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Ortiz M, Hermosillo-Núñez B. Quantifying stability and resilience of eco-social keystone species complexes for coastal marine ecosystems of the Caribbean Sea and eastern Pacific: applications in conservation and monitoring programmes. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230176. [PMID: 39034701 PMCID: PMC11293858 DOI: 10.1098/rstb.2023.0176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/12/2024] [Accepted: 05/29/2024] [Indexed: 07/23/2024] Open
Abstract
The local stability and resilience of 13 eco-social keystone species complexes (eco-social KSCs)-considered as conservation and monitoring units-were quantified in coastal marine ecosystems located in the Caribbean and eastern Pacific. Based on Routh-Hurwitz's criterion and Levins' criteria, the eco-social KSCs corresponding to Islas Marietas National Park (Mexico) emerged as the most locally stable and resilient ecosystem. To the contrary, the eco-social KSCs determined for Guala Guala Bay (Chile) and Xcalak Reef National Park (Caribbean) were the least stable and resilient, respectively. In terms of sensitivity, the eco-social KSCs corresponding to El Cobre Bay (Chile) presented the greatest number of sensitive components. The ecological section of the KSCs is formed by a tri-trophic network, dominating self-negative feedbacks. In the case of the socio-economic section, the fisher could exhibit the three types of self-feedbacks, and instead, the demand should be controlled. The identification of eco-social KSCs and the quantification of their stabilities and resiliences allow us to approach ecosystem-based fisheries management under a climate change context. Therefore, we suggest assessing and monitoring the persistence of the eco-social KSCs herein analysed over time, as a way to conserve the fundamental network structure of these ecosystems intervened by fishing.This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.
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Affiliation(s)
- Marco Ortiz
- Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
- Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Brenda Hermosillo-Núñez
- Unidad Académica de Sistemas Arrecifales Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México
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2
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Dedman S, Moxley JH, Papastamatiou YP, Braccini M, Caselle JE, Chapman DD, Cinner JE, Dillon EM, Dulvy NK, Dunn RE, Espinoza M, Harborne AR, Harvey ES, Heupel MR, Huveneers C, Graham NAJ, Ketchum JT, Klinard NV, Kock AA, Lowe CG, MacNeil MA, Madin EMP, McCauley DJ, Meekan MG, Meier AC, Simpfendorfer CA, Tinker MT, Winton M, Wirsing AJ, Heithaus MR. Ecological roles and importance of sharks in the Anthropocene Ocean. Science 2024; 385:adl2362. [PMID: 39088608 DOI: 10.1126/science.adl2362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/17/2024] [Indexed: 08/03/2024]
Abstract
In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproportionately affected by humans but can influence prey and coastal ecosystems, including facilitating carbon sequestration. Like terrestrial predators, sharks may be crucial to ecosystem functioning under climate change. However, large ecosystem effects of sharks are not ubiquitous. Increasing human uses of oceans are changing shark roles, necessitating management consideration. Rebuilding key populations and incorporating shark ecological roles, including less obvious ones, into management efforts are critical for retaining sharks' functional value. Coupled social-ecological frameworks can facilitate these efforts.
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Affiliation(s)
- Simon Dedman
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
| | - Jerry H Moxley
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
| | - Yannis P Papastamatiou
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
| | - Matias Braccini
- Western Australian Fisheries and Marine Research Laboratories, Department of Primary Industries and Regional Development, North Beach, WA 6920, Australia
| | - Jennifer E Caselle
- Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Demian D Chapman
- Sharks and Rays Conservation Research Program, Mote Marine Laboratory, Sarasota, FL 34236, USA
| | - Joshua Eli Cinner
- Thriving Oceans Research Hub, School of Geosciences, University of Sydney, Camperdown, NSW 2006, Australia
| | - Erin M Dillon
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
- Smithsonian Tropical Research Institute, Balboa, Republic of Panama
| | - Nicholas K Dulvy
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Ruth Elizabeth Dunn
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
- The Lyell Centre, Heriot-Watt University, Edinburgh EH14 4BA, UK
| | - Mario Espinoza
- Centro de Investigación en Ciencias del Mar y Limnología, Universidad de Costa Rica, San Pedro de Montes de Oca, San José 2060-11501, Costa Rica
- Escuela de Biología, Universidad de Costa Rica, San Pedro de Montes de Oca, San José 2060-11501, Costa Rica
- MigraMar, Bodega Bay, CA 94923, USA
| | - Alastair R Harborne
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
| | - Euan S Harvey
- School of Molecular and Life Sciences, Curtin University, WA, Australia
| | - Michelle R Heupel
- Institute of Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7000, Australia
- Australian Institute of Marine Science, Townsville, QLD, Australia
- Integrated Marine Observing System, University of Tasmania, Hobart, TAS, Australia
| | - Charlie Huveneers
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia
| | | | - James T Ketchum
- MigraMar, Bodega Bay, CA 94923, USA
- Pelagios Kakunjá, La Paz, Baja California Sur, Mexico
- Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Baja California Sur, Mexico
| | - Natalie V Klinard
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, NS B3H 4R2, Canada
| | - Alison A Kock
- Cape Research Centre, South African National Parks, Cape Town, South Africa
- South African Institute for Aquatic Biodiversity (SAIAB), Makhanda (Grahamstown), South Africa
| | - Christopher G Lowe
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - M Aaron MacNeil
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, NS B3H 4R2, Canada
| | - Elizabeth M P Madin
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, HI 96744, USA
| | - Douglas J McCauley
- Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Mark G Meekan
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre, Crawley, WA, Australia
| | - Amelia C Meier
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, HI 96744, USA
| | - Colin A Simpfendorfer
- Institute of Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7000, Australia
- College of Science and Engineering, James Cook University, 1 James Cook Drive, Townsville, QLD 4811, Australia
| | - M Tim Tinker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95060, USA
- US Geological Survey, Western Ecological Research Center, Santa Cruz, CA, USA
| | - Megan Winton
- Atlantic White Shark Conservancy, North Chatham, MA 02650, USA
| | - Aaron J Wirsing
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA
| | - Michael R Heithaus
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA
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3
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Stepien EN, Galatius A, Hansen KA, Nabe-Nielsen J, Teilmann J, Wahlberg M. Response of Eurasian otters (Lutra lutra) to underwater acoustic harassment device sounds. Sci Rep 2024; 14:4988. [PMID: 38424202 PMCID: PMC10904746 DOI: 10.1038/s41598-024-55481-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/23/2024] [Indexed: 03/02/2024] Open
Abstract
Seal scarers (or acoustic harassment devices, AHDs) are designed to deter seals from fishing gear and aquaculture operations, as well as to prevent seals from entering rivers to avoid predation on valuable fish. Our study investigated the potential effects of AHDs on non-target species, specifically the Eurasian otters (Lutra lutra), by testing the reaction of two rehabilitated otters to simulated AHDs sounds at 1 and 14 kHz, with a received sound intensity of 105-145 dB re 1 µPa rms. The 1 kHz sounds were used to investigate alternative frequencies for scaring seals without scaring otters. The otters reacted to both 1 and 14 kHz tonal signals when retrieving fish from a feeding station 0.8 m below the surface. Their diving behaviour and time to extract food progressively increased as sound intensity increased for all tested sound levels. Notably, the sound levels used in our tests were significantly lower (40-80 dB) than the source levels from commercial AHDs. These findings highlight the importance of caution when using AHDs in river and sea habitats inhabited by otters, as AHDs can change their behaviour and potentially result in habitat exclusion.
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Affiliation(s)
| | - Anders Galatius
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Kirstin Anderson Hansen
- Marine Biological Research Centre, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Jacob Nabe-Nielsen
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Jonas Teilmann
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Magnus Wahlberg
- Marine Biological Research Centre, Department of Biology, University of Southern Denmark, Odense, Denmark
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4
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Hughes BB, Beheshti KM, Tinker MT, Angelini C, Endris C, Murai L, Anderson SC, Espinosa S, Staedler M, Tomoleoni JA, Sanchez M, Silliman BR. Top-predator recovery abates geomorphic decline of a coastal ecosystem. Nature 2024; 626:111-118. [PMID: 38297171 DOI: 10.1038/s41586-023-06959-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 12/09/2023] [Indexed: 02/02/2024]
Abstract
The recovery of top predators is thought to have cascading effects on vegetated ecosystems and their geomorphology1,2, but the evidence for this remains correlational and intensely debated3,4. Here we combine observational and experimental data to reveal that recolonization of sea otters in a US estuary generates a trophic cascade that facilitates coastal wetland plant biomass and suppresses the erosion of marsh edges-a process that otherwise leads to the severe loss of habitats and ecosystem services5,6. Monitoring of the Elkhorn Slough estuary over several decades suggested top-down control in the system, because the erosion of salt marsh edges has generally slowed with increasing sea otter abundance, despite the consistently increasing physical stress in the system (that is, nutrient loading, sea-level rise and tidal scour7-9). Predator-exclusion experiments in five marsh creeks revealed that sea otters suppress the abundance of burrowing crabs, a top-down effect that cascades to both increase marsh edge strength and reduce marsh erosion. Multi-creek surveys comparing marsh creeks pre- and post-sea otter colonization confirmed the presence of an interaction between the keystone sea otter, burrowing crabs and marsh creeks, demonstrating the spatial generality of predator control of ecosystem edge processes: densities of burrowing crabs and edge erosion have declined markedly in creeks that have high levels of sea otter recolonization. These results show that trophic downgrading could be a strong but underappreciated contributor to the loss of coastal wetlands, and suggest that restoring top predators can help to re-establish geomorphic stability.
