Trophic structure patterns of Brazilian reef fishes: a latitudinal comparison

Aim To investigate how reef fish trophic structure responds to latitudinal changes, using a simple model: the extensive Brazilian coast. Location Six Brazilian tropical and subtropical coral and rocky coastal reefs, and the oceanic island of Atol das Rocas, between latitudes 0° and 27° S. Methods Underwater visual census data collected by the authors (five locations) or obtained from the literature (two locations) were used to estimate the relative abundance of 123 fish species belonging to 33 reef‐associated families. Cryptic species were excluded from the analysis. Fishes were grouped in eight trophic categories: roving herbivores, territorial herbivores, mobile invertebrate feeders, sessile invertebrate feeders, omnivores, planktivores, piscivores and carnivores. After a series of detailed predictions based on phylogeny, physiological constraints and anthropogenic impacts was established, the community trophic structure was analysed along a latitudinal gradient and among coastal, mid‐shore and oceanic sites. Results The trophic structure of Brazilian reef fish assemblages clearly changed with latitude. Roving herbivores such as scarids and acanthurids were proportionally more abundant at low latitudes. The browsing herbivores kyphosids followed an opposite latitudinal pattern. The parrotfish genus Sparisoma, more plastic in its feeding habits than Scarus, presented wider distribution. The relative abundance of territorial herbivores did not decrease towards higher latitudes. Mobile invertebrate feeders were the most important (in low latitudes) or the second most important trophic guild (in high latitudes) at all coastal sites. Sessile invertebrate feeders did not show any clear latitudinal trend, despite an expected increase in abundance towards low latitudes. Omnivores dominated high latitude reefs (27° S) and planktivores the oceanic island Atol das Rocas. Piscivores and carnivores were proportionally better represented in high latitudes. Main conclusions Latitudinal patterns seem to be influenced by phylogeny, physiological constraints (mainly related to temperature), and also by anthropogenic impacts. Grazing scarids and acanthurids are largely restricted to tropical reefs and show an abrupt decline beyond 23° S. This does not reflect the amount of algae present, but probably temperature‐dependent physiological constraints. Other herbivores seem to overcome this through symbiotic microbial digestive processes (kyphosids), manipulating the structure of algal turfs or increasing animal protein from within the territory (pomacentrids). Omnivores dominate the southern sites Arraial do Cabo and Arvoredo, being more adapted to environment constraints related to seasonal and/or stochastic shifts. Large carnivores (including piscivores) extend farther into high‐latitude habitats, apparently not constrained by thermal thresholds that limit the herbivores. Overfishing and/or ornamental harvesting certainly has been modifying local fish communities, but could not be detected properly at the large‐scale patterns found in this study. The data presented put in evidence for the first time how reef fish trophic structure behave in the extensive south‐western Atlantic latitudinal gradient.     

The influence of multiple factors upon reef fish abundance and species richness in a tropical coral complex

The present study was conducted on Tamandaré reefs, northeast Brazil and aimed to analyse the importance of different factors (e.g. tourism activity, fishing activity, coral abundance and algal abundance) on reef fish abundance and species richness. Two distinct reef areas (A ver o mar and Caieiras) with different levels of influence were studied. A total of 8239 reef fish individuals were registered, including 59 species. Site 1 (A ver o mar) presented higher reef fish abundance and richness, with dominance of roving herbivores (29.9 %) and mobile invertebrate feeders (28.7 %). In contrast, at Site 2 (Caieiras) territorial herbivores (40.9 %) predominated, followed by mobile invertebrate feeders (24.6 %). Concerning the benthic community, at Site 1 macroalgae were recorded as the main category (49.3 %); however, Site 2 was dominated by calcareous algae (36.0 %). The most important variable explaining more than 90 % of variance on reef fish abundance and species richness was macroalgae abundance, followed by fishing activity. Phase shifts on coral reefs are evident, resulting in the replacement of coral by macroalgae and greatly influencing reef fish communities. In this context, it is important to understand the burden of the factors that affect reef fish communities and, therefore, influence the extinction vulnerability of coral reef fishes.     

