1
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Brijs J, Moore C, Schakmann M, Souza T, Grellman K, Tran LL, Patton PT, Johansen JL. Eat more, often: The capacity of piscivores to meet increased energy demands in warming oceans. THE SCIENCE OF THE TOTAL ENVIRONMENT 2025; 973:179105. [PMID: 40107143 DOI: 10.1016/j.scitotenv.2025.179105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 01/09/2025] [Accepted: 03/09/2025] [Indexed: 03/22/2025]
Abstract
Marine heatwaves (MHWs) profoundly disturb tropical coral reefs, imperilling species fitness and survival. Ectothermic piscivorous reef fishes are particularly vulnerable to MHWs since all aspects of their survival are dictated by ambient temperature. Severe +4 °C MHWs are projected to escalate daily energy demands by ~32-55 %, compelling piscivores to pursue larger or more frequent prey to survive. However, the feasibility of these responses have been questioned, as evolved predation and digestive strategies are constrained to specific prey types and sizes to safeguard residual aerobic scope (AS) during digestion for other vital processes. Instead, prevailing theory proposes appetite reductions at temperatures above optimal, preserving AS at the expense of growth and/or fitness. We investigated this dichotomy in the thermal foraging responses of Arc-eye hawkfish (Paracirrhites arcatus) and blacktail snapper (Lutjanus fulvus), evaluating energetic demand (standard metabolic rate, SMR), AS, appetite (meal mass intake), and capacity for digestion (specific dynamic action, SDA). Spanning a thermal gradient encompassing present-day winter (24.0 ± 0.1 °C), summer (27.5 ± 0.1 °C), and MHW (31.0 ± 0.1 °C), we show that SMR increased by ~65 % from winter to MHW for both species, while AS increased by ~31-67 %. Contrary to predictions of reduced appetite, both species consumed ~106 % larger meals, yielding a ~ 35-105 % greater SDA magnitude. Surprisingly, increased appetite did not encroach on residual AS as both species maintained the physiological flexibility to process larger meals while retaining ~45-60 % of AS at the post-prandial peak. Although larger meals take longer to digest, both species exhibited faster digestion with rising temperatures resulting in a maintained or shortened SDA duration during MHWs, simultaneously enabling increased feeding rates while preserving aerobic reserves to support heightened predation. Our findings underscore the physiological feasibility of increasing appetite for some piscivores, while highlighting the ecological challenge of increasing prey numbers and sizes amid declining prey densities and prey size-reductions caused by ocean warming.
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Affiliation(s)
- Jeroen Brijs
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA; Institute of Zoology, University of Innsbruck, Technikerstraße 25, Innsbruck 6020, Austria.
| | - Chloe Moore
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
| | - Mathias Schakmann
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
| | - Taylor Souza
- Hopkins Marine Station, Stanford Oceans, Stanford Doerr School of Sustainability, 120 Ocean View Blvd, Pacific Grove 93950, CA, USA.
| | - Katherine Grellman
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
| | - Leon L Tran
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
| | - Philip T Patton
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
| | - Jacob L Johansen
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Rd, Kāne'ohe 96744, HI, USA.
