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765 KiB

Open AccessArticle

Resilience of Florida Keys Coral Communities Following Large-Scale Disturbances

by Deborah L. Santavy, Erich M. Mueller, Lauri MacLaughlin, Esther C. Peters, Robert L. Quarles and Mace G. Barron

Diversity 2011, 3(4), 628-640; https://doi.org/10.3390/d3040628 - 3 Oct 2011

Cited by 3 | Viewed by 8434

Abstract

The decline of coral reefs in the Caribbean over the last 40 years has been attributed to multiple chronic stressors and episodic large-scale disturbances. This study assessed the resilience of coral communities in two different regions of the Florida Keys reef system between [...] Read more.

The decline of coral reefs in the Caribbean over the last 40 years has been attributed to multiple chronic stressors and episodic large-scale disturbances. This study assessed the resilience of coral communities in two different regions of the Florida Keys reef system between 1998 and 2002 following hurricane impacts and coral bleaching in 1998. Resilience was assessed from changes in coral abundance, diversity, disease, and bleaching prevalence in reefs near the remote off-shore islands of the Dry Tortugas compared to reefs near Key West, a center of high population density and anthropogenic influences. During the first assessment in spring 1998, Key West and Dry Tortugas coral communities had similar abundance, species diversity, and disease prevalence. Bleaching and disease significantly increased in all reef areas during the summer 1998 El Niño event, with Key West reefs exhibiting higher bleaching and disease prevalence and severity compared to Dry Tortugas. Acroporids and total coral abundance significantly declined in both regions during 1998 following mass-coral bleaching and hurricane impact, but remained reduced only on Key West reefs during the 5-year assessment. These results provide additional evidence that coral reef systems distant from anthropogenic influences may have greater resilience to large-scale disturbances. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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1886 KiB

Open AccessArticle

Monitoring Coral Health to Determine Coral Bleaching Response at High Latitude Eastern Australian Reefs: An Applied Model for A Changing Climate

by Steven J. Dalton and Andrew G. Carroll

Diversity 2011, 3(4), 592-610; https://doi.org/10.3390/d3040592 - 30 Sep 2011

Cited by 22 | Viewed by 9259

Abstract

Limited information is available on the bleaching susceptibility of coral species that dominate high latitude reefs along the eastern seaboard of Australia. The main aims of this study were to: (i) monitor coral health and spatial patterns of coral bleaching response at the [...] Read more.

Limited information is available on the bleaching susceptibility of coral species that dominate high latitude reefs along the eastern seaboard of Australia. The main aims of this study were to: (i) monitor coral health and spatial patterns of coral bleaching response at the Solitary Islands Marine Park (SIMP) and Lord Howe Island Marine Park (LHIMP), to determine variability of bleaching susceptibility among coral taxa; (ii) predict coral bleaching thresholds at 30 °S and 31.5 °S, extrapolated from published bleaching threshold data; and (iii) propose a subtropical northern New South Wales coral bleaching model from biological and physical data. Between 2005 and 2007 minor bleaching was observed in dominant coral families including Pocilloporidae, Poritidae and Dendrophylliidae in the SIMP and Pocilloporidae, Poritidae and Acroporidae (Isopora and Montipora spp.) in the LHIMP, with a clear difference in bleaching susceptibility found between sites, both within and between locations. Bleaching susceptibility was highest in Porites spp. at the most offshore island site within the SIMP during summer 2005. Patterns of subtropical family bleaching susceptibility within the SIMP and LHIMP differed to those previously reported for the central Great Barrier Reef (GBR). These differences may be due to a number of factors, including temperature history and/or the coral hosts association with different zooxanthellae clades, which may have lower thermal tolerances. An analysis of published estimates of coral bleaching thresholds from the Caribbean, South Africa, GBR and central and northern Pacific regions suggests that the bleaching threshold at 30–31.5 °S ranges between 26.5–26.8 °C. This predicted threshold was confirmed by an extensive coral bleaching event on the world’s southernmost coral reef at Lord Howe Island, during the 2010 austral summer season. These results imply that dominant coral taxa at subtropical reefs along the eastern Australian seaboard are highly susceptible to thermal stress; which, in turn, could lead to a future decline in total live coral cover if predicted rising seawater temperatures lead to more frequent coral bleaching events in future. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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6263 KiB

Open AccessArticle

Using DNA Barcoding and Standardized Sampling to Compare Geographic and Habitat Differentiation of Crustaceans: A Hawaiian Islands Example

by Laetitia Plaisance, Russell Brainard, M. Julian Caley and Nancy Knowlton

Diversity 2011, 3(4), 581-591; https://doi.org/10.3390/d3040581 - 29 Sep 2011

Cited by 18 | Viewed by 9444

Abstract

Recently, the Census of Marine Life has explored methods to assess coral reef diversity by combining standardized sampling (to permit comparison across sites) with molecular techniques (to make rapid counts of species possible). To date, this approach has been applied across geographically broad [...] Read more.

