Coral Reef Fish Diversity Research Articles

The distribution of coral reef fish biodiversity on Bontosua Island, Spermonde Archipelago, South Sulawesi Province

Background: Bontosua Island, located in the Spermonde Archipelago, is one of the strategic and historical islands in the region. The island plays a vital role in ecosystem conservation efforts by the local community, who are committed to preserving their natural environment. With dynamic ecosystem conditions, it is essential to understand the seabed cover and biodiversity on the island to support more effective conservation efforts. Methods: This study was conducted from March to September 2022 to mark the seabed cover of Bontosua Island and understand the relationships between coral reef fish species and the ecosystem. The method used was a stationary visual census, followed by descriptive analysis and one-way ANOVA to assess the biodiversity and diversity of coral reefs. Findings: The results showed a total of 1,306 coral reef fish from 9 families with 63 species identified, including the families Chaetodontidae, Serranidae, Lutjanidae, Haemulidae, Lethrinidae, Scaridae, Acanthuridae, and Siganidae. The families with the highest citations were Scaridae, Acanthuridae, and Siganidae. The highest coral reef fish were found in the north, west, and southwest of the island, where live coral areas are more dominant. Conclusion: This study shows that Bontosua Island has significant coral reef diversity, and certain areas, such as the north and southwest sides, have higher reported fish. These findings indicate the importance of these areas in conservation efforts. Novelty/Originality: This study provides a comprehensive picture of the seabed cover and coral reef fish diversity in Bontosua Island, which has yet to be widely discussed in previous studies. These findings provide a scientific basis for more targeted conservation strategies and help improve understanding of the dynamics of coral reef ecosystems in the Spermonde Islands.. Novelty/Originality of this article: This study proposes developing a community-based coral reef monitoring system that integrates local knowledge with digital mapping technology, aiming to increase the effectiveness of conservation and management efforts of marine resources on small islands.

Other faunas, coral rubbles, and soft coral covers are important predictors of coral reef fish diversity, abundance, and biomass

Other faunas, coral rubbles, and soft coral covers are important predictors of coral reef fish diversity, abundance, and biomass

Reef Fish Biodiversity at Different Depths in Tunda Island, Banten Province, Indonesia

Reef composition and diversity of coral reef fishes play an essential role in the ecosystem. The reef fish diversity is a crucial indicator of the health level of coral reef ecosystems. The benefit of fish diversity in coral reef ecosystems is to describe ecological services. This research intended to determine reef fish diversity among stations at different depths, consisting of shallow water and reef slope. Research sampling was done in July 2018 and July 2019 in Tunda Island waters at eight stations billowing the coral distribution pattern. Collected data of reef fishes were by using Underwater Visual Census (UVC) on Belt Transects Method at 250 m2 transect area (50 meters of length and 2.5 m on either side). The result showed 69 reef fishes in shallow water and 67 species on the reef slope. The total of fish species ware from 13 families consisting of Acanthuridae, Apogonidae, Blenniidae, Chaetodontidae, Ephippidae, Haemulidae, Labridae, Lutjanidae, Nemipteridae, Pomacentridae, Pseudochromidae, Scaridae and Serranidae. The community services structure of coral reef fishes is included in the moderate community stability category with an H’ value ranging from 1.19-1.60 in shallow water and 1.23-1.44 at reef slope, respectively. Diversity in coral reef fish communities might be associated with species' spatial distribution over the reef habitat's physical structure, but these patterns could be highly scale-dependent. In general, it could be said that the higher the coral reef diversity, the higher the reef fish diversity.

