Planktivorous Damselfish Research Articles

The complete mitochondrial genome of Dascyllus trimaculatus (Rüppell, 1829)

Damselfishes (family Pomacentridae) comprise approximately 400 species that play an important ecological role in temperate and coral reefs. Here, for the first time, we assemble and annotate the mitochondrial genome of Dascyllus trimaculatus, the three-spot dascyllus, a planktivorous damselfish that primarily recruits in anemones. The circular genome of D. trimaculatus is 16,967 bp in length and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. Gene arrangement and codon usage is similar to reported mitochondrial genomes of other damselfish genera, and a phylogenetic analysis of a set of damselfish representatives is consistent with known evolutionary analyses.

Intestinal Microbiome Richness of Coral Reef Damselfishes (Actinopterygii: Pomacentridae).

Fish gastro-intestinal system harbors diverse microbiomes that affect the host's digestion, nutrition, and immunity. Despite the great taxonomic diversity of fish, little is understood about fish microbiome and the factors that determine its structure and composition. Damselfish are important coral reef species that play pivotal roles in determining algae and coral population structures of reefs. Broadly, damselfish belong to either of two trophic guilds based on whether they are planktivorous or algae-farming. In this study, we used 16S rRNA gene sequencing to investigate the intestinal microbiome of 5 planktivorous and 5 algae-farming damselfish species (Pomacentridae) from the Great Barrier Reef. We detected Gammaproteobacteria ASVs belonging to the genus Actinobacillus in 80% of sampled individuals across the 2 trophic guilds, thus, bacteria in this genus can be considered possible core members of pomacentrid microbiomes. Algae-farming damselfish had greater bacterial alpha-diversity, a more diverse core microbiome and shared 35 ± 22 ASVs, whereas planktivorous species shared 7 ± 3 ASVs. Our data also highlight differences in microbiomes associated with both trophic guilds. For instance, algae-farming damselfish were enriched in Pasteurellaceae, whilst planktivorous damselfish in Vibrionaceae. Finally, we show shifts in bacterial community composition along the intestines. ASVs associated with the classes Bacteroidia, Clostridia, and Mollicutes bacteria were predominant in the anterior intestinal regions while Gammaproteobacteria abundance was higher in the stomach. Our results suggest that the richness of the intestinal bacterial communities of damselfish reflects host species diet and trophic guild.

In situ three‐dimensional video tracking of tagged individuals within site‐attached social groups of coral‐reef fish

AbstractTracking the movement of all individual group members in their natural environment remains a challenging task. Using advances in computer vision and Deep Learning, we developed and tested a semi‐automated in situ tracking system to reconstruct simultaneous three‐dimensional trajectories of marked individuals in social groups of a coral‐reef fish. Our system has a temporal resolution of 10s of milliseconds, allowing for multiple 30‐min tracking sessions that have been repeated over weeks to months. We present the technique and illustrate its application for Dascyllus marginatus, a planktivorous damselfish that lives in social groups associated with branching corals. Our technique identified all individuals 85–100% of the time, with a mean spatial error of ~ 1.3 cm. It provides a cost‐effective semi‐automated tool for in situ research on movements and foraging of individuals within small site‐attached groups of animals in their natural environment.

Ingestion and Depuration of Microplastics by a Planktivorous Coral Reef Fish, Pomacentrus amboinensis

