Peces criptobentónicos de arrecifes coralinos en el Parque Nacional Archipiélago de Los Roques, Caribe de Venezuela

Habitat structure is known to influence the abundance of fishes on temperate reefs. Biotic interactions play a major role in determining the distribution and abundance of species. The significance of these forces in affecting the abundance of fishes may hinge on the presence of organisms that either create or alter habitat. On temperate reefs, for example, macroalgae are considered autogenic ecosystem engineers because they control resource availability to other species through their physical structure and provide much of the structure used by fish. On both coral and temperate reefs, small cryptic reef fishes may comprise up to half of the fish numbers and constitute a diverse community containing many specialized species. Small cryptic fishes (<100 mm total length) may be responsible for the passage of 57% of the energy flow and constitute ca. 35% of the overall reef fish biomass on coral reefs. These benthic fish exploit restricted habitats where food and shelter are obtained in, or in relation to, conditions of substrate complexity and/or restricted living space. A range of mechanisms has been proposed to account for the diversity and the abundance of small fishes: (1) lifehistory strategies that promote short generation times, (2) habitat associations and behaviour that reduce predation and (3) resource partitioning that allows small species to coexist with larger competitors. Despite their abundance and potential importance within reef systems, little is known of the community ecology of cryptic fishes. Specifically on habitat associations many theories suggested a not clear direction on this subject. My research contributes to the development of marine fish ecology by addressing the effects of habitat characteristics upon distribution of cryptobenthic fish assemblages. My focus was on the important shallow, coastal ecosystems that often serve as nursery habitat for many fish and where different type of habitat is likely to both play important roles in organism distribution and survival. My research included three related studies: (1) identification of structuring forces on cryptic fish assemblages, such as physical and biological forcing; (2) macroalgae as potential tools for cryptic fish and identification of different habitat feature that could explain cryptic fish assemblages distribution; (3) canopy formers loss: consequences on cryptic fish and relationship with benthos modifications. I found that: (1) cryptic fish assemblages differ between landward and seaward sides of coastal breakwaters in Adriatic Sea. These differences are explained by 50% of the habitat characteristics on two sides, mainly due to presence of the Codium fragile, sand and oyster assemblages. Microhabitat structure influence cryptic fish assemblages. (2) Different habitat support different cryptic fish assemblages. High heterogeneity on benthic assemblages reflect different fish assemblages. Biogenic components that explain different and diverse cryptic fish assemblages are: anemonia bed, mussel bed, macroalgal stands and Cystoseira barbata, as canopy formers. (3) Canopy forming loss is not relevant in structuring directly cryptic fish assemblages. A removal of canopy forming algae did not affect the structure of cryptic fish assemblages. Canopy formers algae on Conero cliff, does not seem to act as structuring force, probably due to its regressive status. In conclusion, cryptic fish have been shown to have species-specific associations with habitat features relating to the biological and non biological components afforded by fish. Canopy formers algae do not explain cryptic fish assemblages distribution and the results of this study and information from the literature (both from the Mediterranean Sea and elsewhere) show that there are no univocal responses of fish assemblages. Further exanimations on an non regressive status of Cystoseira canopy habitat are needed to define and evaluate the relationship between canopy formers and fish on Mediterranean sea.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 537:205-215 (2015) - DOI: https://doi.org/10.3354/meps11457 Disturbance and recolonisation by small reef fishes: the role of local movement versus recruitment C. D. Lefèvre, D. R. Bellwood* Australian Research Council Centre of Excellence for Coral Reef Studies, and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia *Corresponding author: David.Bellwood@jcu.edu.au ABSTRACT: An understanding of the responses of fish assemblages to disturbance events is central to the ongoing management of coral reef habitats. To understand the factors shaping patterns of recovery, we examined the recolonisation of populations of small cryptic fishes following experimental removal. After removing resident cryptobenthic reef fish assemblages from otherwise undisturbed coral rubble areas we observed a rapid recovery. Within 8 wk, fish assemblages were similar to their pre-removal structure in terms of fish abundance, species diversity and species richness. However, species differed in the speed and nature of their return. The return of larger species (e.g. Parapercis cylindrica) was largely mediated by recolonisation, while smaller, less mobile species (e.g. Eviota spp. and Enneapterygius spp.) relied primarily on recruitment, presumably from the plankton. Although patterns of settlement and recruitment are ultimately responsible for replenishment of local populations, our data suggest that mobility may play a strong role in restoring fish assemblages in the short term. These results have significant implications for our understanding of the response of coral reef ecosystems to disturbance events and highlight the importance of selecting appropriate criteria for evaluating reef resilience. If these short-lived fish species are a model for their longer-lived counterparts, it suggests that local responses to disturbance will depend largely on the mobility of species. Identifying both the recruitment and movement abilities of species will be critical in understanding the ability of fish assemblages to recover after disturbance. KEY WORDS: Coral reefs · Cryptobenthic reef fish · Assemblage · Habitat disturbance · Postsettlement movement · Resilience · Size at settlement Full text in pdf format PreviousNextCite this article as: Lefèvre CD, Bellwood DR (2015) Disturbance and recolonisation by small reef fishes: the role of local movement versus recruitment. Mar Ecol Prog Ser 537:205-215. https://doi.org/10.3354/meps11457 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 537. Online publication date: October 14, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Community Structure of Coral Reef Fishes: Are the Patterns More Than Those Expected by Chance?

