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Micarelli P, Pireddu M, Persia D, Sanna M, Vicariotto C, Pacifico A, Storelli P, Mahrer M, Venanzi E, Reinero FR. Observations on an Aggregation of Grey Reef Sharks ( Carcharhinus amblyrhynchos) in the Mozambique Channel Off the Coast of Nosy Be (Madagascar) and Tools for Photo-Identification-A New Aggregation Nursery Site? BIOLOGY 2024; 13:661. [PMID: 39336090 PMCID: PMC11428919 DOI: 10.3390/biology13090661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Revised: 08/21/2024] [Accepted: 08/23/2024] [Indexed: 09/30/2024]
Abstract
Following preliminary underwater observations of about 1000 h carried out monthly between 2012 and 2023 (except the years 2021 and 2022), 23 specimens of grey reef sharks were spotted and photo-identified off the coast of Nosy Be in Madagascar, on an emerging reef called "Mokarran" at a depth between 15 and 30 m. Over 10 years of observations, eight specimens were re-sighted, identified with a non-invasive photo-identification technique of part of the first dorsal and the caudal fin, and one specimen was re-identified after 1982 days from the first sighting, i.e., after more than 5 years. In addition, six specimens of probably pregnant females were also identified in the same area. The population was entirely made up of females. The aggregation area could represent a new nursery site which, if confirmed after further investigations, will require greater protection.
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Affiliation(s)
- Primo Micarelli
- Sharks Studies Center-Scientific Institute, 58024 Massa Marittima, Italy
- Department of Physical Sciences, Earth and Environment, University of Siena, 53100 Siena, Italy
| | - Marco Pireddu
- Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
| | - Damiano Persia
- Department of Life and Environmental Sciences, Polytechnic University of Marche, 60131 Ancona, Italy
| | - Marco Sanna
- Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
| | | | - Antonio Pacifico
- Department of Economics and Law, University of Macerata, 62100 Macerata, Italy
| | - Pietro Storelli
- Sharks Studies Center-Scientific Institute, 58024 Massa Marittima, Italy
| | - Makenna Mahrer
- W. M. Keck Science Department, Claremont McKenna College, Claremont, CA 91711, USA
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Priest J, Ferreira CM, Munday PL, Roberts A, Rodolfo-Metalpa R, Rummer JL, Schunter C, Ravasi T, Nagelkerken I. Out of shape: Ocean acidification simplifies coral reef architecture and reshuffles fish assemblages. J Anim Ecol 2024; 93:1097-1107. [PMID: 38926938 DOI: 10.1111/1365-2656.14127] [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: 11/28/2023] [Accepted: 05/06/2024] [Indexed: 06/28/2024]
Abstract
Climate change stressors are progressively simplifying biogenic habitats in the terrestrial and marine realms, and consequently altering the structure of associated species communities. Here, we used a volcanic CO2 seep in Papua New Guinea to test in situ if altered reef architecture due to ocean acidification reshuffles associated fish assemblages. We observed replacement of branching corals by massive corals at the seep, with simplified coral architectural complexity driving abundance declines between 60% and 86% for an assemblage of damselfishes associated with branching corals. An experimental test of habitat preference for a focal species indicated that acidification does not directly affect habitat selection behaviour, with changes in habitat structural complexity consequently appearing to be the stronger driver of assemblage reshuffling. Habitat health affected anti-predator behaviour, with P. moluccensis becoming less bold on dead branching corals relative to live branching corals, irrespective of ocean acidification. We conclude that coral reef fish assemblages are likely to be more sensitive to changes in habitat structure induced by increasing pCO2 than any direct effects on behaviour, indicating that changes in coral architecture and live cover may act as important mediators of reef fish community structures in a future ocean.
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Affiliation(s)
- Jamie Priest
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Camilo M Ferreira
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Philip L Munday
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Amelia Roberts
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Riccardo Rodolfo-Metalpa
- ENTROPIE-UMR 9220 (CNRS, IRD, UR, UNC, IFREMER), IRD Institut de Recherche Pour le Développement, Nouméa Cedex, New Caledonia
| | - Jodie L Rummer
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | - Celia Schunter
- Swire Institute of Marine Science, School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Timothy Ravasi
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Marine Climate Change Unit, Okinawa Institute of Science and Technology (OIST), Onna-son, Okinawa, Japan
| | - Ivan Nagelkerken
- Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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Young HS, McCauley FO, Micheli F, Dunbar RB, McCauley DJ. Shortened food chain length in a fished versus unfished coral reef. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024; 34:e3002. [PMID: 38840322 DOI: 10.1002/eap.3002] [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: 06/15/2023] [Revised: 02/23/2024] [Accepted: 04/09/2024] [Indexed: 06/07/2024]
Abstract
Direct exploitation through fishing is driving dramatic declines of wildlife populations in ocean environments, particularly for predatory and large-bodied taxa. Despite wide recognition of this pattern and well-established consequences of such trophic downgrading on ecosystem function, there have been few empirical studies examining the effects of fishing on whole system trophic architecture. Understanding these kinds of structural impacts is especially important in coral reef ecosystems-often heavily fished and facing multiple stressors. Given the often high dietary flexibility and numerous functional redundancies in diverse ecosystems such as coral reefs, it is important to establish whether web architecture is strongly impacted by fishing pressure or whether it might be resilient, at least to moderate-intensity pressure. To examine this question, we used a combination of bulk and compound-specific stable isotope analyses measured across a range of predatory and low-trophic-level consumers between two coral reef ecosystems that differed with respect to fishing pressure but otherwise remained largely similar. We found that even in a high-diversity system with relatively modest fishing pressure, there were strong reductions in the trophic position (TP) of the three highest TP consumers examined in the fished system but no effects on the TP of lower-level consumers. We saw no evidence that this shortening of the affected food webs was being driven by changes in basal resource consumption, for example, through changes in the spatial location of foraging by consumers. Instead, this likely reflected internal changes in food web architecture, suggesting that even in diverse systems and with relatively modest pressure, human harvest causes significant compressions in food chain length. This observed shortening of these food webs may have many important emergent ecological consequences for the functioning of ecosystems impacted by fishing or hunting. Such important structural shifts may be widespread but unnoticed by traditional surveys. This insight may also be useful for applied ecosystem managers grappling with choices about the relative importance of protection for remote and pristine areas and the value of strict no-take areas to protect not just the raw constituents of systems affected by fishing and hunting but also the health and functionality of whole systems.