Microplastics are ubiquitous contaminants in marine environments and organisms. Concerns about potential impacts on marine organisms are usually associated with uptake of microplastics, especially via ingestion. This study used environmentally relevant exposure conditions to investigate microplastic ingestion and depuration kinetics of the planktivorous damselfish,Pomacentrus amboinensis. Irregular shaped blue polypropylene (PP) particles (longest length 125–250 μm), and regular shaped blue polyester (PET) fibers (length 600–700 μm) were selected based on physical and chemical characteristics of microplastics commonly reported in the marine environment, including in coral reef ecosystems. Individual adult damselfish were exposed to a single dose of PP particles and PET fibers at concentrations reported for waters of the Great Barrier Reef (i.e., environmentally relevant concentrations, ERC), or future projected higher concentrations (10x ERC, 100x ERC). Measured microplastic concentrations were similar to their nominal values, confirming that PP particles and PET fibers were present at the desired concentrations and available for ingestion by individual damselfish. Throughout the 128-h depuration period, the 88 experimental fish were sampled 2, 4, 8, 16, 32, 64, and 128-h post microplastic exposure and their gastrointestinal tracts (GIT) analyzed for ingested microplastics. While damselfish ingested both experimental microplastics at all concentrations, body burden, and depuration rates of PET fibers were significantly larger and longer, respectively, compared to PP particles. For both microplastic types, exposure to higher concentrations led to an increase in body burden and lower depuration rates. These findings confirm ingestion of PP particles and PET fibers byP. amboinensisand demonstrate for the first time the influence of microplastic characteristics and concentrations on body burden and depuration rates. Finally, despite measures put in place to prevent contamination, extraneous microplastics were recovered from experimental fish, highlighting the challenge to completely eliminate contamination in microplastic exposure studies. These results are critical to inform and continuously improve protocols for future microplastics research, and to elucidate patterns of microplastic contamination and associated risks in marine organisms.

Crown-of-thorns starfish larvae are vulnerable to predation even in the presence of alternative prey

Many predators reported to feed on crown-of-thorns starfish (CoTS, Acanthaster spp.) are generalist and opportunistic feeders. However, research into predation on CoTS tends to examine these predator–prey interactions in isolation, and it remains unknown whether many potential predators will prey on CoTS when other, potentially more palatable, food sources are available. Assessing predatory responses to changes in prey availability is critical for gauging the capacity of predators to regulate prey populations. Here, we explored prey preferences and tested for prey switching across nine species of planktivorous damselfish offered varying densities of Pacific CoTS (Acanthaster cf. solaris) larvae versus larvae of a common and co-occurring starfish, Linckia laevigata. Results show that planktivorous damselfishes will consume crown-of-thorns starfish larvae, even in the presence of alternative prey. Feeding responses varied among the nine planktivorous predators with five damselfishes (Acanthochromis polyacanthus, Amblyglyphidodon curacao, Dascyllus reticulatus, Pomacentrus amboinensis and Pomacentrus moluccensis) exhibiting increased consumption of Acanthaster larvae with increasing density, despite the presence of alternative prey. Moreover, Abudefduf sexfasciatus and P. amboinensis exhibited preference for larvae of A. cf. solaris over larvae of L. laevigata. Despite these predation patterns, prey switching between starfish larvae was not observed. These results add to a growing body of evidence which suggests that predators of the early life stages of A. cf. solaris could be important in regulating settlement and recruitment patterns of this starfish, especially at low, non-outbreak, densities.

Differential consumption of scleractinian and non-scleractinian coral larvae by planktivorous damselfishes

Planktivorous fishes are known to consume coral larvae due to their high nutritional value that can benefit both the individual and their progeny. However, how the consumption of coral larvae varies among coral and fish taxa, between day and night and with the density of coral larvae is not well understood. Here, we used a series of laboratory feeding assays to determine how the consumption of coral larvae by five planktivorous damselfish species (Abudefduf sexfasciatus, Amblyglyphidodon curacao, Dascyllus trimaculatus, D. reticulatus, and Chromis viridis) differed (1) between larvae of the broadcast-spawning scleractinian coral Acropora tenuis and the brooding non-scleractinian coral Heliopora coerulea when offered at a constant density (100 larvae/50 L), (2) between day and night (A. tenuis only), and (3) among larval densities (A. tenuis: 5–500 larvae/50 L; H. coerulea: 5–250 larvae/50 L). When coral larvae were offered at 100 larvae/50 L, all five fish species examined consumed A. tenuis (78–97 larvae h−1) at a greater rate than H. coerulea (23–57 larvae h−1), with these differences likely related to the behavior and/or pigmentation of the larvae. Consumption also varied among the fishes examined, though the differences were small when compared to differences between coral species. Consumption of A. tenuis was twofold higher at day than night likely reflecting the diurnally active feeding behavior of the fishes examined. When the density of coral larvae offered to the fishes was varied, three of five species exhibited a type II functional response (decelerating intake rate) for A. tenuis, while four out of five damselfish species exhibited a type III (sigmoidal intake rate) or type I (linear intake rate) for H. coerulea. This study demonstrates that predation by fishes contributes significantly to coral larvae mortality and that differences in consumption rates among coral species may affect the composition of coral recruits and ultimately coral assemblages.