Habitats diversity and MPA regulations are insufficient in promoting healthy coral reef fish assemblages in Punta Francés National Park (Cuba)

Ecosystem monitoring for ecosystem‐based management: using a polycentric approach to balance information trade‐offs

Globally, fish are being removed from our oceans at unsustainable rates. This is particularly true for coral reef fish, which, in addition to overfishing, are also under threat from global warming, ocean acidification, and pollution. Current conservation strategies for coral reef fisheries either indirectly control the amount of fish caught through restrictions on fishing effort, techniques, and areas, or directly limit fish catch using quotas for each fishery. However, to ensure that these conservation strategies function to their utmost potential, we need to identify the fishing techniques and seascape characteristics that have the most impact on coral reefs and their associated fish assemblages. This thesis used a field study on a group of remote Pacific atolls to establish how fishing using traditional techniques for food, not profit (subsistence fishing) affected coral reef fish assemblages. I demonstrate that subsistence fishing may be an effective way of providing food for small island communities, while also maintaining pristine reef fish assemblages. This thesis also investigated how connections in coastal seascapes affected crucial ecosystem functions on coral reefs. I show that connectivity can exert opposing effects on ecosystem functions, and that the distribution of fish and the ecosystem functions they provide may not align. I advocate that if marine spatial plans aim to incorporate ecosystem functions into their framework, they need to explicitly measure ecosystem function, rather than using proxies such as fish abundance. Finally, this thesis reports how the arrangement of mangroves and coral reefs in coastal seascapes varied globally, and how these differences affected the distribution of fish. I show that the configuration of coastal mangrove and coral reef seascapes, and their effects on fish, are correlated with tidal range, and I suggest that we cannot make global generalisations about the scale at which mangrove connections modify fish assemblages on coral reefs. This thesis makes direct recommendations on how to improve the conservation of coral reef fish. By endorsing low-impact fishing techniques and improving our understanding of seascape ecology, we can expect to improve conservation strategies for coral reefs, making them as practical and effective as possible.