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Affiliation(s)
- Hillary S Young
- Department of Ecology, Evolution and Marine Biology, UC Santa Barbara, Santa Barbara, California, USA
| | | | - Fiorenza Micheli
- Oceans Department, Hopkins Marine Station, and Stanford Center for Ocean Solutions, Stanford University, Pacific Grove, California, USA
| | - Robert B Dunbar
- Oceans Department and Earth Systems Science, Stanford University, Pacific Grove, California, USA
| | - Douglas J McCauley
- Department of Ecology, Evolution and Marine Biology, UC Santa Barbara, Santa Barbara, California, USA
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Silveira CB, Luque A, Haas AF, Roach TNF, George EE, Knowles B, Little M, Sullivan CJ, Varona NS, Wegley Kelly L, Brainard R, Rohwer F, Bailey B. Viral predation pressure on coral reefs. BMC Biol 2023; 21:77. [PMID: 37038111 PMCID: PMC10088212 DOI: 10.1186/s12915-023-01571-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 03/17/2023] [Indexed: 04/12/2023] Open
Abstract
BACKGROUND Predation pressure and herbivory exert cascading effects on coral reef health and stability. However, the extent of these cascading effects can vary considerably across space and time. This variability is likely a result of the complex interactions between coral reefs' biotic and abiotic dimensions. A major biological component that has been poorly integrated into the reefs' trophic studies is the microbial community, despite its role in coral death and bleaching susceptibility. Viruses that infect bacteria can control microbial densities and may positively affect coral health by controlling microbialization. We hypothesize that viral predation of bacteria has analogous effects to the top-down pressure of macroorganisms on the trophic structure and reef health. RESULTS Here, we investigated the relationships between live coral cover and viruses, bacteria, benthic algae, fish biomass, and water chemistry in 110 reefs spanning inhabited and uninhabited islands and atolls across the Pacific Ocean. Statistical learning showed that the abundance of turf algae, viruses, and bacteria, in that order, were the variables best predicting the variance in coral cover. While fish biomass was not a strong predictor of coral cover, the relationship between fish and corals became apparent when analyzed in the context of viral predation: high coral cover (> 50%) occurred on reefs with a combination of high predator fish biomass (sum of sharks and piscivores > 200 g m-2) and high virus-to-bacteria ratios (> 10), an indicator of viral predation pressure. However, these relationships were non-linear, with reefs at the higher and lower ends of the coral cover continuum displaying a narrow combination of abiotic and biotic variables, while reefs at intermediate coral cover showed a wider range of parameter combinations. CONCLUSIONS The results presented here support the hypothesis that viral predation of bacteria is associated with high coral cover and, thus, coral health and stability. We propose that combined predation pressures from fishes and viruses control energy fluxes, inhibiting the detrimental accumulation of ecosystem energy in the microbial food web.
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Affiliation(s)
- Cynthia B Silveira
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA.
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, 33149, USA.
| | - Antoni Luque
- Viral Information Institute, San Diego State University, San Diego, CA, 92182, USA
- Computational Science Research Center, San Diego State University, San Diego, CA, 92182, USA
- Department of Mathematics and Statistics, San Diego State University, San Diego, CA, 92182, USA
| | - Andreas F Haas
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Ty N F Roach
- Viral Information Institute, San Diego State University, San Diego, CA, 92182, USA
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, HI, 96744, USA
- Department of Biology, San Diego State University, San Diego, CA, 92182, USA
| | - Emma E George
- Botany Department, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Ben Knowles
- Department of Ecology and Evolutionary Biology, UC Los Angeles, Los Angeles, CA, 90095, USA
| | - Mark Little
- Viral Information Institute, San Diego State University, San Diego, CA, 92182, USA
- Department of Biology, San Diego State University, San Diego, CA, 92182, USA
| | | | - Natascha S Varona
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA
| | - Linda Wegley Kelly
- Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, 92037, USA
| | - Russel Brainard
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
- Pacific Islands Fisheries Science Center, National Oceanic & Atmospheric Administration, Honolulu, HI, 96818, USA
| | - Forest Rohwer
- Viral Information Institute, San Diego State University, San Diego, CA, 92182, USA
- Department of Biology, San Diego State University, San Diego, CA, 92182, USA
| | - Barbara Bailey
- Viral Information Institute, San Diego State University, San Diego, CA, 92182, USA.
- Department of Mathematics and Statistics, San Diego State University, San Diego, CA, 92182, USA.
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Mihalitsis M, Morais RA, Bellwood DR. Small predators dominate fish predation in coral reef communities. PLoS Biol 2022; 20:e3001898. [PMID: 36445867 PMCID: PMC9707750 DOI: 10.1371/journal.pbio.3001898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 10/31/2022] [Indexed: 12/03/2022] Open
Abstract
Ecosystem processes are challenging to quantify at a community level, particularly within complex ecosystems (e.g., rainforests, coral reefs). Predation is one of the most important types of species interactions, determining several ecosystem processes. However, while it is widely recognised, it is rarely quantified, especially in aquatic systems. To address these issues, we model predation on fish by fish, in a hyperdiverse coral reef community. We show that body sizes previously examined in fish-fish predation studies (based on a metanalysis), only represent about 5% of likely predation events. The average fish predator on coral reefs is just 3.65 cm; the average fish prey just 1.5 cm. These results call for a shift in the way we view fish predation and its ability to shape the species or functional composition of coral reef fish communities. Considered from a functional group approach, we found general agreement in the distribution of simulated and observed predation events, among both predator and prey functional groups. Predation on coral reefs is a process driven by small fish, most of which are neither seen nor quantified.
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Affiliation(s)
- Michalis Mihalitsis
- Research Hub for Coral Reef Ecosystem Functions, James Cook University, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Department of Evolution and Ecology, University of California, Davis, California, United States of America
- * E-mail:
| | - Renato A. Morais
- Research Hub for Coral Reef Ecosystem Functions, James Cook University, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - David R. Bellwood
- Research Hub for Coral Reef Ecosystem Functions, James Cook University, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
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Mallinger EC, Olson ER, Vincent GP, Van Stappen J, Van Deelen T. Factors influencing the presence of parasitic trombiculids on red-backed voles in a temperate archipelago. CAN J ZOOL 2022. [DOI: 10.1139/cjz-2021-0143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Parasites can influence host population health and dynamics and are often an overlooked aspect of the ecology of ecosystems. Understanding the impacts of ecological interactions between parasites and small mammals can provide insights into ecosystem dynamics. We live trapped small mammals within the Apostle Islands archipelago (2017-2020) and assessed factors influencing the presence of mites from the Trombiculidae family. Archipelagos provide unique research opportunities because in small mammal-parasitic trombiculid systems, they are essentially closed systems. We detected trombiculids on 47% of Myodes gapperi (Vigors, 1830; red-backed vole) individuals but rarely detected trombiculids on other species. We developed and ranked a set of a priori logistic regression models of trombiculid presence relative to habitat quality, host abundance, body condition, sex, and sexual maturity to identify factors significant in predicting trombiculid infection for M. gapperi. Parasitic trombiculids were more likely when M. gapperi abundance was high and body condition was poor, however it is unknown whether trombiculids affect condition or if trombiculids are more likely to parasitize hosts in poor condition. The significance of host abundance may indicate density-dependent transmission. Our work suggests that host density and body condition are important factors influencing parasitism by trombiculids in M. gapperi populations.