Biak and Wakatobi reefs are the two hottest hotspots of coral reef fish diversity and abundance in the Indonesian Archipelago

The Indonesian Archipelago has a very complex geological history, along with equatorial warm sea temperature, resulting in diverse types of coral reefs and high diversity of coral reef fish. Many livelihoods of the coastal community are dependent on coral reef fisheries. The present study aimed to determine which region and location in the Indonesian Archipelago has the most diverse and abundant coral reef fish. The archipelago was divided into four regions: the Indian Ocean, Sunda Shelf, Wallacea, and the Pacific Ocean. Data were obtained from a national coral reef monitoring program of the Indonesian Research Center for Oceanography (RCO)-the National Board for Research and Innovation (BRIN). The reef fish data were collected using the underwater visual census method, from 321 belt transects on 24 locations (districts) across the archipelago. The results show that coral reef fish diversity of the Pacific region was the highest across the archipelago for all three trophic levels, i.e., corallivore, herbivore, and carnivore fish. The Pacific Ocean region also had the highest fish abundance for the three trophic levels. Comparison among locations revealed that the best ten locations in reef fish diversity and abundance were Sabang, Mentawai, Makassar, Selayar, Buton, Luwuk, Ternate, Raja Ampat, Biak, and Wakatobi. Wakatobi reefs showed their supremacy in carnivore fish diversity and abundance, while Biak reefs were the best in herbivore fish. The abundance of corallivore fish was also considerably high in Sabang reefs, but it is still lower than in Raja Ampat, Biak, and Wakatobi reefs. These results provide empirical evidence that the coral reefs of Wakatobi and Biak are the hottest hotspots of coral reef fish diversity and abundance in the Indonesian Archipelago.

Species diversity of coral reef fishes around the West Island of Sanya City, South China Sea, based on environmental DNA.

West Island is the second largest island in the Hainan Province, China and its surrounding sea area has a well-preserved coral reef ecosystem and high species diversity of coral reef fishes. Undoubtedly, coral reef fishes and coral reefs have complex symbiotic relationships and fish species diversity should reflect the healthy status of coral reef ecosystems. Environmental DNA (eDNA) is a useful and sensitive tool to detect fish species and causes less environmental damage than traditional fish survey methods. This paper investigated coral reef fish species of West Island, Hainan Province, China, based on eDNA and provided scientific data for understanding and protection of the coral reef ecosystem of the South China Sea. The sea area surrounding West Island is the most important component of the coral reef ecosystem in the northern part of the South China Sea, which is also an essential part of the largest National Coral Reef Reserve in China. However, complete data of fish species distributed in this region have been a long-term gap. This study provides information on 41 fish species belonging to 28 genera, 16 families and three orders in this sea area and is the first complete record of coral reef fishes surrounding the West Island. In addition, the information of Molecular Operational Taxonomic Units (MOTUs) for taxon identification were also provided and it could contribute to building specific eDNA taxonomy database of coral reef fishes of the South China Sea. The study includes three datasets, with aspects of fish taxon-occurrences, MOTUs sequences and information of environmental indicators surrounding West Island, Hainan Province, China. The "fish taxon occurrences" dataset presents records involving taxonomic, distribution, habitat condition, latitude and longitude of 41 coral reef fish species detected, based on eDNA, the "MOTUs sequences" dataset provides MOTUs sequences and their abundance of 31 species detected and the "information of environmental indicators" dataset presents records of transparency, temperature, water pressure, dissolved oxygen, electrical conductivity, hydrogen and redox potential measured from five sampling localities.

Diversity of Coral Reef Fishes in the Western Indian Ocean: Implications for Conservation

Communities of coral reef fishes are changing due to global warming and overfishing. To understand these changes and inform conservation, knowledge of species diversity and distributions is needed. The western Indian Ocean (WIO) contains the second highest coral reef biodiversity hotspot globally, yet a detailed analysis of the diversity of coral reef fishes is lacking. This study developed a timed visual census method and recorded 356 species from 19 families across four countries in the WIO to examine patterns in species diversity. Species richness and composition differed most between the island countries of Madagascar and Comoros and both these locations differed from locations in Tanzania and Mozambique which were similar. These three regional groupings helped define WIO ecoregions for conservation planning. The highest species richness was found in Tanzania and Mozambique, and the lowest and most different species composition was found in Comoros. Biogeography explains these differences with naturally lower species diversity expected from the small, oceanic, and isolated islands of Comoros. Present day ocean currents maintain these diversity patterns and help explain the species composition in northeast Madagascar. Species distributions were driven by 46 of the 356 species; these provide guidance on important species for ongoing monitoring. The results provide a benchmark for testing future changes in reef fish species richness.