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2
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Hinchcliffe J, Roques JAC, Ekström A, Hedén I, Sundell K, Sundh H, Sandblom E, Björnsson BT, Jönsson E. Insights into thermal sensitivity: Effects of elevated temperature on growth, metabolic rate, and stress responses in Atlantic wolffish (Anarhichas lupus). JOURNAL OF FISH BIOLOGY 2025; 106:61-74. [PMID: 39709949 PMCID: PMC11758196 DOI: 10.1111/jfb.16017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 11/17/2024] [Accepted: 11/20/2024] [Indexed: 12/24/2024]
Abstract
The Atlantic wolffish (Anarhichas lupus) is a cold-water fish with potential for aquaculture diversification. To unveil the mechanisms underlying the compromised growth in Atlantic wolffish when reared at higher temperatures, we investigated the relationship between temperature, growth rate, aerobic capacity, stress biomarkers, and gut barrier function. Juveniles acclimated to 10°C were maintained at 10°C (control) or exposed to 15°C for either 24 h (acute exposure) or 50 days (chronic exposure). Fish exposed to 15°C exhibited reduced growth, higher standard, and maximum metabolic rates compared to those at 10°C. In the chronically exposed group at 15°C, metabolic rates were lower than those of acutely exposed fish. The absolute aerobic scope exhibited no significant variation in temperatures; however, the factorial scope showed a notable reduction at 15°C in both acute and chronic exposed groups, aligning with a correlated decrease in individual growth rates. Chronic warming led to increased plasma glucose levels, indicating energy mobilization, but cortisol levels were unaffected. Furthermore, chronic warming resulted in reduced intestinal barrier function, as evidenced by increased ion permeability and a negative potential in the serosa layer. We conclude that warming elevates metabolic rates while reducing intestinal barrier function, thus increasing energy expenditure, collectively, limiting energy available for growth at this temperature from increased allostatic load. Thus, juvenile wolffish maintaining their aerobic scope under thermal stress experience slower growth. This research provides insights for improving the welfare and resilience of wolffish in aquaculture at elevated temperatures and understanding their response to increased environmental temperatures.
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Affiliation(s)
- James Hinchcliffe
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
| | - Jonathan A. C. Roques
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
- Blue Food, Center for Future SeafoodUniversity of GothenburgGothenburgSweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
| | - Ida Hedén
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
| | - Kristina Sundell
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
- Blue Food, Center for Future SeafoodUniversity of GothenburgGothenburgSweden
| | - Henrik Sundh
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
- Blue Food, Center for Future SeafoodUniversity of GothenburgGothenburgSweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
| | - Björn Thrandur Björnsson
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
| | - Elisabeth Jönsson
- Department of Biological and Environmental Sciences University of GothenburgGothenburgSweden
- The Swedish Mariculture Research Center (SWEMARC)University of GothenburgGothenburgSweden
- Blue Food, Center for Future SeafoodUniversity of GothenburgGothenburgSweden
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3
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Fernandes TJ, Fu SJ, McKenzie DJ, Killen SS. Expanding the scope: integrating costs of digestive metabolism and growth into estimates of maximum oxygen uptake in fishes. J Exp Biol 2024; 227:jeb248197. [PMID: 39034854 DOI: 10.1242/jeb.248197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2024] [Accepted: 06/20/2024] [Indexed: 07/23/2024]
Affiliation(s)
- Timothy J Fernandes
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada, L5L 1C6
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada, M5S 3B2
- School of Biodiversity, One Health, and Comparative Medicine, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Shi-Jian Fu
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China
| | - David J McKenzie
- UMR Marine Biodiversity, Exploitation, and Conservation, Université Montpellier, CNRS, IRD, IFREMER, INRAE, 34090 Montpellier, France
| | - Shaun S Killen
- School of Biodiversity, One Health, and Comparative Medicine, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
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4
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Fernandes TJ, Li H, Shuter BJ, McMeans BC. Consistent seasonal flexibility of the gut and its regions across wild populations of a winter-quiescent fish. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231975. [PMID: 38511079 PMCID: PMC10951726 DOI: 10.1098/rsos.231975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/22/2024] [Accepted: 02/27/2024] [Indexed: 03/22/2024]
Abstract
Seasonality in north-temperate environments imposes drastic temperature and resource variations that shape the seasonal ecophysiology of resident organisms. A better understanding of an organism's capacity to flexibly respond to this drastic seasonal variation may reveal important mechanisms for tolerating or responding to environmental variation introduced by global change. In fishes, the digestive system is both the interface between resource and energy acquisition and one of the most expensive organ systems to maintain. However, little evidence describing the capacity for seasonal flexibility in the digestive tract of wild northern fishes exists. Here, we investigated phenotypic flexibility in the size of the gastrointestinal (GI) tract across three northern populations of a winter-dormant warm-water fish, pumpkinseed sunfish (Lepomis gibbosus). In all populations, pumpkinseed exhibited pronounced structural flexibility in the GI tract, aligned with winter and the timing of reproduction. The dry mass of the GI increased by 1.3- to nearly 2.5-fold in the early spring. The pyloric caeca demonstrated the greatest capacity for flexibility, increasing by up to 3.7-fold prior to reproduction. In all populations, minimum dry GI mass was consistently achieved during winter and mid-summer. This capacity for gut flexibility may represent a novel mechanism for facilitating rapid adaptive responses (e.g. metabolic plasticity) to future environmental change.