Recently, the Census of Marine Life has explored methods to assess coral reef diversity by combining standardized sampling (to permit comparison across sites) with molecular techniques (to make rapid counts of species possible). To date, this approach has been applied across geographically broad scales (seven sites spanning the Indian, Pacific and Atlantic Oceans), focusing on similar habitats at all sites (10–12 m forereef). Here we examine crustacean spatial diversity patterns for a single atoll, comparing results for four sites (comprising forereef, backreef, and lagoon habitats) at French Frigate Shoals (FFS), Northwestern Hawaiian Islands, Hawaii, USA, within the Papahanaumokuakea Marine National Monument. The Bray-Curtis index of similarity across these habitats at FFS was the same or greater than the similarity between similar habitats on Heron Island and Lizard Island in the Great Barrier Reef and much greater than similarity between more widely separated localities in the Indo-Pacific Ocean (e.g., Ningaloo, Moorea, French Polynesia or the Line Islands). These results imply that, at least for shallow reefs, sampling multiple locations versus sampling multiple habitats within a site maximizes the rate at which we can converge on the best global estimate of coral reef biodiversity. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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1285 KiB

Open AccessArticle

Greater Genetic Diversity in Spatially Restricted Coral Reef Fishes Suggests Secondary Contact among Differentiated Lineages

by Line K. Bay and M. Julian Caley

Diversity 2011, 3(3), 483-502; https://doi.org/10.3390/d3030483 - 14 Sep 2011

Cited by 9 | Viewed by 8149

Abstract

The maintenance of genetic diversity is a central goal of conservation. It is the raw material for evolutionary change and if lost, can accelerate extinction of species. According to theory, total genetic diversity should be less in species with restricted ranges and in [...] Read more.

The maintenance of genetic diversity is a central goal of conservation. It is the raw material for evolutionary change and if lost, can accelerate extinction of species. According to theory, total genetic diversity should be less in species with restricted ranges and in populations on the margins of distributional ranges, making such species or populations more vulnerable to environmental perturbations. Using mtDNA and nuclear Inter Simple Sequence Repeat (ISSR) data we investigated how the genetic diversity and structure of three con-generic species pairs of coral reef fishes (Pomacentridae) was related to species’ range size and position of populations within these ranges. Estimates of genetic structure did not differ significantly among species, but mtDNA and nucDNA genetic diversities were up to 10 times greater in spatially restricted species compared to their widespread congeners. In two of the three species pairs, the distribution of genetic variation indicated secondary contact among differentiated lineages in the spatially restricted species. In contrast, the widespread species displayed a typical signature of population expansion suggesting recent genetic bottlenecks, possibly associated with the (re) colonization of the Great Barrier Reef. These results indicate that historical processes, involving hybridization and founder effects, possibly associated with Pleistocene sea level fluctuations, have differentially influenced the widespread and spatially restricted coral reef damselfish species studied here. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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459 KiB

Open AccessArticle

Raiding the Coral Nurseries?

by Alison M. Jones

Diversity 2011, 3(3), 466-482; https://doi.org/10.3390/d3030466 - 24 Aug 2011

Cited by 8 | Viewed by 9645

Abstract

A recent shift in the pattern of commercial harvest in the Keppel Island region of the southern inshore Great Barrier Reef raises concern about the depletion of a number of relatively rare restricted range taxa. The shift appears to be driven by demand [...] Read more.

A recent shift in the pattern of commercial harvest in the Keppel Island region of the southern inshore Great Barrier Reef raises concern about the depletion of a number of relatively rare restricted range taxa. The shift appears to be driven by demand from the United States (US) for corals for domestic aquaria. Data from the annual status reports from the Queensland Coral Fishery were compared with export trade data to the US from the Convention on International Trade in Endangered Species (CITES). Evidence was found of recent increases in the harvest of species from the Mussidae family (Acanthastrea spp.) which appears to be largely driven by demand from the US. On present trends, the industry runs the risk of localized depletion of Blastomussa and Scolymia; evidenced by an increase in the harvest of small specimens and the trend of decreasing harvest despite a concurrent increase in demand. Considering their relatively high sediment tolerance compared to other reef-building species, and the current lack of information about their functional role in reef stability, the trend raises concerns about the impact of the harvest on local coral communities. The recent shift in harvest patterns could have impacts on slow-growing species by allowing harvest beyond the rate of population regeneration. In light of these factors, combined with the value of such species to local tourism, a commercial coral fishery based on uncommon but highly sought-after species may not be ecologically sustainable or economically viable in the Keppels. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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540 KiB