Sediments are a ubiquitous feature of all coral reefs, yet our understanding of how they affect complex ecological processes on coral reefs is limited. Sediment in algal turfs has been shown to suppress herbivory by coral reef fishes on high-sediment, low-herbivory reef flats. Here, we investigate the role of sediment in suppressing herbivory across a depth gradient (reef base, crest and flat) by observing fish feeding following benthic sediment reductions. We found that sediment suppresses herbivory across all reef zones. Even slight reductions on the reef crest, which has 35 times less sediment than the reef flat, resulted in over 1800 more herbivore bites (h(-1) m(-2)). The Acanthuridae (surgeonfishes) were responsible for over 80 per cent of all bites observed, and on the reef crest and flat took over 1500 more bites (h(-1) m(-2)) when sediment load was reduced. These findings highlight the role of natural sediment loads in shaping coral reef herbivory and suggest that changes in benthic sediment loads could directly impair reef resilience.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 371:253-262 (2008) - DOI: https://doi.org/10.3354/meps07591 Descending to the twilight-zone: changes in coral reef fish assemblages along a depth gradient down to 65 m Eran Brokovich1,2,*, Shai Einbinder1,3, Nadav Shashar4,5, Moshe Kiflawi1,4, Salit Kark2 1The Interuniversity Institute for Marine Sciences at Eilat (IUI), Marine Twilight-Zone Research & Exploration (MTRX), PO Box 469, Eilat 88103, Israel 2The Biodiversity Research Group, Department of Evolution, Systematics and Ecology, The Institute of Life Sciences, The Hebrew University of Jerusalem, 91904, Israel 3Department of Evolution, Systematics and Ecology, The Institute of Life Sciences, The Hebrew University of Jerusalem, 91904, Israel 4Faculty of Life Sciences, Ben Gurion University, PO Box 653, Beer-Sheva, 84105, Israel 5Eilat Campus, Ben Gurion University, Hatmarim St., Eilat, 88000, Israel *Email: eran.brokovich@mail.huji.ac.il ABSTRACT: In contrast to the abundance of literature on the relationship between fish assemblages and habitat structure in the upper 30 m of coral reefs, the deeper (>40 m) parts of coral reefs are rarely studied. We examined changes in reef fish diversity and habitat structure along an increasing depth gradient, including the unknown deep reef. We ran visual and video transects along a substantial depth gradient (0 to 65 m) in the northern Red Sea and extended the known depth distribution for 48 reef species. We found a change in assemblage composition highly correlated to both the depth gradient and a reduction in the abundance of branching corals with depth. The number of reef fish species declined with depth and we also measured a high species turnover as measured by beta diversity (βt, βw) in the deep reef. This pattern is mainly due to the replacement of the abundant damselfishes in the shallow reef, which prey on zooplankton, by zooplanktivorous sea basses and wrasses in the deep reef. The steep reduction in branching corals, which most damselfishes use for cover, may be the main factor contributing to this change. We found a peak in species richness (alpha diversity) at 30 m, a peak in βw at 50 to 65 m, and peaks in βt at 30 to 50 m and 50 to 65 m. The 30 m depth stratum shows species of both shallow and deep assemblages generating a transition zone with characters of both deep and shallow habitats. The fish assemblage continues to change with depth, and future research will determine if there exists a depth threshold at which the assemblage will stabilize. KEY WORDS: Depth gradient · Deep reef fish · Gulf of Aqaba · Red Sea · Twilight zone Full text in pdf format Supplementary appendix PreviousNextCite this article as: Brokovich E, Einbinder S, Shashar N, Kiflawi M, Kark S (2008) Descending to the twilight-zone: changes in coral reef fish assemblages along a depth gradient down to 65 m. Mar Ecol Prog Ser 371:253-262. https://doi.org/10.3354/meps07591 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 371. Online publication date: November 19, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Spatial variability in habitat structure and heterogenic coral reef fish assemblages inside a small-scale marine reserve after a coral mass mortality event

