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Chromis tweddlei, a new species of damselfish, is described from seven specimens, 88.8–111.1 mm standard length (SL), collected during a 2008 expedition by the R.V. Dr. Fridtjof Nansen at 214–219 m depth (an unusually deep occurrence for the genus) on the Cargados Carajos Bank, Mascarene Plateau, southwestern Indian Ocean. Chromis tweddlei sp. nov. closely resembles Chromis axillaris, Chromis pelloura, and Chromis woodsi, the only congeners occurring in the western Indian Ocean (WIO) that share the character of having 14 dorsal‐fin spines and a dark caudal band. Chromis tweddlei sp. nov. can be distinguished from its regional congeners by having II,13–14 anal‐fin rays, 19–20 pectoral‐fin rays, 18–19 tubed lateral‐line scales, 4 scales above lateral line to the origin of dorsal fin, 29–32 total gill rakers, and colouration, including a caudal band that tapers anteriorly the full length of the caudal peduncle. A key to the 14 dorsal‐fin spine species of Chromis from the WIO is provided. [ABSTRACT FROM AUTHOR]

The ability to detect and respond to the presence of predation risk is under intense selection, especially for small‐bodied fishes. Damselfishes (Pomacentridae) use auditory vocalizations during inter‐ and intrasexual interactions, but it is not known if they can use vocalizations in the context of predator–prey interactions. Here, we test if yellowtail damselfish, Chrysiptera parasema, can learn to associate the territorial vocalization of heterospecific humbug damselfish Dascyllus aruanus with predation risk. In conditioning trials yellowtail damselfish were presented with the territorial call of humbug damselfish while either blank water (control treatment) or chemical alarm cue derived from damaged skin of conspecific yellowtail damselfish was introduced. In conditioning trials, fish exposed to alarm cue exhibited increased activity and spent more time in the water column relative to fish that received the control treatment. After a single conditioning trial, conditioned fish were exposed again to the territorial call of humbug damselfish. Fish conditioned with the call + alarm cue showed increased activity and spent more time in the water column relative to fish that had been conditioned with the control treatment. These data indicate associative learning of an auditory stimulus with predation risk in a species that regularly uses auditory signalling in other contexts. Recordings of conditioning and test trials failed to detect any acoustic calls produced by test fish in response to the perception of predation risk. Thus, although yellowtail damselfish can associate risk with auditory stimuli, we found no evidence that they produce an alarm call. [ABSTRACT FROM AUTHOR]

Restoration is an emerging tool for coral reef conservation, yet despite small‐scale successes there are concerns about high costs and ecological setbacks. Integration between reef ecology and restoration could help address such concerns. A prime example is the use of grazing by herbivores to reduce coral nursery cleaning costs. However, the relation between herbivore communities and cleaning benefits remains unquantified. This study aimed to measure links between herbivorous fish communities, grazing intensity and coral nursery performance. Six reefs were selected in southern Kenya, equally divided across three levels of fisheries management (fished < reserve < no‐take). Fish surveys determined herbivorous fish biomass and composition, and remote underwater videos recorded grazing intensity on coral nurseries. Accumulated fouling and coral growth were measured at the end of the 4‐month study. Grazing intensity was sixfold lower and fouling density fourfold higher in the fished areas compared to protected zones. Higher fouling strongly correlated with lower coral growth: exponential growth constants in fished areas were respectively twice and three times as low compared to marine reserves and no‐take zones. Across study sites grazing was dominated by bristletooth tangs (Ctenochaetus spp.), except where these were outcompeted by territorial damselfish. Thus, better coral nursery performance in protected areas can be partially linked to higher grazing intensity, which in turn is determined by both fish biomass and local species composition. We recommend protecting herbivorous fish species and placing coral nurseries in areas with high biomass of key grazers to improve coral nursery performance and reduce maintenance costs. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of food availability on the transcript levels of genes related to reproduction and growth in the sapphire devil (Chrysiptera cyanea), a tropical damselfish. Nonbreeding fish were reared at high‐food (HF) and low‐food (LF) levels for 4 weeks under long‐days. Vitellogenic oocytes could be observed in the ovaries of the HF group. The quantitative polymerase chain reaction analysis revealed that lhβ and cyp19b in the brains, vtg and igf1 in the livers and cyp19a in the ovaries of HF fish were significantly higher than that of LF fish, suggesting that estradiol‐17β (E2) synthesis in the ovary and brain is activated when suitable permissive factors are available to fish. Food limitation lowered hepatic igf1 and dio2, suggesting that the TH‐IGF1 signaling system functions in the liver, and that food availability altered hepatic deiodination activities related to intercellular levels of thyroid hormones. Hepatic dio2 significantly decreased when fish were immersed for 3 days in E2‐containing seawater; this suggests that E2 impedes the conversion of T4 to T3 in the liver. Our study shows that igf1 was upregulated in accordance with HF‐induced vitellogenesis but downregulated by E2 treatment, suggesting that igf1 is bidirectional and altered by maturational status. Once vitellogenesis begins under a suitable range of proximal factors, fish need to maintain their nutritional status because food availability is a permissive factor for their reproduction. Highlights: Nonbreeding sapphire devils were reared with high‐food (HF) and low‐food (LF) levels under suitable breeding condition.HF started vitellogenesis and upregulated igf1, dio2, lhβ, cyp19a, cyp19b, and vtg.Interplay between the reproduction and growth axis exists due to nutritional status. [ABSTRACT FROM AUTHOR]