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Affiliation(s)
- Timothy J. Fernandes
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, OntarioL5L 1C6, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, 27 King's College Circle, Toronto, OntarioM5S 1A1, Canada
| | - Hugo Li
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, OntarioL5L 1C6, Canada
| | - Brian J. Shuter
- Department of Ecology and Evolutionary Biology, University of Toronto, 27 King's College Circle, Toronto, OntarioM5S 1A1, Canada
- Aquatic Research and Development Section, Ontario Ministry of Natural Resources and Forestry, 300 Water Street, Peterborough, OntarioK9J 8M5, Canada
| | - Bailey C. McMeans
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, OntarioL5L 1C6, Canada
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5
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McArley TJ, Morgenroth D, Zena LA, Ekström AT, Sandblom E. Experimental hyperoxia (O
2
supersaturation) reveals a gill diffusion limitation of maximum aerobic performance in fish. Biol Lett 2022; 18:20220401. [DOI: 10.1098/rsbl.2022.0401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several studies have demonstrated that hyperoxia increases the maximal O
2
consumption rate (ṀO
2max
) in fish, but exactly how this occurs remains to be explained. Here, we tested the hypothesis that hyperoxia improves arterial oxygenation in rainbow trout during exhaustive exercise. We demonstrate a 35% higher ṀO
2max
in hyperoxia (200% air saturation) relative to normoxia, which was achieved through a combined 15% increase in cardiac output due to elevated peak heart rate, and a 19% increase of the arterial–venous (A-V) O
2
content difference. While arterial O
2
partial pressure (PaO
2
) and O
2
saturation of haemoglobin declined post-exhaustive exercise in normoxia, this did not occur in hyperoxia. This protective effect of hyperoxia on arterial oxygenation led to a 22% higher arterial O
2
content post-exhaustive exercise, thereby allowing a higher A-V O
2
content difference. These findings indicate that ṀO
2max
is gill diffusion limited in exhaustively exercised rainbow trout. Moreover, as previous studies in salmonids have demonstrated collapsing PaO
2
in normoxia at maximal swimming speed and at acutely high temperatures, a diffusion limitation may constrain ṀO
2
in other situations eliciting peak metabolic demand. These findings, along with the fact that hyperoxia increases ṀO
2max
in several other fishes, suggest that gill diffusion limitations of ṀO
2max
may be widespread in fishes.
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Affiliation(s)
- T. J. McArley
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - D. Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - L. A. Zena
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - A. T. Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - E. Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
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6
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Yin L, Chen L, Wang M, Li H, Yu X. An acute increase in water temperature can decrease the swimming performance and energy utilization efficiency in rainbow trout (Oncorhynchus mykiss). FISH PHYSIOLOGY AND BIOCHEMISTRY 2021; 47:109-120. [PMID: 33211244 DOI: 10.1007/s10695-020-00897-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 11/05/2020] [Indexed: 06/11/2023]
Abstract
In order to evaluate the effects of acute temperature exposure on the swimming performance of rainbow trout (Oncorhynchus mykiss), the critical swimming speed (Ucrit) and oxygen consumption rates (MO2) were determined at different temperatures (13.2, 18.4, and 22.5 °C). The Ucrit and MO2 of different body mass (109.44, 175.74, and 249.42 g) fish were also obtained at 13.4 °C. The Ucrit first increased as the temperature increased from 13.2 to 15.2 °C, which was calculated to be the optimal temperature for the Ucrit, and then decreased with increasing temperature. The optimal swimming speed (Uopt) showed a similar trend to the Ucrit. At a given swimming speed, the MO2 and cost of transport (COT) were significantly higher at 22.5 than at 13.2 °C, suggesting the energy utilization efficiency decreased with increasing temperature. The absolute values of Ucrit and Uopt increased as the body mass increased from 109.44 to 249.42 g, whereas the relative values decreased. Although not statistically significant, the maximum metabolic rate (MMR) tended to increase with temperature but decrease with body mass. Results can be of value in understanding the behavioral and physiological response of rainbow trout to acute temperature change.