Environmental DNA in a global biodiversity hotspot: Lessons from coral reef fish diversity across the Indonesian archipelago

AbstractIndonesia is the heart of the Coral Triangle, the world’s most diverse marine ecosystem. Preserving the biological and economic value of this marine biodiversity requires efficient and economical ecosystem monitoring, yet our understanding of marine biodiversity in this region remains limited. This study uses environmental DNA (eDNA) to survey fish communities across a well‐documented biodiversity gradient in Indonesia. A total of 6,608,693 sequence reads of MiFish12SrRNA from 39 sites spanning seven regions of Indonesia revealed 1099 fish amplified sequence variants (ASVs), 80.4% of which could be identified to species. Regional fish diversity broadly conformed to expectations, with the highest fish biodiversity in Raja Ampat and lowest in Western Indonesia. Similarly, zeta diversity analysis showed greater community turnover in higher diversity reefs of Eastern Indonesia and greater community similarity in low diversity regions of Western Indonesia. However, despite a twofold difference in fish diversity between Eastern and Western Indonesia, mean ASVs recovered per 1‐L seawater was relatively similar across all regions. Moreover, although ASV recovery from individual seawater samples saturated, ASV recovery did not saturate at the site or region level, indicating that sampling/sequencing efforts employed in lower diversity ecosystems are insufficient for biodiversity hotspots like the Coral Triangle. Despite these limitations, eDNA substantially increased (36.3%–84.1%; mean 57.1%) the number of fish species recorded during intensive visual surveys, adding pelagic (tuna, jacks, scads, mackerels), nocturnal (soldierfish, lanternfish), and crevice‐dwelling species (eels, blennies, gobies) that are difficult to document in visual surveys. Results demonstrate the added value of eDNA in biodiversity hotspots like the Coral Triangle and highlight the need for research to understand how best to sample eDNA in high diversity regions to deliver on the promise of eDNA as a tool to monitor marine biodiversity effectively and efficiently.

An assessment of small islands coral cover and coral-reef fish diversity at Oba Sub-district, Halmahera Island

Study on the percentage of coral cover four small islands of Oba Sub-district, Halmahera Island of North Maluku Utara Province was carried out in April 2021.The four small islands of Oba Sub-district studied are Woda Island, Raja Island, Tamin Island, and Guratu Island. The study applied systematic sampling method that included collecting coral reef data using UPT (Underwater Photo Transect) method and coral fish data collection using visual census method. Study results showed that live coral coverage of reefs on the four small islands of Oba Sub-district had the highest value of 5.415% and the lowest value of 4.29%. There was positive relationship between coral growth form diversity and fish diversity. High diversity of coral growth forms was significantly related to high diversity of target reef fish.

Impact of marine protected areas on economical important coral reef fish communities: An evaluation of the biological monitoring of coral reef fish in Anambas Islands, Indonesia

Abstract. Putra RD, Siringiringo RM, Suryanti A, Sari NWP, Sinaga M, Hidayati NV, Hukom FD, Abrar M, Makatipu PC, Sianturi R, Ilham Y. 2021. Impact of marine protected areas on economical important coral reef fish communities: An evaluation of the biological monitoring of coral reef fish in Anambas Islands, Indonesia. Biodiversitas 22: 4169-4181. The use of Marine Protected Areas (MPAs) is the core strategy to reduce the impact of the anthropogenic stressor on marine fisheries, especially in reducing the overexploitation of fisheries resources and destructive fishing in which this plays a significant role in the conservation of marine biodiversity and populations. We conducted a study over 4 years to evaluate and assess the impact of MPAs on economically important reef fish in the Anambas Islands. We compared density, size, biomass, and diversity indices from the seven families of coral reef fish (Acanthuridae, Haemulidae, Lethrinidae, Lutjanidae, Scaridae, Siganidae, and Serranidae) using Underwater Visual Census (UVC) with a total of 12 MPAs stations (70-m transect). Multivariate analysis of variance (MANOVA) was used to evaluate and assess reserve protection on the coral reef fish, and several ecological indices were used to compare the potential change of economically coral reef fish diversity. We also measured the rate of change in coral cover to identify the effectiveness of the MPAs. After 4 years of studies, our result showed that there was an increase of economical reefs. Fish diversity, density, and biomass increased by 244%, 257%, and 179% respectively. There was no significant difference in the rate of coral cover change among MPAs stations. Economical coral reef fish in Anambas Islands were restored in marine reserve overtimes after fisheries restriction protection, but this does not change the rate of coral cover through time. In addition, the government managed and increased community awareness that significantly influenced decreasing destructive fishing practices and overexploited reef fish species in Anambas Islands but no change in coral cover. The MPAs environmental condition and natural disturbance, including thermal stress and high sedimentation, play a key role in coral cover recovery besides fisheries restriction in the MPAs area.