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Affiliation(s)
- Brent B Hughes
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA.
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC, USA.
| | - Kathryn M Beheshti
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - M Tim Tinker
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
- Nhydra Ecological Research, Head of St Margarets Bay, Nova Scotia, Canada
| | - Christine Angelini
- Department of Environmental Engineering Sciences, Engineering School for Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | - Charlie Endris
- Moss Landing Marine Laboratories, Geological Oceanography Lab, Moss Landing, CA, USA
| | - Lee Murai
- Division of Regional Assistance, California Department of Water Resources, West Sacramento, CA, USA
| | - Sean C Anderson
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada
- Department of Mathematics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sarah Espinosa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | | | - Joseph A Tomoleoni
- Western Ecological Research Center, U.S. Geological Survey, Santa Cruz, CA, USA
| | - Madeline Sanchez
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Brian R Silliman
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC, USA
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5
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Southern Sea Otter Rehabilitation: Lessons and Impacts from the Monterey Bay Aquarium. JOURNAL OF ZOOLOGICAL AND BOTANICAL GARDENS 2022. [DOI: 10.3390/jzbg3040047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
As biodiversity continues to decline across the globe, conservation of wildlife species and the ecosystems they inhabit is more important than ever. When species dwindle, ecosystems that depend on them are also impacted, often leading to a decrease in the life-giving services healthy ecosystems provide to humans, wildlife, and the global environment. Methods of wildlife conservation are complex and multi-faceted, ranging from education and advocacy to, research, restoration, and rehabilitation. Here, we review a conservation program focused on helping recover the federally listed threatened southern sea otter (Enhydra lutris nereis) population. We describe the development of unique rehabilitation methods and steps taken to advance the program’s conservation impact. Understanding this evolution can inform conservation efforts for other vulnerable species and their ecosystems.
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Eby R, Rosso S, Copriviza J, Scoles R, Gideon Y, Mancino J, Mayer K, Yee J, Wasson K. Sea otters in a California estuary: Detecting temporal and spatial dynamics with volunteer monitoring. Ecosphere 2022. [DOI: 10.1002/ecs2.4300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Ron Eby
- Elkhorn Slough National Estuarine Research Reserve Watsonville California USA
| | - Susan Rosso
- Elkhorn Slough National Estuarine Research Reserve Watsonville California USA
| | - John Copriviza
- Elkhorn Slough National Estuarine Research Reserve Watsonville California USA
| | - Robert Scoles
- Elkhorn Slough National Estuarine Research Reserve Watsonville California USA
| | - Yohn Gideon
- Elkhorn Slough Safari Moss Landing California USA
| | | | - Karl Mayer
- Monterey Bay Aquarium Monterey California USA
| | - Julie Yee
- U.S. Geological Survey Western Ecological Research Center Santa Cruz California USA
| | - Kerstin Wasson
- Elkhorn Slough National Estuarine Research Reserve Watsonville California USA
- Department of Ecology and Evolutionary Biology University of California Santa Cruz Santa Cruz California USA
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7
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TRANSTHORACIC ECHOCARDIOGRAPHIC EVALUATION AND SERUM CARDIAC TROPONIN VALUES IN ANESTHETIZED HEALTHY FEMALE SOUTHERN SEA OTTERS ( ENHYDRA LUTRIS NEREIS). J Zoo Wildl Med 2021; 52:490-498. [PMID: 34130391 DOI: 10.1638/2020-0137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 11/21/2022] Open
Abstract
Information about antemortem cardiac evaluation in sea otters (Enhydra lutris) is limited, despite well-established clinical care and rehabilitation procedures and a reported elevated risk of cardiac disease for this species. Serum cardiac troponin I (cTnI) concentration and echocardiographic assessment are two ways of screening for and diagnosing cardiac disease. However, no baseline data or reference intervals for either evaluation are published for sea otters. The objectives of this prospective study were to establish serum cTnI concentrations and echocardiographic technique and quantitative measurements in anesthetized healthy female southern sea otters (Enhydra lutris nereis) (n=15). Serum cTnI values were assessed by a high-sensitivity assay. Serum cTnI concentration ranged from <0.006 to 0.038 ng/ml. A complete echocardiogram, including two-dimensional and M-mode modalities, was performed. Echocardiographic measurements for left atrial size, aorta size, left ventricular structure, and left ventricular function were reported. The median left atrial size to aorta ratio was 1.22 (range 0.80-1.59) in short-axis and 1.70 (range 1.39-2.15) in long-axis. The median left ventricular internal dimension was 3.53 cm (range 2.87-4.92 cm) when assessed in two dimensions and 3.58 cm (range 2.80-4.48 cm) by M-mode. Serum concentrations of cTnI and transthoracic echocardiography may represent valuable tools for the antemortem diagnosis of cardiac disease in sea otters.
