L W Adams
- National Centre for Coasts and Climate, School of BioSciences, The University of Melbourne, Victoria, Australia
| | - R L Morris
- National Centre for Coasts and Climate, School of BioSciences, The University of Melbourne, Victoria, Australia
| | - R B Hull
- National Centre for Coasts and Climate, School of BioSciences, The University of Melbourne, Victoria, Australia
| | - T Dempster
- National Centre for Coasts and Climate, School of BioSciences, The University of Melbourne, Victoria, Australia
| | - E M A Strain
- National Centre for Coasts and Climate, School of BioSciences, The University of Melbourne, Victoria, Australia; Institute for Marine and Antarctic Science, University Tasmania, Hobart, Tasmania, Australia.
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6
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Coates A, Johnsen IA, Dempster T, Phillips BL. Parasite management in aquaculture exerts selection on salmon louse behaviour. Evol Appl 2021; 14:2025-2038. [PMID: 34429746 PMCID: PMC8372093 DOI: 10.1111/eva.13255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/18/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022] Open
Abstract
The evolution of pest resistance to management strategies is a major challenge for farmed systems. Mitigating the effects of pest adaptation requires identifying the selective pressures imposed by these strategies. In Atlantic salmon (Salmo salar) aquaculture, barriers are used to prevent salmon louse (Lepeophtheirus salmonis) larvae (copepodids) from entering salmon cages. These barriers are effective against shallow-swimming copepodids, but those swimming deeper can pass underneath and infest salmon. Laboratory experiments suggest that depth regulation in copepodids is a variable behavioural trait with a genetic basis. We used biological-hydrodynamic dispersal models to assess how this trait variation alters the dispersion of lice through the ocean environment and into farms. The dispersal of copepodids with 3 behavioural phenotypes (deep, mean or shallow) was modelled over winter-spring and spring-summer periods in a Norwegian fjord system with intensive aquaculture. The infestation pressure of each phenotype on barrier cages was estimated from their modelled depth distributions: copepodids deeper than 10 m were predicted to successfully pass underneath barriers. The deep phenotype was the most abundant below 10 m and reached infestation pressures 3 times higher than that of the mean phenotype. In contrast, the shallow phenotype infestation pressure reached less than half that of the mean phenotype. These differences in relative fitness indicate that barriers can impose strong directional selection on the swimming behaviour of copepodids. The strength of this selection varied seasonally and geographically, with selection for the deep phenotype stronger in winter-spring and at coastal locations than in spring-summer and within fjords. These findings can be applied across farms to slow louse adaptation, by limiting barriers during situations of strong selection, although this must be balanced against trade-offs to short-term efficacy. More broadly, our study highlights new ways in which dispersal models can address evolutionary questions crucial for sustainable parasite management in aquaculture.
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Affiliation(s)
- Andrew Coates
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
- Spatial Ecology and Evolution Lab (SPEEL)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
| | | | - Tim Dempster
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
| | - Ben L. Phillips
- Spatial Ecology and Evolution Lab (SPEEL)School of BioSciencesUniversity of MelbourneParkvilleVic.Australia
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Barrett LT, Swearer SE, Dempster T. Native predator limits the capacity of an invasive seastar to exploit a food-rich habitat. Mar Environ Res 2020; 162:105152. [PMID: 32956970 DOI: 10.1016/j.marenvres.2020.105152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/03/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
Biodiverse ecosystems are sometimes inherently resistant to invasion, but environmental change can facilitate invasion by disturbing natural communities and providing resources that are underutilised by native species. In such cases, sufficiently abundant native predators may help to limit invasive population growth. We studied native and invasive seastars feeding under two mussel aquaculture sites in south-east Australia, to determine whether food-rich farm habitats are likely to be reproductive hotspots for the invasive seastar (Asterias amurensis) and whether the larger native seastar (Coscinasterias muricata) reduces the value of the farms for the invader. We found that invaders were not significantly more abundant inside the farms, despite individuals residing within the farms having higher body condition metrics and reproductive investment than those outside. By contrast, the native seastar was 25 × more abundant inside the two farms than outside. We observed several intraguild predation events and an absence of small invaders at the farms despite reports of high larval recruitment to these environments, consistent with some level of biotic control by the native predator. A laboratory choice experiment showed that invaders were strongly attracted to mussels except when the native predator was present. Together, these findings indicate that a combination of predation and predator evasion may play a role in reducing the value of food-rich anthropogenic habitats for this invasive species.
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Affiliation(s)
- Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville 3010 Victoria, Australia; National Centre for Coasts and Climate (NCCC), University of Melbourne, Parkville 3010 Victoria, Australia.
| | - Stephen E Swearer
- National Centre for Coasts and Climate (NCCC), University of Melbourne, Parkville 3010 Victoria, Australia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville 3010 Victoria, Australia
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Shelley JJ, Delaval A, LE Feuvre MC, Dempster T, Raadik TA, Swearer SE. Revision of the genus Hannia (Teleostei, Terapontidae), with description of a new species, Hannia wintoni, from the Kimberley, Western Australia. Zootaxa 2020; 4869:zootaxa.4869.4.5. [PMID: 33311345 DOI: 10.11646/zootaxa.4869.4.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Indexed: 11/04/2022]
Abstract
The systematics of the genus Hannia Vari 1978, endemic to freshwater habitats of remote north-western Australia, is revised in light of recent collections in the region and a molecular study of the group that identified an undescribed candidate species. A new freshwater fish species (Hannia wintoni sp. nov) is described based on analysis of multiple nuclear genetic markers (53 allozyme loci), mitochondrial DNA sequence data (601 bp cytochrome b) and morphology (examination of a suite of 66 morphometric and meristic characters). Head profile, postorbital length, maximum length, preopercular spines and pectoral-fin rays are characters that best distinguish H. wintoni sp. nov from its only congener, H. greewayi. While the existing description of H. greenwayi is robust and accurate, we present a number of additional characters that enhance to the original description, based on type and fresh material. Information on the known distribution, habitats and conservation status of the two species is summarised. The new species is a narrow-range endemic.
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Affiliation(s)
- James J Shelley
- School of BioSciences, University of Melbourne, Victoria 3010, Australia Ichthyology, Sciences Department, Museums Victoria, Victoria 3001, Australia Arthur Rylah Institute for Environmental Research, Department of Environment, Land, Water and Planning, 123 Brown Street, Heidelberg, Victoria 3084, Australia. Aquatic Biodiversity and Conservation Program, Arthur Rylah Institute for Environmental Research, Vic 3084, Australia..
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Oldham T, Dempster T, Crosbie P, Adams M, Nowak B. Cyclic Hypoxia Exposure Accelerates the Progression of Amoebic Gill Disease. Pathogens 2020; 9:pathogens9080597. [PMID: 32707755 PMCID: PMC7460382 DOI: 10.3390/pathogens9080597] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/15/2020] [Accepted: 07/20/2020] [Indexed: 12/23/2022] Open
Abstract
Amoebic gill disease (AGD), caused by the amoeba Neoparamoeba perurans, has led to considerable economic losses in every major Atlantic salmon producing country, and is increasing in frequency. The most serious infections occur during summer and autumn, when temperatures are high and poor dissolved oxygen (DO) conditions are most common. Here, we tested if exposure to cyclic hypoxia at DO saturations of 40–60% altered the course of infection with N. perurans compared to normoxic controls maintained at ≥90% DO saturation. Although hypoxia exposure did not increase initial susceptibility to N. perurans, it accelerated progression of the disease. By 7 days post-inoculation, amoeba counts estimated from qPCR analysis were 1.7 times higher in the hypoxic treatment than in normoxic controls, and cumulative mortalities were twice as high (16 ± 4% and 8 ± 2%), respectively. At 10 days post-inoculation, however, there were no differences between amoeba counts in the hypoxic and normoxic treatments, nor in the percentage of filaments with AGD lesions (control = 74 ± 2.8%, hypoxic = 69 ± 3.3%), or number of lamellae per lesion (control = 30 ± 0.9%, hypoxic = 27.9 ± 0.9%) as determined by histological examination. Cumulative mortalities at the termination of the experiment were similarly high in both treatments (hypoxic = 60 ± 2%, normoxic = 53 ± 11%). These results reveal that exposure to cyclic hypoxia in a diel pattern, equivalent to what salmon are exposed to in marine aquaculture cages, accelerated the progression of AGD in post-smolts.
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Affiliation(s)
- Tina Oldham
- Institute of Marine Research, 5984 Matre, Norway
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
- Correspondence:
| | - Tim Dempster
- Sustainable Aquaculture Laboratory–Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, VIC 3010, Australia;
| | - Philip Crosbie
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
| | - Mark Adams
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
| | - Barbara Nowak
- Aquatic Animal Health Group, Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7248, Australia; (P.C.); (M.A.); (B.N.)
