1
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Clements CS, Pratte ZA, Stewart FJ, Hay ME. Biodiversity of macroalgae does not differentially suppress coral performance: The other side of a biodiversity issue. Ecology 2024; 105:e4329. [PMID: 38772876 DOI: 10.1002/ecy.4329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 02/16/2024] [Accepted: 04/13/2024] [Indexed: 05/23/2024]
Abstract
Hundreds of studies now document positive relationships between biodiversity and critical ecosystem processes, but as ecological communities worldwide shift toward new species configurations, less is known regarding how the biodiversity of undesirable species will shape the functioning of ecosystems or foundation species. We manipulated macroalgal species richness in experimental field plots to test whether and how the identity and diversity of competing macroalgae affected the growth, survival, and microbiome of a common coral in Mo'orea, French Polynesia. Compared to controls without algal competitors, coral growth was significantly suppressed across three macroalgal monocultures, a polyculture of the same three macroalgae, and plots containing inert seaweed mimics; coral mortality was limited and did not differ significantly among treatments. One macroalga suppressed coral growth significantly less than the other two, but none differed from the inert mimic in terms of coral suppression. The composition, dispersion, and diversity of coral microbiomes in treatments with live macroalgae or inert plastic mimics did not differ from controls experiencing no competition. Microbiome composition differed between two macroalgal monocultures and a monoculture versus plastic mimics, but no other microbiome differences were observed among macroalgal or mimic treatments. Together, these findings suggest that algal diversity does not alter harmful impacts of macroalgae on coral performance, which could be accounted for by physical structure alone in these field experiments. While enhancing biodiversity is a recognized strategy for promoting desirable species, it would be worrisome if biodiversity also enhanced the negative impacts of undesirable species. We documented no such effects in this investigation.
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Affiliation(s)
- Cody S Clements
- School of Biological Sciences and Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Zoe A Pratte
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Frank J Stewart
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Mark E Hay
- School of Biological Sciences and Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
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2
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Fong J, Tang PPY, Deignan LK, Seah JCL, McDougald D, Rice SA, Todd PA. Chemically Mediated Interactions with Macroalgae Negatively Affect Coral Health but Induce Limited Changes in Coral Microbiomes. Microorganisms 2023; 11:2261. [PMID: 37764105 PMCID: PMC10535309 DOI: 10.3390/microorganisms11092261] [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: 08/19/2023] [Revised: 09/05/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Allelopathic chemicals facilitated by the direct contact of macroalgae with corals are potentially an important mechanism mediating coral-macroalgal interactions, but only a few studies have explored their impacts on coral health and microbiomes and the coral's ability to recover. We conducted a field experiment on an equatorial urbanized reef to assess the allelopathic effects of four macroalgal species (Bryopsis sp., Endosiphonia horrida, Hypnea pannosa and Lobophora challengeriae) on the health and microbiomes of three coral species (Merulina ampliata, Montipora stellata and Pocillopora acuta). Following 24 h of exposure, crude extracts of all four macroalgal species caused significant coral tissue bleaching and reduction in effective quantum yield. The corals were able to recover within 72 h of the removal of extracts, except those that were exposed to L. challengeriae. While some macroalgal extracts caused an increase in the alpha diversity of coral microbiomes, there were no significant differences in the composition and variability of coral microbiomes between controls and macroalgal extracts at each sampling time point. Nevertheless, DESeq2 differential abundance analyses showed species-specific responses of coral microbiomes. Overall, our findings provide insights on the limited effect of chemically mediated interactions with macroalgae on coral microbiomes and the capacity of corals to recover quickly from the macroalgal chemicals.
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Affiliation(s)
- Jenny Fong
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
| | - Peggy P. Y. Tang
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Lindsey K. Deignan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Jovena C. L. Seah
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
| | - Diane McDougald
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Scott A. Rice
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; (P.P.Y.T.); (L.K.D.); (D.M.); (S.A.R.)
| | - Peter A. Todd
- Experimental Marine Ecology Laboratory, National University of Singapore, Singapore 117558, Singapore; (J.C.L.S.); (P.A.T.)