西沙群岛礁栖鱼类物种多样性及其食性特征

通过新的方法(即潜水调查法)调查了西沙群岛浅水区的礁栖鱼类, 并从食性角度分析鱼类群落特征及其对水质环境变化的响应。2006年5-6月, 对西沙群岛6个岛礁(东岛、永兴岛、羚羊礁、金银岛、华光礁和中建岛)共10个站位的礁栖鱼类种类、数量和长度进行了调查, 结合公开资料(FishBase等)确定鱼类食性。共记录到29科71属119种鱼, 其中50种是新记录。至此, 西沙群岛的鱼类总记录已达到717种。从不同站位来看, 永兴岛西的种类数量和Shannon-Wiener多样性指数均最高。多数鱼种分布范围狭小。摄食浮游动物和底栖无脊椎动物的鱼类是优势类群, 而草食性、杂食性和食物链顶端食性的鱼类数量和生物量较低, 反映出西沙群岛珊瑚礁生态系统整体上健康稳定。永兴岛的杂食性鱼类的数量比例和生物量比例均高于其他岛礁, 反映出鱼类群落已对水体富营养化产生响应。     

Diet of combtooth blennies (Blenniidae) in Kochi and Okinawa,Japan

Combtooth blennies (Blenniidae) have a wide array of diets, including coral polyps, fish scales/mucus/rays, and detritus. However, there is limited knowledge about the diet of some species. We described the diet of 30 blenny species from subtidal, intertidal, or supralittoral habitats in Kochi (warm temperate) and Okinawa (tropical), Japan. Cluster analysis of dietary overlap grouped blennies into seven feeding groups: omnivores, herbivores, detritivores, molluscivores, corallivores, worm-like invertebrate feeders, and fish mucus/scale/ray feeders. The largest cluster, detritivores, contained 17 blenny species from all habitat zones and both climate zones. Our findings suggest that closely related species fill similar feeding niches and detritus is an important component of many blenny diets.     

Reef fish community structure in the Tropical Eastern Pacific (Panamá): living on a relatively stable rocky reef environment

We compared the community structure of reef fish over different physical complexities in 12 study zones of Bahía Honda, Gulf of Chiriquí (BH-GCH), Tropical Eastern Pacific (TEP), Panama, aiming at an analysis of the importance of the physical structure provided by corals, rocks and benthic sessile organisms. This was the first region that emerged in the Isthmus of Panama; it exhibits the oldest benthic fauna and has constant conditions in terms of temperature and salinity. Two hundred and eighty-eight visual fish censuses were conducted on 48 benthic transects from February to July 2003. One hundred and twenty-six fish species of 44 families were found. Plankton feeding pomacentrids and labrids along with haemulids that feed on mobile invertebrates were the most abundant, particularly in shallow areas. Fourteen species showed size-segregations between zones, suggesting ontogenetic migrations (smaller fishes in shallow high-complexity zones, larger-sized fishes in deeper habitats). Highly mobile and site-attached genera were abundant in most shallow, wave-exposed zones particularly on exposed rocky substrates. Planktivores were the most abundant, followed by carnivores, feeders on mobile invertebrate and piscivores. Herbivores and feeders on sessile invertebrate were lower in abundance. Species richness exceeds that of any other studied region close to the mainland in the TEP and correlates with substrate diversity, increasing size-heterogeneity of holes and structural complexity. Species diversity increases with habitat complexity and benthic diversity. It seems that water current strength, tides and waves which select for swimming, play an important role in the community organization. The study region has been proposed as a refuge-centre in the TEP, where reef fishes that evolved on coral reefs have shifted their distribution onto rocky reef habitats.     

Habitat type and complexity drive fish assemblages in a tropical seascape

Inshore marine seascapes support a diversity of interconnected habitats and are an important focus for biodiversity conservation. This study examines the importance of habitat attributes to fish assemblages across a mosaic of inshore habitats: coral reefs, rocky reefs, macroalgae beds and sand/rubble beds. Fishes and benthic habitats were surveyed at 34 sites around continental islands of the central Great Barrier Reef using baited remote underwater video stations (BRUVS). Species richness was influenced foremost by habitat type and also by structural complexity within habitat types. The most speciose assemblages occurred in coral and rocky reef habitats with high structural complexity, provided by the presence of coral bommies/overhangs, boulders and rock crevices. Nonetheless, macroalgae and sand/rubble beds also supported unique species, and therefore contributed to the overall richness of fish assemblages in the seascape. Most trophic groups had positive associations with complexity, which was the most important predictor for abundance of piscivorous fishes and mobile planktivores. There was significant differentiation of fish assemblages among habitats, with the notable exception of coral and rocky reefs. Species assemblages overlapped substantially between coral and rocky reefs, which had 60% common species, despite coral cover being lower on rocky reefs. This suggests that, for many species, rocky and coral substrates can provide equivalent habitat structure, emphasizing the importance of complexity in providing habitat refuges, and highlighting the contribution of rocky reefs to habitat provision within tropical seascapes. The results of this study support an emerging recognition of the collective value of habitat mosaics in inshore marine ecosystems.     