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Coates A, Phillips BL, Oppedal F, Bui S, Overton K, Dempster T. Parasites under pressure: salmon lice have the capacity to adapt to depth-based preventions in aquaculture. Int J Parasitol 2020; 50:865-872. [PMID: 32652129 DOI: 10.1016/j.ijpara.2020.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/04/2020] [Accepted: 05/12/2020] [Indexed: 10/23/2022]
Abstract
The evolution of pesticide resistance has driven renewed interest in non-chemical pest controls in agriculture. Spatial manipulations (physical barriers and fallowing, for example) can be an effective method of prevention, but these too might impose selection and cause rapid adaptation in pests. In salmon aquaculture, various non-chemical approaches have emerged to combat parasitic salmon lice (Lepeophtheirus salmonis) - a major pest with clear signs of evolved chemical resistance. 'Depth-based' preventions, now widely implemented, reduce infestation rates by physically segregating salmon from lice in their infective copepodid stage occurring in surface waters. Copepodids distributed deeper in the water column, however, can bypass these barriers and infest farms. If swimming depth is a heritable trait, we may see rapid evolutionary shifts in response to widespread depth-based prevention. We collected lice from Norwegian salmon farms and assayed more than 11,250 of their laboratory-reared offspring across 37 families. The vertical distributions of copepodids were measured using experimental water columns pressurised to simulate conditions at 0, 5 and 10 m depths. We demonstrated that lice respond strongly to hydrostatic pressure: an increase in pressure doubled the number of lice that migrated to the top of columns. There was also a large effect of family on this response, with the percentage of lice ascending to the top of pressurised columns ranging from 17 to 79% across families. Families with a weak swimming response to pressure are expected to occur deeper in the water column and so be more likely to infest farms employing depth-based preventions. If this between-family variation reflects genetic variation, then the parasite population may have the capacity to adapt to preventative measures. Such adaptation would have important commercial and ecological implications.
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Affiliation(s)
- Andrew Coates
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia; Spatial Ecology and Evolution Lab (SpEEL), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Ben L Phillips
- Spatial Ecology and Evolution Lab (SpEEL), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Frode Oppedal
- Institute of Marine Research, Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Samantha Bui
- Institute of Marine Research, Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.
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Feit B, Dempster T, Jessop TS, Webb JK, Letnic M. A trophic cascade initiated by an invasive vertebrate alters the structure of native reptile communities. Glob Chang Biol 2020; 26:2829-2840. [PMID: 32034982 DOI: 10.1111/gcb.15032] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/16/2019] [Accepted: 02/04/2020] [Indexed: 06/10/2023]
Abstract
Invasive vertebrates are frequently reported to have catastrophic effects on the populations of species which they directly impact. It follows then, that if invaders exert strong suppressive effects on some species then other species will indirectly benefit due to ecological release from interactions with directly impacted species. However, evidence that invasive vertebrates trigger such trophic cascades and alter community structure in terrestrial ecosystems remains rare. Here, we ask how the cane toad, a vertebrate invader that is toxic to many of Australia's vertebrate predators, influences lizard assemblages in a semi-arid rangeland. In our study area, the density of cane toads is influenced by the availability of water accessible to toads. We compared an index of the abundance of sand goannas, a large predatory lizard that is susceptible to poisoning by cane toads and the abundances of four lizard families preyed upon by goannas (skinks, pygopods, agamid lizards and geckos) in areas where cane toads were common or rare. Consistent with the idea that suppression of sand goannas by cane toads initiates a trophic cascade, goanna activity was lower and small lizards were more abundant where toads were common. The hypothesis that suppression of sand goannas by cane toads triggers a trophic cascade was further supported by our findings that small terrestrial lizards that are frequently preyed upon by goannas were more affected by toad abundance than arboreal geckos, which are rarely consumed by goannas. Furthermore, the abundance of at least one genus of terrestrial skinks benefitted from allogenic ecosystem engineering by goannas where toads were rare. Overall, our study provides evidence that the invasion of ecosystems by non-native species can have important effects on the structure and integrity of native communities extending beyond their often most obvious and frequently documented direct ecological effects.
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Affiliation(s)
- Benjamin Feit
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Tim Dempster
- School of Biosciences, University of Melbourne, Melbourne, Vic., Australia
| | - Tim S Jessop
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia
| | - Jonathan K Webb
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
| | - Mike Letnic
- Centre for Ecosystem Science, School of BEES, University of New South Wales, Sydney, NSW, Australia
- Evolution and Ecology Research Centre, School of BEES, University of New South Wales, Sydney, NSW, Australia
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12
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Barrett LT, Pert CG, Bui S, Oppedal F, Dempster T. Sterilization of sea lice eggs with ultraviolet C light: towards a new preventative technique for aquaculture. Pest Manag Sci 2020; 76:901-906. [PMID: 31441192 DOI: 10.1002/ps.5595] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Sea lice infestations on Atlantic salmon (Salmo salar) farms are a considerable burden on the industry and put wild salmonid populations at risk. Frequent delousing treatments are necessary to keep lice densities below allowable limits, but currently viable treatments have drawbacks in terms of financial cost, animal welfare, or environmental impacts. We tested if 254 nm ultraviolet C light (UVC) could function as a new preventative method to suppress reproduction of salmon lice (Lepeophtheirus salmonis) by sterilizing fertilized eggs. We exposed salmon lice eggstrings to a range of UVC intensities and durations to identify effective doses. RESULTS A cumulative dose of 0.008 J cm-2 induced 5% egg mortality, while 95% egg mortality occurred at 0.09 J cm-2 , indicating that UVC can be effective as a preventative treatment. The total cumulative dose appeared to be more important than the duration or number of individual exposures by which the total dose was achieved. CONCLUSION UVC treatment has immediate applications for the salmon aquaculture industry, including for the treatment of wastewater from delousing or other operations. Future work will assess the feasibility of UVC dose delivery on host salmon in sea cage environments that involves little or no fish handling and creates negligible environmental impacts. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
| | - Cassandra G Pert
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
| | - Samantha Bui
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria, Australia
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13
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Barrett LT, Overton K, Stien LH, Oppedal F, Dempster T. Effect of cleaner fish on sea lice in Norwegian salmon aquaculture: a national scale data analysis. Int J Parasitol 2020; 50:787-796. [PMID: 32035989 DOI: 10.1016/j.ijpara.2019.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/25/2019] [Accepted: 12/03/2019] [Indexed: 11/24/2022]
Abstract
The salmon aquaculture industry has adopted the use of invertivorous 'cleaner fishes' (CF) for biological control of sea louse infestations on farmed salmon. At present, ~50 million CF are used annually in Norway alone, with variable success in experimental and industrial contexts. We used a national scale database of louse counts, delousing treatments and CF stocking events on Norwegian salmon farms to test for evidence of CF efficacy at 488 sites that completed a grow-out cycle within 2016-2018. Our analysis revealed that sites using more CF over the duration of a grow-out cycle did not have fewer lice on average, likely because CF use is reactive and in proportion to the scale of the louse problem. Over time within sites, we found that (i) sites using more CF early in the grow-out cycle were able to wait slightly longer (conservatively, a 5.2 week delay with 5000 CF stocked week-1) before conducting the first delousing treatment, and (ii) CF stocking events were followed, on average, by a small reduction in louse population growth rates. However, both effects were small and highly variable, and louse population growth rates remained positive on average, even when large numbers of CF were used (tens of thousands per site). Moreover, effects of CF on louse density tended to be short-lived, likely reflecting mortality and escape of stocked CF. Overall, the data indicate that while some sites consistently obtain good results from CF, there is also widespread suboptimal use. A better understanding of factors affecting CF efficacy in commercial sea cages is required to inform legislation and drive more efficient and ethical use of CF by the salmon aquaculture industry.
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Affiliation(s)
- Luke T Barrett
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.
| | - Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Lars H Stien
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
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14
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Wright DW, Stien LH, Dempster T, Oppedal F. Differential effects of internal tagging depending on depth treatment in Atlantic salmon: a cautionary tale for aquatic animal tag use. Curr Zool 2019; 65:665-673. [PMID: 31857813 PMCID: PMC6911844 DOI: 10.1093/cz/zoy093] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 12/03/2018] [Indexed: 11/17/2022] Open
Abstract
Electronic tags are widespread tools for studying aquatic animal behavior; however, tags risk behavioral manipulation and negative welfare outcomes. During an experiment to test behavioral differences of Atlantic salmon Salmo salar in different aquaculture cage types, including ones expected to elicit deeper swimming behavior, we found negative tagging effects depending on whether cages were depth-modified. In the experiment, data storage tags implanted in Atlantic salmon tracked their depth behavior and survival in unmodified sea-cages and depth-modified sea-cages that forced fish below or into a narrow seawater- or freshwater-filled snorkel tube from a 4 m net roof to the surface. All tagged individuals survived in unmodified cages; however, survival was reduced to 62% in depth-modified cages. Survivors in depth-modified cages spent considerably less time above 4 m than those in unmodified cages, and dying individuals in depth-modified cages tended to position in progressively shallower water. The maximum depth that fish in our study could attain neutral buoyancy was estimated at 22 m in seawater. We calculated that the added tag weight in water reduced this to 8 m, and subtracting the tag volume from the peritoneal cavity where the swim bladder reinflates reduced this further to 4 m. We conclude that the internal tag weight and volume affected buoyancy regulation as well as the survival and behavior of tagged fish. Future tagging studies on aquatic animals should carefully consider the buoyancy-related consequences of internal tags with excess weight in water, and the inclusion of data from dying tagged animals when estimating normal depth behaviors.