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Reverter M, Helber SB, Rohde S, de Goeij JM, Schupp PJ. Coral reef benthic community changes in the Anthropocene: Biogeographic heterogeneity, overlooked configurations, and methodology. GLOBAL CHANGE BIOLOGY 2022; 28:1956-1971. [PMID: 34951504 DOI: 10.1111/gcb.16034] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 12/04/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
Non-random community changes are becoming more frequent in many ecosystems. In coral reefs, changes towards communities dominated by other than hard corals are increasing in frequency, with severe impacts on ecosystem functioning and provision of ecosystem services. Although new research suggests that a variety of alternative communities (i.e. not dominated by hard corals) exist, knowledge on the global diversity and functioning of alternative coral reef benthic communities, especially those not dominated by algae, remains scattered. In this systematic review and meta-analysis of 523 articles, we analyse the different coral reef benthic community changes reported to date and discuss the advantages and limitations of the methods used to study these changes. Furthermore, we used field cover data (1116 reefs from the ReefCheck database) to explore the biogeographic and latitudinal patterns in dominant benthic organisms. We found a mismatch between literature focus on coral-algal changes (over half of the studies analysed) and observed global natural patterns. We identified strong biogeographic patterns, with the largest and most biodiverse biogeographic regions (Western and Central Indo-Pacific) presenting previously overlooked soft-coral-dominated communities as the most abundant alternative community. Finally, we discuss the potential biases associated with methods that overlook ecologically important cryptobenthic communities and the potential of new technological advances in improving monitoring efforts. As coral reef communities inevitably and swiftly change under changing ocean conditions, there is an urgent need to better understand the distribution, dynamics as well as the ecological and societal impacts of these new communities.
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Affiliation(s)
- Miriam Reverter
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Wilhelmshaven, Germany
| | - Stephanie B Helber
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Wilhelmshaven, Germany
| | - Sven Rohde
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Wilhelmshaven, Germany
| | - Jasper M de Goeij
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, The Netherlands
| | - Peter J Schupp
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Wilhelmshaven, Germany
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Oldenburg, Germany
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4
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Inagaki KY, Pennino MG, Floeter SR, Hay ME, Longo GO. Trophic interactions will expand geographically but be less intense as oceans warm. GLOBAL CHANGE BIOLOGY 2020; 26:6805-6812. [PMID: 33021041 DOI: 10.1111/gcb.15346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
Interactions among species are likely to change geographically due to climate-driven species range shifts and in intensity due to physiological responses to increasing temperatures. Marine ectotherms experience temperatures closer to their upper thermal limits due to the paucity of temporary thermal refugia compared to those available to terrestrial organisms. Thermal limits of marine ectotherms also vary among species and trophic levels, making their trophic interactions more prone to changes as oceans warm. We assessed how temperature affects reef fish trophic interactions in the Western Atlantic and modeled projections of changes in fish occurrence, biomass, and feeding intensity across latitudes due to climate change. Under ocean warming, tropical reefs will experience diminished trophic interactions, particularly herbivory and invertivory, potentially reinforcing algal dominance in this region. Tropicalization events are more likely to occur in the northern hemisphere, where feeding by tropical herbivores is predicted to expand from the northern Caribbean to extratropical reefs. Conversely, feeding by omnivores is predicted to decrease in this area with minor increases in the Caribbean and southern Brazil. Feeding by invertivores declines across all latitudes in future predictions, jeopardizing a critical trophic link. Most changes are predicted to occur by 2050 and can significantly affect ecosystem functioning, causing dominance shifts and the rise of novel ecosystems.
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Affiliation(s)
- Kelly Y Inagaki
- Laboratório de Ecologia Marinha, Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - Maria Grazia Pennino
- Instituto Español de Oceanografía Centro Oceanográfico de Vigo, Vigo (Pontevedra), Spain
| | - Sergio R Floeter
- Laboratório de Biogeografia e Macroecologia Marinha, Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Mark E Hay
- School of Biological Sciences and Aquatic, Chemical Ecology Center, Georgia Institute of Technology, Atlanta, GA, USA
| | - Guilherme O Longo
- Laboratório de Ecologia Marinha, Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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5
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Neilson BJ, Wall CB, Mancini FT, Gewecke CA. Herbivore biocontrol and manual removal successfully reduce invasive macroalgae on coral reefs. PeerJ 2018; 6:e5332. [PMID: 30123695 PMCID: PMC6087420 DOI: 10.7717/peerj.5332] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/06/2018] [Indexed: 11/22/2022] Open
Abstract
Invasive macroalgae pose a serious threat to coral reef biodiversity by monopolizing reef habitats, competing with native species, and directly overgrowing, and smothering reef corals. Several invasive macroalgae (Eucheuma clade E, Kappaphycus clade A and B, Gracilaria salicornia, and Acanthophora spicifera) are established within Kāne‘ohe Bay (O‘ahu, Hawai‘i, USA), and reducing invasive macroalgae cover is a coral reef conservation and management priority. Invasive macroalgae control techniques, however, are limited and few successful large-scale applications exist. Therefore, a two-tiered invasive macroalgae control approach was designed, where first, divers manually remove invasive macroalgae (Eucheuma and Kappaphycus) aided by an underwater vacuum system (“The Super Sucker”). Second, hatchery-raised juvenile sea urchins (Tripneustes gratilla), were outplanted to graze and control invasive macroalgae regrowth. To test the effectiveness of this approach in a natural reef ecosystem, four discrete patch reefs with high invasive macroalgae cover (15–26%) were selected, and macroalgae removal plus urchin biocontrol (treatment reefs, n = 2), or no treatment (control reefs, n = 2), was applied at the patch reef-scale. In applying the invasive macroalgae treatment, the control effort manually removed ∼19,000 kg of invasive macroalgae and ∼99,000 juvenile sea urchins were outplanted across to two patch reefs, totaling ∼24,000 m2 of reef area. Changes in benthic cover were monitored over 2 years (five sampling periods) before-and-after the treatment was applied. Over the study period, removal and biocontrol reduced invasive macroalgae cover by 85% at treatment reefs. Our results show manual removal in combination with hatchery raised urchin biocontrol to be an effective management approach in controlling invasive macroalgae at reef-wide spatial scales and temporal scales of months to years.