The Distribution of Planktivorous Damselfishes (Pomacentridae) on the Great Barrier Reef and the Relative Influences of Habitat and Predation

Planktivorous damselfishes (Pomacentridae) are diverse and abundant on the Great Barrier Reef (GBR), are important prey for commercially harvested coral trout (Plectropomus spp.) and their feeding mode plays a central role in transferring energy from the plankton to the reef. However, little is known about their distribution patterns throughout the GBR and how those patterns are influenced by predators and habitat despite increasing pressures on both. Here we quantify the distribution and abundance of GBR planktivorous damselfishes, then examine the role of coral trout and habitat in shaping their assemblages. The assemblage structure of planktivorous damselfishes varied across the continental shelf, yet their total abundances varied sub-regionally, dependent on differences in coral habitat. Latitudinal patterns were relatively weak. Damselfish assemblages generally retained characteristics of their sub-regional setting over 20 years and assemblage degradation was only associated with major coral losses. Damselfish numbers were not negatively influenced by top-down control from coral trout. Instead, numbers of coral trout and damselfishes were both positively associated with coral habitat and each other. Our findings suggest that a complexity of factors and interactions shape reef fish assemblages and reinforce the fundamental importance of coral as the foundation of healthy reef communities.

High prevalence of homing behaviour among juvenile coral-reef fishes and the role of body size

Adult coral-reef fishes display a remarkable ability to return home after being displaced. However, we know very little about homing behaviour in juvenile fishes. Homing behaviour in juvenile fishes is of interest because it will shape subsequent spatial distributions of adult fish communities. Comparing multiple species, families and functional groups allows us to distinguish between species-specific traits and more generalised, species-independent traits that may drive homing behaviour. Using displacement experiments of up to 150 m, we quantified homing behaviour of juvenile, newly recruited reef fishes of seven species in three families, including herbivorous parrotfishes and rabbitfishes, carnivorous wrasse and planktivorous damselfishes. All species showed the ability to home successfully, but success rates differed among species. Juvenile parrotfishes were the most successful (67% returning home), while return rates in the other species ranged from 10.5% (Siganus doliatus) to 28.9% (Coris batuensis). However, across all species body size appeared to be the main driver of homing success, rather than species-specific traits. With every cm increase in body size, odds of returning home almost tripled (170% increase) across all species. Interestingly, the probability of getting lost was not related to body size, which suggests that mortality was not a major driver of unsuccessful homing. Homing probability halved beyond displacement distances of 10 m and then remained stable. Higher likelihood of homing over short distances may suggest that different sensory cues are used to navigate. Overall, our results suggest that homing ability is a widespread trait among juvenile reef fishes. A ‘sense of home’ and site attachment appear to develop early during ontogeny, especially above taxon-specific size thresholds. Hence, spatial flexibility exists only in a brief window after settlement, with direct implications for subsequent patterns of connectivity and ecosystem function in adult reef fish populations.