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Affiliation(s)
- Daniel W Wright
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Lars H Stien
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, Parkville, Australia
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, Matredal, Norway
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15
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Barrett LT, Dempster T, Swearer SE. A nonnative habitat-former mitigates native habitat loss for endemic reef fishes. Ecol Appl 2019; 29:e01956. [PMID: 31219635 DOI: 10.1002/eap.1956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/17/2019] [Accepted: 05/28/2019] [Indexed: 06/09/2023]
Abstract
Animals that select the best available habitats are most likely to succeed in degraded environments, but ecological change can create evolutionarily unfamiliar habitats that may be under- or over-utilized by native fauna. In temperate coastal waters, eutrophication and grazing have driven a global decline in native seaweeds and facilitated the establishment of nonnative seaweeds that provide novel macrophyte habitat. We tested whether a nonnative kelp canopy (wakame Undaria pinnatifida) functions as a viable habitat or ecological trap for several endemic reef fishes on urchin-grazed reefs in southern Australia. We assessed the willingness of fish to utilize native vs. wakame kelp canopy via a laboratory habitat choice experiment and by recording natural recruitment to specially constructed boulder reefs with manipulated kelp canopy. We also compared fish communities on natural reefs using a before-after-control-impact survey of wakame patches, and to assess the quality of wakame habitat for resident fish, compared fitness metrics for fish collected from habitats with native vs. wakame kelp canopy. Endemic fishes did not distinguish between the native or wakame canopy but preferred both to barren reef habitats. On urchin-grazed natural reefs, fish occurred in higher abundance and diversity where seasonal wakame canopy was present. Fitness metrics in fish collected from wakame patches were comparable to those in fish from adjacent native kelp patches. These findings indicate that the nonnative canopy provides a viable habitat for endemic fish and may play a role in sustaining native fauna populations in this degraded ecosystem. More broadly, we recommend that managers consider the role of nonnative habitats within the context of environmental change, as endemic fauna may benefit from nonnative habitat-formers in areas where their native counterparts cannot persist.
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Affiliation(s)
- Luke T Barrett
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Tim Dempster
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Stephen E Swearer
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
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16
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Geitung L, Oppedal F, Stien LH, Dempster T, Karlsbakk E, Nola V, Wright DW. Snorkel sea-cage technology decreases salmon louse infestation by 75% in a full-cycle commercial test. Int J Parasitol 2019; 49:843-846. [PMID: 31525373 DOI: 10.1016/j.ijpara.2019.06.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/28/2019] [Accepted: 06/03/2019] [Indexed: 01/06/2023]
Abstract
Methods to prevent parasite infestations in farmed fish are becoming widespread, yet tests of their effectiveness often lack commercial relevance and statistical power, which may lead to technology misuse. Here, we examined salmon louse infestation on Atlantic salmon in triplicate commercial snorkel louse barrier and standard cages over a 12 month production cycle. Barrier cages reduced newly settling lice on Atlantic salmon by 75%, with variability in parasite reduction over time depending upon environmental variables. The commercial, triplicate, long-term study design serves as a template to validate performance and detect weaknesses in anti-parasite techniques in fish mariculture.
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Affiliation(s)
- Lena Geitung
- Bremnes Seashore AS, Øklandsvegen 90, 5430 Bremnes, Norway; Department of Biology, University of Bergen, 5006 Bergen, Norway.
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Lars Helge Stien
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory-Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - Egil Karlsbakk
- Department of Biology, University of Bergen, 5006 Bergen, Norway
| | - Velimir Nola
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
| | - Daniel W Wright
- Institute of Marine Research, Matre Research Station, 5984 Matredal, Norway
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17
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Shelley JJ, Dempster T, Le Feuvre MC, Unmack PJ, Laffan SW, Swearer SE. A revision of the bioregionalisation of freshwater fish communities in the Australian Monsoonal Tropics. Ecol Evol 2019; 9:4568-4588. [PMID: 31031928 PMCID: PMC6476826 DOI: 10.1002/ece3.5059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/16/2019] [Accepted: 02/25/2019] [Indexed: 11/25/2022] Open
Abstract
The Australian freshwater fish fauna is very unique, but poorly understood. In the Australian Monsoonal Tropics (AMT) biome of northern Australia, the number of described and candidate species has nearly doubled since the last attempt to analyse freshwater fish species composition patterns and determine a bioregionalisation scheme. Here, we utilise the most complete database of catchment-scale freshwater fish distributions from the AMT to date to: (a) reanalyze spatial patterns of species richness, endemism and turnover of freshwater fishes; (b) propose a biogeographic regionalisation based on species turnover; (c) assess the relationship between species turnover and patterns of environmental change and historic drainage connectivity; and (d) identify sampling gaps. Biogeographic provinces were identified using an agglomerative cluster analysis of a Simpson's beta (β sim) dissimilarity matrix. A generalised dissimilarity model incorporating eighteen environmental variables was used to investigate the environmental correlates of species turnover. Observed and estimated species richness and endemism were calculated and inventory completeness was estimated based on the ratio of observed to estimated species richness. Three major freshwater fish biogeographic provinces and 14 subprovinces are proposed. These differ substantially from the current bioregionalisation scheme. Species turnover was most strongly influenced by environmental variables that are interpreted to reflect changes in terrain (catchment relief and confinement), geology and climate (runoff perenniality, stream density), and biotic responses to climate (net primary productivity). Past connectivity between rivers during low sea-level events is also influential highlighting the importance of historical processes in explaining contemporary patterns of biodiversity in the AMT. The inclusion of 49 newly discovered species and candidate species only reinforced known focal points of species richness and endemism in the AMT. However, a number of key sampling gaps remain that need to be filled to fully characterise the proposed bioregionalisation.
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Affiliation(s)
- James J. Shelley
- School of BioSciencesUniversity of MelbourneMelbourneVictoriaAustralia
| | - Tim Dempster
- School of BioSciencesUniversity of MelbourneMelbourneVictoriaAustralia
| | | | - Peter J. Unmack
- Institute for Applied EcologyUniversity of CanberraCanberraAustralian Capital TerritoryAustralia
| | - Shawn W. Laffan
- School of Biological Earth and Environmental SciencesUniversity of New South WalesSydneyNew South WalesAustralia
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18
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Samsing F, Johnsen I, Treml EA, Dempster T. Identifying 'firebreaks' to fragment dispersal networks of a marine parasite. Int J Parasitol 2019; 49:277-286. [PMID: 30660636 DOI: 10.1016/j.ijpara.2018.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/02/2018] [Accepted: 11/03/2018] [Indexed: 10/27/2022]
Abstract
Marine ecosystems are beset by disease outbreaks, and efficient strategies to control dispersal of pathogens are scarce. We tested whether introducing no-farming areas or 'firebreaks' could disconnect dispersal networks of a parasitic disease affecting the world's largest marine fish farming industry (∼1000 farms). Larval salmon lice (Lepeophtheirus salmonis) are released from and transported among salmon farms by ocean currents, creating inter-farm networks of louse dispersal. We used a state-of-the-art biophysical model to predict louse movement along the Norwegian coastline and network analysis to identify firebreaks to dispersal. At least one firebreak that fragmented the network into two large unconnected groups of farms was identified for all seasons. During spring, when wild salmon migrate out into the ocean, and louse levels per fish at farms must be minimised, two effective firebreaks were created by removing 13 and 21 farms (1.3% and 2.2% of all farms in the system) at ∼61°N and 67°N, respectively. We have demonstrated that dispersal models coupled with network analysis can identify no-farming zones that fragment dispersal networks. Reduced dispersal pathways should lower infection pressure at farms, slow the evolution of resistance to parasite control measures, and alleviate infection pressure on wild salmon populations.