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Affiliation(s)
- Leiming Yin
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China
| | - Lei Chen
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China
| | - Maolin Wang
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China
| | - Hongquan Li
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China
| | - Xiaoming Yu
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian, 116023, China.
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7
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Nonnis S, Angiulli E, Maffioli E, Frabetti F, Negri A, Cioni C, Alleva E, Romeo V, Tedeschi G, Toni M. Acute environmental temperature variation affects brain protein expression, anxiety and explorative behaviour in adult zebrafish. Sci Rep 2021; 11:2521. [PMID: 33510219 PMCID: PMC7843641 DOI: 10.1038/s41598-021-81804-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 01/08/2021] [Indexed: 12/11/2022] Open
Abstract
This study investigated the effect of 4-d acute thermal treatments at 18 °C, 26 °C (control) and 34 °C on the nervous system of adult zebrafish (Danio rerio) using a multidisciplinary approach based on behavioural tests and brain proteomic analysis. The behavioural variations induced by thermal treatment were investigated using five different tests, the novel tank diving, light and dark preference, social preference, mirror biting, and Y-Maze tests, which are standard paradigms specifically tailored for zebrafish to assess their anxiety-like behaviour, boldness, social preference, aggressiveness, and explorative behaviour, respectively. Proteomic data revealed that several proteins involved in energy metabolism, messenger RNA translation, protein synthesis, folding and degradation, cytoskeleton organisation and synaptic vesiculation are regulated differently at extreme temperatures. The results showed that anxiety-like behaviours increase in zebrafish at 18 °C compared to those at 26 °C or 34 °C, whereas anxiety-related protein signalling pathways are downregulated. Moreover, treatments at both 18 °C and 34 °C affect the exploratory behaviour that appears not to be modulated by past experiences, suggesting the impairment of fish cognitive abilities. This study is the continuation of our previous work on the effect of 21-d chronic treatment at the same constant temperature level and will enable the comparison of acute and chronic treatment effects on the nervous system function in adult zebrafish.
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Affiliation(s)
- S Nonnis
- Department of Veterinary Medicine, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy.,CRC "Innovation for Well-Beeing and Environment" (I-WE), Università degli Studi di Milano, Milano, Italy
| | - E Angiulli
- Department of Biology and Biotechnology ''Charles Darwin", Sapienza University, Via Alfonso Borelli 50, 00161, Rome, Italy
| | - E Maffioli
- Department of Veterinary Medicine, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy. .,CIMAINA, Università degli Studi di Milano, Milano, Italy.
| | - F Frabetti
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - A Negri
- Department of Veterinary Medicine, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy.,CIMAINA, Università degli Studi di Milano, Milano, Italy
| | - C Cioni
- Department of Biology and Biotechnology ''Charles Darwin", Sapienza University, Via Alfonso Borelli 50, 00161, Rome, Italy
| | - E Alleva
- Center for Behavioural Sciences and Mental Health, IstitutoSuperiore di Sanità, Rome, Italy
| | - V Romeo
- Department of Veterinary Medicine, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy
| | - G Tedeschi
- Department of Veterinary Medicine, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy.,CRC "Innovation for Well-Beeing and Environment" (I-WE), Università degli Studi di Milano, Milano, Italy.,CIMAINA, Università degli Studi di Milano, Milano, Italy
| | - M Toni
- Department of Biology and Biotechnology ''Charles Darwin", Sapienza University, Via Alfonso Borelli 50, 00161, Rome, Italy.
