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Baetscher DS, Beck J, Anderson EC, Ruegg K, Ramey AM, Hatch S, Nevins H, Fitzgerald SM, Garza JC. Genetic assignment of fisheries bycatch reveals disproportionate mortality among Alaska Northern Fulmar breeding colonies. Evol Appl 2022; 15:447-458. [PMID: 35386403 PMCID: PMC8965376 DOI: 10.1111/eva.13357] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 11/26/2022] Open
Abstract
Global fisheries kill millions of seabirds annually through bycatch, but little is known about population‐level impacts, particularly in species that form metapopulations. U.S. North Pacific groundfish fisheries catch thousands of Northern Fulmars (Fulmarus glacialis rodgersii) each year, making fulmars the most frequently caught seabird in federally managed U.S. fisheries. Here, we used genetic stock identification to assign 1,536 fulmars sampled as bycatch to one of four Alaska breeding colonies and quantified the similarity of bycatch locations at sea among colonies. We found disproportionately high bycatch from the Pribilof Islands (6% of metapopulation, 23% of bycatch), and disproportionately low bycatch from Chagulak Island (34% of metapopulation, 14% of bycatch). Overlap between fisheries and colony‐specific foraging areas diverge more during the summer breeding season, leading to greater differences in bycatch susceptibility. Contemporary and historical gene flow likely contributes to low genetic differentiation among colonies (FST = 0.003–0.01), yet these values may not represent present connectivity. Our findings illustrate how genetic stock identification can link at‐sea threats to colonies and inform management to reduce bycatch from impacted colonies.
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Affiliation(s)
- Diana S. Baetscher
- University of California Santa Cruz Santa Cruz CA USA
- NOAA Southwest Fisheries Science Center Santa Cruz CA USA
- NOAA Alaska Fisheries Science Center, Auke Bay Laboratories Juneau AK USA
| | - Jessie Beck
- Oikonos Ecosystem Knowledge Santa Cruz CA USA
| | | | | | - Andrew M. Ramey
- U.S. Geological Survey Alaska Science Center Anchorage AK USA
| | - Scott Hatch
- Institute for Seabird Research and Conservation Anchorage AK USA
| | | | | | - John Carlos Garza
- University of California Santa Cruz Santa Cruz CA USA
- NOAA Southwest Fisheries Science Center Santa Cruz CA USA
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Michalko R, Košulič O, Martinek P, Birkhofer K. Disturbance by invasive pathogenic fungus alters arthropod predator-prey food-webs in ash plantations. J Anim Ecol 2021; 90:2213-2226. [PMID: 34013522 DOI: 10.1111/1365-2656.13537] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/17/2021] [Indexed: 11/29/2022]
Abstract
According to the disturbance-succession theory, natural disturbances support biodiversity and are expected to increase the complexity of food-webs in forest ecosystems by opening canopies and creating a heterogeneous environment. However, a limited number of studies have investigated the impact of disturbance by invasive pathogenic species and succession on arthropod predator-prey food-webs in forest ecosystems. Hymenoscyphus fraxineus is a pathogenic fungus of ash trees that is invasive in Europe and causes massive dieback, mainly of the common ash Fraxinus excelsior across its native range. Here we investigated how this pathogenic fungus affects food-webs of web-building spiders and their prey in understorey vegetation of ash plantations. In 23 young and middle-aged ash plantations that were distributed along a gradient of infestation by H. fraxineus (29%-86% infestation), we measured the vegetation structure (canopy openness, shrub coverage, herb/grass coverage), the trait composition of local spider communities (web type, body size), the prey availability and the prey intercepted by spider webs. We then evaluated the multivariate prey composition (prey type, body size) and network properties. Hymenoscyphus fraxineus opened the ash tree canopy, which resulted in denser shrub coverage. The dense shrub vegetation changed the composition of web types in local spider communities and increasing fungus infestation resulted in reduced mean body size of spiders. Infestation by H. fraxineus reduced the availability of predaceous Coleoptera and increased the availability of herbivorous Coleoptera as potential prey. The mean body size of captured prey and the per capita capture rates of most prey groups decreased with increasing fungus infestation. Hymenoscyphus fraxineus infestation indirectly reduced the complexity in bipartite networks and the trophic functional complementarity in local web-building spider communities. The plantation age affected the vegetation structure but did not affect the studied food-webs. Forest disturbance by the invasive pathogen affected four trophic levels (plant-herbivore-coleopteran intermediate predator-top predator web-building spiders) and, contrary to the disturbance-succession theory, disturbance by the fungus simplified the web-building spider-prey food-webs. The results support the view that H. fraxineus represents a threat to the biodiversity and ecosystem functioning in the simplified ecosystems of ash plantations.