Interspecific variation in potential importance of planktivorous damselfishes as predators of Acanthaster sp. eggs

Coral-eating crown-of-thorns starfish (Acanthaster sp.) often exhibit dramatic population outbreaks, suggesting that their local abundance may be relatively unchecked by predators. This may be due to high concentrations of anti-predator chemicals (saponins and plancitoxins), but the effectiveness of chemical deterrents in protecting Acanthaster sp., especially spawned eggs, from predation remains controversial. We show that planktivorous damselfishes will readily consume food pellets with low proportions (≤80%) of eggs of crown-of-thorns starfish. However, all fishes exhibited increasing rejection of food pellets with higher proportions of starfish eggs, suggesting that chemicals in eggs of crown-of-thorns starfish do deter potential predators. Interestingly, palatability thresholds varied greatly among the nine species of planktivorous fish tested. Most notably, Amblyglyphidodon curacao consumed food pellets comprising 100% starfish eggs 1.5 times more than any other fish species, and appeared largely insensitive to increases in the concentration of starfish eggs. After standardising for size, smaller fish species consumed a disproportionate amount of pellets comprising high proportions of starfish eggs, indicating that abundant small-bodied fishes could be particularly important in regulating larval abundance and settlement success of crown-of-thorns starfish. Collectively, this study shows that reef fishes vary in their tolerance to anti-predator chemicals in crown-of-thorns starfish and may represent important predators on early life-history stages.

Predation on crown-of-thorns starfish larvae by damselfishes

Examining the functional response of predators can provide insight into the role of predation in structuring prey populations and ecological communities. This study explored feeding behaviour and functional responses of planktivorous damselfishes when offered captive reared larvae of crown-of-thorns starfish, Acanthaster sp., with the aim of determining whether these predators could ever play a role in moderating outbreaks of Acanthaster sp. We examined predatory behaviour of 11 species of planktivorous damselfish, testing: (1) the relationship between predator size and predation rate, both within and among fish species; (2) consumption rates on larvae of Acanthaster sp. versus larvae of a common, co-occurring coral reef asteroid Linckia laevigata; (3) maximal feeding rates upon both Acanthaster sp. and L. laevigata; and (4) functional responses of planktivorous fishes to increasing densities of Acanthaster sp. Consumption rates of crown-of-thorns larvae by damselfishes were independent of predator size; however, there was a significant negative relationship between predator size and consumption rate of L. laevigata, when pooling across all predatory species. Some damselfishes, including Acanthochromis polyacanthus and Amblyglyphidodon curacao, consumed larval Acanthaster sp. at a greater rate than for L. laevigata. Most predatory species (all except A. curacao and Pomacentrus amboinensis) exhibited a Type II functional response whereby the increasing feeding rate decelerated with increasing prey density. In addition to revealing that a wide range of planktivorous fishes can prey upon larvae of Acanthaster sp., these data suggest that planktivorous damselfishes may have the capacity to buffer against population fluctuations of Acanthaster sp. Importantly, predators with Type II functional responses often contribute to stability of prey populations, though planktivorous fishes may be swamped by an abnormally high influx of larvae, potentially contributing to the characteristic population fluctuations of Acanthaster sp.

Non-random feeding enhances the contribution of oceanic zooplankton to the diet of the planktivorous coral reef fish Dascyllus flavicaudus

Combining gut content analysis and sampling of ambient zooplankton, we examine departures from random feeding in a planktivorous coral reef fish and explore the effects of apparent non-random feeding behavior on the relative contribution of oceanic versus reef-associated zooplankton to fish diet. The planktivorous damselfish Dascyllus flavicaudus appears to exhibit strong positive electivity for oceanic copepods including Candacia spp. and copepods from the families Oncaeidae and Corycaeidae and consistent negative electivity for cyclopoid copepods (Oithonidae). In total, prey taxa categorized as oceanic in origin contributed 10–76 % of total zooplankton biomass in fish guts. The summed contribution of oceanic prey taxa to fish diet was significantly higher than expected under a model of random feeding based on the availability of oceanic versus reef-associated prey as sampled by zooplankton net tows. The feeding behavior of D. flavicaudus appears to be visibility-selective rather than or in addition to size-selective, as electivity across prey taxa could not be explained by differences in prey size alone.