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8
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The gaseous gastrointestinal tract of a seawater teleost, the English sole (Parophrys vetulus). Comp Biochem Physiol A Mol Integr Physiol 2020; 247:110743. [PMID: 32531535 DOI: 10.1016/j.cbpa.2020.110743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 02/07/2023]
Abstract
There has been considerable recent progress in understanding the respiratory physiology of the gastrointestinal tract (GIT) in teleosts, but the respiratory conditions inside the GIT remain largely unknown, particularly the luminal PCO2 and PO2 levels. The GIT of seawater teleosts is of special interest due to its additional function of water absorption linked to HCO3- secretion, a process that may raise luminal PCO2 levels. Direct measurements of GIT PCO2 and PO2 using micro-optodes in the English sole (Parophrys vetulus; anaesthetized, artificially ventilated, 10-12 °C) revealed extreme luminal gas levels. Luminal PCO2 was 14-17 mmHg in the stomach and intestinal segments of fasted sole, considerably higher than arterial blood levels of 5 mmHg. Moreover, feeding, which raised intestinal HCO3- concentration, also raised luminal PCO2 to 34-50 mmHg. All these values were higher than comparable measurements in freshwater teleosts, and also greater than environmental CO2 levels of concern in aquaculture or global change scenarios. The PCO2 values in subintestinal vein blood draining the GIT of fed fish (28 mmHg) suggested some degree of equilibration with high luminal PCO2, whereas subintestinal vein PO2 levels were relatively low (9 mmHg). All luminal sections of the GIT were virtually anoxic (PO2 ≤ 0.3 mmHg), in both fasted and fed animals, a novel finding in teleosts.
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9
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Element G, Engel K, Neufeld JD, Casselman JM, van Coeverden de Groot P, Greer CW, Walker VK. Seasonal habitat drives intestinal microbiome composition in anadromous Arctic char (Salvelinus alpinus). Environ Microbiol 2020; 22:3112-3125. [PMID: 32363711 PMCID: PMC7496496 DOI: 10.1111/1462-2920.15049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 04/25/2020] [Indexed: 12/13/2022]
Abstract
Intestinal microbial communities from 362 anadromous Arctic char (Salvelinus alpinus) from the high Arctic Kitikmeot region, Nunavut, Canada, were characterized using high-throughput 16S rRNA gene sequencing. The resulting bacterial communities were compared across four seasonal habitats that correspond to different stages of annual migration. Arctic char intestinal communities differed by sampling site, salinity and stages of freshwater residence. Although microbiota from fish sampled in brackish water were broadly consistent with taxa seen in other anadromous salmonids, they were enriched with putative psychrophiles, including the nonluminous gut symbiont Photobacterium iliopiscarium that was detected in >90% of intestinal samples from these waters. Microbiota from freshwater-associated fish were less consistent with results reported for other salmonids, and highly variable, possibly reflecting winter fasting behaviour of these char. We identified microbiota links to age for those fish sampled during the autumn upriver migration, but little impact of the intestinal content and water microbiota on the intestinal community. The strongest driver of intestinal community composition was seasonal habitat, and this finding combined with identification of psychrophiles suggested that water temperature and migratory behaviour are key to understanding the relationship between Arctic char and their symbionts.