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Affiliation(s)
| | - Erik R Olson
- Northland College, 1341, Natural Resources, 1411 Ellis Ave, Ashland, Wisconsin, United States, 54806-3999
| | | | - Julie Van Stappen
- Apostle Islands National Lakeshore, Resource Management , Bayfield , Wisconsin, United States
| | - T.R. Van Deelen
- University of Wisconsin, Department of Wildlife Ecology, 217 Russell Labs, Madison, Wisconsin, United States, 53706,
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Emerging insights on effects of sharks and other top predators on coral reefs. Emerg Top Life Sci 2022; 6:57-65. [PMID: 35258079 PMCID: PMC9023017 DOI: 10.1042/etls20210238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/23/2021] [Accepted: 01/17/2022] [Indexed: 12/04/2022]
Abstract
Predation is ubiquitous on coral reefs. Among the most charismatic group of reef predators are the top predatory fishes, including sharks and large-bodied bony fishes. Despite the threat presented by top predators, data describing their realized effects on reef community structure and functioning are challenging to produce. Many innovative studies have capitalized on natural experimental conditions to explore predator effects on reefs. Gradients in predator density have been created by spatial patterning of fisheries management. Evidence of prey release has been observed across some reefs, namely that potential prey increase in density when predator density is reduced. While such studies search for evidence of prey release among broad groups or guilds of potential prey, a subset of studies have sought evidence of release at finer population levels. We find that some groups of fishes are particularly vulnerable to the effects of predators and more able to capitalize demographically when predator density is reduced. For example, territorial damselfish appear to realize reliable population expansion with the reduction in predator density, likely because their aggressive, defensive behavior makes them distinctly vulnerable to predation. Relatedly, individual fishes that suffer from debilitating conditions, such as heavy parasite loads, appear to realize relatively stronger levels of prey release with reduced predator density. Studying the effects of predators on coral reefs remains a timely pursuit, and we argue that efforts to focus on the specifics of vulnerability to predation among potential prey and other context-specific dimensions of mortality hold promise to expand our knowledge.
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Mihalitsis M, Bellwood DR. Functional groups in piscivorous fishes. Ecol Evol 2021; 11:12765-12778. [PMID: 34594537 PMCID: PMC8462170 DOI: 10.1002/ece3.8020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/23/2021] [Accepted: 07/29/2021] [Indexed: 01/17/2023] Open
Abstract
Piscivory is a key ecological function in aquatic ecosystems, mediating energy flow within trophic networks. However, our understanding of the nature of piscivory is limited; we currently lack an empirical assessment of the dynamics of prey capture and how this differs between piscivores. We therefore conducted aquarium-based performance experiments, to test the feeding abilities of 19 piscivorous fish species. We quantified their feeding morphology, striking, capturing, and processing behavior. We identify two major functional groups: grabbers and engulfers. Grabbers are characterized by horizontal, long-distance strikes, capturing their prey tailfirst and subsequently processing their prey using their oral jaw teeth. Engulfers strike from short distances, from high angles above or below their prey, engulfing their prey and swallowing their prey whole. Based on a meta-analysis of 2,209 published in situ predator-prey relationships in marine and freshwater aquatic environments, we show resource partitioning between grabbers and engulfers. Our results provide a functional classification for piscivorous fishes delineating patterns, which transcend habitats, that may help explain size structures in fish communities.
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Affiliation(s)
- Michalis Mihalitsis
- Research Hub for Coral Reef Ecosystem FunctionsJames Cook UniversityTownsvilleQldAustralia
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
- Australian Research CouncilCentre of Excellence for Coral Reef StudiesJames Cook UniversityTownsvilleQldAustralia
| | - David R. Bellwood
- Research Hub for Coral Reef Ecosystem FunctionsJames Cook UniversityTownsvilleQldAustralia
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
- Australian Research CouncilCentre of Excellence for Coral Reef StudiesJames Cook UniversityTownsvilleQldAustralia
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Holmes MJ, Venables B, Lewis RJ. Critical Review and Conceptual and Quantitative Models for the Transfer and Depuration of Ciguatoxins in Fishes. Toxins (Basel) 2021; 13:toxins13080515. [PMID: 34437386 PMCID: PMC8402393 DOI: 10.3390/toxins13080515] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/05/2021] [Accepted: 07/16/2021] [Indexed: 02/08/2023] Open
Abstract
We review and develop conceptual models for the bio-transfer of ciguatoxins in food chains for Platypus Bay and the Great Barrier Reef on the east coast of Australia. Platypus Bay is unique in repeatedly producing ciguateric fishes in Australia, with ciguatoxins produced by benthic dinoflagellates (Gambierdiscus spp.) growing epiphytically on free-living, benthic macroalgae. The Gambierdiscus are consumed by invertebrates living within the macroalgae, which are preyed upon by small carnivorous fishes, which are then preyed upon by Spanish mackerel (Scomberomorus commerson). We hypothesise that Gambierdiscus and/or Fukuyoa species growing on turf algae are the main source of ciguatoxins entering marine food chains to cause ciguatera on the Great Barrier Reef. The abundance of surgeonfish that feed on turf algae may act as a feedback mechanism controlling the flow of ciguatoxins through this marine food chain. If this hypothesis is broadly applicable, then a reduction in herbivory from overharvesting of herbivores could lead to increases in ciguatera by concentrating ciguatoxins through the remaining, smaller population of herbivores. Modelling the dilution of ciguatoxins by somatic growth in Spanish mackerel and coral trout (Plectropomus leopardus) revealed that growth could not significantly reduce the toxicity of fish flesh, except in young fast-growing fishes or legal-sized fishes contaminated with low levels of ciguatoxins. If Spanish mackerel along the east coast of Australia can depurate ciguatoxins, it is most likely with a half-life of ≤1-year. Our review and conceptual models can aid management and research of ciguatera in Australia, and globally.
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Affiliation(s)
- Michael J. Holmes
- Queensland Department of Environment and Science, Brisbane 4102, Australia;
| | | | - Richard J. Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia
- Correspondence:
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10
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Tebbett SB, Morais RA, Goatley CHR, Bellwood DR. Collapsing ecosystem functions on an inshore coral reef. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 289:112471. [PMID: 33812145 DOI: 10.1016/j.jenvman.2021.112471] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/23/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
Ecosystem functions underpin productivity and key services to humans, such as food provision. However, as the severity of environmental stressors intensifies, it is becoming increasingly unclear if, and to what extent, critical functions and services can be sustained. This issue is epitomised on coral reefs, an ecosystem at the forefront of environmental transitions. We provide a functional profile of a coral reef ecosystem, linking time-series data to quantified processes. The data reveal a prolonged collapse of ecosystem functions in this previously resilient system. The results suggest that sediment accumulation in algal turfs has led to a decline in resource yields to herbivorous fishes and a decrease in fish-based ecosystem functions, including a collapse of both fish biomass and productivity. Unfortunately, at present, algal turf sediment accumulation is rarely monitored nor managed in coral reef systems. Our examination of functions through time highlights the value of directly assessing functions, their potential vulnerability, and the capacity of algal turf sediments to overwhelm productive high-diversity coral reef ecosystems.