Offshore natural banks in the Gulf of Mexico (GOM) are unique model systems for examining the mechanisms structuring reef fish communities due to their substantial geographic isolation, and the presence of replicate experimental units of both low (mid-shelf) and high coral diversity (shelf-edge) reef habitats. Here, we examined the species assemblage structure of juvenile and adult fishes at two mid-shelf reefs (Sonnier and Stetson Bank) and two shelf-edge reefs (East and West Flower Garden Banks) in the northwestern GOM to evaluate the relative importance of habitat (i.e. coral diversity) vs. recruitment in structuring resident fish assemblages. Visual reef fish surveys (n = 400) were conducted at the four coral reefs during two seasons, spring-early summer and late summer-fall in 2009 and 2010. Two depth zones were surveyed at each reef, representing the reef crest (15-23 m depth) and upper slope (23-30 m depth) habitats. Seasonal variability in recruitment to both mid-shelf and shelf-edge reefs was observed, with higher mean juvenile density and diversity (Hʹ) observed during the late season at all reefs in 2009 and all but Stetson in 2010, supporting an early fall recruitment peak. Likewise, considerable inter-annual variability in juvenile recruitment was observed, with significantly lower juvenile density and Hʹ observed at mid-shelf reefs in 2010 relative to 2009. Species diversity was strongly linked to coral diversity, with greater reef fish diversity consistently observed at shelf-edge relative to mid-shelf reefs. Observed differences in the composition of juvenile and adult assemblages at mid-shelf reefs suggest that reef fish communities at these reefs were more strongly influenced by post-settlement processes (e.g. juvenile mortality) than shelf-edge reefs, which may be a function of several limiting factors (e.g., predation, coral diversity, water quality). Results indicate that reef fish assemblages associated with mid-shelf and shelf-edge reefs in the northwestern GOM have sufficient stabilizing mechanisms in place to facilitate recovery from anomalous recruitment events and maintain consistent resident assemblages. The strong, reef type-specific differences in assemblage composition observed throughout the study indicate that mid-shelf and shelf-edge coral reef habitats may fill different functional roles for demersal fishes in the northwestern GOM.

Size-structural shifts reveal intensity of exploitation in coral reef fisheries

An influential paradigm in coral reef ecology is that fishing causes trophic cascades through reef fish assemblages, resulting in reduced herbivory and thus benthic phase shifts from coral to algal dominance. Few long‐term field tests exist of how fishing affects the trophic structure of coral reef fish assemblages, and how such changes affect the benthos. Alternatively, benthic change itself may drive the trophic structure of reef fish assemblages. Reef fish trophic structure and benthic cover were quantified almost annually from 1983 to 2014 at two small Philippine islands (Apo, Sumilon). At each island a No‐Take Marine Reserve (NTMR) site and a site open to subsistence reef fishing were monitored. Thirteen trophic groups were identified. Large planktivores often accounted for >50% of assemblage biomass. Significant NTMR effects were detected at each island for total fish biomass, but for only 2 of 13 trophic components: generalist large predators and large planktivores. Fishing‐induced changes in biomass of these components had no effect on live hard coral (HC) cover. In contrast, HC cover affected biomass of 11 of 13 trophic components significantly. Positive associations with HC cover were detected for total fish biomass, generalist large predators, piscivores, obligate coral feeders, large planktivores, and small planktivores. Negative associations with HC cover were detected for large benthic foragers, detritivores, excavators, scrapers, and sand feeders. These associations of fish biomass to HC cover were most clear when environmental disturbances (e.g., coral bleaching, typhoons) reduced HC cover, often quickly (1–2 yr), and when HC recovered, often slowly (5–10 yr). As HC cover changed, the biomass of 11 trophic components of the fish assemblage changed. Benthic and fish assemblages were distinct at all sites from the outset, remaining so for 31 yr, despite differences in fishing pressure and disturbance history. HC cover alone explained ~30% of the variability in reef fish trophic structure, whereas fishing alone explained 24%. Furthermore, HC cover affected more trophic groups more strongly than fishing. Management of coral reefs must include measures to maintain coral reef habitats, not just measures to reduce fishing by NTMRs.

Spatial variation and habitat preference of reef fish and gastropod assemblages from two coastal habitats in subtropical reef, Port Shelter, Hong Kong.