The evolution of parental care opens the door for the evolution of brood parasitic strategies that allow individuals to gain the benefits of parental care without paying the costs. Here we provide the first documentation for alloparental care in coral reef fish and we discuss why these patterns may reflect conspecific and interspecific brood parasitism. Species‐specific barcodes revealed the existence of low levels (3.5% of all offspring) of mixed interspecific broods, mostly juvenile Amblyglyphidodon batunai and Pomacentrus smithi damselfish in Altrichthys broods. A separate analysis of conspecific parentage based on microsatellite markers revealed that mixed parentage broods are common in both species, and the genetic patterns are consistent with two different modes of conspecific brood parasitism, although further studies are required to determine the specific mechanisms responsible for these mixed parentage broods. While many broods had offspring from multiple parasites, in many cases a given brood contained only a single foreign offspring, perhaps a consequence of the movement of lone juveniles between nests. In other cases, broods contained large numbers of putative parasitic offspring from the same parents and we propose that these are more likely to be cases where parasitic adults laid a large number of eggs in the host nest than the result of movements of large numbers of offspring from a single brood after hatching. The evidence that these genetic patterns reflect adaptive brood parasitism, as well as possible costs and benefits of parasitism to hosts and parasites, are discussed. [ABSTRACT FROM AUTHOR]

Embryonic development and larval morphology of Chromis crusma was described from five nests sampled between 21 and 25 m depth in central Chile (33°S). From each nest, a set of c. 100 randomly selected eggs were hand‐collected and transported in seawater to the laboratory. Subsets of c. 30 eggs per nest were maintained in 50 ml glass containers at a constant ambient temperature of c. 12°C (range 11.5–12.9°C). Egg length (L) and width (W) and larval notochordal length (LN) were measured from photographs. Geometric morphometric analyses were performed in newly hatched and 1 week old larvae to quantify shape changes. Ellipsoid eggs had an average (mean ± SE) size of 1.12 ± 0.05 mm L and 0.67 ± 0.02 mm W, with volume being similar throughout 15 developmental stages (i.e., ellipsoid‐shaped; 0.27 mm3). Planktonic larvae hatched between 5 and 11 days at 12°C and had a mean LN of 3.13 ± 0.25 mm, a yolk sack volume of 0.03 mm3 and an oil droplet volume of 0.005 mm3. Morphological traits at hatching included: (a) lack of paired fins and jaws; (b) single medial fin fold; (c) lack of eye pigmentation; (d) yolk sac present near anterior tip; (e) melanophores distributed along ventral surface with one pair over the forehead. In order to generate an up‐to‐date summary of developmental traits within Pomacentridae, we reviewed literature on egg development (e.g., shape and number of oil droplets), hatching and larval traits (e.g., morphology, pigmentation patterns). Thirty‐two publications accounting for 35 species were selected, where eggs, embryonic development, hatching and larval traits were found for 26, 21, 24 and 34 species, respectively. In order to evaluate potential phylogenetic and environmental relationships within the early stages of Pomacentridae, cluster analyses (Bray Curtis similarity, group average) were also performed on egg and larval traits of 22 species divided by subfamily (Stegastinae, Chrominae, Abudefdufinae, Pomacentrinae) and thermal ranges (i.e., low: 16.5°C (range: 12–21°C), medium: 24.5°C (range:21–28°C) and high: 27°C (range: 26–28°C)), suggesting that early developmental patterns can be segregated by both temperature and phylogenetic relationships. [ABSTRACT FROM AUTHOR]