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Affiliation(s)
- Geraint Element
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Katja Engel
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Josh D Neufeld
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - John M Casselman
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
| | | | - Charles W Greer
- National Research Council Canada, Energy, Mining and Environment Research Centre, Montreal, QC, H4P 2R2, Canada
| | - Virginia K Walker
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada.,School of Environmental Studies, Queen's University, Kingston, ON, K7L 3N6, Canada
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10
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Thermal acclimation of rainbow trout myotomal muscle, can trout acclimate to a warming environment? Comp Biochem Physiol A Mol Integr Physiol 2020; 245:110702. [PMID: 32278083 DOI: 10.1016/j.cbpa.2020.110702] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 11/23/2022]
Abstract
Climate change is a looming threat to the planet. Cold-water aquatic species will face significant physiological challenges due to elevated summer temperatures. Salmonids, such as rainbow trout (Oncorhynchus mykiss) maintain fidelity to native streams, limiting their ability to mitigate the impact of climate change through migration. We examined how rainbow trout swimming performance and muscle function were shaped by the thermal environment. We hypothesized that trout would show slower muscle contractile properties and slower swimming performance with long-term exposure to warmer water. For fish held at either 10 °C or 20 °C, maximum steady swimming speed (Ucrit) was determined, and contractile properties of both fast-twitch (white) and slow-twitch (red) myotomal muscle were examined. In addition, immunohistochemistry and quantitative PCR were used to assess changes in myosin content of the myotomal muscle in response to holding temperature. Rainbow trout exposed to warm water for six weeks displayed relatively limited thermal acclimation response. When tested at a common temperature (10 °C), 20 °C acclimated fish had modestly slower muscle performance compared to 10 °C acclimated fish. Significant differences in swimming performance and muscle contractile properties were primarily at colder test temperatures (e.g. 2 °C for muscle mechanics). Shifts in myosin heavy chain protein composition and myosin heavy chain gene expression in the swimming muscle were observed in white but not red muscle. Our results suggest that rainbow trout will have a limited ability to mitigate elevated environmental temperature through thermal acclimation of their myotomal or swimming muscle.
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11
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Morgenroth D, Ekström A, Hjelmstedt P, Gräns A, Axelsson M, Sandblom E. Hemodynamic responses to warming in euryhaline rainbow trout: implications of the osmo-respiratory compromise. ACTA ACUST UNITED AC 2019; 222:jeb.207522. [PMID: 31395678 DOI: 10.1242/jeb.207522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/31/2019] [Indexed: 12/19/2022]
Abstract
In seawater, rainbow trout (Oncorhynchus mykiss) drink and absorb water through the gastrointestinal tract to compensate for water passively lost to the hyperosmotic environment. Concomitantly, they exhibit elevated cardiac output and a doubling of gastrointestinal blood flow to provide additional O2 to the gut and increase convective flux of absorbed ions and water. Yet, it is unknown how warming waters, which elevate tissue O2 demand and the rate of diffusion of ions and water across the gills (i.e. the osmo-respiratory compromise), affects these processes. We measured cardiovascular and blood variables of rainbow trout acclimated to freshwater and seawater during acute warming from 11 to 17°C. Relative to freshwater-acclimated trout, cardiac output was 34% and 55% higher in seawater-acclimated trout at 11 and 17°C, respectively, which allowed them to increase gastrointestinal blood flow significantly more during warming (increases of 75% in seawater vs. 31% in freshwater). These adjustments likely served to mitigate the impact of warming on osmotic balance, as changes in ionic and osmotic blood composition were minor. Furthermore, seawater-acclimated trout seemingly had a lower tissue O2 extraction, explaining why trout acclimated to freshwater and seawater often exhibit similar metabolic rates, despite a higher cardiac output in seawater. Our results highlight a novel role of gastrointestinal blood perfusion in the osmo-respiratory compromise in fish, and improve our understanding of the physiological changes euryhaline fishes must undergo when faced with interacting environmental challenges such as transient warming events.