Planktivores as trophic drivers of global coral reef fish diversity patterns

One of the most prominent features of life on Earth is the uneven number of species across large spatial scales. Despite being inherently linked to energetic constraints, these gradients in species richness distribution have rarely been examined from a trophic perspective. Here we dissect the global diversity of over 3,600 coral reef fishes to reveal patterns across major trophic groups. By analyzing multiple nested spatial scales, we show that planktivores contribute disproportionally to the formation of the Indo-Australian Archipelago (IAA) marine biodiversity hotspot. Besides being "hotter" at the hotspot, planktivorous fishes display the steepest decline in species numbers with distance from the IAA when compared to other trophic groups. Surprisingly, we did not detect differences in diversification, transition, and dispersal rates in extant species phylogenies that would explain this remarkable gradient in planktivorous fish richness. Thus, we identify two potential complementary drivers for this pattern. First, exceptional levels of partitioning among planktivorous coral reef fishes were driven by temporally stable oceanographic conditions and abundant planktonic resources in the IAA. Second, extinctions of planktivores outside the IAA have been particularly pronounced during Quaternary climate fluctuations. Overall, our results highlight trophic ecology as an important component of global species richness gradients.

Inventory of commercially important coral reef fishes in Tawi-Tawi Islands, Southern Philippines: The Heart of the Coral Triangle

Tawi-Tawi, Southern Philippines, which has over 300 islands and huge reef systems, is geographically located at the heart of the Coral Triangle, the global center of coral reef biodiversity. In this study, we conducted an inventory survey of market fishes in Tawi-Tawi from October 2015 to December 2018. We considered 11 major commercially important coral reef fishes, namely, surgeonfish (family Acanthuridae), parrotfish (subfamily Scarinae, family Labridae), snapper (family Lutjanidae), grouper (subfamily Epinephelinae, family Serranidae), sweetlips (family Haemulidae), goatfish (family Mullidae), emperor (family Lethrinidae), triggerfish (family Balistidae), coral bream (family Nemipteridae except genus Nemipterus), fusilier (family Caesionidae) and rabbitfish (family Siganidae). We further compared the results with published reports from Palawan and Panay Island which are also located along the Sulu Sea, the region with the highest coral reef fish diversity in the Philippines. Overall, we recorded a total of 266 species of reef fish in Tawi-Tawi with Epinephelinae (48 species), Lutjanidae (40 species) and Acanthuridae (33 species) as the most speciose groups. Further investigation showed that the average relative abundance of the three most abundant species in each family/subfamily is about 64.5% (range, 51.6% for Acanthuridae to 87.6% for Balistidae) of their respective groups. Based on the status assessment of the International Union for Conservation of Nature, one species (Scarus hypselopterus) was considered as Near Threatened (NT), four species (Bolbometopon muricatum, Epinephelus fuscoguttatus, Epinephelus polyphekadion and Plectropomus areolatus) as Vulnerable (VU) while the majority were considered as Least Concern (LC). The number of species recorded in Tawi-Tawi was much higher than in Palawan and Panay Island which had a total of only 159 species and 139 species, respectively. Moreover, Tawi-Tawi had about five times more unique species than either of the two other areas. Our study indicates the importance of the reefs of Tawi-Tawi and the Sulu Archipelago in general as the richest in the Philippines in terms of commercially important coral reef fish species diversity. Various factors that explain the high diversity of reef fishes on the reefs of Tawi-Tawi and the importance of conserving these valuable ecosystems are discussed.