In response to the growing human population and our impacts on the environment, we design programs for conservation, restoration and rehabilitation to maintain and enhance productivity, biodiversity and ecosystem resilience. To ensure the greatest return on these investments, there is an implicit requirement for identifying disproportionately important species, processes and landscape elements as high-value targets for conservation and management. Connectivity is commonly favoured among these because it provides the mechanism for reserves to sustain exploited populations beyond their borders, and is critical for reversing the ecosystem impacts of trophic cascades. Few studies have, however, adopted a quantitative approach, like that provided under the framework of landscape ecology, to assess the value of connectivity in conservation. This conceptual division between the disciplines of conservation and landscape ecology must be bridged to better enable the management of healthy functioning ecosystems. This thesis used heterogeneous reef seascapes in Moreton Bay, Queensland, as a model system for examining the potential effect of connectivity in enhancing marine reserve performance. A positive effect of connectivity between mangroves and coral reefs was demonstrated on the performance of marine reserves, including effects on productivity, biodiversity and ecological resilience. This finding represents a critical first step in improving the integration of spatial ecology into conservation planning and assessment. This thesis then illustrates how neighbouring mangroves and seagrasses can exert different effects on reef fish assemblages and extends our current understanding of the role of connectivity in reef seascapes. This indicates that a reef’s position in the seascape can be of greater significance to the composition of fish assemblages than its area or complexity, and highlights the shortcoming of management approaches that focus solely on representing measures of habitat area, complexity or condition. Herbivorous fish play a key role in coral reef seascapes; by removing algae they promote coral growth and recruitment, and help to increase resilience. Habitat connectivity and reserves both influence herbivore populations and herbivory, but their potential interactive effects have not been investigated. This thesis shows that these factors can indeed exert synergistic effects on herbivore populations and grazing intensity, which facilitated a trophic cascade that reduced algal cover and enhanced coral recruitment and reef resilience on protected reefs near mangroves. The effects of reserves and connectivity for fish assemblages were then extended from a local to regional scale, by examining the potential interaction of these factors across the tropical and subtropical waters of the western Pacific Ocean. Habitat connectivity improved the performance of marine reserves across this region, and spatial variation in the magnitude of the reserve-connectivity interaction was explained by differences among reserves in the area of mangroves and reef, duration of mangrove inundation and distance to rivers. The management of heterogeneous inshore reef ecosystems as functional seascape units is considered necessary for preservation of critical interconnections among habitats. By further improving our understanding of seascape ecology and connectivity, and by incorporating this field of research into conservation ecology and decisionmaking, we should expect to have greater success in restoring exploited populations and the functioning of ecosystems.

Global coral reef ecosystems face various levels of disturbance pressure. Understanding the depth-structured variation in coral reef fish communities can help us to better grasp and predict the adaptive changes of the ecosystem under different stressors. This study applied eDNA metabarcoding technology to analyze the spatial distribution of the coral reef fish at various depths (0 m, 5 m, 10 m, 15 m, 20 m, 30 m, 40 m, 50 m, and 60 m) within the Xisha Islands of China. The results indicated that the eDNA technology detected a total of 213 amplicon sequence variants (ASVs), including 33 species that were not identified using traditional methods. Herbivorous fish generally dominated in relative abundance across different depths. Moreover, the similarity among depth groups was largely absent, and significant differences existed in fish assemblages across depth gradients, consistent with the unique depth preferences of fish microhabitats. Importantly, our findings revealed distinct depth-structured variation among different functional groups of coral reef fish. Large carnivorous fish initially increased and then decreased along the depth gradient from 0 to 60 m, with a turning point around 20 m, while large herbivorous fish displayed the opposite trend. Small carnivorous and small herbivorous fish consistently declined along the same depth gradient. Additionally, the Margalef index (D) and Function richness (FRic) both displayed a consistent downward trend with increasing depth, while the Shannon–Wiener index (H′), Pielou index (J′), Quadratic entropy (RaoQ), Functional dispersion (FDis), and Functional evenness (FEve) initially increased and then decreased, peaking around 20 m. This study revealed that eDNA metabarcoding is an effective tool for evaluating coral reef fish biodiversity, community composition, and spatial distribution. It enhances our understanding of distribution dynamics and offers valuable insights for coral reef conservation and restoration efforts.