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Affiliation(s)
- Radek Michalko
- Department of Forest Ecology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
| | - Ondřej Košulič
- Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
| | - Petr Martinek
- Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
| | - Klaus Birkhofer
- Department of Ecology, Brandenburg University of Technology, Cottbus, Germany
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Kurle CM, Zilliacus KM, Sparks J, Curl J, Bock M, Buckelew S, Williams JC, Wolf CA, Holmes ND, Plissner J, Howald GR, Tershy BR, Croll DA. Indirect effects of invasive rat removal result in recovery of island rocky intertidal community structure. Sci Rep 2021; 11:5395. [PMID: 33686134 PMCID: PMC7940711 DOI: 10.1038/s41598-021-84342-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
Eleven years after invasive Norway rats (Rattus norvegicus) were eradicated from Hawadax Island, in the Aleutian Islands, Alaska, the predicted three-level trophic cascade in the rocky intertidal, with native shorebirds as the apex predator, returned, leading to a community resembling those on rat-free islands with significant decreases in invertebrate species abundances and increases in fleshy algal cover. Rats had indirectly structured the intertidal community via their role as the apex predator in a four-level trophic cascade. Our results are an excellent example of an achievable and relatively short-term community-level recovery following removal of invasive animals. These conservation successes are especially important for islands as their disproportionately high levels of native biodiversity are excessively threatened by invasive mammals.
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Affiliation(s)
- Carolyn M Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California San Diego, 9500 Gilman Dr, La Jolla, CA, 92023, USA.
| | - Kelly M Zilliacus
- Conservation Action Lab, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
| | - Jenna Sparks
- Conservation Action Lab, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA.,Oikonos Ecosystem Knowledge, PO Box 2570, Santa Cruz, CA, 95063, USA
| | - Jen Curl
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA.,Alaska Department of Fish and Game, Division of Wildlife Conservation, 1300 College Rd, Fairbanks, AK, 99701, USA
| | - Mila Bock
- Conservation Action Lab, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA.,Great Basin Institute, 16750 Mt. Rose Highway, Reno, NV, 89511, USA
| | - Stacey Buckelew
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA.,Axiom Data Science, 1016 W 6th Ave, Ste. 105, Anchorage, AK, 99501, USA
| | - Jeffrey C Williams
- US Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge, 95 Sterling Highway, Suite 1, Homer, AK, 99603, USA
| | - Coral A Wolf
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA
| | - Nick D Holmes
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA.,The Nature Conservancy, 201 Mission Street #4, San Francisco, CA, 94105, USA
| | - Jonathan Plissner
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA
| | - Gregg R Howald
- Island Conservation, 2100 Delaware Ave, Suite 1, Santa Cruz, CA, 95060, USA.,FreshWater Life, Telluride, CO, USA
| | - Bernie R Tershy
- Conservation Action Lab, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
| | - Donald A Croll
- Conservation Action Lab, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA.