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Affiliation(s)
- Sterling B Tebbett
- Research Hub for Coral Reef Ecosystem Functions, College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, 4811, Australia.
| | - Renato A Morais
- Research Hub for Coral Reef Ecosystem Functions, College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, 4811, Australia
| | - Christopher H R Goatley
- Function, Evolution and Anatomy Research Lab and Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, 2351, Australia; Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, New South Wales, 2010, Australia
| | - David R Bellwood
- Research Hub for Coral Reef Ecosystem Functions, College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, 4811, Australia
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11
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Desbiens AA, Roff G, Robbins WD, Taylor BM, Castro-Sanguino C, Dempsey A, Mumby PJ. Revisiting the paradigm of shark-driven trophic cascades in coral reef ecosystems. Ecology 2021; 102:e03303. [PMID: 33565624 DOI: 10.1002/ecy.3303] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/19/2020] [Accepted: 12/06/2020] [Indexed: 01/17/2023]
Abstract
Global overfishing of higher-level predators has caused cascading effects to lower trophic levels in many marine ecosystems. On coral reefs, which support highly diverse food webs, the degree to which top-down trophic cascades can occur remains equivocal. Using extensive survey data from coral reefs across the relatively unfished northern Great Barrier Reef (nGBR), we quantified the role of reef sharks in structuring coral reef fish assemblages. Using a structural equation modeling (SEM) approach, we explored the interactions between shark abundance and teleost mesopredator and prey functional group density and biomass, while explicitly accounting for the potentially confounding influence of environmental variation across sites. Although a fourfold difference in reef shark density was observed across our survey sites, this had no impact on either the density or biomass of teleost mesopredators or prey, providing evidence for a lack of trophic cascading across nGBR systems. Instead, many functional groups, including sharks, responded positively to environmental drivers. We found reef sharks to be positively associated with habitat complexity. In turn, physical processes such as wave exposure and current velocity were both correlated well with multiple functional groups, reflecting how changes to energetic conditions and food availability, or modification of habitat affect fish distribution. The diversity of species within coral reef food webs and their associations with bottom-up drivers likely buffers against trophic cascading across GBR functional guilds when reef shark assemblages are depleted, as has been demonstrated in other complex ecosystems.
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Affiliation(s)
- Amelia A Desbiens
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - George Roff
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - William D Robbins
- Wildlife Marine, Perth, Western Australia, Australia.,Department of Environment and Agriculture, Curtin University, Perth, Western Australia, Australia.,School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia.,Marine Science Program, Department of Biodiversity, Conservation and Attractions, Perth, Western Australia, Australia
| | - Brett M Taylor
- The Australian Institute of Marine Science, Crawley, Western Australia, Australia
| | - Carolina Castro-Sanguino
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - Alexandra Dempsey
- Khaled bin Sultan Living Oceans Foundation, Annapolis, Maryland, USA
| | - Peter J Mumby
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
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Madin EMP, Madin JS, Harmer AMT, Barrett NS, Booth DJ, Caley MJ, Cheal AJ, Edgar GJ, Emslie MJ, Gaines SD, Sweatman HPA. Latitude and protection affect decadal trends in reef trophic structure over a continental scale. Ecol Evol 2020; 10:6954-6966. [PMID: 32760504 PMCID: PMC7391320 DOI: 10.1002/ece3.6347] [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: 04/17/2020] [Accepted: 04/17/2020] [Indexed: 01/02/2023] Open
Abstract
The relative roles of top-down (consumer-driven) and bottom-up (resource-driven) forcing in exploited marine ecosystems have been much debated. Examples from a variety of marine systems of exploitation-induced, top-down trophic forcing have led to a general view that human-induced predator perturbations can disrupt entire marine food webs, yet other studies that have found no such evidence provide a counterpoint. Though evidence continues to emerge, an unresolved debate exists regarding both the relative roles of top-down versus bottom-up forcing and the capacity of human exploitation to instigate top-down, community-level effects. Using time-series data for 104 reef communities spanning tropical to temperate Australia from 1992 to 2013, we aimed to quantify relationships among long-term trophic group population density trends, latitude, and exploitation status over a continental-scale biogeographic range. Specifically, we amalgamated two long-term monitoring databases of marine community dynamics to test for significant positive or negative trends in density of each of three key trophic levels (predators, herbivores, and algae) across the entire time series at each of the 104 locations. We found that trophic control tended toward bottom-up driven in tropical systems and top-down driven in temperate systems. Further, alternating long-term population trends across multiple trophic levels (a method of identifying trophic cascades), presumably due to top-down trophic forcing, occurred in roughly fifteen percent of locations where the prerequisite significant predator trends occurred. Such alternating trophic trends were significantly more likely to occur at locations with increasing predator densities over time. Within these locations, we found a marked latitudinal gradient in the prevalence of long-term, alternating trophic group trends, from rare in the tropics (<5% of cases) to relatively common in temperate areas (~45%). Lastly, the strongest trends in predator and algal density occurred in older no-take marine reserves; however, exploitation status did not affect the likelihood of alternating long-term trophic group trends occurring. Our data suggest that the type and degree of trophic forcing in this system are likely related to one or more covariates of latitude, and that ecosystem resiliency to top-down control does not universally vary in this system based on exploitation level.
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Affiliation(s)
- Elizabeth M. P. Madin
- Department of Biological SciencesMacquarie UniversitySydneyNSWAustralia
- School of Life SciencesUniversity of Technology SydneySydneyNSWAustralia
- Hawai'i Institute of Marine BiologyUniversity of Hawai'iKane'oheHIUSA
| | - Joshua S. Madin
- Department of Biological SciencesMacquarie UniversitySydneyNSWAustralia
- Hawai'i Institute of Marine BiologyUniversity of Hawai'iKane'oheHIUSA
| | - Aaron M. T. Harmer
- Department of Biological SciencesMacquarie UniversitySydneyNSWAustralia
- School of Natural and Computational SciencesMassey UniversityAucklandNew Zealand
| | - Neville S. Barrett
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTASAustralia
| | - David J. Booth
- School of Life SciencesUniversity of Technology SydneySydneyNSWAustralia
| | - M. Julian Caley
- School of Mathematical SciencesQueensland University of TechnologyBrisbaneQLDAustralia
- Australian Research Council Centre of Excellence for Mathematical and Statistical FrontiersThe University of MelbourneParkvilleVICAustralia
| | | | - Graham J. Edgar
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTASAustralia
| | | | - Steven D. Gaines
- Bren School of Environmental Science and ManagementUniversity of CaliforniaSanta BarbaraCAUSA
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13
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Phenix LM, Tricarico D, Quintero E, Bond ME, Brandl SJ, Gallagher AJ. Evaluating the effects of large marine predators on mobile prey behavior across subtropical reef ecosystems. Ecol Evol 2019; 9:13740-13751. [PMID: 31938478 PMCID: PMC6953565 DOI: 10.1002/ece3.5784] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/25/2019] [Accepted: 09/25/2019] [Indexed: 11/14/2022] Open
Abstract
The indirect effect of predators on prey behavior, recruitment, and spatial relationships continues to attract considerable attention. However, top predators like sharks or large, mobile teleosts, which can have substantial top-down effects in ecosystems, are often difficult to study due to their large size and mobility. This has created a knowledge gap in understanding how they affect their prey through nonconsumptive effects. Here, we investigated how different functional groups of predators affected potential prey fish populations across various habitats within Biscayne Bay, FL. Using baited remote underwater videos (BRUVs), we quantified predator abundance and activity as a rough proxy for predation risk and analyzed key prey behaviors across coral reef, sea fan, seagrass, and sandy habitats. Both predator abundance and prey arrival times to the bait were strongly influenced by habitat type, with open homogenous habitats receiving faster arrival times by prey. Other prey behaviors, such as residency and risk-associated behaviors, were potentially driven by predator interaction. Our data suggest that small predators across functional groups do not have large controlling effects on prey behavior or stress responses over short temporal scales; however, habitats where predators are more unpredictable in their occurrence (i.e., open areas) may trigger risk-associated behaviors such as avoidance and vigilance. Our data shed new light on the importance of habitat and context for understanding how marine predators may influence prey behaviors in marine ecosystems.