Coral and fish distribution patterns in Mafia Island Marine Park, Tanzania: fish–habitat interactions

We examined coral reef communities at 11 sites within Mafia Island Marine Park using a point count method for substrate and visually censused belt transects for fish populations. Multivariate ordinations showed that the benthic habitat differed among reefs. The patterns were mainly attributed to variations in depth, hydrodynamics and benthic composition. In total, the substratum was dominated by dead coral (49%) and algae (25%), with a live coral cover of only 14%. Three hundred and ninety-four fish species belonging to 56 families were recorded. According to MDS-ordinations and RELATE procedures, fish assemblage composition varied among sites in concordance with the habitats provided. Sites with highest proportion of dead coral exhibited highest degree of dispersion in the multivariate ordinations of fish assemblages. Stepwise multiple regression was used to determine the proportion of variance among sites which could be explained by depth, exposure, rugosity, substrate diversity, branching substrate, live coral cover, dead coral cover and different types of algae. The results showed that habitat variables explained up to 92% of the variation in species numbers and in total, and taxon-specific, abundance. Live coral cover was the foremost predictor of both numerical and species abundance, as well as of corallivores, invertivores, planktivores and of the families Pomacentridae, Chaetodontidae and Pomacanthidae. Our results suggest that habitat characteristics play a dominant role in determining fish assemblage composition on coral reefs.     

Foragers versus farmers: contrasting effects of two behavioural groups of herbivores on coral reefs

Herbivorous fishes have been attributed a central role in structuring benthic communities on coral reefs. However, the relative importance of different behavioural groups of herbivores may differ and their interactions may be complex. This study focuses on an experiment that discriminates between two groups of herbivorous fish: (1) “Foragers” (relatively mobile, schooling grazers, including parrotfishes and surgeonfishes) and (2) “Farmers” (highly site-attached, territorial species, primarily damselfishes). Preliminary observations at Kimbe Bay (Papua New Guinea) showed that both groups were common, and that farmers defended areas from foragers and maintained algal communities that were distinct from the surrounding undefended substratum. An orthogonal combination of a farmer removal treatment and a forager exclusion treatment was applied to isolate their separate effects on algae and corals, and to determine whether farmer territory composition results from forager exclusion or algal cultivation. The experiment showed that foragers had quantitatively greater and qualitatively different effects on sessile benthic community structure than farmers. Where foragers were excluded, there were substantial increases in the cover and biomass of macro-algae and a decline in some corals, regardless of the presence of farmers. Where farmers were removed there was a moderate decline in the cover of some food algal species, regardless of whether foragers had access. No effect of the exclusion of foragers by farmers could be detected. Our results support prevailing views that foragers have a major impact on coral reefs and farmers cultivate selected algae, but challenge the hypothesis that damselfish influence habitat structure by moderating forager disturbance.     

Importance of live coral habitat for reef fishes

Live corals are the key habitat forming organisms on coral reefs, contributing to both biological and physical structure. Understanding the importance of corals for reef fishes is, however, restricted to a few key families of fishes, whereas it is likely that a vast number of fish species will be adversely affected by the loss of live corals. This study used data from published literature together with independent field based surveys to quantify the range of reef fish species that use live coral habitats. A total of 320 species from 39 families use live coral habitats, accounting for approximately 8 % of all reef fishes. Many of the fishes reported to use live corals are from the families Pomacentridae (68 spp.) and Gobiidae (44 spp.) and most (66 %) are either planktivores or omnivores. 126 species of fish associate with corals as juveniles, although many of these fishes have no apparent affiliation with coral as adults, suggesting an ontogenetic shift in coral reliance. Collectively, reef fishes have been reported to use at least 93 species of coral, mainly from the genus Acropora and Porities and associate predominantly with branching growth forms. Some fish associate with a single coral species, whilst others can be found on more than 20 different species of coral indicating there is considerable variation in habitat specialisation among coral associated fish species. The large number of fishes that rely on coral highlights that habitat degradation and coral loss will have significant consequences for biodiversity and productivity of reef fish assemblages.     