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Tanaka KR, Van Houtan KS, Mailander E, Dias BS, Galginaitis C, O’Sullivan J, Lowe CG, Jorgensen SJ. North Pacific warming shifts the juvenile range of a marine apex predator. Sci Rep 2021; 11:3373. [PMID: 33564038 PMCID: PMC7873075 DOI: 10.1038/s41598-021-82424-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 01/20/2021] [Indexed: 01/30/2023] Open
Abstract
During the 2014-2016 North Pacific marine heatwave, unprecedented sightings of juvenile white sharks (Carcharodon carcharias) emerged in central California. These records contradicted the species established life history, where juveniles remain in warmer waters in the southern California Current. This spatial shift is significant as it creates potential conflicts with commercial fisheries, protected species conservation, and public safety concerns. Here, we integrate community science, photogrammetry, biologging, and mesoscale climate data to describe and explain this phenomenon. We find a dramatic increase in white sharks from 2014 to 2019 in Monterey Bay that was overwhelmingly comprised of juvenile sharks < 2.5 m in total body length. Next, we derived thermal preferences from 22 million tag measurements of 14 juvenile sharks and use this to map the cold limit of their range. Consistent with historical records, the position of this cold edge averaged 34° N from 1982 to 2013 but jumped to 38.5° during the 2014-2016 marine heat wave. In addition to a poleward shift, thermally suitable habitat for juvenile sharks declined 223.2 km2 year-1 from 1982 to 2019 and was lowest in 2015 at the peak of the heatwave. In addition to advancing the adaptive management of this apex marine predator, we discuss this opportunity to engage public on climate change through marine megafauna.
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Affiliation(s)
- Kisei R. Tanaka
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA ,grid.3532.70000 0001 1266 2261Present Address: Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration, Honolulu, HI 96818 USA
| | - Kyle S. Van Houtan
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA ,grid.26009.3d0000 0004 1936 7961Nicholas School of the Environment, Duke University, Durham, NC 27708 USA
| | - Eric Mailander
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA
| | - Beatriz S. Dias
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA
| | - Carol Galginaitis
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA
| | - John O’Sullivan
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA
| | - Christopher G. Lowe
- grid.213902.b0000 0000 9093 6830Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90815 USA
| | - Salvador J. Jorgensen
- grid.448395.70000 0001 2322 4726Monterey Bay Aquarium, Monterey, CA 93940 USA ,grid.205975.c0000 0001 0740 6917Present Address: Institute of Marine Sciences, University of California, Santa Cruz, CA 95064 USA
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9
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Rudebusch J, Hughes BB, Boyer KE, Hines E. Assessing anthropogenic risk to sea otters ( Enhydra lutris nereis) for reintroduction into San Francisco Bay. PeerJ 2020; 8:e10241. [PMID: 33240611 PMCID: PMC7678461 DOI: 10.7717/peerj.10241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 10/05/2020] [Indexed: 11/29/2022] Open
Abstract
Southern sea otters have been actively managed for their conservation and recovery since listing on the federal Endangered Species Act in 1977. Still, they remain constrained to a geographically small area on the central coast of California relative to their former coast-wide range, with population numbers far below those of the estimated optimal sustainable population size. Species managers have discussed reintroducing southern sea otters into parts of their historic range to facilitate sustained population growth and geographic range expansion. San Francisco Bay (SFB), historically home to several thousand sea otters, is one location identified as a candidate release site for these reintroductions. The return of sea otters to SFB could bring benefits to local ecosystem restoration and tourism, in addition to spurring sea otter population growth to meet recovery goals. However, this is a highly urbanized estuary, so sea otters could also be exposed to serious anthropogenic threats that would challenge a successful reintroduction. In light of these potential detriments we performed a spatially-explicit risk assessment to analyze the suitability of SFB for southern sea otter reintroduction. We looked at threats to sea otters specific to SFB, including: the impacts of vessel