Assessing the utility of eDNA as a tool to survey reef-fish communities in the Red Sea

Relatively small volumes of water may contain sufficient environmental DNA (eDNA) to detect target aquatic organisms via genetic sequencing. We therefore assessed the utility of eDNA to document the diversity of coral reef fishes in the central Red Sea. DNA from seawater samples was extracted, amplified using fish-specific 16S mitochondrial DNA primers, and sequenced using a metabarcoding workflow. DNA sequences were assigned to taxa using available genetic repositories or custom genetic databases generated from reference fishes. Our approach revealed a diversity of conspicuous, cryptobenthic, and commercially relevant reef fish at the genus level, with select genera in the family Labridae over-represented. Our approach, however, failed to capture a significant fraction of the fish fauna known to inhabit the Red Sea, which we attribute to limited spatial sampling, amplification stochasticity, and an apparent lack of sequencing depth. Given an increase in fish species descriptions, completeness of taxonomic checklists, and improvement in species-level assignment with custom genetic databases as shown here, we suggest that the Red Sea region may be ideal for further testing of the eDNA approach.

Multi‐component β‐diversity approach reveals conservation dilemma between species and functions of coral reef fishes

AbstractAimWe applied a multicomponent approach based on the decomposition of taxonomic (both presence–absence and abundance) and functional beta diversity to determine the influence of ecological factors in shaping spatial distribution diversity of coral reef fishes, and the implications for conservation decisions.LocationLagoons of ten atolls characterized by low human pressure but with contrasted geomorphology in the Tuamotu Archipelago, French Polynesia.MethodsWe computed beta diversities and their partitioning components, both at local (inter‐transect, from 200 m to 10 km) and large (among atolls, from 22 to 350 km) spatial scales. Null models were applied to test whether the observed beta diversity differed from random expectation. Multiple generalized dissimilarity models were run to test which environmental factors were the best predictors of observed beta diversities.ResultsBeta diversity was indistinguishable from randomness at both spatial scales. Species remained generally interchangeable among transects within an atoll and to some extent among atolls. However, strong deviance explained by models showed that the number of species, the number of individuals and functional traits present in transects and atolls were determined by deterministic factors (i.e. environmental factors). Modelling each beta diversity component separately also revealed partial mismatch among atolls and among species and functional dissimilarities. The influence of environmental variables strongly varied among atolls, species and functional dissimilarities.Main conclusionsBy revealing the spatial scaling of ecological factors and partial congruence among species and functional diversity, assessment of beta diversity provides insight into conservation planning. Our results support the idea that conservation planning applied to protect taxonomic diversity cannot be fully extended to functional diversity. We have addressed the dilemma of which diversity component should be favoured in conservation strategies.

Climate-driven coral reorganisation influences aggressive behaviour in juvenile coral-reef fishes

Globally, habitat degradation is altering the abundance and diversity of species in a variety of ecosystems. This study aimed to determine how habitat degradation, in terms of changing coral composition under climate change, affected abundance, species richness and aggressive behaviour of juveniles of three damselfishes (Pomacentrus moluccensis, P. amboinensis and Dischistodus perspicillatus, in order of decreasing reliance on coral). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced coral bleaching, and reefs with more bleaching-robust coral taxa, thereby simulating the likely future of coral reefs under a warming climate. Fish communities were allowed to establish naturally on the reefs during the summer recruitment period. Climate-robust reefs had lower total species richness of coral-reef fishes than climate-vulnerable reefs, but total fish abundance was not significantly different between reef types (pooled across all species and life-history stages). The nature of aggressive interactions, measured as the number of aggressive chases, varied according to coral composition; on climate-robust reefs, juveniles used the substratum less often to avoid aggression from competitors, and interspecific aggression became relatively more frequent than intraspecific aggression for juveniles of the coral-obligate P. moluccensis. This study highlights the importance of coral composition as a determinant of behaviour and diversity of coral-reef fishes.