Stable between‐group differences in collective behavior have been documented in a variety of social taxa. Here we evaluate the effects of such variation, often termed collective or colony‐level personality, on coral recovery in a tropical marine farmerfish system. Groups of the farmerfish Stegastes nigricans cultivate and defend gardens of palatable algae on coral reefs in the Indo‐Pacific. These gardens can promote the recruitment, growth, and survival of corals by providing a refuge from coral predation. Here we experimentally evaluate whether the collective response of farmerfish colonies is correlated across intruder feeding guilds – herbivores, corallivores and egg‐eating predators. Further, we evaluate if overall colony responsiveness or situation‐specific responsiveness (i.e. towards herbivores, corallivores, or egg‐eaters in particular) best predicts the growth of outplanted corals. Finally, we experimentally manipulated communities within S. nigricans gardens, adding either macroalgae or large colonies of coral, to assess if farmerfish behavior changes in response to the communities they occupy. Between‐group differences in collective responsiveness were repeatable across intruder guilds. Despite this consistency, responsiveness towards corallivores (porcupinefish and ornate butterflyfish) was a better predictor of outplanted coral growth than responsiveness towards herbivores or egg‐eaters. Adding large corals to farmerfish gardens increased farmerfish attacks towards intruders, pointing to possible positive feedback loops between their aggression towards intruders and the presence of corals whose growth they facilitate. These data provide evidence that among‐group behavioral variation could strongly influence the ecological properties of whole communities. [ABSTRACT FROM AUTHOR]

Steps taken for broodstock development of Neopomacentrus nemurus, Coral demoiselle (Bleeker, 1857) in a hatchery, its spawning and development of egg to the juvenile stage are described. Among the three treatments tried, only the trial using Parvocalanus crassirostris nauplii as the first diet helped in the development of larvae. Larval and post‐larval growth was studied for a period of 65 days post hatch. The larva measured 2–2.4 mm in total length at the time of hatching. The mouth size of larva at the time of hatching measured 237.92 µm. By the 5th day, the width of the larval body had significantly increased. All the fins were conjoined, except for the caudal fin which had begun its appearance on the 2nd day itself. The digestive system was functional by the 5th day and the copepod remains were seen in the digestive tract. The larva metamorphosed by the 15th day with fully developed fins and fin rays. On the 20th day, the larval body had begun to display signs of fin pigmentation. The larva assumed adult pigmentation by the 35th day. By the 65th day, the larva grew to a total length of about 27 mm and weighed about 0.56 g. [ABSTRACT FROM AUTHOR]

Abstract: Climate change is expected to pose a significant risk to species that exhibit strong behavioural preferences for specific habitat types, with generalist species assumed to be less vulnerable. In this study, we conducted habitat choice experiments to determine how water temperature influences habitat preference for three common species of coral reef damselfish (Pomacentridae) that differ in their levels of habitat specialisation. The lemon damselfish Pomacentrus moluccensis, a habitat specialist, consistently selected complex coral habitat across all temperature treatments (selected based on local average seasonal temperatures naturally experienced in situ: ambient winter 22°C; ambient summer 28°C; and elevated 31°C). Unexpectedly, the neon damselfish Pomacentrus coelestis and scissortail sergeant Abudefduf sexfasciatus, both of which have more generalist habitat associations, developed strong habitat preferences (for complex coral and boulder habitat, respectively) at the elevated temperature treatment (31°C) compared to no single preferred habitat at 22°C or 28°C. The observed shifts in habitat preference with temperature suggest that we may be currently underestimating the vulnerability of some habitat generalists to climate change and highlight that the ongoing loss of complex live coral through coral bleaching could further exacerbate resource overlap and species competition in ways not currently considered in climate change models. [ABSTRACT FROM AUTHOR]

The damselfish Chromis chromis is typically the most abundant fish species in the rocky littoral environment of the Mediterranean Sea, where it feeds in huge shoals on incoming zooplankton and rests near the seabed each night. Research has shown that large populations of C. chromis play a fundamental role by transferring carbon, nitrogen and phosphorus directly from the pelagic system to the littoral in the form of solid and liquid wastes and therefore that this species acts as a vital conduit for nutrients. In addition, C. chromis represents a major prey item for predatory fish and seabirds, it has been shown to exert significant predation pressure on coastal zooplankton populations, but it is also a major consumer of fish eggs and hence may have a strong influence on the dynamics of other fish species. In this review paper the contention is that C. chromis represents a key species in the Mediterranean Sea rocky littoral. This view is supported by quantitative evidence that has been amassed over a number of years, but is collated here for the first time. Chromis chromis is of only minor importance to commercial fisheries (it is usually discarded), but trends in population abundance of this species can be indicative of levels of fishing pressure on other commercial species. It has been demonstrated that where predator numbers are able to recover from intensive fishing (e.g.in marine protected areas; MPAs), this is often mirrored by lower densities of C. chromis. Several papers have championed C. chromis as a possible indicator species for human disturbance. As well as being directly and indirectly affected by fishing, the species is also sensitive to a number of other anthropogenic pressures, most notably poor water quality and noise pollution. [ABSTRACT FROM AUTHOR]