Maintenance of fish diversity on disturbed coral reefs

Habitat perturbations play a major role in shaping community structure; however, the elements of disturbance-related habitat change that affect diversity are not always apparent. This study examined the effects of habitat disturbances on species richness of coral reef fish assemblages using annual surveys of habitat and 210 fish species from 10 reefs on the Great Barrier Reef (GBR). Over a period of 11 years, major disturbances, including localised outbreaks of crown-of-thorns sea star (Acanthaster planci), severe storms or coral bleaching, resulted in coral decline of 46–96% in all the 10 reefs. Despite declines in coral cover, structural complexity of the reef framework was retained on five and species richness of coral reef fishes maintained on nine of the disturbed reefs. Extensive loss of coral resulted in localised declines of highly specialised coral-dependent species, but this loss of diversity was more than compensated for by increases in the number of species that feed on the epilithic algal matrix (EAM). A unimodal relationship between areal coral cover and species richness indicated species richness was greatest at approximately 20% coral cover declining by 3–4 species (6–8% of average richness) at higher and lower coral cover. Results revealed that declines in coral cover on reefs may have limited short-term impact on the diversity of coral reef fishes, though there may be fundamental changes in the community structure of fishes.     

Reef fish structure and distribution in a south-western Atlantic Ocean tropical island

The community structure of the reef fish fauna of Trindade Island, a volcanic oceanic island located 1160 km off the coast of Brazil, is described based on intensive visual censuses. Seventy-six species were encountered in 252 censuses, with mean ± S.E. of 99 ± 3 individuals and 15.7 ± 0.3 species 40 m(-2) transect. The average fish biomass, calculated from length-class estimation, was 22.1 kg 40 m(-2) transect. The species contributing most to biomass were, in decreasing order, Melichthys niger, Cephalopholis fulva, Kyphosus spp., Holocentrus adscensionis, Sparisoma amplum, Sparisoma axillare, Acanthurus bahianus and Epinephelus adscensionis. Carnivorous fishes were the largest trophic group in terms of biomass, followed by omnivores and roving herbivores. The two predominant types of reef habitat, fringing reefs built by coralline algae and rocky reefs made of volcanic boulders, showed significant differences in the biomass and the abundance of the trophic guilds. Within each habitat type, significant differences in species richness, density and biomass were detected among crest, slope and interface zones. Although similar in overall species composition to coastal reefs in Brazil, the fish fauna of Trindade Island shares certain characteristics, such as a high abundance of planktivores, with other Brazilian oceanic islands. Despite comparatively high fish biomass, including the macro-carnivorous species habitually targeted by fisheries, signs of overfishing were evident. These findings highlight the urgency for a conservation initiative for this isolated, unique and vulnerable reef system.     

Herbivory drives large‐scale spatial variation in reef fish trophic interactions

Trophic interactions play a critical role in the structure and function of ecosystems. Given the widespread loss of biodiversity due to anthropogenic activities, understanding how trophic interactions respond to natural gradients (e.g., abiotic conditions, species richness) through large‐scale comparisons can provide a broader understanding of their importance in changing ecosystems and support informed conservation actions. We explored large‐scale variation in reef fish trophic interactions, encompassing tropical and subtropical reefs with different abiotic conditions and trophic structure of reef fish community. Reef fish feeding pressure on the benthos was determined combining bite rates on the substrate and the individual biomass per unit of time and area, using video recordings in three sites between latitudes 17°S and 27°S on the Brazilian Coast. Total feeding pressure decreased 10‐fold and the composition of functional groups and species shifted from the northern to the southernmost sites. Both patterns were driven by the decline in the feeding pressure of roving herbivores, particularly scrapers, while the feeding pressure of invertebrate feeders and omnivores remained similar. The differential contribution to the feeding pressure across trophic categories, with roving herbivores being more important in the northernmost and southeastern reefs, determined changes in the intensity and composition of fish feeding pressure on the benthos among sites. It also determined the distribution of trophic interactions across different trophic categories, altering the evenness of interactions. Feeding pressure was more evenly distributed at the southernmost than in the southeastern and northernmost sites, where it was dominated by few herbivores. Species and functional groups that performed higher feeding pressure than predicted by their biomass were identified as critical for their potential to remove benthic biomass. Fishing pressure unlikely drove the large‐scale pattern; however, it affected the contribution of some groups on a local scale (e.g., large‐bodied parrotfish) highlighting the need to incorporate critical functions into conservation strategies.     