Open AccessArticle

Infection Dynamics Vary between Symbiodinium Types and Cell Surface Treatments during Establishment of Endosymbiosis with Coral Larvae

by Line Kolind Bay, Vivian Ruth Cumbo, David Abrego, Johnathan Travis Kool, Tracy Danielle Ainsworth and Bette Lynn Willis

Diversity 2011, 3(3), 356-374; https://doi.org/10.3390/d3030356 - 19 Jul 2011

Cited by 35 | Viewed by 11551

Abstract

Symbioses between microbes and higher organisms underpin high diversity in many ecosystems, including coral reefs, however mechanisms underlying the early establishment of symbioses remain unclear. Here we examine the roles of Symbiodinium type and cell surface recognition in the establishment of algal endosymbiosis [...] Read more.

Symbioses between microbes and higher organisms underpin high diversity in many ecosystems, including coral reefs, however mechanisms underlying the early establishment of symbioses remain unclear. Here we examine the roles of Symbiodinium type and cell surface recognition in the establishment of algal endosymbiosis in the reef-building coral, Acropora tenuis. We found 20–70% higher infection success (proportion of larvae infected) and five-fold higher Symbiodinium abundance in larvae exposed to ITS-1 type C1 compared to ITS-1 type D in the first 96 h following exposure. The highest abundance of Symbiodinium within larvae occurred when C1-type cells were treated with enzymes that modified the 40–100 kD glycome, including glycoproteins and long chain starch residues. Our finding of declining densities of Symbiodinium C1 through time in the presence of intact cell surface molecules supports a role for cell surface recognition molecules in controlling post-phagocytosis processes, leading to rejection of some Symbiodinium types in early ontogeny. Reductions in the densities of unmodified C1 symbionts after 96 h, in contrast to increases in D symbionts may suggest the early initiation of a winnowing process contributing to the establishment of Symbiodinium D as the dominant type in one-month old juveniles of A. tenuis. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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1596 KiB

Open AccessArticle

Species Richness and Community Structure on a High Latitude Reef: Implications for Conservation and Management

by Alison M. Jones, Ray Berkelmans and Wayne Houston

Diversity 2011, 3(3), 329-355; https://doi.org/10.3390/d3030329 - 19 Jul 2011

Cited by 18 | Viewed by 18799

Abstract

In spite of the wealth of research on the Great Barrier Reef, few detailed biodiversity assessments of its inshore coral communities have been conducted. Effective conservation and management of marine ecosystems begins with fine-scale biophysical assessments focused on diversity and the architectural species [...] Read more.

In spite of the wealth of research on the Great Barrier Reef, few detailed biodiversity assessments of its inshore coral communities have been conducted. Effective conservation and management of marine ecosystems begins with fine-scale biophysical assessments focused on diversity and the architectural species that build the structural framework of the reef. In this study, we investigate key coral diversity and environmental attributes of an inshore reef system surrounding the Keppel Bay Islands near Rockhampton in Central Queensland, Australia, and assess their implications for conservation and management. The Keppels has much higher coral diversity than previously found. The average species richness for the 19 study sites was ~40 with representatives from 68% of the ~244 species previously described for the southern Great Barrier Reef. Using scleractinian coral species richness, taxonomic distinctiveness and coral cover as the main criteria, we found that five out of 19 sites had particularly high conservation value. A further site was also considered to be of relatively high value. Corals at this site were taxonomically distinct from the others (representatives of two families were found here but not at other sites) and a wide range of functionally diverse taxa were present. This site was associated with more stressful conditions such as high temperatures and turbidity. Highly diverse coral communities or biodiversity ‘hotspots’ and taxonomically distinct reefs may act as insurance policies for climatic disturbance, much like Noah’s Arks for reefs. While improving water quality and limiting anthropogenic impacts are clearly important management initiatives to improve the long-term outlook for inshore reefs, identifying, mapping and protecting these coastal ‘refugia’ may be the key for ensuring their regeneration against catastrophic climatic disturbance in the meantime. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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2401 KiB

Open AccessArticle

Juvenile Coral Abundance Has Decreased by More Than 50% in Only Three Decades on a Small Caribbean Island

by Mark J.A. Vermeij, Judith Bakker, Noam van der Hal and Rolf P.M. Bak

Diversity 2011, 3(3), 296-307; https://doi.org/10.3390/d3030296 - 27 Jun 2011

Cited by 48 | Viewed by 11737

Abstract

A comparison of the community structure of juvenile hermatypic corals of 2 to 37 m depth at the fringing reefs of Curaçao between 1975 and 2005 shows a decline of 54.7% in juvenile coral abundance and a shift in species composition. Agaricia species [...] Read more.