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Affiliation(s)
- Daniel Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Per Hjelmstedt
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
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Wood CM, Eom J. The internal CO 2 threat to fish: high PCO 2 in the digestive tract. Proc Biol Sci 2019; 286:20190832. [PMID: 31311467 DOI: 10.1098/rspb.2019.0832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Our goal was to use novel fibreoptic sensors to make the first direct PCO2 measurements in the digestive tracts of live freshwater fish (anaesthetized, artificially ventilated, 12°C). PCO2 levels in gastrointestinal fluids were substantially higher than in blood, and were elevated after feeding. In the carnivorous, gastric rainbow trout, the mean PCO2 in various parts of the tract increased from 7-13 torr (1 torr = 0.1333 kPa) during fasting to 20-41 torr after feeding, relative to arterial levels of 3.5-4 torr. In the agastric, omnivorous goldfish, the mean gut levels varied from 10-13 torr in fasted animals to 14-18 torr in fed animals, relative to arterial levels of 5-7 torr. These elevated PCO2 values were associated with surprisingly high [Formula: see text] concentrations (greater than 40 mmol l-1) in the intestinal chyme. Incubations of food pellets with acid or water revealed endogenous PCO2 generation sufficient to explain gastric PCO2 in fed trout and anterior intestine PCO2 in fed goldfish. The impacts of possible equilibration with venous blood draining the tract are assessed. We conclude that fish are already coping with PCO2 levels in the internal gastrointestinal environment many-fold greater than those of current concern in the external environment for climate change and aquacultural scenarios.
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Affiliation(s)
- Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Junho Eom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture. Sci Rep 2019; 9:9090. [PMID: 31235773 PMCID: PMC6591390 DOI: 10.1038/s41598-019-45657-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 02/06/2023] Open
Abstract
Investigating the mechanisms that fish employ to maintain homeostasis in their everyday life requires measurements of physiological and behavioural responses in the field. With multivariate bio-loggers, we continuously measured gastrointestinal blood flow (GBF), heart rate, activity and body temperature in rainbow trout (Oncorhynchus mykiss) swimming freely amongst ~5000 conspecifics in a sea cage. Our findings clearly demonstrate that while both acute aquaculture-related stress and spontaneous activity resulted in transient reductions in GBF (i.e. reductions of up to 65%), recovery from stressful handling practices subsequently involved a substantial and prolonged gastrointestinal hyperemia far beyond the level observed prior to the stressor. The gastrointestinal hyperemia may be necessary to repair the damage to the gastrointestinal tract caused by acute stress. Furthermore, heart rate responses to acute stress or voluntary activity differed depending on the individual’s physiological state. Stressed fish (i.e. mean heart rates >70 beats min−1) exhibited a bradycardic response to acute stress or activity, whereas fish with mean heart rates <60 beats min−1 instead demonstrated strong tachycardic responses. Remote monitoring of physiological and behavioural variables using bio-loggers can provide unique insights into ‘real-life’ responses of animals, which can largely differ from the responses observed in confined laboratory settings.
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Relative Mass of Brain- and Intestinal Tissue in Juvenile Brown Trout: No Long-Term Effects of Compensatory Growth; with Additional Notes on Emerging Sex-Differences. FISHES 2018. [DOI: 10.3390/fishes3040038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study investigated whether compensatory growth causes long-term effects in relative brain- or intestine size in a wild, predominantly anadromous, population of brown trout (Salmo trutta). The subject fish belonged to two treatment groups; one group had undergone starvation and subsequent growth compensation, while the other were unrestricted controls. The main hypothesis that compensatory growth would negatively affect brain and intestinal size, as a consequence of growth trade-offs during the compensatory phase, could not be supported as no significant differences were detected between the treatment groups. Further exploratory analyses suggested that males and females started to diverge in both brain and intestine size at around 130 mm fork length, with females developing relatively smaller brains and larger intestines. The size at which the differences appear is a typical size for smoltification (saltwater preadaptation), and females tend to smoltify to a higher proportion than males. Smoltification is known to cause a more elongated morphology and relatively smaller heads in salmonids, and the marine lifestyle is associated with rapid growth, which could require relatively larger intestines. Hence, these emerging sex differences could be a consequence of sex-biased smoltification rates. An investigation of wild smolts of both sexes indicated no differences in brain or intestine mass between male and female smolts.
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