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Affiliation(s)
- Brian J Neilson
- State of Hawai'i Division of Aquatic Resources, Honolulu, Hawai'i, United States of America
| | - Christopher B Wall
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, United States of America
| | - Frank T Mancini
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, United States of America
| | - Catherine A Gewecke
- State of Hawai'i Division of Aquatic Resources, Honolulu, Hawai'i, United States of America
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Ceccarelli DM, Loffler Z, Bourne DG, Al Moajil-Cole GS, Boström-Einarsson L, Evans-Illidge E, Fabricius K, Glasl B, Marshall P, McLeod I, Read M, Schaffelke B, Smith AK, Jorda GT, Williamson DH, Bay L. Rehabilitation of coral reefs through removal of macroalgae: state of knowledge and considerations for management and implementation. Restor Ecol 2018. [DOI: 10.1111/rec.12852] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Daniela M. Ceccarelli
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville QLD 4811 Australia
- Marine Ecology Consultant, 36 Barton Street; Magnetic Island QLD 4819 Australia
| | - Zoe Loffler
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville QLD 4811 Australia
| | - David G. Bourne
- College of Science and Engineering; James Cook University; Townsville, QLD 4811 Australia
- Australian Institute of Marine Science; Townsville QLD 4810 Australia
| | - Grace S. Al Moajil-Cole
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville QLD 4811 Australia
- College of Science and Engineering; James Cook University; Townsville, QLD 4811 Australia
- AIMS@JCU; Townsville, QLD 4810 Australia
| | | | | | | | - Bettina Glasl
- College of Science and Engineering; James Cook University; Townsville, QLD 4811 Australia
- Australian Institute of Marine Science; Townsville QLD 4810 Australia
- AIMS@JCU; Townsville, QLD 4810 Australia
| | - Paul Marshall
- Reef Ecologic, 14 Cleveland Terrace, North Ward; Townsville, QLD 4810 Australia
| | - Ian McLeod
- TropWATER; James Cook University; Townsville, QLD 4811 Australia
| | - Mark Read
- Great Barrier Reef Marine Park Authority; Townsville, QLD 4810 Australia
| | - Britta Schaffelke
- Australian Institute of Marine Science; Townsville QLD 4810 Australia
| | - Adam K. Smith
- Reef Ecologic, 14 Cleveland Terrace, North Ward; Townsville, QLD 4810 Australia
| | - Georgina T. Jorda
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville QLD 4811 Australia
| | - David H. Williamson
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville QLD 4811 Australia
- College of Science and Engineering; James Cook University; Townsville, QLD 4811 Australia
| | - Line Bay
- Australian Institute of Marine Science; Townsville QLD 4810 Australia
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7
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Johns KA, Emslie MJ, Hoey AS, Osborne K, Jonker MJ, Cheal AJ. Macroalgal feedbacks and substrate properties maintain a coral reef regime shift. Ecosphere 2018. [DOI: 10.1002/ecs2.2349] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Kerryn A. Johns
- Australian Institute of Marine Science; PMB 3, Townsville MC Townsville 4810 Queensland Australia
| | - Michael J. Emslie
- Australian Institute of Marine Science; PMB 3, Townsville MC Townsville 4810 Queensland Australia
| | - Andrew S. Hoey
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville 4811 Queensland Australia
| | - Kate Osborne
- Australian Institute of Marine Science; PMB 3, Townsville MC Townsville 4810 Queensland Australia
| | - Michelle J. Jonker
- Australian Institute of Marine Science; PMB 3, Townsville MC Townsville 4810 Queensland Australia
| | - Alistair J. Cheal
- Australian Institute of Marine Science; PMB 3, Townsville MC Townsville 4810 Queensland Australia
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8
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Davis SL. Associational refuge facilitates phase shifts to macroalgae in a coral reef ecosystem. Ecosphere 2018. [DOI: 10.1002/ecs2.2272] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Samantha L. Davis
- Department of Ecology, Evolution and Marine Biology University of California Santa Barbara Santa Barbara California 93106 USA