traffic from commercial shipping, high-speed ferries, and recreational vessels; environmental contaminants of methylmercury and polychlorinated biphenyls; major oil spills; and commercial fishing. Factors that influenced the relative threat imposed by each stressor included the spatio-temporal extent and intensity of the stressor and its mitigation potential. Our analysis revealed the complex spatial and temporal variation in risk distribution across the SFB. The type and magnitude of anthropogenic risk was not uniformly distributed across the study area. For example, the central SFB housed the greatest cumulative risk, where a high degree of vessel traffic and other stressors occurred in conjunction. The individual stressors that contributed to this risk score varied across different parts of the study area as well. Whereas vessel traffic, particularly of fast ferries, was a high scoring risk factor in in the north and central bay, in the south bay it was environmental contaminants that caused greater risk potential. To help identify areas within the study area that managers might want to target for release efforts, the spatially-explicit risk map revealed pockets of SFB that could provide both suitable habitat and relatively low overall risk. However in some cases these were adjacent or in close proximity to identified high-risk portions of habitat in SFB. This predictive suitability and risk assessment can be used by managers to consider the spatial distribution of potential threats, and risk abatement that may be necessary for sea otters to re-occupy their historic home range in SFB.
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Affiliation(s)
- Jane Rudebusch
- Estuary & Ocean Science Center, San Francisco State University, Tiburon, CA, United States of America.,Department of Geography & Environment, San Francisco State University, San Francisco, CA, United States of America
| | - Brent B Hughes
- Department of Biology, Sonoma State University, Rohnert Park, CA, United States of America
| | - Katharyn E Boyer
- Estuary & Ocean Science Center, San Francisco State University, Tiburon, CA, United States of America.,Department of Biology, San Francisco State University, San Francisco, CA, United States of America
| | - Ellen Hines
- Estuary & Ocean Science Center, San Francisco State University, Tiburon, CA, United States of America.,Department of Geography & Environment, San Francisco State University, San Francisco, CA, United States of America
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10
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Nicholson TE, Mayer KA, Staedler MM, Gagné TO, Murray MJ, Young MA, Tomoleoni JA, Tinker MT, Van Houtan KS. Robust age estimation of southern sea otters from multiple morphometrics. Ecol Evol 2020; 10:8592-8609. [PMID: 32884643 PMCID: PMC7452773 DOI: 10.1002/ece3.6493] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 02/02/2023] Open
Abstract
Reliable age estimation is an essential tool to assess the status of wildlife populations and inform successful management. Aging methods, however, are often limited by too few data, skewed demographic representation, and by single or uncertain morphometric relationships. In this study, we synthesize age estimates in southern sea otters Enhydra lutris nereis from 761 individuals across 34 years of study, using multiple noninvasive techniques and capturing all life stages from 0 to 17 years of age. From wild, stranded, and captive individuals, we describe tooth eruptions, tooth wear, body length, nose scarring, and pelage coloration across ontogeny and fit sex-based growth functions to the data. Dental eruption schedules provided reliable and identifiable metrics spanning 0.3-9 months. Tooth wear was the most reliable predictor of age of individuals aged 1-15 years, which when combined with total length, explained >93% of observed age. Beyond age estimation, dental attrition also indicated the maximum lifespan of adult teeth is 13‒17 years, corresponding with previous estimates of life expectancy. Von Bertalanffy growth function model simulations of length at age gave consistent estimates of asymptotic lengths (male Loo = 126.0‒126.8 cm, female Loo = 115.3‒115.7 cm), biologically realistic gestation periods (t 0 = 115 days, SD = 10.2), and somatic growth (male k = 1.8, SD = 0.1; female k = 2.1, SD = 0.1). Though exploratory, we describe how field radiographic imaging of epiphyseal plate development or fusions may improve aging of immature sea otters. Together, our results highlight the value of integrating information from multiple and diverse datasets to help resolve conservation problems.