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Affiliation(s)
- Francisca Samsing
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia; CSIRO, Castray Esplanade, Hobart 7004 TAS, Australia.
| | - Ingrid Johnsen
- Institute of Marine Research, P.O. Box 1870 Nordnes, N-5817 Bergen, Norway
| | - Eric A Treml
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia; School of Life and Environmental Sciences, Deakin University, Victoria 3220, Australia
| | - Tim Dempster
- School of BioSciences, University of Melbourne, 3010 Victoria, Australia
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19
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Jessop TS, Webb J, Dempster T, Feit B, Letnic M. Interactions between corticosterone phenotype, environmental stressor pervasiveness and irruptive movement-related survival in the cane toad. J Exp Biol 2018; 221:jeb.187930. [PMID: 30352824 DOI: 10.1242/jeb.187930] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 10/19/2018] [Indexed: 11/20/2022]
Abstract
Animals use irruptive movement to avoid exposure to stochastic and pervasive environmental stressors that impact fitness. Beneficial irruptive movements transfer individuals from high-stress areas (conferring low fitness) to alternative localities that may improve survival or reproduction. However, being stochastic, environmental stressors can limit an animal's preparatory capacity to enhance irruptive movement performance. Thus individuals must rely on pre-existing, or rapidly induced, physiological and behavioural responses. Rapid elevation of glucocorticoid hormones in response to environmental stressors are widely implicated in adjusting physiological and behaviour processes that could influence irruptive movement capacity. However, there remains little direct evidence demonstrating that corticosterone-regulated movement performance or interaction with pervasiveness of environmental stress, confers adaptive movement outcomes. Here, we compared how movement-related survival of cane toads (Rhinella marina) varied with three different experimental corticosterone phenotypes across four increments of increasing environmental stressor pervasiveness (i.e. distance from water in a semi-arid landscape). Our results indicated that toads with phenotypically increased corticosterone levels attained higher movement-related survival compared with individuals with control or lowered corticosterone phenotypes. However, the effects of corticosterone phenotypes on movement-related survival to some extent co-varied with stressor pervasiveness. Thus, our study demonstrates how the interplay between an individual's corticosterone phenotype and movement capacity alongside the arising costs of movement and the pervasiveness of the environmental stressor can affect survival outcomes.
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Affiliation(s)
- Tim S Jessop
- Centre for Integrative Ecology, Deakin University, Victoria, 3220, Australia
| | - Jonathan Webb
- School of the Environment, University of Technology Sydney, NSW 2007, Australia
| | - Tim Dempster
- School of Biosciences, University of Melbourne, Victoria, 3010, Australia
| | - Benjamin Feit
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.,School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW 2052, Australia
| | - Mike Letnic
- School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW 2052, Australia
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20
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Wright DW, Nowak B, Oppedal F, Crosbie P, Stien LH, Dempster T. Repeated sublethal freshwater exposures reduce the amoebic gill disease parasite, Neoparamoeba perurans, on Atlantic salmon. J Fish Dis 2018; 41:1403-1410. [PMID: 29938799 DOI: 10.1111/jfd.12834] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
Freshwater bathing is one of the main treatment options available against amoebic gill disease (AGD) affecting multiple fish hosts in mariculture systems. Prevailing freshwater treatments are designed to be long enough to kill Neoparamoeba perurans, the ectoparasite causing AGD, which may select for freshwater tolerance. Here, we tested whether using shorter, sublethal freshwater treatment durations are a viable alternative to lethal ones for N. perurans (2-4 hr). Under in vitro conditions, gill-isolated N. perurans attached to plastic substrate in sea water lifted off after ≥2 min in freshwater, but survival was not impacted until 60 min. In an in vivo experiment, AGD-affected Atlantic salmon Salmo salar subjected daily to 30 min (sublethal to N. perurans) and 120 min (lethal to N. perurans) freshwater treatments for 6 days consistently reduced N. perurans cell numbers on gills (based on qPCR analysis) compared to daily 3 min freshwater or seawater treatments for 6 days. Our results suggest that targeting cell detachment rather than cell death with repeated freshwater treatments of shorter duration than typical baths could be used in AGD management. However, the consequences of modifying the intensity of freshwater treatment regimes on freshwater tolerance evolution in N. perurans populations require careful consideration.
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Affiliation(s)
- Daniel William Wright
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, Melbourne, Vic., Australia
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Barbara Nowak
- Institute of Marine and Antarctic Studies, University of Tasmania, Launceston, TAS, Australia
| | - Frode Oppedal
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Phil Crosbie
- Institute of Marine and Antarctic Studies, University of Tasmania, Launceston, TAS, Australia
| | - Lars Helge Stien
- Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, Melbourne, Vic., Australia
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21
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Overton K, Samsing F, Oppedal F, Stien LH, Dempster T. Lowering treatment temperature reduces salmon mortality: a new way to treat with hydrogen peroxide in aquaculture. Pest Manag Sci 2018; 74:1533. [PMID: 29738115 DOI: 10.1002/ps.4897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 02/06/2018] [Accepted: 02/20/2018] [Indexed: 06/08/2023]
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22
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Bui S, Dalvin S, Dempster T, Skulstad OF, Edvardsen RB, Wargelius A, Oppedal F. Susceptibility, behaviour, and retention of the parasitic salmon louse (Lepeophtheirus salmonis) differ with Atlantic salmon population origin. J Fish Dis 2018; 41:431-442. [PMID: 28921589 DOI: 10.1111/jfd.12707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/18/2017] [Accepted: 07/25/2017] [Indexed: 06/07/2023]
Abstract
Atlantic salmon populations across the world have diverse ecological and evolutionary histories, from wild anadromous or landlocked, to domestication and genetic modification. The natural host behaviours confer protection from infestation by ectoparasitic salmon lice Lepeophtheirus salmonis, yet whether genetic origin results in different behaviours and thus susceptibility to infestation is unknown. In common garden experiments, we tested antiparasite behaviours, susceptibility and retention of salmon lice in wild anadromous, wild landlocked, domesticated and genetically modified domesticated strains. Within domesticated strains, we tested two infestation histories (previously infested and naïve) and a new phenotype (albino colouring). Farmed stocks initially acquired 24%-44% higher levels of parasite density than the wild and landlocked strains. Burst swimming and displacement behaviours were higher in the domesticated groups, and jumping was more prevalent in the domesticated strains. At 34 days post-infestation, domesticated strains and the wild anadromous strain did not differ significantly from each other; however, landlocked salmon had increased infestation levels considerably. Domesticated strains lost ~20% (±9.9%-16.5%; 95% CI) of their initial parasite load, while parasite load increased by 5.5% (±30.1%) for wild salmon and 20.1% (±28.5%) in landlocked salmon. This study provides early evidence for diverged host-parasite interactions associated with domestication in this system.
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Affiliation(s)
- S Bui
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, Vic, Australia
- Institute of Marine Research, Bergen, Norway
| | - S Dalvin
- Institute of Marine Research, Bergen, Norway
| | - T Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Parkville, Vic, Australia
- Institute of Marine Research, Bergen, Norway
| | | | | | - A Wargelius
- Institute of Marine Research, Bergen, Norway
| | - F Oppedal
- Institute of Marine Research, Bergen, Norway
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23
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Overton K, Samsing F, Oppedal F, Stien LH, Dempster T. Lowering treatment temperature reduces salmon mortality: a new way to treat with hydrogen peroxide in aquaculture. Pest Manag Sci 2018; 74:535-540. [PMID: 28980393 DOI: 10.1002/ps.4751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/20/2017] [Accepted: 09/27/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Hydrogen peroxide (H2 O2 ) baths are widely used to reduce numbers of salmon lice on farmed Atlantic salmon. Fish mortalities often occur after baths, with warmer temperatures increasing lethality. We tested whether mortality could be reduced and lice removal efficacy maintained by lowering bath temperatures relative to ambient temperatures. Post-smolt salmon infected with lice were held at 10, 13 or 16 °C, and treated with 1.5 g/L H2 O2 for 20 min at equal or lower bath temperatures of 7, 10 or 13 °C. RESULTS Salmon mortality decreased as ambient and bath temperatures decreased. No mortality occurred when fish at 13 °C were treated at 7 °C. For ambient temperatures of 16 °C, the number of lice remaining was reduced by four-fold when treated at 7 °C compared with 13 °C. All treatments in which mortality was zero had similar efficacies regardless of bath temperature. CONCLUSION We took salmon from warmer to colder temperatures to determine the optimum bathing temperature to prevent mortality. A temperature of 7 °C was optimal when treating with 1.5 g/L of H2 O2 , as mortality was zero and pre-adult lice removal was unchanged. By manipulating temperature, we developed a new method of H2 O2 bathing that reduces mortality. When ambient temperatures are >10 °C, we recommend that the industry decrease H2 O2 bath temperatures. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Kathy Overton
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
| | - Francisca Samsing
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
| | | | | | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), University of Melbourne, Parkville, Australia
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Feit B, Gordon CE, Webb JK, Jessop TS, Laffan SW, Dempster T, Letnic M. Invasive cane toads might initiate cascades of direct and indirect effects in a terrestrial ecosystem. Biol Invasions 2018. [DOI: 10.1007/s10530-018-1665-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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Sievers M, Fitridge I, Bui S, Dempster T. To treat or not to treat: a quantitative review of the effect of biofouling and control methods in shellfish aquaculture to evaluate the necessity of removal. Biofouling 2017; 33:755-767. [PMID: 28876130 DOI: 10.1080/08927014.2017.1361937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/26/2017] [Indexed: 06/07/2023]
Abstract
The global growth of farmed shellfish production has resulted in considerable research investigating how biofouling compromises farm productivity. Shellfish fitness can be compared between fouled stock and stock which has undergone treatment. As treatment options are often harsh, they may deleteriously affect stock. The projected impact of biofouling may therefore be confounded by the impact of treatments. Given the substantial cost of fouling removal, some have questioned the necessity of biofouling mitigation strategies. Meta-analysis revealed that biofouling typically reduces shellfish fitness. However, the fitness of treated stock was often lower or equal to fouled control stock, indicating that many common antifouling (AF) strategies are ineffective at enhancing farm productivity. Overall, caution and diligence are required to successfully implement biofouling mitigation strategies. The need remains for increased passive prevention approaches and novel AF strategies suitable for shellfish culture, such as strategic siting of bivalve farms in areas of low biofouling larval supply.