A comparison of the community structure of juvenile hermatypic corals of 2 to 37 m depth at the fringing reefs of Curaçao between 1975 and 2005 shows a decline of 54.7% in juvenile coral abundance and a shift in species composition. Agaricia species and Helioseris cucullata, the most common juveniles in 1975, showed the largest decline in juvenile abundance (a 9 and 120 fold decrease in density respectively) with Helioseris cucullata being nearly extirpated locally. In 2005, Porites astreoides contributed most colonies to the juvenile coral community, increasing from 8.2% (in 1975) to 19.9% of the total juvenile community. Between 1975 and 2005, juveniles of brooding species decreased in relative abundance while the abundance of juveniles of broadcast spawning species increased or remained the same. These data illustrate the magnitude of the changes that have occurred in only three decades in the composition of juvenile coral communities. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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Review

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1605 KiB

Open AccessReview

Challenges for Managing Fisheries on Diverse Coral Reefs

by Douglas Fenner

Diversity 2012, 4(1), 105-160; https://doi.org/10.3390/d4010105 - 13 Mar 2012

Cited by 60 | Viewed by 16931

Abstract

Widespread coral reef decline has included the decline of reef fish populations, and the subsistence and artisanal fisheries that depend on them. Overfishing and destructive fishing have been identified as the greatest local threats to coral reefs, but the greatest future threats are [...] Read more.

Widespread coral reef decline has included the decline of reef fish populations, and the subsistence and artisanal fisheries that depend on them. Overfishing and destructive fishing have been identified as the greatest local threats to coral reefs, but the greatest future threats are acidification and increases in mass coral bleaching caused by global warming. Some reefs have shifted from dominance by corals to macroalgae, in what are called “phase shifts”. Depletion of herbivores including fishes has been identified as a contributor to such phase shifts, though nutrients are also involved in complex interactions with herbivory and competition. The depletion of herbivorous fishes implies a reduction of the resilience of coral reefs to the looming threat of mass coral mortality from bleaching, since mass coral deaths are likely to be followed by mass macroalgal blooms on the newly exposed dead substrates. Conventional stock assessment of each fish species would be the preferred option for understanding the status of the reef fishes, but this is far too expensive to be practical because of the high diversity of the fishery and poverty where most reefs are located. In addition, stock assessment models and fisheries in general assume density dependent populations, but a key prediction that stocks recover from fishing is not always confirmed. Catch Per Unit Effort (CPUE) has far too many weaknesses to be a useful method. The ratio of catch to stock and the proportion of catch that is mature depend on fish catch data, and are heavily biased toward stocks that are in good condition and incapable of finding species that are in the worst condition. Near-pristine reefs give us a reality check about just how much we have lost. Common fisheries management tools that control effort or catch are often prohibitively difficult to enforce for most coral reefs except in developed countries. Ecosystem-based management requires management of impacts of fishing on the ecosystem, but also vice versa. Marine Protected Areas (MPAs) have been a favorite management tool, since they require little information. MPAs are excellent conservation and precautionary tools, but address only fishing threats, and may be modest fisheries management tools, which are often chosen because they appear to be the only feasible alternative. “Dataless management” is based on qualitative information from traditional ecological knowledge and/or science, is sufficient for successful reef fisheries management, and is very inexpensive and practical, but requires either customary marine tenure or strong governmental leadership. Customary marine tenure has high social acceptance and compliance and may work fairly well for fisheries management and conservation where it is still strong. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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563 KiB

Open AccessReview

Responses of Cryptofaunal Species Richness and Trophic Potential to Coral Reef Habitat Degradation

by Ian C. Enochs and Derek P. Manzello

Diversity 2012, 4(1), 94-104; https://doi.org/10.3390/d4010094 - 15 Feb 2012

Cited by 37 | Viewed by 9257

Abstract

Coral reefs are declining worldwide as a result of many anthropogenic disturbances. This trend is alarming because coral reefs are hotspots of marine biodiversity and considered the ‘rainforests of the sea. As in the rainforest, much of the diversity on a coral reef [...] Read more.