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Affiliation(s)
| | | | | | | | | | | | | | - Martin Tim Tinker
- U.S. Geological SurveyWestern Ecological Research CenterSanta CruzCAUSA
- Department of Ecology and Evolutionary BiologyLong Marine LaboratoryUniversity of CaliforniaSanta CruzCAUSA
| | - Kyle S. Van Houtan
- Monterey Bay AquariumMontereyCAUSA
- Nicholas School of the EnvironmentDuke UniversityDurhamNCUSA
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11
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Hughes BB, Wasson K, Tinker MT, Williams SL, Carswell LP, Boyer KE, Beck MW, Eby R, Scoles R, Staedler M, Espinosa S, Hessing-Lewis M, Foster EU, M Beheshti K, Grimes TM, Becker BH, Needles L, Tomoleoni JA, Rudebusch J, Hines E, Silliman BR. Species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries. PeerJ 2019; 7:e8100. [PMID: 31844568 PMCID: PMC6910117 DOI: 10.7717/peerj.8100] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/25/2019] [Indexed: 11/20/2022] Open
Abstract
Recovering species are often limited to much smaller areas than they historically occupied. Conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. Southern sea otters (Enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the California outer coast, where most of their recovery has occurred. However, studies of recently-recolonized estuaries have revealed that estuaries can provide southern sea otters with high quality habitats featuring shallow waters, high production and ample food, limited predators, and protected haul-out opportunities. Moreover, sea otters can have strong effects on estuarine ecosystems, fostering seagrass resilience through their consumption of invertebrate prey. Using a combination of literature reviews, population modeling, and prey surveys we explored the former estuarine habitats outside the current southern sea otter range to determine if these estuarine habitats can support healthy sea otter populations. We found the majority of studies and conservation efforts have focused on populations in exposed, rocky coastal habitats. Yet historical evidence indicates that sea otters were also formerly ubiquitous in estuaries. Our habitat-specific population growth model for California's largest estuary-San Francisco Bay-determined that it alone can support about 6,600 sea otters, more than double the 2018 California population. Prey surveys in estuaries currently with (Elkhorn Slough and Morro Bay) and without (San Francisco Bay and Drakes Estero) sea otters indicated that the availability of prey, especially crabs, is sufficient to support healthy sea otter populations. Combining historical evidence with our results, we show that conservation practitioners could consider former estuarine habitats as targets for sea otter and ecosystem restoration. This study reveals the importance of understanding how recovering species interact with all the ecosystems they historically occupied, both for improved conservation of the recovering species and for successful restoration of ecosystem functions and processes.
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Affiliation(s)
- Brent B Hughes
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA.,Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC, USA
| | - Kerstin Wasson
- Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA, USA.,Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - M Tim Tinker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA.,U. S. Geological Survey, Western Ecological Research Center, Santa Cruz, CA, USA
| | - Susan L Williams
- Department of Evolution and Ecology, Bodega Marine Laboratory, University of California, Davis, Bodega Bay, CA, USA
| | - Lilian P Carswell
- Ventura Fish and Wildlife Office, United States Fish and Wildlife Service, Ventura, CA, USA
| | - Katharyn E Boyer
- Estuary & Ocean Science Center, Department of Biology, San Francisco State University, Tiburon, CA, USA
| | - Michael W Beck
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Ron Eby
- Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA, USA
| | - Robert Scoles
- Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA, USA
| | | | - Sarah Espinosa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | | | - Erin U Foster
- Hakai Institute, Heriot Bay, BC, Canada.,Applied Conservation Science Lab, University of Victoria, Victoria, BC, USA
| | - Kathryn M Beheshti
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Tracy M Grimes
- Department of Biology, San Diego State University, San Diego, CA, USA
| | - Benjamin H Becker
- Point Reyes National Seashore, United States National Park Service, Point Reyes Station, CA, USA
| | - Lisa Needles
- Center for Coastal Marine Sciences, Department of Biological Sciences, California Polytechnic State University-San Luis Obispo, San Luis Obispo, CA, USA
| | - Joseph A Tomoleoni
- U. S. Geological Survey, Western Ecological Research Center, Santa Cruz, CA, USA
| | - Jane Rudebusch
- Estuary & Ocean Science Center, Department of Geography and Environment, San Francisco State University, Tiburon, CA, USA
| | - Ellen Hines
- Estuary & Ocean Science Center, Department of Geography and Environment, San Francisco State University, Tiburon, CA, USA
| | - Brian R Silliman
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC, USA
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