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Affiliation(s)
- Lindsay M. Phenix
- Beneath the WavesHerndonVAUSA
- Three Seas ProgramNortheastern UniversityNahantMAUSA
| | | | | | - Mark E. Bond
- Florida International UniversityNorth MiamiFLUSA
| | - Simon J. Brandl
- Department of Biological SciencesSimon Fraser UniversityBurnabyBCCanada
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14
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Speed CW, Rees MJ, Cure K, Vaughan B, Meekan MG. Protection from illegal fishing and shark recovery restructures mesopredatory fish communities on a coral reef. Ecol Evol 2019; 9:10553-10566. [PMID: 31624567 PMCID: PMC6787830 DOI: 10.1002/ece3.5575] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/13/2019] [Accepted: 07/30/2019] [Indexed: 12/17/2022] Open
Abstract
The recovery of communities of predatory fishes within a no-take marine reserve after the eradication of illegal fishing provides an opportunity to examine the role of sharks and other large-bodied mesopredatory fishes in structuring reef fish communities. We used baited remote underwater video stations to investigate whether an increase in sharks was associated with a change in structure of the mesopredatory fish community at Ashmore Reef, Western Australia. We found an almost fourfold increase in shark abundance in reef habitat from 0.64 hr-1 ± 0.15 SE in 2004, when Ashmore Reef was being fished illegally, to 2.45 hr-1 ± 0.37 in 2016, after eight years of full-time enforcement of the reserve. Shark recovery in reef habitat was accompanied by a two and a half-fold decline in the abundance of small mesopredatory fishes (≤50 cm TL) (14.00 hr-1 ± 3.79 to 5.6 hr-1 ± 1.20) and a concomitant increase in large mesopredatory fishes (≥100 cm TL) from 1.82 hr-1 ± 0.48 to 4.27 hr-1 ± 0.93. In contrast, near-reef habitats showed an increase in abundance of large mesopredatory fishes between years (2.00 hr-1 ± 0.65 to 4.56 hr-1 ± 1.11), although only smaller increases in sharks (0.67 hr-1 ± 0.25 to 1.22 hr-1 ± 0.34) and smaller mesopredatory fishes. Although the abundance of most mesopredatory groups increased with recovery from fishing, we suggest that the large decline of small mesopredatory fish in reef habitat was mostly due to higher predation pressure following the increase in sharks and large mesopredatory fishes. At the regional scale, the structure of fished communities at Ashmore Reef in 2004 resembled those of present day Scott Reefs, where fishing still continues today. In 2016, Ashmore fish communities resembled those of the Rowley Shoals, which have been protected from fishing for decades.
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Affiliation(s)
- Conrad W. Speed
- Australian Institute of Marine ScienceIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
- Global FinPrint ProjectIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
| | - Matthew J. Rees
- Australian Institute of Marine ScienceIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
- Global FinPrint ProjectIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
| | - Katherine Cure
- Australian Institute of Marine ScienceIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
| | - Brigit Vaughan
- Australian Institute of Marine ScienceIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
| | - Mark G. Meekan
- Australian Institute of Marine ScienceIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
- Global FinPrint ProjectIndian Ocean Marine Research CentreUWA (MO96)CrawleyWAAustralia
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15
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Synergistic Effects of Climate Change and Marine Pollution: An Overlooked Interaction in Coastal and Estuarine Areas. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16152737. [PMID: 31370308 PMCID: PMC6696450 DOI: 10.3390/ijerph16152737] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/24/2019] [Accepted: 07/27/2019] [Indexed: 11/17/2022]
Abstract
Coastal areas have been increasingly affected by human activities, marine pollution and climate change are among the most important pressures affecting these environments. Human-induced pressures occur in a cumulative way and generate additive, antagonistic or synergistic effects. Knowledge on synergistic effects is crucial to coastal zone management, since they may imply a change in human uses of these systems, as well as dedicated action plans in order to reduce hazards and environmental risks. In this work, we provide an overview of the available literature on synergistic effects between climate change and chemical pollution, and discuss current knowledge, methodological approaches, and research gaps and needs. Interactions between these two pressures may be climate change dominant (climate change leads to an increase in contaminant exposure or toxicity) or contaminant-dominant (chemical exposure leads to an increase in climate change susceptibility), but the mechanistic drivers of such processes are not well known. Results from a few meta-analyses studies and reviews showed that synergistic interactions tend to be more frequent compared to additive and antagonistic ones. However, most of the studies are individual-based and assess the cumulative effects of a few contaminants individually in laboratory settings together with few climate variables, particularly temperature and pH. Nevertheless, a wide diversity of contaminants have already been individually tested, spanning from metals, persistent organic pollutants and, more recently, emergent pollutants. Population and community based approaches are less frequent but have generated very interesting and more holistic perspectives. Methodological approaches are quite diverse, from laboratory studies to mesocosm and field studies, or based on statistical or modelling tools, each with their own potential and limitations. More holistic comparisons integrating several pressures and their combinations and a multitude of habitats, taxa, life-stages, among others, are needed, as well as insights from meta-analyses and systematic reviews.