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Beatty DS, Clements CS, Stewart FJ, Hay ME. Intergenerational effects of macroalgae on a reef coral: major declines in larval survival but subtle changes in microbiomes. MARINE ECOLOGY PROGRESS SERIES 2018; 589:97-114. [PMID: 30505048 PMCID: PMC6261492 DOI: 10.3354/meps12465] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Tropical reefs are shifting from coral to macroalgal dominance, with macroalgae suppressing coral recovery, potentially via effects on coral microbiomes. Understanding how macroalgae affect corals and their microbiomes requires comparing algae- versus coral-dominated reefs without confounding aspects of time and geography. We compared survival, settlement, and post-settlement survival of larvae, as well as the microbiomes of larvae and adults, of the Pacific coral Pocillopora damicornis between an Marine Protected Area (MPA) dominated by corals versus an adjacent fished area dominated by macroalgae. Microbiome composition in adult coral, larval coral, and seawater did not differ between the MPA and fished area. However, microbiomes of adult coral were more variable in the fished area and Vibrionaceae bacteria, including strains most closely related to the pathogen Vibrio shilonii, were significantly enriched, but rare, in adult and larval coral from the fished area. Larvae from the macroalgae-dominated area exhibited higher pre-settlement mortality and reduced settlement compared to those from the coral-dominated area. Juveniles planted into a coral-dominated area survived better than those placed into a fished area dominated by macroalgae. Differential survival depended on whether macroalgae were immediately adjacent to juvenile coral rather than on traits of the areas per se. Contrary to our expectations, coral microbiomes were relatively uniform at the community level despite dramatic differences in macroalgal cover between the MPA (~2% cover) and fished (~90%) area. Reducing macroalgae may elicit declines in rare but potentially harmful microbes in coral and their larvae, as well as positive intergenerational effects on offspring survival.
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Affiliation(s)
- Deanna S. Beatty
- School of Biological Sciences and Aquatic Chemical Ecology Center Georgia Institute of Technology, Atlanta, GA 30332-0230
| | - Cody S. Clements
- School of Biological Sciences and Aquatic Chemical Ecology Center Georgia Institute of Technology, Atlanta, GA 30332-0230
| | - Frank J. Stewart
- School of Biological Sciences and Aquatic Chemical Ecology Center Georgia Institute of Technology, Atlanta, GA 30332-0230
| | - Mark E. Hay
- School of Biological Sciences and Aquatic Chemical Ecology Center Georgia Institute of Technology, Atlanta, GA 30332-0230
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Clements CS, Rasher DB, Hoey AS, Bonito VE, Hay ME. Spatial and temporal limits of coral-macroalgal competition: the negative impacts of macroalgal density, proximity, and history of contact. MARINE ECOLOGY PROGRESS SERIES 2018; 586:11-20. [PMID: 30505047 PMCID: PMC6261525 DOI: 10.3354/meps12410] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Tropical reefs are commonly transitioning from coral- to macroalgal-dominance, producing abrupt, and often lasting, shifts in community composition and ecosystem function. Although negative effects of macroalgae on corals are well documented, whether such effects vary with spatial scale or the density of macroalgae remains inadequately understood, as does the legacy of their impact on coral growth. Using closely adjacent coral- versus macroalgal-dominated areas, we tested effects of macroalgal competition on the Indo-Pacific corals Acropora millepora and Porites cylindrica. When corals were transplanted to areas of: i) macroalgal-dominance, ii) macroalgal-dominance but with nearby macroalgae removed, or iii) coral-dominance lacking macroalgae, coral growth was equivalently high in plots without macroalgae and low (62-90% less) in plots with macroalgae, regardless of location. In a separate experiment, we raised corals above the benthos in each area and exposed them to differing densities of the dominant macroalga Sargassum polycystum. Coral survivorship was high (≥ 93% after 3 months) and did not differ among treatments, whereas the growth of both coral species decreased as a function of Sargassum density. When Sargassum was removed after two months, there was no legacy effect of macroalgal density on coral growth over the next seven months; however, there was no compensation for previously depressed growth. In sum, macroalgal impacts were density dependent, occurred only if macroalgae were in close contact, and coral growth was resilient to prior macroalgal contact. The temporal and spatial constraints of these interactions suggest that corals may be surprisingly resilient to periodic macroalgal competition, which could have important implications for ecosystem trajectories that lead to reef decline or recovery.