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Duron Q, Cornulier T, Vidal E, Bourguet E, Ruffino L. Combining live and lethal trapping to inform the management of alien invasive rodent populations in a tropical montane forest. NEOBIOTA 2020. [DOI: 10.3897/neobiota.63.53811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
On large inhabited islands where complete eradication of alien invasive rodents through the use of poison delivery is often not practical or acceptable, mechanical trapping may represent the only viable option to reduce their impact in areas of high biodiversity value. However, the feasibility of sustained rodent control by trapping remains uncertain under realistic operational constraints. This study aimed to assess the effectiveness of non-toxic rat control strategies through a combination of lethal and live-trapping experiments, and scenario modelling, using the example of a remote montane rainforest of New Caledonia. Rat densities, estimated with spatially-explicit capture-recapture models, fluctuated seasonally (9.5–33.6 ind.ha-1). Capture probability (.01–.25) and home range sizes (HR95, .23–.75 ha) varied greatly according to trapping session, age class, sex and species. Controlling rats through the use of lethal trapping allowed maintaining rat densities at ca. 8 ind.ha-1 over a seven-month period in a 5.5-ha montane forest. Simulation models based on field parameter estimates over a 200-ha pilot management area indicated that without any financial and social constraints, trapping grids with the finest mesh sizes achieved cumulative capture probabilities > .90 after 15 trapping days, but were difficult to implement and sustain with the local workforce. We evaluated the costs and effectiveness of alternative trapping strategies taking into account the prevailing set of local constraints, and identified those that were likely to be successful. Scenario modelling, informed by trapping experiments, is a flexible tool for informing the design of sustainable control programs of island-invasive rodent populations, under idiosyncratic local circumstances.
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Peltzer DA, Bellingham PJ, Dickie IA, Houliston G, Hulme PE, Lyver PO, McGlone M, Richardson SJ, Wood J. Scale and complexity implications of making New Zealand predator-free by 2050. J R Soc N Z 2019. [DOI: 10.1080/03036758.2019.1653940] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | | | - Ian A. Dickie
- Bio-Protection Research Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | | | - Philip E. Hulme
- Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand
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Benkwitt CE, Wilson SK, Graham NAJ. Seabird nutrient subsidies alter patterns of algal abundance and fish biomass on coral reefs following a bleaching event. GLOBAL CHANGE BIOLOGY 2019; 25:2619-2632. [PMID: 31157944 DOI: 10.1111/gcb.14643] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
Cross-ecosystem nutrient subsidies play a key role in the structure and dynamics of recipient communities, but human activities are disrupting these links. Because nutrient subsidies may also enhance community stability, the effects of losing these inputs may be exacerbated in the face of increasing climate-related disturbances. Nutrients from seabirds nesting on oceanic islands enhance the productivity and functioning of adjacent coral reefs, but it is unknown whether these subsidies affect the response of coral reefs to mass bleaching events or whether the benefits of these nutrients persist following bleaching. To answer these questions, we surveyed benthic organisms and fishes around islands with seabirds and nearby islands without seabirds due to the presence of invasive rats. Surveys were conducted in the Chagos Archipelago, Indian Ocean, immediately before the 2015-2016 mass bleaching event and, in 2018, two years following the bleaching event. Regardless of the presence of seabirds, relative coral cover declined by 32%. However, there was a post-bleaching shift in benthic community structure around islands with seabirds, which did not occur around islands with invasive rats, characterized by increases in two types of calcareous algae (crustose coralline algae [CCA] and Halimeda spp.). All feeding groups of fishes were positively affected by seabirds, but only herbivores and piscivores were unaffected by the bleaching event and sustained the greatest difference in biomass between islands with seabirds versus those with invasive rats. By contrast, corallivores and planktivores, both of which are coral-dependent, experienced the greatest losses following bleaching. Even though seabird nutrients did not enhance community-wide resistance to bleaching, they may still promote recovery of these reefs through their positive influence on CCA and herbivorous fishes. More broadly, the maintenance of nutrient subsidies, via strategies including eradication of invasive predators, may be important in shaping the response of ecological communities to global climate change.
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Affiliation(s)
| | - Shaun K Wilson
- Department of Biodiversity, Conservation and Attractions, Perth, Western Australia, Australia
- Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia
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