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Affiliation(s)
- Michael Sievers
- a Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences , University of Melbourne , Parkville , Australia
- b School of Ecosystem and Forest Sciences , University of Melbourne , Parkville , Australia
| | - Isla Fitridge
- a Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences , University of Melbourne , Parkville , Australia
| | - Samantha Bui
- a Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences , University of Melbourne , Parkville , Australia
- c Institute of Marine Research , Matre , Norway
| | - Tim Dempster
- a Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences , University of Melbourne , Parkville , Australia
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Affiliation(s)
- S. Bui
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT) School of BioSciences University of Melbourne Melbourne Vic Australia
- Institute of Marine Research Matredal Norway
| | - F. Oppedal
- Institute of Marine Research Matredal Norway
| | - F. Samsing
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT) School of BioSciences University of Melbourne Melbourne Vic Australia
| | - T. Dempster
- Sustainable Aquaculture Laboratory – Temperate and Tropical (SALTT) School of BioSciences University of Melbourne Melbourne Vic Australia
- Institute of Marine Research Matredal Norway
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Oppedal F, Samsing F, Dempster T, Wright DW, Bui S, Stien LH. Sea lice infestation levels decrease with deeper 'snorkel' barriers in Atlantic salmon sea-cages. Pest Manag Sci 2017; 73:1935-1943. [PMID: 28247541 DOI: 10.1002/ps.4560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/13/2017] [Accepted: 02/22/2017] [Indexed: 05/04/2023]
Abstract
BACKGROUND Salmon lice (Lepeophtheirus salmonis) are the most important parasites of farmed salmon. Infective larvae position themselves in the upper part of the water column to increase encounter probabilities with potential hosts. Previous studies have shown that a 'snorkel' sea-cage technology protects salmon from infection in surface waters. We tested whether deep snorkels would more effectively reduce lice infestation than shallow snorkels and still uphold adequate conditions for the fish. Five sea-cages (12 m × 12 m) each holding approximately 3000 Atlantic salmon (Salmo salar) (53 ± 10 g) were fitted with snorkels that gave protection from infection for 0, 4, 8, 12 or 16 m. We tested whether reductions in the settlement of new salmon lice copepodids were consistent among four separate infection periods. RESULTS Lice infestation decreased exponentially with depth in all time periods. Infection levels in shallow snorkels (0 and 4 m) were consistently 4-10 times higher than those in deep snorkels (12 and 16 m). Key welfare and production performance indices were similar across all snorkel depths. CONCLUSION Deeper snorkels dramatically and consistently reduced infection levels of salmon lice compared with shallow snorkels, without consequences for fish welfare and production performance. Therefore, reducing salmon sea lice encounters using a depth-based barrier is a powerful management tool for salmon farming. © 2017 Society of Chemical Industry.
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Affiliation(s)
| | - Francisca Samsing
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Tim Dempster
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Daniel W Wright
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
| | - Samantha Bui
- Institute of Marine Research, Matredal, Norway
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Victoria, Australia
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White CA, Nichols PD, Ross DJ, Dempster T. Dispersal and assimilation of an aquaculture waste subsidy in a low productivity coastal environment. Mar Pollut Bull 2017; 120:309-321. [PMID: 28535958 DOI: 10.1016/j.marpolbul.2017.05.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 06/07/2023]
Abstract
To understand dispersal and assimilation of aquaculture waste subsidies in a naturally low-productivity environment, we applied a novel, rapid transmethylation technique to analyse sediment and biota fatty acid composition. This technique was initially validated at Atlantic salmon farms in Macquarie Harbour, Australia, where sediments were collected at farm and control locations. Subsequently, sediment, benthic polychaete and zooplankton were sampled at sites 0, 50, 250, 500 and 1000m distant from multiple cages. Results demonstrated an acute deposition zone up to 50m from cages and a diffuse zone extending 500m from cages. Changes in sediment concentration of linoleic acid, oleic acid and total fatty acids were effective tracers of farm deposition. Bacterial biomarkers indicated that aquaculture waste stimulates bacterial productivity in sediments, with elevated biomarker concentrations also detected in benthic polychaetes. Overall, fatty acid analysis was a sensitive technique to characterize the benthic footprint of aquaculture influence.
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Affiliation(s)
- C A White
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, VIC 3010, Australia; Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS 7000, Australia.
| | - P D Nichols
- Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS 7000, Australia
| | - D J Ross
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 49, Hobart, TAS 7000, Australia
| | - T Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, VIC 3010, Australia
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White CA, Bannister RJ, Dworjanyn SA, Husa V, Nichols PD, Kutti T, Dempster T. Consumption of aquaculture waste affects the fatty acid metabolism of a benthic invertebrate. Sci Total Environ 2017; 586:1170-1181. [PMID: 28222923 DOI: 10.1016/j.scitotenv.2017.02.109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/29/2017] [Accepted: 02/13/2017] [Indexed: 06/06/2023]
Abstract
Trophic subsidies can drive widespread ecological change, thus knowledge of how keystone species respond to subsidies is important. Aquaculture of large carnivorous fish generates substantial waste as faeces and lost feed, providing a food source to mobile benthic invertebrates. We used a controlled feeding study combined with a field survey to better understand the interaction between salmon aquaculture and the sea urchin, Echinus acutus, a dominant mobile invertebrate in Norwegian fjords. We tested if diets affected urchin fatty acid composition by feeding them one of three diet treatments ("aquafeed", "composite" and "natural") for 10weeks. To test if proximity to fish farms altered E. acutus fatty acid composition, populations were sampled at 10 locations in Hardangerfjord and Masfjord (Western Norway) from directly adjacent and up to 12km from farms. Fatty acids were measured in gonads and eggs in the diet experiment and in gonads and gut contents from wild animals. Urchins directly assimilated aquaculture waste at farm sites, as evidenced by elevated linoleic acid (LA), oleic acid (OA) and ∑LA, OA in their tissues. The diet experiment highlighted the biosynthetic and selective dietary sparing capacity of E. acutus in both gonads and eggs, with evidence for the elongation and desaturation of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) from C18 fatty acid precursors. Elevated biosynthesis of non-methylene interrupted (NMI) fatty acids, in particular 20:3Δ7,11,14 and 20:2 Δ5,11, were also linked to a high C18 fatty acid, low ≥C20 long-chain polyunsaturated fatty acid (LC-PUFA) diet. Fatty acid composition of gonads of wild urchins indicated a highly variable diet. The study indicates that the generalist feeding ecology of E. acutus, coupled with extensive biosynthetic capacity, enables it to exploit aquaculture waste as an energy-rich trophic subsidy.
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Affiliation(s)
- Camille A White
- Sustainable Aquaculture Laboratory, Temperate and Tropical, School of BioSciences, University of Melbourne, Parkville, VIC 3010, Australia; Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS, 7000, Australia.
| | | | - Symon A Dworjanyn
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW 2450, Australia
| | - Vivian Husa
- Institute of Marine Research, P.O. Box 1870, 5817 Bergen, Norway
| | - Peter D Nichols
- Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS, 7000, Australia
| | - Tina Kutti
- Institute of Marine Research, P.O. Box 1870, 5817 Bergen, Norway
| | - Tim Dempster
- Sustainable Aquaculture Laboratory, Temperate and Tropical, School of BioSciences, University of Melbourne, Parkville, VIC 3010, Australia
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Reimer T, Dempster T, Wargelius A, Fjelldal PG, Hansen T, Glover KA, Solberg MF, Swearer SE. Rapid growth causes abnormal vaterite formation in farmed fish otoliths. J Exp Biol 2017; 220:2965-2969. [DOI: 10.1242/jeb.148056] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 06/01/2017] [Indexed: 01/06/2023]
Abstract
Sagittal otoliths are essential components of the sensory organs that enable all teleost fish to hear and maintain balance, and are primarily composed of calcium carbonate. A deformity, where aragonite (the normal crystal form) is replaced with vaterite, was first noted over 50 years ago but its underlying cause is unresolved. We evaluated the prevalence of vateritic otoliths from two captive rearing studies which suggested that fast growth, due to environmental rather than genetic control, led to vaterite development. We then tested this by varying light and temperature to create phenotypes with different growth rates, which resulted in fast growers (5x larger) having 3 times more vaterite than slow growers. A decrease in either the ratio of otolith matrix proteins (otolin-1/OMM-64) or [Ca2+]/[CO32–] may explain why fast growth causes vaterite deposition. As vaterite decreases hearing sensitivity, reducing growth rates in hatcheries may improve the welfare of farmed fish and increase the success of conservation efforts.