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Affiliation(s)
- Cody S. Clements
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Andrew S. Hoey
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | | | - Mark E. Hay
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Corresponding author:
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Small Marine Protected Areas in Fiji Provide Refuge for Reef Fish Assemblages, Feeding Groups, and Corals. PLoS One 2017; 12:e0170638. [PMID: 28122006 PMCID: PMC5266309 DOI: 10.1371/journal.pone.0170638] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/09/2017] [Indexed: 11/23/2022] Open
Abstract
The establishment of no-take marine protected areas (MPAs) on coral reefs is a common management strategy for conserving the diversity, abundance, and biomass of reef organisms. Generally, well-managed and enforced MPAs can increase or maintain the diversity and function of the enclosed coral reef, with some of the benefits extending to adjacent non-protected reefs. A fundamental question in coral reef conservation is whether these benefits arise within small MPAs (<1 km2), because larval input of reef organisms is largely decoupled from local adult reproduction. We examined the structure of fish assemblages, composition of fish feeding groups, benthic cover, and key ecosystem processes (grazing, macroalgal browsing, and coral replenishment) in three small (0.5–0.8 km2) no-take MPAs and adjacent areas where fisheries are allowed (non-MPAs) on coral reefs in Fiji. The MPAs exhibited greater species richness, density, and biomass of fishes than non-MPAs. Furthermore, MPAs contained a greater abundance and biomass of grazing herbivores and piscivores as well as a greater abundance of cleaners than fished areas. We also found differences in fish associations when foraging, with feeding groups being generally more diverse and having greater biomass within MPAs than adjacent non-MPAs. Grazing by parrotfishes was 3–6 times greater, and macroalgal browsing was 3–5 times greater in MPAs than in non-MPAs. On average, MPAs had 260–280% as much coral cover and only 5–25% as much macroalgal cover as their paired non-MPA sites. Finally, two of the three MPAs had three-fold more coral recruits than adjacent non-MPAs. The results of this study indicate that small MPAs benefit not only populations of reef fishes, but also enhance ecosystem processes that are critical to reef resilience within the MPAs.
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12
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Dell C, Hay ME. Induced defence to grazing by vertebrate herbivores: uncommon or under-investigated? MARINE ECOLOGY PROGRESS SERIES 2016; 561:137-145. [PMID: 29123328 PMCID: PMC5673266 DOI: 10.3354/meps11928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
There are many examples of macroalgae inducing defence in response to small invertebrate herbivores like amphipods, isopods, and gastropods but few cases of induction in response to vertebrate macrograzers like herbivorous fishes. This may be because larger grazers rapidly consume large quantities of seaweed before induction can occur, thus selecting for constitutive rather than induced defences. Alternatively, the pattern could occur because induction due to feeding by macrograzers is less commonly investigated. In Fiji, field assays with the brown macroalga Sargassum polycystum demonstrated that thalli growing in marine protected areas (MPAs) with abundant herbivorous fishes were significantly less palatable than those growing in adjacent fished areas (non-MPAs) with few herbivorous fishes. This significant preference occurred in 11 of 13 trials over 5 time periods and across 3 pairs of MPAs and spatially associated non-MPAs. This preference was not positively associated with algal nitrogen content or with the toughness of algal fronds. When S. polycystum ramets were taken from the non-MPA and half were partially grazed by fishes while the other half were protected from grazing, new growth from the controls was strongly preferred to new growth from the previously grazed ramets although these fronds originated from the same holdfast. This suggests that S. polycystum upregulates defences (probably chemical) in response to grazing by herbivorous fishes. This is one of the few published examples of induction of macroalgal defence in response to feeding by large, mobile grazers. It is unclear whether induced defences against fishes are rare or just under-investigated.
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Affiliation(s)
- Claire Dell
- School of Biological Sciences and Aquatic Chemical Ecology Center, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA
| | - Mark E. Hay
- School of Biological Sciences and Aquatic Chemical Ecology Center, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, GA 30332, USA
- Corresponding author:
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