First comprehensive list of the coral reef fishes of Tunku Abdul Rahman Park, Sabah, Malaysia (Borneo)

A 573 species-long checklist of the fishes in this 50 km2 tropical marine park was created predominantly by combining an unpublished scientific survey from 1992 with a hobbyist’s large photograph collection from between 2006 and 2009. Of the Indo-Pacific region’s coral reef-associated fish species, 15.2% are found here. Drawn from 83 families, the most speciose are Pomacentridae (71), Gobiidae (68) and Lab-ridae (55). A regression formula using the Coral reef Fish Diversity Index (CFDI) for species seen in 1992 suggests the park hosts 464 species, compared with the CFDI-based estimate of 495 based only on da-ta collected between 2006 and 2009, and 596 for the combined Index. With only 62% of the Index’s species seen both in the earlier and later lists, the utility of the CFDI is questionable at a site or over a time-span like this.

Additive Partitioning of Coral Reef Fish Diversity across Hierarchical Spatial Scales throughout the Caribbean

There is an increasing need to examine regional patterns of diversity in coral-reef systems since their biodiversity is declining globally. In this sense, additive partitioning might be useful since it quantifies the contribution of alpha and beta to total diversity across different scales. We applied this approach using an unbalanced design across four hierarchical scales (80 sites, 22 subregions, six ecoregions, and the Caribbean basin). Reef-fish species were compiled from the Reef Environmental Education Foundation (REEF) database and distributions were confirmed with published data. Permutation tests were used to compare observed values to those expected by chance. The primary objective was to identify patterns of reef-fish diversity across multiple spatial scales under different scenarios, examining factors such as fisheries and demographic connectivity. Total diversity at the Caribbean scale was attributed to β-diversity (nearly 62% of the species), with the highest β-diversity at the site scale. -diversity was higher than expected by chance in all scenarios and at all studied scales. This suggests that fish assemblages are more homogenous than expected, particularly at the ecoregion scale. Within each ecoregion, diversity was mainly attributed to alpha, except for the Southern ecoregion where there was a greater difference in species among sites. β-components were lower than expected in all ecoregions, indicating that fishes within each ecoregion are a subsample of the same species pool. The scenario involving the effects of fisheries showed a shift in dominance for β-diversity from regions to subregions, with no major changes to the diversity patterns. In contrast, demographic connectivity partially explained the diversity pattern. β-components were low within connectivity regions and higher than expected by chance when comparing between them. Our results highlight the importance of ecoregions as a spatial scale to conserve local and regional coral reef-fish diversity.

Additive Diversity Partitioning of Fish in a Caribbean Coral Reef Undergoing Shift Transition

Shift transitions in dominance on coral reefs from hard coral cover to fleshy macroalgae are having negative effects on Caribbean coral reef communities. Data on spatiotemporal changes in biodiversity during these modifications are important for decision support for coral reef biodiversity protection. The main objective of this study is to detect the spatiotemporal patterns of coral reef fish diversity during this transition using additive diversity-partitioning analysis. We examined α, β and γ fish diversity from 2000 to 2010, during which time a shift transition occurred at Mahahual Reef, located in Quintana Roo, Mexico. Data on coral reef fish and benthic communities were obtained from 12 transects per geomorphological unit (GU) in two GUs (reef slope and terrace) over six years (2000, 2005, 2006, 2007, 2008, 2010). Spatial analysis within and between the GUs indicated that the γ-diversity was primarily related to higher β-diversity. Throughout the six study years, there were losses of α, β and γ-diversity associated spatially with the shallow (reef slope) and deeper (reef terrace) GUs and temporally with the transition in cover from mound corals to fleshy macroalgae and boulder corals. Despite a drastic reduction in the number of species over time, β-diversity continues to be the highest component of γ-diversity. The shift transition had a negative effect on α, β and γ-diversity, primarily by impacting rare species, leading a group of small and less vulnerable fish species to become common and an important group of rare species to become locally extinct. The maintenance of fish heterogeneity (β-diversity) over time may imply the abetment of vulnerability in the face of local and global changes.

