1 Curtin University – Perth, Australia
Cryptobenthic fish are a crucial part of marine fauna assemblages and play an important role in ecosystem trophodynamics. An increasingly large body of research exists on the highly diverse cryptobenthic assemblages on coral and rocky reefs. While these are highly important habitats, they cover only a small percentage of shallow water substrates in the Indo-Pacific region. Shallow water is dominated by soft sediment habitats, which despite their omnipresence, remain largely unstudied. It is frequently assumed that soft sediment communities are depauperate in terms of cryptobenthic fish fauna, but limited research has been done to test this theory. Recent research shows that dive tourism focused on cryptobenthic fauna on soft sediment sites is worth more than USD $150 million/year, yet little is known about the diversity or abundance of the species responsible for creating thousands of sustainable jobs through tourism. Using UVC and roving diver surveys, we assessed the abundance and diversity of cryptobenthic assemblages on 20 soft sediment sites across Indonesia and Philippines. Surveys were done at two depths (6m, 16m) across three locations (Dauin, Lembeh Strait, north Bali). Additional site-specific data was collected on benthic cover and grain size morphology. Results showed a higher than expected diversity (> 130 species, excluding gobies and blennies), with some sites rivalling the diversity found on coral reef sites on the GBR. Significant differences were found between locations and sites, but not for depth. Benthic cover and grain size morphology only explained limited variation ( ˜11%) in assemblage composition. This suggests that unmeasured or larger scale processes may be influencing the assemblage composition at these locations. Roving diver surveys found 32%
more species than UVC transects, indicating that exclusively using UVC transects is insufficient to assess the diversity of cryptobenthic fishes. In light of their high ecological and economic value, the surprisingly high diversity combined with the low explanatory value of the habitat variables tested indicates that more research on soft sediment cryptobenthic fishes is urgently needed.
Microhabitat association of cryptobenthic gobies (family Gobiidae) in the Central Red
Sea
Emily Troyer ∗ 1, Michael Berumen 1
1 King Abdullah University of Science and Technology (KAUST) – King Abdullah University of Science and Technology Thuwal- Jeddah, Saudi Arabia 23955-6900, Saudi Arabia
Knowledge of biodiversity within an ecosystem is essential when trying to understand the function and importance of that ecosystem. A challenge when assessing biodiversity of reef habi- tats is cryptobenthic fishes, which encompass many groups that have close associations with the substrate. These fish can be behaviorally cryptic, by seeking refuge within the reef matrix, or visually cryptic, using cryptic coloration to match the surrounding habitat. These factors make visual surveys inadequate for sampling these fishes. One such group of cryptobenthic fishes are the gobies, family Gobiidae, which currently represent over 2000 species, although new species are continually being discovered. Gobies are often small (less than 5 cm), and many species will be associated with a very specific microhabitat type.Due to the understudied nature of the Red Sea, little is known about habitat preferences of gobies within the region. In order to determine the differences in goby community structure within the central Red Sea, fish were sampled at one reef using 1 m2 enclosed rotenone stations from three distinct microhabitats: hard coral, rubble, and sand. Following collection, specimens were photographed and sequenced using COI, to aid in species identification. Over 200 individuals were collected representing more than 30 species of goby. A rubble microhabitat was found to host the majority of collected fishes, followed by hard coral, then sand. These results provide essential baseline information about the ecology of understudied cryptobenthic fish which can be used in future large scale studies.
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Not just a flat face: the underappreciated role of blennies on coral reefs
Zoe Loffler ∗ 1, Andrew Hoey 1
1 ARC Centre of Excellence for Coral Reef Studies (CoralCoE) – ARC Centre of Excellence for Coral Reef StudiesJames Cook University TownsvilleQueensland 4811 Australia, Australia
Herbivorous fishes are widely accepted as being key players in preventing and reversing shifts to macroalgal-dominance on coral reefs. Recent studies have highlighted that different fish species feed on adult macroalgae vs. the epilithic algal matrix. While it has been assumed that those species feeding on the EAM (i.e., acanthurids, siganids, and scarines) incidentally remove macroalgal propagules from the reef substratum when feeding, our understanding of the species that may remove macroalgal propagules is limited. To investigate which coral reef fishes remove Sargassum recruits from the benthos, we settled Sargassum propagules (Sargassum propagules to tiles with EAM only. Paired tiles and caged controls were transplanted to the reef flat and exposed to local herbivore assemblages for 3 days, and feeding on the tiles was monitored using stationary underwater video cameras. Analyses of the video footage revealed that of the four species of blenny and one species of pomacentrid that took a large number of bites on the tiles, only one species, Salarius fasciatus, took more bites on the tiles with a Sargassum/turf algae mixture than the tiles with only turf algae. Moreover,S. fasciatus took two-fold more bites on theSargassum/turf tiles compared to the turf only tiles, whilst other fish species took 2-3 fold fewer bites on the Sargassum/turf tiles compared to the turf only tiles. Very little feeding by larger roving herbivorous fishes was recorded. These results suggest thatSargassum propagules may be avoided by certain small reef fishes and this mechanism may facilitate the expansion of macroalgal beds on coral reefs.