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Affiliation(s)
- T. Reimer
- School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - T. Dempster
- School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - A. Wargelius
- Section of Molecular Biology, Institute of Marine Research (IMR), Bergen, Norway
| | - P. G. Fjelldal
- Institute of Marine Research (IMR), Matre Research Station, 5984 Matredal, Norway
| | - T. Hansen
- Institute of Marine Research (IMR), Matre Research Station, 5984 Matredal, Norway
| | - K. A. Glover
- Population Genetics Research Group, Institute of Marine Research (IMR), Bergen, Norway
- Sea Lice Research Centre, Department of Biology, University of Bergen, Norway
| | - M. F. Solberg
- Population Genetics Research Group, Institute of Marine Research (IMR), Bergen, Norway
| | - S. E. Swearer
- School of BioSciences, University of Melbourne, Victoria 3010, Australia
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White CA, Dworjanyn SA, Nichols PD, Mos B, Dempster T. Future aquafeeds may compromise reproductive fitness in a marine invertebrate. Mar Environ Res 2016; 122:67-75. [PMID: 27686389 DOI: 10.1016/j.marenvres.2016.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 06/06/2023]
Abstract
Aquaculture of higher trophic level species is increasingly dependent on the use of terrestrial oil products. The input of terrestrially derived n-6 polyunsaturated fatty acids (PUFA) into marine environments has subsequently increased, with unknown consequences for recipient species. We exposed a sea urchin, Heliocidaris erythrogramma to three experimental diets for 78 days: a high n-3 PUFA marine imitation treatment, a high n-6 PUFA "future aquafeed" treatment and an intermediate "current aquafeed" treatment. Female urchins fed the high n-6 PUFA diet produced larvae with lower survival rates than all other treatments. Males fed the high n-6 PUFA diet produced no viable sperm. Fatty acid composition in reproductive material revealed comprehensive biosynthetic and dietary sparing capabilities in H. erythrogramma. Despite this, the ratio of n-6 PUFA to n-3 PUFA in reproductive tissue increased significantly with diet. We suggest alterations to this ratio is the likely mechanism of negative impact on larval development.
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Affiliation(s)
- Camille A White
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, VIC, 3010, Australia; Oceans and Atmosphere, Food Nutrition and Bio-based Products, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS, 7000, Australia.
| | - Symon A Dworjanyn
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, 2450, Australia
| | - Peter D Nichols
- Oceans and Atmosphere, Food Nutrition and Bio-based Products, Commonwealth Scientific and Industrial Research Organization, Castray Esplanade, Hobart, TAS, 7000, Australia
| | - Benjamin Mos
- National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, 2450, Australia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, VIC, 3010, Australia
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Wright DW, Oppedal F, Dempster T. Early-stage sea lice recruits on Atlantic salmon are freshwater sensitive. J Fish Dis 2016; 39:1179-1186. [PMID: 26956953 DOI: 10.1111/jfd.12452] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 11/19/2015] [Accepted: 11/20/2015] [Indexed: 06/05/2023]
Abstract
Sea lice are significant parasites of marine and brackish farmed fishes. Freshwater bathing is a potential control option against numerous sea lice species, although has been viewed as futile against those that are capable of tolerating freshwater for extended periods. By comparing freshwater survival times across host-attached stages of Lepeophtheirus salmonis (Krøyer), a key parasite in Atlantic salmon farming, we show the first attached (copepodid) stage undergoes 96-100% mortality after 1 h in freshwater, whereas later attached stages can tolerate up to 8 days. Thus, regular freshwater bathing methods targeting the more susceptible attached copepodid stage may successfully treat against L. salmonis and potentially other sea lice on fish cultured in marine and brackish waters.
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Affiliation(s)
- D W Wright
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, Melbourne, Vic., Australia
| | - F Oppedal
- Institute of Marine Research, Matre, Norway
| | - T Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical, School of BioSciences, University of Melbourne, Melbourne, Vic., Australia
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Reimer T, Dempster T, Warren-Myers F, Jensen AJ, Swearer SE. High prevalence of vaterite in sagittal otoliths causes hearing impairment in farmed fish. Sci Rep 2016; 6:25249. [PMID: 27121086 PMCID: PMC4848507 DOI: 10.1038/srep25249] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/13/2016] [Indexed: 11/09/2022] Open
Abstract
The rapid growth of aquaculture raises questions about the welfare status of mass-produced species. Sagittal otoliths are primary hearing structures in the inner ear of all teleost (bony) fishes and are normally composed of aragonite, though abnormal vaterite replacement is sometimes seen in the wild. We provide the first widespread evaluation of the prevalence of vaterite in otoliths, showing that farmed fish have levels of vaterite replacement over 10 times higher than wild fish, regardless of species. We confirm this observation with extensive sampling of wild and farmed Atlantic salmon in Norway, the world's largest producer, and verify that vateritic otoliths are common in farmed salmon worldwide. Using a mechanistic model of otolith oscillation in response to sound, we demonstrate that average levels of vaterite replacement result in a 28-50% loss of otolith functionality across most of a salmonid's known hearing range and throughout its life cycle. The underlying cause(s) of vaterite formation remain unknown, but the prevalence of hearing impairment in farmed fish has important implications for animal welfare, the survival of escapees and their effects on wild populations, and the efficacy of restocking programs based on captive-bred fish.
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Affiliation(s)
- T Reimer
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.,Research on the Ecology and Evolution of Fishes (REEF) laboratory, School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - T Dempster
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - F Warren-Myers
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of BioSciences, University of Melbourne, Victoria 3010, Australia.,Research on the Ecology and Evolution of Fishes (REEF) laboratory, School of BioSciences, University of Melbourne, Victoria 3010, Australia
| | - A J Jensen
- Norwegian Institute for Nature Research (NINA), PO Box 5685 Sluppen, 7485 Trondheim, Norway
| | - S E Swearer
- Research on the Ecology and Evolution of Fishes (REEF) laboratory, School of BioSciences, University of Melbourne, Victoria 3010, Australia
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Warren-Myers F, Dempster T, Fjelldal PG, Hansen T, Swearer SE. An industry-scale mass marking technique for tracing farmed fish escapees. PLoS One 2015; 10:e0118594. [PMID: 25738955 PMCID: PMC4349866 DOI: 10.1371/journal.pone.0118594] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/21/2015] [Indexed: 11/18/2022] Open
Abstract
Farmed fish escape and enter the environment with subsequent effects on wild populations. Reducing escapes requires the ability to trace individuals back to the point of escape, so that escape causes can be identified and technical standards improved. Here, we tested if stable isotope otolith fingerprint marks delivered during routine vaccination could be an accurate, feasible and cost effective marking method, suitable for industrial-scale application. We tested seven stable isotopes, (134)Ba, (135)Ba, (136)Ba, (137)Ba, (86)Sr, (87)Sr and (26)Mg, on farmed Atlantic salmon reared in freshwater, in experimental conditions designed to reflect commercial practice. Marking was 100% successful with individual Ba isotopes at concentrations as low as 0.001 µg. g-1 fish and for Sr isotopes at 1 µg. g-1 fish. Our results suggest that 63 unique fingerprint marks can be made at low cost using Ba (0.0002 - 0.02 $US per mark) and Sr (0.46 - 0.82 $US per mark) isotopes. Stable isotope fingerprinting during vaccination is feasible for commercial application if applied at a company level within the world's largest salmon producing nations. Introducing a mass marking scheme would enable tracing of escapees back to point of origin, which could drive greater compliance, better farm design and improved management practices to reduce escapes.