Feeling the heat: the effect of acute temperature changes on predator-prey interactions in coral reef fish.

Recent studies demonstrate that the elevated temperatures predicted to occur by the end of the century can affect the physiological performance and behaviour of larval and juvenile fishes; however, little is known of the effect of these temperatures on ecological processes, such as predator-prey interactions. Here, we show that exposure to elevated temperatures significantly affected the predator-prey interactions of a pair of common reef fish, the planktivorous damselfish (Pomacentrus wardi) and the piscivorous dottyback (Pseudochromis fuscus). When predators exposed to elevated temperatures interacted with prey exposed in a similar manner, maximal attack speeds increased. This effect coupled with decreasing prey escape speeds and escape distances led to increased predation rates. Prey exposed to elevated temperatures also had decreased reaction distances and increased apparent looming threshold, suggesting that their sensory performance was affected. This occurred despite the increase in maximal attack speeds, which in other species has been shown to increase reaction distances. These results suggest that the escape performance of prey is sensitive to short-term increases in ambient temperature. As marine environments become more thermally variable in the future, our results demonstrate that some predators may become more successful, suggesting that there will be strong selection for the maintenance of maximal escape performance in prey. In the present era of rapid climate change, understanding how changes to individual performance influence the relationships between predators and their prey will be increasingly important in predicting the effects of climate change within ecosystems.

Experimental evaluation of diversity-productivity relationships in a coral reef fish assemblage.

The global decline in biodiversity is causing increasing concern about the effects of biodiversity loss on ecosystem services such as productivity. Biodiversity has been hypothesised to be important in maintaining productivity of biological assemblages because niche complementarity and facilitation among the constituent species can result in more efficient use of resources. However, these conclusions are primarily based on studies with plant communities, and the relationship between diversity and productivity at higher trophic levels is largely unknown, especially in the marine environment. Here, we used a manipulative field experiment to test the effects of species richness and species identity on biomass accumulation in coral reef fish assemblages at Lizard Island. Small patch reefs were stocked with a total of 30 juveniles belonging to three planktivorous damselfish (genus Pomacentrus) according to three different levels of fish species richness (one, two and three species) and seven different combinations of fish species. Species richness had no effect on the relative growth in this assemblage after 18 days, but relative growth differed among individual fish species and the different combinations of species. Patterns of increase in biomass were best explained by species-specific differences and variable effects of intra- and interspecific competition on growth. These results suggest that niche complementarity and facilitation are not the most influential drivers of total productivity within this guild of planktivorous fishes. Total productivity may be resilient to declining reef fish biodiversity, but this will depend on which species are lost and on the life-history traits of remaining species.

Sediment‐induced turbidity impairs foraging performance and prey choice of planktivorous coral reef fishes

Sedimentation is a substantial threat to aquatic ecosystems and a primary cause of habitat degradation on near-shore coral reefs. Although numerous studies have demonstrated major impacts of sedimentation and turbidity on corals, virtually nothing is known of the sensitivity of reef fishes. Planktivorous fishes are an important trophic group that funnels pelagic energy sources into reef ecosystems. These fishes are visual predators whose foraging is likely to be impaired by turbidity, but the threshold for such effects and their magnitude are unknown. This study examined the effect of sediment-induced turbidity on foraging in four species of planktivorous damselfishes (Pomacentridae) of the Great Barrier Reef, including inshore and offshore species that potentially differ in tolerance for turbidity. An experimental flow tunnel was used to quantify their ability to catch mobile and immobile planktonic prey under different levels of turbidity and velocity in the range encountered on natural and disturbed reefs. Turbidity of just 4 NTU (nephelometric turbidity units) reduced average attack success by up to 56%, with higher effect sizes for species with offshore distributions. Only the inshore species (Neopomacentrus bankieri), which frequently encounters this turbidity on coastal reefs, could maintain high prey capture success. At elevated turbidity similar to that found on disturbed reefs (8 NTU), attack success was reduced in all species examined by up to 69%. These reductions in attack success led to a 21-24% decrease in foraging rates for all mid to outer-shelf species, in spite of increasing attack rates at high turbidity. Although effects of turbidity varied among species, it always depended heavily on prey mobility and ambient velocity. Attack success was up to 14 times lower on mobile prey, leaving species relatively incapable of foraging on anything but immobile prey at high turbidity. Effects of turbidity were particularly prominent at higher velocities, as attack success was overall 20-fold lower and foraging rates 3.3-fold lower at flow velocities > 30 cm/s relative to < or = 10 cm/s. Given that many planktivorous reef fishes predominantly occupy exposed, high-flow habitats, these results provide a reasonable explanation for the lack of planktivores on inshore coral reefs and warn that the performance of visual predators could be impaired at turbidity levels of only 4 NTU.