Non-Random Variability in Functional Composition of Coral Reef Fish Communities along an Environmental Gradient

Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased degradation of coral reefs is associated with increased variability in fish community functional composition resulting from selective impacts on specific traits, thereby affecting the functional response of these communities to increasing perturbations.     

Phase shift to algal dominated communities at mesophotic depths associated with lionfish (<Emphasis Type="Italic">Pterois volitans</Emphasis>) invasion on a Bahamian coral reef

Mesophotic coral reefs (30–150 m) have been assumed to be physically and biologically connected to their shallow-water counterparts, and thus may serve as refugia for important taxonomic groups such as corals, sponges, and fish. The recent invasion of the Indo–Pacific lionfish (Pterois volitans) onto shallow reefs of the Caribbean and Bahamas has had significant, negative, effects on shallow coral reef fish populations. In the Bahamas, lionfish have extended their habitat range into mesophotic depths down to 91 m where they have reduced the diversity of several important fish guilds, including herbivores. A phase shift to an algal dominated (>50% benthic cover) community occurred simultaneously with the loss of herbivores to a depth of 61 m and caused a significant decline in corals and sponges at mesophotic depths. The effects of this invasive lionfish on mesophotic coral reefs and the subsequent changes in benthic community structure could not be explained by coral bleaching, overfishing, hurricanes, or disease independently or in combination. The significant ecological effects of the lionfish invasion into mesophotic depths of coral reefs casts doubt on whether these communities have the resilience to recover themselves or contribute to the recovery of their shallow water counterparts as refugia for key coral reef taxa.     

Trophic analysis and trophodynamic functioning of mangrove fish fauna of New Caledonia]

Fish communities from geomorphologically different mangrove forests showed distinct trophic structures. A mangrove area located near fringing reefs (Bouraké) was dominated by large invertebrate (> 2 mm) feeders (40.7% of total wet weight of the fish fauna) and herbivores (26.7%) whilst an estuarine mangrove (Ouenghi) was characterized by detritus feeders (28.2%), piscivorous (18.2%) and large invertebrate feeders (17.9%). In spite of these differences in trophic structure, similar food webs occurred in both areas, whereas the intensity of fluxes between trophic compartments was different. Resident species were usually at the base of the trophic structure. This component of the fish fauna used available sources of energy, such as microalgae in Bouraké or detritus and phytoplankton in Ouenghi. In contrast, transient species were high level predators, mainly piscivorous and large invertebrate feeders. These species actively contributed to net exports of energy from mangrove areas to nearby coastal habitats. Food webs and energy fluxes associated with trophic migration of fishes were particularly important in non-estuarine mangrove forests because of hydrologic conditions (salinity and turbidity) which were more suitable to the invasion of numerous marine foraging species (carangids, lutjanids, sphyraenids).     

Relationships between habitat structure and fish communities on coral

The influence of habitat structure on reef-fish communities at Bar Reef Marine Sanctuary, Sri Lanka, was investigated. The relationship between habitat characteristics and the distribution and abundance of 135 species of fishes was examined on two reef types: coral and sandstone reefs. Results suggested that the reef-fish communities were strongly influenced by various aspects of reef structure. However, relationships between habitat variables and fish communities structure, varied between the two reef types. Fish species diversity was correlated with a number of habitat variables on the sandstone reefs, although structural complexity seemed to play the dominant role. There were no correlations between habitat structure and fish diversity on the coral reefs. Total abundance was not related to any one habitat parameter on either reef type. However, abundances of some species, families and trophic groups were correlated with habitat features. These specific correlations were commonly related to food or shelter availability. For example, coral feeders were correlated with live coral cover, and pomacentrid species, which used branching corals for protection, showed a significant relationship with the density of Acropora colonies. This shows that a summary statistic such as total abundance may hide important information. Effects of habitat structure on the distribution patterns of the fish communities was further investigated using multi-dimensional scaling ordination (MDS) and the RELATE-procedure. With the MDS ordinations for both habitat and fish-community composition it was possible to show that the multivariate pattern between the two ecological components was clearly correlated.     