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Affiliation(s)
- Fletcher Warren-Myers
- School of BioSciences, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
| | - Tim Dempster
- School of BioSciences, University of Melbourne, Parkville, Victoria, Australia
| | - Per Gunnar Fjelldal
- Institute of Marine Research, Matre Aquaculture Research Station, Matredal, Norway
| | - Tom Hansen
- Institute of Marine Research, Matre Aquaculture Research Station, Matredal, Norway
| | - Stephen E. Swearer
- School of BioSciences, University of Melbourne, Parkville, Victoria, Australia
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Affiliation(s)
- Mike Letnic
- School of Biological, Earth and Environmental Sciences; University of New South Wales; Sydney NSW 2052 Australia
- Centre for Ecosystem Science; University of New South Wales; Sydney NSW 2052 Australia
- School of Biological Sciences; University of Sydney; Sydney NSW 2006 Australia
| | - Jonathan K. Webb
- School of Biological Sciences; University of Sydney; Sydney NSW 2006 Australia
- School of the Environment; University of Technology Sydney; Sydney NSW 2007 Australia
| | - Tim S. Jessop
- Department of Zoology; University of Melbourne; Melbourne Vic. 3010 Australia
| | - Tim Dempster
- Department of Zoology; University of Melbourne; Melbourne Vic. 3010 Australia
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Cavallo C, Dempster T, Kearney MR, Kelly E, Booth D, Hadden KM, Jessop TS. Predicting climate warming effects on green turtle hatchling viability and dispersal performance. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12389] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Catherine Cavallo
- Department of Zoology University of Melbourne Parkville Victoria3010 Australia
| | - Tim Dempster
- Department of Zoology University of Melbourne Parkville Victoria3010 Australia
| | - Michael R. Kearney
- Department of Zoology University of Melbourne Parkville Victoria3010 Australia
| | - Ella Kelly
- Department of Zoology University of Melbourne Parkville Victoria3010 Australia
| | - David Booth
- School of Biological Sciences University of Queensland St. Lucia Queensland4067 Australia
| | - Kate M. Hadden
- Tiwi Land Council PO Box 38545 Winnellie Northern Territory0821 Australia
| | - Tim S. Jessop
- Department of Zoology University of Melbourne Parkville Victoria3010 Australia
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Jessop TS, Dempster T, Letnic M, Webb JK. Interplay among nocturnal activity, melatonin, corticosterone and performance in the invasive cane toad (Rhinella marinus). Gen Comp Endocrinol 2014; 206:43-50. [PMID: 25063397 DOI: 10.1016/j.ygcen.2014.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 06/26/2014] [Accepted: 07/14/2014] [Indexed: 10/25/2022]
Abstract
Most animals conduct daily activities exclusively either during the day or at night. Here, hormones such as melatonin and corticosterone, greatly influence the synchronization or regulation of physiological and behavioral cycles needed for daily activity. How then do species that exhibit more flexible daily activity patterns, responses to ecological, environmental or life-history processes, regulate daily hormone profiles important to daily performance? This study examined the consequences of (1) nocturnal activity on diel profiles of melatonin and corticosterone and (2) the effects of experimentally increased acute melatonin levels on physiological and metabolic performance in the cane toad (Rhinella marinus). Unlike inactive captive toads that had a distinct nocturnal melatonin profile, nocturnally active toads sampled under field and captive conditions, exhibited decreased nocturnal melatonin profiles with no evidence for any phase shift. Nocturnal corticosterone levels were significantly higher in field active toads than captive toads. In toads with experimentally increased melatonin levels, plasma lactate and glucose responses following recovery post exercise were significantly different from control toads. However, exogenously increased melatonin did not affect resting metabolism in toads. These results suggest that toads could adjust daily hormone profiles to match nocturnal activity requirements, thereby avoiding performance costs induced by high nocturnal melatonin levels. The ability of toads to exhibit plasticity in daily hormone cycles, could have broad implications for how they and other animals utilize behavioral flexibility to optimize daily activities in response to natural and increasingly human mediated environmental variation.
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Affiliation(s)
- Tim S Jessop
- Department of Zoology, University of Melbourne, Victoria 3010, Australia.
| | - Tim Dempster
- Department of Zoology, University of Melbourne, Victoria 3010, Australia
| | - Mike Letnic
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, NSW 2052, Australia
| | - Jonathan K Webb
- School of the Environment, University of Technology, Broadway, NSW 2007, Australia
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Letnic M, Webb JK, Jessop TS, Florance D, Dempster T. Artificial water points facilitate the spread of an invasive vertebrate in arid Australia. J Appl Ecol 2014. [DOI: 10.1111/1365-2664.12232] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Mike Letnic
- Centre for Ecosystem Science; School of Biological; Earth and Environmental Sciences; University of New South Wales; Sydney NSW 2052 Australia
| | - Jonathan K. Webb
- School of the Environment; University of Technology Sydney; Sydney NSW 2007 Australia
| | - Tim S. Jessop
- Department of Zoology; University of Melbourne; Melbourne Vic. 3010 Australia
| | - Daniel Florance
- School of Biological Sciences; University of Sydney; Sydney NSW 2006 Australia
| | - Tim Dempster
- Department of Zoology; University of Melbourne; Melbourne Vic. 3010 Australia
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Abstract
Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad (Rhinella marina) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April-October). We investigated whether cane toads have shifted their ancestral nocturnal rehydration behaviour to one that exploits water resources during the day. Such a shift in hydration behaviour could increase the fitness of individual toads by reducing exposure to desiccation and thermal stress suffered during the day even within terrestrial shelters. We used a novel method (acoustic tags) to monitor the daily hydration behaviour of 20 toads at two artificial reservoirs on Camfield station, Northern Territory. Remarkably, cane toads visited reservoirs to rehydrate during daylight hours, with peaks in activity between 9.00 and 17.00. This diurnal pattern of rehydration activity contrasts with nocturnal rehydration behaviour exhibited by adult toads in their native geographical range and more mesic parts of Australia. Our results demonstrate that cane toads phase shift a key behaviour to survive in a harsh semi-arid landscape. Behavioural phase shifts have rarely been reported in invasive species but could facilitate ongoing invasion success.
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Affiliation(s)
- Jonathan K Webb
- School of the Environment, University of Technology Sydney, , Broadway, New South Wales 2007, Australia
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Sievers M, Dempster T, Fitridge I, Keough MJ. Monitoring biofouling communities could reduce impacts to mussel aquaculture by allowing synchronisation of husbandry techniques with peaks in settlement. Biofouling 2014; 30:203-212. [PMID: 24401014 DOI: 10.1080/08927014.2013.856888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Managing biofouling is typically reactive, and involves time- and labour-intensive removal techniques. Mussel spat settlement and biofouling were documented over 20 months at three mussel farms within Port Phillip Bay (PPB), Australia to determine if knowledge of settlement patterns could assist farmers in avoiding biofouling. Mussel spat settlement was largely confined to a 2-month period at one farm. Of the problematic foulers, Ectopleura crocea settlement varied in space and time at all three farms, whilst Ciona intestinalis and Pomatoceros taeniata were present predominantly at one farm and exhibited more distinct settlement periods. Within PPB, complete avoidance of biofouling is impossible. However, diligent monitoring may help farmers avoid peaks in detrimental biofouling species and allow them to implement removal strategies such as manual cleaning, and postpone grading and re-socking practices, until after these peaks.
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Affiliation(s)
- Michael Sievers
- a Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), Department of Zoology , University of Melbourne , Melbourne , Australia
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41
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Jessop TS, Letnic M, Webb JK, Dempster T. Adrenocortical stress responses influence an invasive vertebrate's fitness in an extreme environment. Proc Biol Sci 2013; 280:20131444. [PMID: 23945686 DOI: 10.1098/rspb.2013.1444] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Continued range expansion into physiologically challenging environments requires invasive species to maintain adaptive phenotypic performance. The adrenocortical stress response, governed in part by glucocorticoid hormones, influences physiological and behavioural responses of vertebrates to environmental stressors. However, any adaptive role of this response in invasive populations that are expanding into extreme environments is currently unclear. We experimentally manipulated the adrenocortical stress response of invasive cane toads (Rhinella marina) to investigate its effect on phenotypic performance and fitness at the species' range front in the Tanami Desert, Australia. Here, toads are vulnerable to overheating and dehydration during the annual hot-dry season and display elevated plasma corticosterone levels indicative of severe environmental stress. By comparing unmanipulated control toads with toads whose adrenocortical stress response was manipulated to increase acute physiological stress responsiveness, we found that control toads had significantly reduced daily evaporative water loss and higher survival relative to the experimental animals. The adrenocortical stress response hence appears essential in facilitating complex phenotypic performance and setting fitness trajectories of individuals from invasive species during range expansion.
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Affiliation(s)
- Tim S Jessop
- Department of Zoology, University of Melbourne, Victoria 3010, Australia.
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42
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Bui S, Oppedal F, Korsøen ØJ, Sonny D, Dempster T. Group behavioural responses of Atlantic salmon (Salmo salar L.) to light, infrasound and sound stimuli. PLoS One 2013; 8:e63696. [PMID: 23691087 PMCID: PMC3656933 DOI: 10.1371/journal.pone.0063696] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 04/05/2013] [Indexed: 11/18/2022] Open
Abstract
Understanding species-specific flight behaviours is essential in developing methods of guiding fish spatially, and requires knowledge on how groups of fish respond to aversive stimuli. By harnessing their natural behaviours, the use of physical manipulation or other potentially harmful procedures can be minimised. We examined the reactions of sea-caged groups of 50 salmon (1331±364 g) to short-term exposure to visual or acoustic stimuli. In light experiments, fish were exposed to one of three intensities of blue LED light (high, medium and low) or no light (control). Sound experiments included exposure to infrasound (12 Hz), a surface disturbance event, the combination of infrasound and surface disturbance, or no stimuli. Groups that experienced light, infrasound, and the combination of infrasound and surface disturbance treatments, elicited a marked change in vertical distribution, where fish dived to the bottom of the sea-cage for the duration of the stimulus. Light treatments, but not sound, also reduced the total echo-signal strength (indicative of swim bladder volume) after exposure to light, compared to pre-stimulus levels. Groups in infrasound and combination treatments showed increased swimming activity during stimulus application, with swimming speeds tripled compared to that of controls. In all light and sound treatments, fish returned to their pre-stimulus swimming depths and speeds once exposure had ceased. This work establishes consistent, short-term avoidance responses to these stimuli, and provides a basis for methods to guide fish for aquaculture applications, or create avoidance barriers for conservation purposes. In doing so, we can achieve the manipulation of group position with minimal welfare impacts, to create more sustainable practices.
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Affiliation(s)
- Samantha Bui
- Sustainable Aquaculture Laboratory - Temperate and Tropical, Department of Zoology, University of Melbourne, Victoria, Australia.