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16
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Casey JM, Meyer CP, Morat F, Brandl SJ, Planes S, Parravicini V. Reconstructing hyperdiverse food webs: Gut content metabarcoding as a tool to disentangle trophic interactions on coral reefs. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13206] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jordan M. Casey
- PSL Université Paris: EPHE‐UPVD‐CNRS, USR 3278 CRIOBE Université de Perpignan Perpignan France
- Laboratoire d'Excellence “CORAIL” Perpignan France
- Department of Invertebrate Zoology National Museum of Natural History, Smithsonian Institution Washington District of Columbia USA
| | - Christopher P. Meyer
- Department of Invertebrate Zoology National Museum of Natural History, Smithsonian Institution Washington District of Columbia USA
| | - Fabien Morat
- PSL Université Paris: EPHE‐UPVD‐CNRS, USR 3278 CRIOBE Université de Perpignan Perpignan France
- Laboratoire d'Excellence “CORAIL” Perpignan France
| | - Simon J. Brandl
- Department of Biological Sciences Simon Fraser University Burnaby BC Canada
| | - Serge Planes
- PSL Université Paris: EPHE‐UPVD‐CNRS, USR 3278 CRIOBE Université de Perpignan Perpignan France
- Laboratoire d'Excellence “CORAIL” Perpignan France
| | - Valeriano Parravicini
- PSL Université Paris: EPHE‐UPVD‐CNRS, USR 3278 CRIOBE Université de Perpignan Perpignan France
- Laboratoire d'Excellence “CORAIL” Perpignan France
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17
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Madin EMP, Harborne AR, Harmer AMT, Luiz OJ, Atwood TB, Sullivan BJ, Madin JS. Marine reserves shape seascapes on scales visible from space. Proc Biol Sci 2019; 286:20190053. [PMID: 31014221 PMCID: PMC6501923 DOI: 10.1098/rspb.2019.0053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/22/2019] [Indexed: 11/15/2022] Open
Abstract
Marine reserves can effectively restore harvested populations, and 'mega-reserves' increasingly protect large tracts of ocean. However, no method exists of monitoring ecological responses at this large scale. Herbivory is a key mechanism structuring ecosystems, and this consumer-resource interaction's strength on coral reefs can indicate ecosystem health. We screened 1372, and measured features of 214, reefs throughout Australia's Great Barrier Reef using high-resolution satellite imagery, combined with remote underwater videography and assays on a subset, to quantify the prevalence, size and potential causes of 'grazing halos'. Halos are known to be seascape-scale footprints of herbivory and other ecological interactions. Here we show that these halo-like footprints are more prevalent in reserves, particularly older ones (approx. 40 years old), resulting in predictable changes to reef habitat at scales visible from space. While the direct mechanisms for this pattern are relatively clear, the indirect mechanisms remain untested. By combining remote sensing and behavioural ecology, our findings demonstrate that reserves can shape large-scale habitat structure by altering herbivores' functional importance, suggesting that reserves may have greater value in restoring ecosystems than previously appreciated. Additionally, our results show that we can now detect macro-patterns in reef species interactions using freely available satellite imagery. Low-cost, ecosystem-level observation tools will be critical as reserves increase in number and scope; further investigation into whether halos may help seems warranted. Significance statement: Marine reserves are a widely used tool to mitigate fishing impacts on marine ecosystems. Predicting reserves' large-scale effects on habitat structure and ecosystem functioning is a major challenge, however, because these effects unfold over longer and larger scales than most ecological studies. We use a unique approach merging remote sensing and behavioural ecology to detect ecosystem change within reserves in Australia's vast Great Barrier Reef. We find evidence of changes in reefs' algal habitat structure occurring over large spatial (thousands of kilometres) and temporal (40+ years) scales, demonstrating that reserves can alter herbivory and habitat structure in predictable ways. This approach demonstrates that we can now detect aspects of reefs' ecological responses to protection even in remote and inaccessible reefs globally.
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Affiliation(s)
- Elizabeth M. P. Madin
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- Hawaii Institute of Marine Biology, University of Hawaii, Manoa, HI 96744, USA
| | - Alastair R. Harborne
- Marine Spatial Ecology Laboratory and Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
- Department of Biological Sciences, Florida International University, 3000 NE 151st Street, North Miami, FL 33181, USA
| | - Aaron M. T. Harmer
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- Institute of Natural and Mathematical Sciences, Massey University, Auckland 0745, New Zealand
| | - Osmar J. Luiz
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Trisha B. Atwood
- Global Change Institute, University of Queensland, St Lucia, Queensland, Australia
- Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, USA
| | | | - Joshua S. Madin
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- Hawaii Institute of Marine Biology, University of Hawaii, Manoa, HI 96744, USA
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18
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Diversity and Structure of Parrotfish Assemblages across the Northern Great Barrier Reef. DIVERSITY-BASEL 2019. [DOI: 10.3390/d11010014] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The structure and dynamics of coral reef environments vary across a range of spatial scales, with patterns of associated faunal assemblages often reflecting this variability. However, delineating drivers of biological variability in such complex environments has proved challenging. Here, we investigated the assemblage structure and diversity of parrotfishes—a common and ecologically important group—across 6° of latitude on the Northern Great Barrier Reef (GBR), Australia. Parrotfish abundance and biomass were determined from stereo-video surveys across 82 sites spanning 31 reefs and assessed against geographic, biophysical, and management-related factors in a multivariate framework to determine major drivers and associated scales of assemblage structure. Large cross-shelf variation in parrotfish assemblages pervaded along the entire Northern GBR, with distinct assemblages associated with sheltered and exposed reefs. Species abundances and diversity generally decreased with decreasing latitude. The gradient of explicit predator biomass associated with management zoning had no effect on parrotfish assemblage structure, but was positively correlated with parrotfish diversity. Our results highlight the ubiquitous presence of cross-shelf variation, where the greatest differences in parrotfish community composition existed between sheltered (inner and mid shelf) and exposed (outer shelf) reef systems. Prior attempts to explain linkages between parrotfishes and fine-scale biophysical factors have demonstrated parrotfishes as habitat generalists, but recent developments in nutritional ecology suggest that their cross-shelf variation on the GBR is likely reflective of benthic resource distribution and species-specific feeding modes.
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19
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Denis V, Chen J, Chen Q, Hsieh YE, Lin YV, Wang C, Wang H, Sturaro N. Biogeography of functional trait diversity in the Taiwanese reef fish fauna. Ecol Evol 2019; 9:522-532. [PMID: 30680133 PMCID: PMC6342120 DOI: 10.1002/ece3.4771] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 01/23/2023] Open
Abstract
The richness of Taiwanese reef fish species is inversely correlated to latitude as a direct consequence of the abiotic environment and its effects on benthic habitats. However, to date, no studies have investigated the variations in the diversity of traits (FD) linked with the role of these fishes in the ecosystem. FD is usually considered more sensitive than species richness in detecting early changes in response to disturbances, and therefore could serve as an indicator of ecological resilience to environmental changes. Here, we aim to characterize FD in the Taiwanese reef fish fauna and to document its regional variations. Six traits were used to categorize the 1,484 reef fish species occurring in four environmentally contrasted regions around Taiwan. The number of unique trait combinations (FEs), their richness (FRic), their redundancy (FR), their over-redundancy (FOR), and their vulnerability (FV) were compared among these regions. Overall, 416 FEs were identified. Their number decreased from south to north in step with regional species richness but FRic remained similar among regions. FR and FOR were higher to the south. At the local scale, variations in FEs and FRic are in concordance with the worldwide pattern of FD. High-latitude, impoverished fish assemblages, offer a range of trait combinations similar to diversified tropical assemblages. Increasing diversity in the latter mainly contributes to raising FR and supports already over-redundant entities. High vulnerability makes many combinations highly sensitive to species loss, and was higher at intermediate latitudes when using a fine resolution in trait categories. It suggests that the loss of FEs may first be characterized by an increase in their vulnerability, a pattern that could have been overlooked in previous global scale analyses. Overall, this study provides new insights into reef fish trait biogeography with potential ramifications for ecosystem functioning.