High macroalgal cover and low coral recruitment undermines the potential resilience of the world's southernmost coral reef assemblages

Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience) is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32'S, 159°04'E), the worlds' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment), and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4%) and fleshy macroalgae (20.9%). Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m(-2)), however, were 5-200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha(-1)), and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1%) with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances.     

Mesophotic depths as refuge areas for fishery-targeted species on coral reefs

Coral reefs are subjected to unprecedented levels of disturbance with population growth and climate change combining to reduce standing coral cover and stocks of reef fishes. Most of the damage is concentrated in shallow waters (<30 m deep) where humans can comfortably operate and where physical disturbances are most disruptive to marine organisms. Yet coral reefs can extend to depths exceeding 100 m, potentially offering refuge from the threats facing shallower reefs. We deployed baited remote underwater stereo-video systems (stereo-BRUVs) at depths of 10–90 m around the southern Mariana Islands to investigate whether fish species targeted by fishing in the shallows may be accruing benefits from being at depth. We show that biomass, abundance and species richness of fishery-targeted species increased from shallow reef areas to a depth of 60 m, whereas at greater depths, a lack of live coral habitat corresponded to lower numbers of fish. The majority of targeted species were found to have distributions that ranged from shallow depths (10 m) to depths of at least 70 m, emphasising that habitat, not depth, is the limiting factor in their vertical distribution. While the gradient of abundance and biomass versus depth was steepest for predatory species, the first species usually targeted by fishing, we also found that fishery-targeted herbivores prevailed in similar biomass and species richness to 60 m. Compared to shallow marine protected areas, there was clearly greater biomass of fishery-targeted species accrued in mesophotic depths. Particularly some species typically harvested by depth-limited fishing methods (e.g., spearfishing), such as the endangered humphead wrasse Cheilinus undulatus, were found in greater abundance on deeper reefs. We conclude that mesophotic depths provide essential fish habitat and refuge for fishery-targeted species, representing crucial zones for fishery management and research into the resilience of disturbed coral reef ecosystems.     

Cleaning interactions by gobies on a tropical eastern Pacific coral reef

The present study describes the cleaning interactions among species of cleaner gobies Tigrigobius spp. and Elacatinus puncticulatus (family Gobiidae) and the client fish species they clean in a coral reef of Gorgona Island, Colombia. In 419 cleaning events, we observed 27 species acting as clients of Tigrigobius spp., whereas only nine were clients of E. puncticulatus. Paranthias colonus and Cephalopholis panamensis were the species most commonly cleaned by Tigrigobius spp., while Ophioblennius steindachneri and Stegastes acalpulcoensis were the clients most commonly cleaned by E. puncticulatus. The abundance (but not the body size) of clients was an important variable predicting the cleaning frequency observed for clients of Tigrigobius spp., but this was not the case for clients of E. puncticulatus. Additionally, Tigrigobius spp. preferred cleaning planktivores, sessile invertebrate feeders and territorial herbivores (Ivlev's index >0·15), whereas E. puncticulatus did not exhibit any preference. We observed two major peaks of cleaning activity for Tigrigobius spp., one in the early morning and another one in the late afternoon. These results suggest that Tigrigobius spp. is a specialized cleaner goby, whereas E. puncticulatus is a facultative cleaner that cleans sporadically.     

Ecological condition of coral reef assemblages in the Cuban Archipelago

The condition of coral reefs in the Cuban Archipelago is poorly known. We aimed to analyse coral assemblages across 199 reef sites belonging to 12 localities. Crest and fore reefs were assessed using six metrics: species richness, density, coral cover, mortality, coral size and reef complexity. The condition of reefs varied across the archipelago from healthy to depleted reefs. The localities with best scores were Cienfuegos, Bahía de Cochinos and Cazones. These reefs have values of living coral cover (>20%) and complexity (>50?cm) similar to the best preserved Caribbean reefs. However, the majority of crest biotopes suffered important deterioration with old mortality of Acropora palmata populations and moderate coral cover (15%); although crest reefs still maintained their structural complexity. Despite moderate levels of coral cover in fore reefs (18%), their condition was alarming because 25% of the sites had cover below the recovery threshold of 10%, accumulated mortality and structural flattening. Compared with the 1980s, the species richness was roughly the same (42) for crest and fore reefs, although dominance has changed to widespread tolerant species. Coral reef assemblages varied at local and regional scales in similar magnitude, suggesting the combined effects of natural and anthropogenic drivers.