Wave-induced abiotic stress shapes phenotypic diversity in a coral reef fish across a geographical cline

While morphological variation across geographical clines has been well documented, it is often unclear whether such changes enhance individual performance to local environments. We examined whether the damselfish Acanthochromis polyacanthus display functional changes in swimming phenotype across a 40-km cline in wave-driven water motion on the Great Barrier Reef, Australia. A. polyacanthus populations displayed strong intraspecific variation in swimming morphology and performance that matched local levels of water motion: individuals on reefs subject to high water motion displayed higher aspect-ratio fins and faster swimming speeds than conspecifics on sheltered reefs. Remarkably, intraspecific variation within A. polyacanthus spanned over half the diversity seen among closely related damselfish species from the same region. We find that local selection driven by wave-induced abiotic stress is an overarching ecological mechanism shaping the inter- and intraspecific locomotor diversity of coral reef fishes.

Suspended sediment prolongs larval development in a coral reef fish

Increasing sediment input into coastal environments is having a profound influence on shallow marine habitats and associated species. Coral reef ecosystems appear to be particularly sensitive, with increased sediment deposition and re-suspension being associated with declines in the abundance and diversity of coral reef fishes. While recent research has demonstrated that suspended sediment can have negative impacts on post-settlement coral reef fishes, its effect on larval development has not been investigated. In this study, we tested the effects of different levels of suspended sediment on larval growth and development time in Amphiprion percula, a coral reef damselfish. Larvae were subjected to four experimental concentrations of suspended sediment spanning the range found around coastal coral reefs (0-45 mg l(-1)). Larval duration was significantly longer in all sediment treatments (12 days) compared with the average larval duration in the control treatment (11 days). Approximately 75% of the fish in the control had settled by day 11, compared with only 40-46% among the sediment treatments. In the highest sediment treatment, some individuals had a larval duration twice that of the median duration in the control treatment. Unexpectedly, in the low sediment treatment, fish at settlement were significantly longer and heavier compared with fish in the other treatments, suggesting delayed development was independent of individual condition. A sediment-induced extension of the pelagic larval stage could significantly reduce numbers of larvae competent to settle and, in turn, have major effects on adult population dynamics.

Increasing suspended sediment reduces foraging, growth and condition of a planktivorous damselfish

Increasing sediment inputs into many coastal marine environments are having a profound influence on shallow marine habitats and their constituent species. Coral reef habitats appear to be particularly sensitive, with increased sediment deposition and turbidity regimes associated with declines in the abundance and diversity of coral reef fishes due to an indirect effect of habitat loss. The direct causes of these declines are largely unknown. In this study we tested the hypothesis that suspended sediment can negatively affect the foraging efficiency, nutritional state and survival of the planktivorous coral reef damselfish, Acanthochromis polyacanthus. Food acquisition, growth rate and body condition were measured in juvenile A. polyacanthus subjected to four experimental concentrations of suspended sediment (up to 180mgl−1; 30 NTU). There was a clear effect of suspended sediment on food acquisition. Fish took longer to find food and consumed less of the food provided with increasing sediment. The decline in food acquisition was associated with a significant reduction in juvenile growth and body condition. Fish reared in the medium and high sediment treatments increased in size by less than half the growth rates observed in the control group. Fish held in the control and low sediment treatment had double the surface area of hepatocyte vacuoles in the liver (a proxy for lipid storage) than the fish held in the medium and high sediment treatments. Suspended sediment also caused a significant increase in mortality of the juvenile fish in the high sediment treatment. Mortality reached almost 50% in the high sediment treatment, with no mortality in the control and less than 10% in the intermediate treatments. This study underscores the need to ameliorate increasing suspended sediment in inshore waters due to its potential impact on the growth and survival of planktivorous organisms, which form a vital trophic link between secondary production and fish biomass.