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Affiliation(s)
- Vianney Denis
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
| | - Jian‐Wen Chen
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
| | - Qi Chen
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
- Institute of Fisheries ScienceNational Taiwan UniversityTaipeiTaiwan
| | | | | | - Ching‐Wei Wang
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
| | - Hui‐Yu Wang
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
- Institute of Fisheries ScienceNational Taiwan UniversityTaipeiTaiwan
| | - Nicolas Sturaro
- Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan
- Present address:
Laboratory of OceanologyFOCUS, University of LiègeLiègeBelgium
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20
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Tebbett SB, Bellwood DR. Functional links on coral reefs: Urchins and triggerfishes, a cautionary tale. MARINE ENVIRONMENTAL RESEARCH 2018; 141:255-263. [PMID: 30249458 DOI: 10.1016/j.marenvres.2018.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/05/2018] [Accepted: 09/09/2018] [Indexed: 06/08/2023]
Abstract
Urchins are ubiquitous components of coral reefs ecosystems, with significant roles in bioerosion and herbivory. By controlling urchin densities, triggerfishes have been identified as keystone predators. However, the functional linkages between urchins and triggerfishes, in terms of distributional patterns and concomitant effects on ecosystem processes, are not well understood, especially in relatively unexploited systems. To address this we censused urchins and triggerfishes on two cross-shelf surveys on the Great Barrier Reef (GBR) at the same times and locations. We also evaluated the role of urchins in bioerosion. Although urchin abundance and triggerfish biomass varied by 80% and nearly 900% across sites, respectively, this variability was driven primarily by shelf position with no evidence of top-down control on urchins by triggerfishes. Low urchin abundances meant urchins only played a minor role in bioerosion. We highlight the potential variability in functional links, and contributions to ecosystem processes, among regions.
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Affiliation(s)
- Sterling B Tebbett
- ARC Centre of Excellence for Coral Reef Studies, College of Science and Engineering, James Cook University, Townsville, Queensland, 4811, Australia.
| | - David R Bellwood
- ARC Centre of Excellence for Coral Reef Studies, College of Science and Engineering, James Cook University, Townsville, Queensland, 4811, Australia
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21
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Brandl SJ, Goatley CHR, Bellwood DR, Tornabene L. The hidden half: ecology and evolution of cryptobenthic fishes on coral reefs. Biol Rev Camb Philos Soc 2018; 93:1846-1873. [PMID: 29736999 DOI: 10.1111/brv.12423] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/30/2018] [Accepted: 04/05/2018] [Indexed: 01/04/2023]
Abstract
Teleost fishes are the most diverse group of vertebrates on Earth. On tropical coral reefs, their species richness exceeds 6000 species; one tenth of total vertebrate biodiversity. A large proportion of this diversity is composed of cryptobenthic reef fishes (CRFs): bottom-dwelling, morphologically or behaviourally cryptic species typically less than 50 mm in length. Yet, despite their diversity and abundance, these fishes are both poorly defined and understood. Herein we provide a new quantitative definition and synthesise current knowledge on the diversity, distribution and life history of CRFs. First, we use size distributions within families to define 17 core CRF families as characterised by the high prevalence (>10%) of small-bodied species (<50 mm). This stands in strong contrast to 42 families of large reef fishes, in which virtually no small-bodied species have evolved. We posit that small body size has allowed CRFs to diversify at extremely high rates, primarily by allowing for fine partitioning of microhabitats and facilitation of allopatric reproductive isolation; yet, we are far from understanding and documenting the biodiversity of CRFs. Using rates of description since 1758, we predict that approximately 30 new species of cryptobenthic species will be described per year until 2050 (approximately twice the annual rate compared to large fishes). Furthermore, we predict that by the year 2031, more than half of the described coral reef fish biodiversity will consist of CRFs. These fishes are the 'hidden half' of vertebrate biodiversity on coral reefs. Notably, global geographic coverage and spatial resolution of quantitative data on CRF communities is uniformly poor, which further emphasises the remarkable reservoir of biodiversity that is yet to be discovered. Although small body size may have enabled extensive diversification within CRF families, small size also comes with a suite of ecological challenges that affect fishes' capacities to feed, survive and reproduce; we identify a range of life-history adaptations that have enabled CRFs to overcome these limitations. In turn, these adaptations bestow a unique socio-ecological role on CRFs, which includes a key role in coral reef trophodynamics by cycling trophic energy provided by microscopic prey to larger consumers. Although small in body size, the ecology and evolutionary history of CRFs may make them a critical component of coral-reef food webs; yet our review also shows that these fishes are highly susceptible to a variety of anthropogenic disturbances. Understanding the consequences of these changes for CRFs and coral reef ecosystems will require us to shed more light on this frequently overlooked but highly diverse and abundant guild of coral reef fishes.
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Affiliation(s)
- Simon J Brandl
- Department of Biological Sciences, Simon Fraser University, Burnaby, V5A 1S6, Canada.,Tennenbaum Marine Observatories Network, Smithsonian Institution, Edgewater, MD, 21037, U.S.A
| | - Christopher H R Goatley
- Function, Evolution and Anatomy Research (FEAR) Lab and Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, 2351, Australia
| | - David R Bellwood
- College of Science and Engineering, James Cook University, Townsville, 4811, Australia.,ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, 4811, Australia
| | - Luke Tornabene
- School of Aquatic and Fishery Sciences, and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, 98105, U.S.A
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22
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Rasher DB, Hoey AS, Hay ME. Cascading predator effects in a Fijian coral reef ecosystem. Sci Rep 2017; 7:15684. [PMID: 29146986 PMCID: PMC5691076 DOI: 10.1038/s41598-017-15679-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 10/31/2017] [Indexed: 11/22/2022] Open
Abstract
Coral reefs are among Earth’s best-studied ecosystems, yet the degree to which large predators influence the ecology of coral reefs remains an open and contentious question. Recent studies indicate the consumptive effects of large reef predators are too diffuse to elicit trophic cascades. Here, we provide evidence that such predators can produce non-consumptive (fear) effects that flow through herbivores to shape the distribution of seaweed on a coral reef. This trophic cascade emerged because reef topography, tidal oscillations, and shark hunting behaviour interact to create predictable “hot spots” of fear on the reef where herbivores withhold feeding and seaweeds gain a spatial refuge. Thus, in risky habitats, sharks can exert strong ecological impacts even though they are trophic generalists that rarely feed. These findings contextualize the debate over whether predators influence coral reef structure and function and move us to ask not if, but under what specific conditions, they generate trophic cascades.