Elevated CO2 Affects Predator-Prey Interactions through Altered Performance

Recent research has shown that exposure to elevated carbon dioxide (CO2) affects how fishes perceive their environment, affecting behavioral and cognitive processes leading to increased prey mortality. However, it is unclear if increased mortality results from changes in the dynamics of predator-prey interactions or due to prey increasing activity levels. Here we demonstrate that ocean pCO2 projected to occur by 2100 significantly effects the interactions of a predator-prey pair of common reef fish: the planktivorous damselfish Pomacentrus amboinensis and the piscivorous dottyback Pseudochromis fuscus. Prey exposed to elevated CO2 (880 µatm) or a present-day control (440 µatm) interacted with similarly exposed predators in a cross-factored design. Predators had the lowest capture success when exposed to elevated CO2 and interacting with prey exposed to present-day CO2. Prey exposed to elevated CO2 had reduced escape distances and longer reaction distances compared to prey exposed to present-day CO2 conditions, but this was dependent on whether the prey was paired with a CO2 exposed predator or not. This suggests that the dynamics of predator-prey interactions under future CO2 environments will depend on the extent to which the interacting species are affected and can adapt to the adverse effects of elevated CO2.

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.

Indirect effects of species interactions on habitat provisioning

Species that shelter in a biogenic habitat can influence their refugia and, in turn, play an essential role in shaping local patterns of biodiversity. Here we explore a positive feedback loop between the provisioning rate of habitat-forming branching corals and their associated fishes and show how interactions between two groups of fish—the planktivorous damselfish and predatory hawkfish—altered the feedback. A field experiment confirmed that skeletal growth of branching coral (genus Pocillopora) increased substantially with increasing numbers (biomass) of resident fishes, likely because they greatly increased the interstitial concentrations of nutrients. Because there is a positive relationship between colony size and number (biomass) of associated fishes (primarily damselfishes in the Family Pomacentridae), a structure–function feedback loop exists in which increasing numbers of damselfish enhance coral growth and larger corals host greater abundances (and species richness) of fish. However, interactions between damselfishes and arc-eye hawkfish, Paracirrhites arcatus, a largely solitary resident, can disrupt this positive feedback loop. Field surveys revealed a marked pattern of fish occupancy related to coral size: Pocillopora colonies of sufficient size to host fish (>40 cm circumference) had either groups of damselfish or an arc-eye hawkfish; only larger colonies (>75 cm) were occupied by both the damselfish and hawkfish. Subsequent short- and long-term experiments revealed that on intermediate-sized Pocillopora colonies, arc-eye hawkfish prevented the establishment of damselfish by suppressing their recruitment. The demographic consequences to the host coral were substantial; in a 1-year-long experiment, intermediate-size Pocillopora occupied by hawkfish grew at half the rate of corals that hosted groups of damselfish. These findings indicate that: (1) species which occupy a biogenic habitat can enhance the provisioning rate of their habitat; (2) such positive feedbacks between community structure and ecosystem function can be disrupted by a strong interactor; (3) even substantial consequences on ecosystem processes that arise can be difficult to discern.