Coral reefs are declining worldwide as a result of many anthropogenic disturbances. This trend is alarming because coral reefs are hotspots of marine biodiversity and considered the ‘rainforests of the sea. As in the rainforest, much of the diversity on a coral reef is cryptic, remaining hidden among the cracks and crevices of structural taxa. Although the cryptofauna make up the majority of a reef’s metazoan biodiversity, we know little about their basic ecology or how these communities respond to reef degradation. Emerging research shows that the species richness of the motile cryptofauna is higher among dead (framework) vs. live coral substrates and, surprisingly, increases within successively more eroded reef framework structures, ultimately reaching a maximum in dead coral rubble. Consequently, the paradigm that abundant live coral is the apex of reef diversity needs to be clarified. This provides guarded optimism amidst alarming reports of declines in live coral cover and the impending doom of coral reefs, as motile cryptic biodiversity should persist independent of live coral cover. Granted, the maintenance of this high species richness is contingent on the presence of reef rubble, which will eventually be lost due to physical, chemical, and biological erosion if not replenished by live coral calcification and mortality. The trophic potential of a reef, as inferred from the abundance of cryptic organisms, is highest on live coral. Among dead framework substrates, however, the density of cryptofauna reaches a peak at intermediate levels of degradation. In summary, the response of the motile cryptofauna, and thus a large fraction of the reef’s biodiversity, to reef degradation is more complex and nuanced than currently thought; such that species richness may be less sensitive than overall trophic function. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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594 KiB

Open AccessReview

Changes in Biodiversity and Functioning of Reef Fish Assemblages following Coral Bleaching and Coral Loss

by Morgan S. Pratchett, Andrew S. Hoey, Shaun K. Wilson, Vanessa Messmer and Nicholas A.J. Graham

Diversity 2011, 3(3), 424-452; https://doi.org/10.3390/d3030424 - 12 Aug 2011

Cited by 219 | Viewed by 34173

Abstract

Coral reef ecosystems are increasingly subject to severe, large-scale disturbances caused by climate change (e.g., coral bleaching) and other more direct anthropogenic impacts. Many of these disturbances cause coral loss and corresponding changes in habitat structure, which has further important effects on abundance [...] Read more.

Coral reef ecosystems are increasingly subject to severe, large-scale disturbances caused by climate change (e.g., coral bleaching) and other more direct anthropogenic impacts. Many of these disturbances cause coral loss and corresponding changes in habitat structure, which has further important effects on abundance and diversity of coral reef fishes. Declines in the abundance and diversity of coral reef fishes are of considerable concern, given the potential loss of ecosystem function. This study explored the effects of coral loss, recorded in studies conducted throughout the world, on the diversity of fishes and also on individual responses of fishes within different functional groups. Extensive (>60%) coral loss almost invariably led to declines in fish diversity. Moreover, most fishes declined in abundance following acute disturbances that caused >10% declines in local coral cover. Response diversity, which is considered critical in maintaining ecosystem function and promoting resilience, was very low for corallivores, but was much higher for herbivores, omnivores and carnivores. Sustained and ongoing climate change thus poses a significant threat to coral reef ecosystems and diversity hotspots are no less susceptible to projected changes in diversity and function. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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1022 KiB

Open AccessReview

Novel Genetic Diversity Through Somatic Mutations: Fuel for Adaptation of Reef Corals?

by Madeleine J. H. Van Oppen, Petra Souter, Emily J. Howells, Andrew Heyward and Ray Berkelmans

Diversity 2011, 3(3), 405-423; https://doi.org/10.3390/d3030405 - 12 Aug 2011

Cited by 90 | Viewed by 15702

Abstract

Adaptation of reef corals to climate change is an issue of much debate, and often viewed as too slow a process to be of relevance over decadal time scales. This notion is based on the long sexual generation times typical for some coral [...] Read more.

Adaptation of reef corals to climate change is an issue of much debate, and often viewed as too slow a process to be of relevance over decadal time scales. This notion is based on the long sexual generation times typical for some coral species. However, the importance of somatic mutations during asexual reproduction and growth on evolution and adaptation (i.e., cell lineage selection) is rarely considered. Here we review the existing literature on cell lineage selection and show that the scope for somatic mutations to arise in the coral animal and associated Symbiodinium is large. For example, we estimate that ~100 million somatic mutations can arise within a branching Acropora coral colony of average size. Similarly, the large population sizes and rapid turn-over times of in hospite Symbiodinium likely result in considerable numbers of somatic mutations. While the fate of new mutations depends on many factors, including ploidy level and force and direction of selection, we argue that they likely play a key role in the evolution of reef corals. Full article

(This article belongs to the Special Issue Coral Reef Diversity: Climate Change and Coral Reef Degradation)

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