Spatial patterns of cryptobenthic coral reef fishes in the Red Sea
Darren Coker ∗ 1, Joseph Dibattista 2, Tane Sinclair-Taylor 1, Michael Berumen 1
1 King Abdullah University of Science and Technology (KAUST) – Red Sea Research Center, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and
Technology, Thuwal 23955-6900, Saudi Arabia, Saudi Arabia
2 Curtin University – Department of Environment and Agriculture, Curtin University, PO Box U1987, Perth, WA 6845, Australia, Australia
Understanding the ecology of coral reef ecosystems requires a fundamental knowledge of the distribution and abundance of their associated fishes. However, reef fish surveys are often limited to visually conspicuous species, thus excluding a significant proportion of the biodiversity.
Given the potential for even the smallest fishes to play an important ecological role and the increasing disturbances to coral reefs globally, it is critical to increase our knowledge of all reef- associated groups. Our study is the first to systematically document cryptobenthic reef fishes at a community level within the Red Sea. A total of 238 species or operational-taxonomic-units (OTUs) from 35 families of reef fish were collected from sites in the central and southern Red Sea.
Abundance and species richness increased by 60% and 30%, respectively, from the northern most site to the southern most site. Models revealed key coral groups, and changes in environmental parameters (Chl-a, SST, salinity) structured these patterns with higher levels of productivity and complex corals favoring abundance and richness. Community composition also differed among the regions, with proximity to shore within the central Red Sea further supporting the importance of reef rich habitat. Our study provides a baseline estimate of the cryptobenthic species in the Red Sea but also illustrates the issues with taxonomic resolution for this group and region; only 40% confidently identified to species level. To overcome these issues, we produced a voucher catalogue of all collected specimens, which includes paired high-resolution photographs and DNA sequences (i.e. COI barcoding gene) for all the identified OTUs. This catalogue will assist with future fish biodiversity studies within the Red Sea, connectivity studies (including fish from adjacent oceans and seas), in addition to the improving the ability to confidently identify new occurrence records.
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E3/ Fishes of Mesophotic Coral Ecosystems in the Indo-Pacific
Ecological determinants of depth ranges in a coral-obligate reef fish and depth patterns in
habitat disturbance: Are deep reefs a refuge?
Chancey Macdonald ∗ 1,2, Tom Bridge 2,3, Geoffrey Jones 1,2
1 College of Marine and Aquaculture Science, James Cook University (JCU) – Townsville, Australia
2 Australian Research Council, Centre of Excellence for Coral Reef Studies (ARC COE) – Townsville, Australia
3Queensland Museum – Townsville, Australia
Declining coral abundance on many reefs globally is altering the composition of coral reef fish communities. Many reef fish species depend on live coral for a range of ecological processes, but coral specialists such as obligate coral feeders are among the most threatened. The most se- vere declines in coral abundance often occurs in shallower water, and deeper reefs may therefore provide a refuge for reef fish if they can provide suitable stable habitat in the face of shallow reef degradation. However, ecological factors influencing depth distributions, in coral reef fishes are currently poorly understood. Here, we analyse how larval settlement and adult distributions, resource use, territorial area, territorial behavior, diet, movement, and body condition of an obligate coral feeding butterflyfish species vary along a depth gradient from 0-40m. We further relate patterns in these behaviours to changes in the availability, nutritional quality and trophic position of food sources along the depth gradient and across two disturbance events. In doing so we demonstrate that whilst not a panacea, suitable deep-water habitat can provide a significant refuge from some disturbance events for an obligate coral feeding reef fish in a clear-water, low- latitude reef system. However, the health and abundance of primary habitat and food corals declined in deep and shallow water following a warm-water bleaching event. If populations be- come restricted to deep-water habitats, fish behaviour, body condition and reproductive energy allocation are likely to remain similar to those in current healthy reef systems, however the abundance and density of population contributors will likely decline.
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Mesophotic coral ecosystems are not a refuge for the shallow reef fauna