Indirect effects of heterospecific interactions on progeny size through maternal stress

Maternal effects are increasingly being recognized as an important pre‐natal source of life history variation in the next generation. The present study uses a field experiment to explore the influence of heterospecific interactions on the reproductive output and offspring characteristics of a common Indo‐Pacific damselfish, Pomacentrus amboinensis. On the Great Barrier Reef pairs of breeding P. amboinensis were placed on isolated patch reefs and to half of the pairs resource competitors (other planktivorous damselfishes), and predators of eggs and juveniles were added. Females inhabiting patches with heterospecifics had more aggressive interactions and higher levels of the stress hormone, cortisol. Neither the number of clutches nor number of eggs produced differed among treatments. The size of larvae at hatching was found to be reduced as a result of the stress associated with increased interactions with heterospecific and the transfer of cortisol to offspring. This stress‐associated mechanism appears to be an important and directional source of life history variability, but the individual nature of the maternal response is likely to result in a conclusion of a diversified bet hedging reproductive strategy when viewed at the local population level. These findings highlight the complex determinants of individual success and the important role of parental well‐being in the population dynamics of the next generation.

A new cleaner species of Elacatinus (Actinopterygii: Gobiidae) from the Southwestern Atlantic

A new species of cleaner goby, Elacatinus phthirophagus sp. n., is described from Fernando de Noronha Archipelago, off northeastern Brazil. It differs from its congeners of the putative “randalli-evelynae” cleaning clade by the following combination of characters: mouth subterminal, pale (bright yellow in life) elliptical spot on dark snout, width of lateral pale (bright yellow in life) stripe almost equal as eye diameter (slightly narrower in live individuals), light purplish sheen (in life) extending laterally from below eye to tail origin, no blue line (in life) from below eye to end of opercular margin, teeth multiserial on the distal portion of both jaws, males with 3 enlarged and recurved teeth on dentary inner row. The new species was recorded at depths ranging from 3 to 18 m and is ubiquitous in the archipelago islets. It tends cleaning stations on coral heads, sponges, and rocky substrata, with up to 15 individuals present in large stations, particularly those on sponges. Elacatinus phthirophagus sp. n. was recorded to clean about 30 species of fish clients, including large carnivores such as the shark Carcharhinus perezi and smaller carnivores such as the grouper Cephalopholis fulva, besides small clients like the planktivorous damselfish Chromis multilineata and the zoobenthivorous butterflyfish Chaetodon ocellatus. The new species increases to three the number of cleaner gobies recorded for Southwestern Atlantic, one from the coast and two from oceanic islands.

Daily carbon, nitrogen and phosphorus budgets for the Mediterranean planktivorous damselfish Chromis chromis

The planktivorous damselfish Chromis chromis is one of the most numerous fish species in the Mediterranean rocky littoral, yet the role this species plays in the overall functioning of the ecosystem is poorly understood. In this study nitrogen, carbon and phosphorus budgets were constructed for C. chromis from the Bay of Calvi, Corsica and an attempt was made to resolve the possible fates of these nutrients from ingested materials, to somatic growth ( P s), reproductive tissues ( P r), respiration ( R), assimilation ( A′), faeces ( F) and dissolved wastes ( U). C. chromis were estimated to consume on average 4.7% of their own body mass of zooplankton per day, in two separate feeding episodes — at dawn and at dusk. This is equivalent to 8288 individual copepods or 42.1 mg carbon, 9.7 mg nitrogen, 0.8 g phosphorus. 44% of all phosphorus ingested was shown to be excreted as dissolved waste, and 46% as faeces; this may be of considerable importance in the Mediterranean, where littoral macrophytes are often severely phosphorus-limited. 85% of all nitrogen was excreted as dissolved waste (mostly ammonia) and local nutrient enrichment may enhance littoral primary productivity, particularly around C. chromis night-shelters.