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Affiliation(s)
- Douglas B Rasher
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, ME, 04544, USA.
| | - Andrew S Hoey
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, 1 James Cook Drive, Townsville, QLD, 4811, Australia
| | - Mark E Hay
- School of Biological Sciences and Aquatic Chemical Ecology Centre, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA, 30332, USA
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23
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Castro-Sanguino C, Bozec YM, Dempsey A, Samaniego BR, Lubarsky K, Andrews S, Komyakova V, Ortiz JC, Robbins WD, Renaud PG, Mumby PJ. Detecting conservation benefits of marine reserves on remote reefs of the northern GBR. PLoS One 2017; 12:e0186146. [PMID: 29117191 PMCID: PMC5695593 DOI: 10.1371/journal.pone.0186146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/26/2017] [Indexed: 11/19/2022] Open
Abstract
The Great Barrier Reef Marine Park (GBRMP) is the largest network of marine reserves in the world, yet little is known of the efficacy of no-fishing zones in the relatively lightly-exploited remote parts of the system (i.e., northern regions). Here, we find that the detection of reserve effects is challenging and that heterogeneity in benthic habitat composition, specifically branching coral cover, is one of the strongest driving forces of fish assemblages. As expected, the biomass of targeted fish species was generally greater (up to 5-fold) in no-take zones than in fished zones, but we found no differences between the two forms of no-take zone: 'no-take' versus 'no-entry'. Strong effects of zoning were detected in the remote Far-North inshore reefs and more central outer reefs, but surprisingly fishing effects were absent in the less remote southern locations. Moreover, the biomass of highly targeted species was nearly 2-fold greater in fished areas of the Far-North than in any reserve (no-take or no-entry) further south. Despite high spatial variability in fish biomass, our results suggest that fishing pressure is greater in southern areas and that poaching within reserves may be common. Our results also suggest that fishers 'fish the line' as stock sizes in exploited areas decreased near larger no-take zones. Interestingly, an analysis of zoning effects on small, non-targeted fishes appeared to suggest a top-down effect from mesopredators, but was instead explained by variability in benthic composition. Thus, we demonstrate the importance of including appropriate covariates when testing for evidence of trophic cascades and reserve successes or failures.
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Affiliation(s)
- Carolina Castro-Sanguino
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Yves-Marie Bozec
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
- ARC Centre of Excellence for Coral Reef Studies, Brisbane, Queensland, Australia
| | - Alexandra Dempsey
- Khaled bin Sultan Living Oceans Foundation, Annapolis, United States of America
| | - Badi R Samaniego
- School of Environmental Science and Management, University of the Philippines, Los Baños, Philippines
| | - Katie Lubarsky
- State of Hawai'i Division of Aquatic Resources, Honolulu, United States of America
| | - Stefan Andrews
- School of Biological Sciences, The University of Western Australia, Crawley, Perth, Western Australia, Australia
| | - Valeriya Komyakova
- School of BioSciences, University of Melbourne, Parkville, Victoria, Australia
| | - Juan Carlos Ortiz
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - William D Robbins
- Wildlife Marine, Perth, Western Australia, Australia
- Department of Environment and Agriculture, Curtin University, Perth, Western Australia, Australia
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Philip G Renaud
- Khaled bin Sultan Living Oceans Foundation, Annapolis, United States of America
| | - Peter J Mumby
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
- ARC Centre of Excellence for Coral Reef Studies, Brisbane, Queensland, Australia
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Witman JD, Smith F, Novak M. Experimental demonstration of a trophic cascade in the Galápagos rocky subtidal: Effects of consumer identity and behavior. PLoS One 2017; 12:e0175705. [PMID: 28430794 PMCID: PMC5400256 DOI: 10.1371/journal.pone.0175705] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/30/2017] [Indexed: 11/18/2022] Open
Abstract
In diverse tropical webs, trophic cascades are presumed to be rare, as species interactions may dampen top-down control and reduce their prevalence. To test this hypothesis, we used an open experimental design in the Galápagos rocky subtidal that enabled a diverse guild of fish species, in the presence of each other and top predators (sea lions and sharks), to attack two species of sea urchins grazing on benthic algae. Time-lapse photography of experiments on natural and experimental substrates revealed strong species identity effects: only two predator species–blunthead triggerfish (Pseudobalistes naufragium) and finescale triggerfish (Balistes polylepis)–drove a diurnal trophic cascade extending to algae, and they preferred large pencil urchins (Eucidaris galapagensis) over green urchins (Lytechinus semituberculatus). Triggerfish predation effects were strong, causing a 24-fold reduction of pencil urchin densities during the initial 21 hours of a trophic cascade experiment. A trophic cascade was demonstrated for pencil urchins, but not for green urchins, by significantly higher percent cover of urchin-grazed algae in cages that excluded predatory fish than in predator access (fence) treatments. Pencil urchins were more abundant at night when triggerfish were absent, suggesting that this species persists by exploiting a nocturnal predation refuge. Time-series of pencil urchin survivorship further demonstrated per capita interference effects of hogfish and top predators. These interference effects respectively weakened and extended the trophic cascade to a fourth trophic level through behavioral modifications of the triggerfish-urchin interaction. We conclude that interference behaviors capable of modifying interaction strength warrant greater attention as mechanisms for altering top-down control, particularly in speciose food webs.
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Affiliation(s)
- Jon D. Witman
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States of America
- * E-mail:
| | - Franz Smith
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States of America
| | - Mark Novak
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
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25
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Selden RL, Gaines SD, Hamilton SL, Warner RR. Protection of large predators in a marine reserve alters size-dependent prey mortality. Proc Biol Sci 2017; 284:20161936. [PMID: 28123086 PMCID: PMC5310031 DOI: 10.1098/rspb.2016.1936] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/03/2017] [Indexed: 11/12/2022] Open
Abstract
Where predator-prey interactions are size-dependent, reductions in predator size owing to fishing has the potential to disrupt the ecological role of top predators in marine ecosystems. In southern California kelp forests, we investigated the size-dependence of the interaction between herbivorous sea urchins and one of their predators, California sheephead (Semicossyphus pulcher). Empirical tests examined how differences in predator size structure between reserve and fished areas affected size-specific urchin mortality. Sites inside marine reserves had greater sheephead size and biomass, while empirical feeding trials indicated that larger sheephead were required to successfully consume urchins of increasing test diameter. Evaluations of the selectivity of sheephead for two urchin species indicated that shorter-spined purple urchins were attacked more frequently and successfully than longer-spined red urchins of the same size class, particularly at the largest test diameters. As a result of these size-specific interactions and the higher biomass of large sheephead inside reserves, urchin mortality rates were three times higher inside the reserve for both species. In addition, urchin mortality rates decreased with urchin size, and very few large urchins were successfully consumed in fished areas. The truncation of sheephead size structure that commonly occurs owing to fishing will probably result in reductions in urchin mortality, which may reduce the resilience of kelp beds to urchin barren formation. By contrast, the recovery of predator size structure in marine reserves may restore this resilience, but may be delayed until fish grow to sizes capable of consuming larger urchins.
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Affiliation(s)
- Rebecca L Selden
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Steven D Gaines
- Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106, USA
| | - Scott L Hamilton
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA
| | - Robert R Warner
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
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