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Sievers M, Fitridge I, Dempster T, Keough MJ. Biofouling leads to reduced shell growth and flesh weight in the cultured mussel Mytilus galloprovincialis. Biofouling 2013; 29:97-107. [PMID: 23256892 DOI: 10.1080/08927014.2012.749869] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Competitive interactions between cultured mussels and fouling organisms may result in growth and weight reductions in mussels, and compromised aquaculture productivity. Mussel ropes were inoculated with Ciona intestinalis, Ectopleura crocea or Styela clava, and growth parameters of fouled and unfouled Mytilus galloprovincialis were compared after two months. Small mussels (≈ 50 mm) fouled by C. intestinalis and E. crocea were 4.0 and 3.2% shorter in shell length and had 21 and 13% reduced flesh weight, respectively, compared to the controls. Large mussels (≈ 68 mm) fouled by S. clava, C. intestinalis and E. crocea were 4.4, 3.9 and 2.1% shorter than control mussels, respectively, but flesh weights were not significantly reduced. A series of competitive feeding experiments indicated that S. clava and C. intestinalis did not reduce mussels' food consumption, but that E. crocea, through interference competition, did. Fouling by these species at the densities used here reduced mussel growth and flesh weight, likely resulting in economic losses for the industry, and requires consideration when developing biofouling mitigation strategies.
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Affiliation(s)
- Michael Sievers
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), Department of Zoology, University of Melbourne, Victoria, Australia.
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Somaweera R, Shine R, Webb J, Dempster T, Letnic M. Why does vulnerability to toxic invasive cane toads vary among populations of Australian freshwater crocodiles? Anim Conserv 2012. [DOI: 10.1111/j.1469-1795.2012.00578.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Somaweera
- School of Biological Sciences; The University of Sydney; Sydney; NSW; Australia
| | - R. Shine
- School of Biological Sciences; The University of Sydney; Sydney; NSW; Australia
| | | | - T. Dempster
- Department of Zoology; University of Melbourne; Melbourne; Vic.; Australia
| | - M. Letnic
- School of Biological, Earth and Environmental Sciences; University of New South Wales; Sydney; NSW; Australia
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Bustnes JO, Borgå K, Dempster T, Lie E, Nygård T, Uglem I. Latitudinal distribution of persistent organic pollutants in pelagic and demersal marine fish on the Norwegian Coast. Environ Sci Technol 2012; 46:7836-7843. [PMID: 22734881 DOI: 10.1021/es301191t] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The latitudinal distribution of persistent organic pollutants (POPs: legacy organochlorines [OCs], polybrominated diphenyl ethers [PBDEs,] and hexabromocyclododecane [HBCD]) was examined in livers of two species of marine fish, the pelagic saithe (Pollachius virens,n = 40) and the demersal cod (Gadus morhua,n = 40), along a south-north gradient (59°-70°N) on the Norwegian Coast. Cod had in general two to three times higher concentrations of POPs than saithe, probably because of higher exposure in the benthic food chain. The concentrations of heavy halogenated compounds were higher in the southernmost region than further north. Moreover, the POP pattern showed a gradual shift in the compositions from south to north, especially for OCs in cod: i.e. the relative importance of low-chlorinated polychlorinated biphenyl (PCB) congeners and some OC-pesticides (e.g., hexachlorobenzen [HCB]) in the contaminant burdens increased with latitude. The latitudinal fractionation signal was weaker in saithe, possibly due to its pelagic and nomadic behavior. Hence, this study shows not only a strong latitudinal fractionation in the compositional patterns of POPs in marine fish but also the effects of habitat use and fish behavior.
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Affiliation(s)
- Jan Ove Bustnes
- Norwegian Institute for Nature Research, FRAM - High North Research Centre on Climate and the Environment, NO-9296 Tromsø, Norway.
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46
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Abstract
Biofouling in marine aquaculture is a specific problem where both the target culture species and/or infrastructure are exposed to a diverse array of fouling organisms, with significant production impacts. In shellfish aquaculture the key impact is the direct fouling of stock causing physical damage, mechanical interference, biological competition and environmental modification, while infrastructure is also impacted. In contrast, the key impact in finfish aquaculture is the fouling of infrastructure which restricts water exchange, increases disease risk and causes deformation of cages and structures. Consequently, the economic costs associated with biofouling control are substantial. Conservative estimates are consistently between 5-10% of production costs (equivalent to US$ 1.5 to 3 billion yr(-1)), illustrating the need for effective mitigation methods and technologies. The control of biofouling in aquaculture is achieved through the avoidance of natural recruitment, physical removal and the use of antifoulants. However, the continued rise and expansion of the aquaculture industry and the increasingly stringent legislation for biocides in food production necessitates the development of innovative antifouling strategies. These must meet environmental, societal, and economic benchmarks while effectively preventing the settlement and growth of resilient multi-species consortia of biofouling organisms.
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Affiliation(s)
- Isla Fitridge
- Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), Department of Zoology, University of Melbourne, 3010 Victoria, Australia.
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Dempster T, Kristiansen TS, Korsøen ØJ, Fosseidengen JE, Oppedal F. Technical note: Modifying Atlantic salmon (Salmo salar) jumping behavior to facilitate innovation of parasitic sea lice control techniques1. J Anim Sci 2011; 89:4281-5. [PMID: 21821806 DOI: 10.2527/jas.2011-3894] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- T Dempster
- Sustainable Aquaculture Laboratory-Temperate and Tropical (SALTT), Department of Zoology, University of Melbourne, Victoria, Australia.
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Dempster T, Cooper L, Petty G. Grief and bereavement - supporting siblings of a children's hospice service. BMJ Support Palliat Care 2011. [DOI: 10.1136/bmjspcare-2011-000105.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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49
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Bustnes JO, Nygård T, Dempster T, Ciesielski T, Jenssen BM, Bjørn PA, Uglem I. Do salmon farms increase the concentrations of mercury and other elements in wild fish? J Environ Monit 2011; 13:1687-94. [PMID: 21589984 DOI: 10.1039/c1em10083a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Earlier assessments have suggested that salmon farms may act as a source of mercury (Hg) and other elements in local marine environments. In this study, we measured 30 elements in the livers of demersal Atlantic cod (Gadus morhua) and pelagic saithe (Pollachius virens) caught in association with salmon farms (farm associated [FA]; n = 75) or at reference locations (control; n = 80) in three regions throughout the latitudinal extent of Norway (59-70° N). Concentrations of most elements (24 of 30) were higher (20-70%) in cod compared to saithe. In particular, Hg was 6.8 times higher in cod than saithe. Nine elements were significantly different between FA saithe and control saithe, but only four (Hg, U, Cr and Mn) were highest in FA saithe, and this pattern was only detected consistently across all locations for Hg. Thirteen elements differed in concentration between FA cod and control cod, but only three elements (U, Al and Ba) were higher in FA cod than controls, and this pattern was only detected consistently across all locations for Al. After controlling for a set of potentially confounding variables, the estimated concentrations of Hg in saithe livers were ∼80% higher in FA fish compared to controls. In contrast, Hg concentrations were ∼40% higher in control cod compared to FA cod. Our results do not support the notion that salmon farms in general increase the concentrations of potentially harmful elements in wild fish, and the distribution of Hg and other elements in cod and saithe in Norwegian coastal waters may be more influenced by habitat use, diet, geochemical conditions and water chemistry.
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Affiliation(s)
- Jan Ove Bustnes
- Norwegian Institute for Nature Research, Fram-High North Research Centre for Climate and the Environment, NO-9296 Tromsø, Norway.
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Florance D, Webb JK, Dempster T, Kearney MR, Worthing A, Letnic M. Excluding access to invasion hubs can contain the spread of an invasive vertebrate. Proc Biol Sci 2011; 278:2900-8. [PMID: 21345870 DOI: 10.1098/rspb.2011.0032] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many biological invasions do not occur as a gradual expansion along a continuous front, but result from the expansion of satellite populations that become established at 'invasion hubs'. Although theoretical studies indicate that targeting control efforts at invasion hubs can effectively contain the spread of invasions, few studies have demonstrated this in practice. In arid landscapes worldwide, humans have increased the availability of surface water by creating artificial water points (AWPs) such as troughs and dams for livestock. By experimentally excluding invasive cane toads (Bufo marinus) from AWP, we show that AWP provide a resource subsidy for non-arid-adapted toads and serve as dry season refuges and thus invasion hubs for cane toads in arid Australia. Using data on the distribution of permanent water in arid Australia and the dispersal potential of toads, we predict that systematically excluding toads from AWP would reduce the area of arid Australia across which toads are predicted to disperse and colonize under average climatic conditions by 38 per cent from 2,242,000 to 1,385,000 km(2). Our study shows how human modification of hydrological regimes can create a network of invasion hubs that facilitates a biological invasion, and confirms that targeted control at invasion hubs can reduce landscape connectivity to contain the spread of an invasive vertebrate.
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Affiliation(s)
- Daniel Florance
- School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
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