Damselfish are prolific callers, identified as being able to produce different kinds of sounds (pops and chirps) associated with various behaviors. During courtship and chase behaviors, the coral reef damselfish Pomacentrus amboinensis produces a previously unknown additional kind of call that we have named the wiping sound. These calls have two to three long (54 ± 13 ms) units that do not show the usual percussive aspect of the pomacentrid sounds. Calls consist of a high-pitched (from 550 to 775 Hz) tonal sound in which the cycle repetition rate corresponds to the peak frequency. The high frequency of this tonal sound can be excluded as coming from the contraction of sound producing muscles. These sounds could be the result of a mechanism that drives the merging of successive pops. In the noisy environment of coral reefs and the resulting competition for acoustic space, the wiping sounds appear to be a good way to increase signal distinctiveness and opportunities for correct signal discrimination. This new kind of sound supports that acoustic communication is highly important in the biology of damselfishes and their diversification. [ABSTRACT FROM AUTHOR]

Coral branches partially block the flow of water through the colony, creating an inner zone of reduced water exchange where hypoxic conditions can develop during the night. Previous studies have shown that this oxygen deficiency is alleviated by the fanning behavior of mutualistic damselfish that spend the night between the coral branches, constantly moving their fins. Our findings show that fin-stroking frequency during fanning by the damselfish Dascyllus marginatus is moderately plastic, with lower frequency under higher oxygen concentration, and vice versa. The inter-play between oxygen concentration and fin motion maintains nearly steady oxygen concentration between the coral branches during the night. [ABSTRACT FROM AUTHOR]

Habitat degradation is predicted to exacerbate competition for critical resources; however, the relationship between habitat quality and competition is poorly understood. In this study, we used a manipulative experiment to test the effects of habitat degradation on competition between two planktivorous, coral-dwelling damselfishes, Chrysiptera parasema and Dascyllus melanurus. Experimental reefs were constructed with either healthy (100% live) or degraded (10% live) Acropora longicyathus coral, stocked with varying densities of these two fish species, and monitored for two months. On healthy habitat, the mortality of C. parasema was density dependent, and increased substantially in the presence of the dominant interspecific competitor D. melanurus. In contrast, on reefs where habitat was degraded, C. parasema mortality was highly variable, density independent, and was no longer influenced by the presence of dominant competitor D. melanurus. Behavioral observations revealed that agonistic interactions for both species increased with density on degraded habitat, but not on healthy habitat. In addition, on degraded reefs, both species displayed a reduced association with reef habitat and ventured further away from shelter with increasing densities of the dominant competitor D. melanurus. These results suggest that reduced habitat quality can have such a profound effect on reef fishes, that it eliminates density-dependent mortality and competitive dominance hierarchies, thereby substantially altering the mechanisms that structure reef fish communities. [ABSTRACT FROM AUTHOR]

The article reports on a study which has identified an Indo-Pacific reef fish with Francisella noatunensis subspecies infection in the U.S. It notes that broad mantles of epithelioid macrophages have predominated granuloma with large cytoplasmic vacuole. It mentions that haematoxylin and eosin have been used for tissue staining.

The southeast coast of Australia is a global hotspot for increasing ocean temperatures due to climate change. The temperate incursion of the East Australian Current (EAC) is increasing, affording increased connectivity with the Great Barrier Reef. The survival of tropically sourced juveniles over the winter is a significant stumbling block to poleward range shifts of marine organisms in this region. Here we examine the dependence of overwintering on winter severity and prewinter recruitment for eight species of juvenile coral reef fishes which are carried into temperate SE Australia (30–37 °S) by the EAC during the austral summer. The probability of persistence was most strongly influenced by average winter temperature and there was no effect of recruitment strength. Long-term (138 years) data indicate that winter water temperatures throughout this region are increasing at a rate above the global average and predictions indicate a further warming of >2 °C by the end of the century. Rising ocean temperatures are resulting in a higher frequency of winter temperatures above survival thresholds. Current warming trajectories predict 100% of winters will be survivable by at least five of the study species as far south as Sydney (34 °S) by 2080. The implications for range expansions of these and other species of coral reef fish are discussed. [ABSTRACT FROM AUTHOR]

Replenishment of many marine populations occurs through the entry of juveniles to adult populations following a pelagic larval stage. Because mortality during the pelagic stage is thought to be high and density independent, larval abundance and traits of individual larvae should have strong effects on overall population dynamics in marine organisms. Surprisingly, few experiments have tested how localized interactions among breeding adults affect the quantity and phenotypic traits of larvae they produce. Here I experimentally test for the influence of food competition, mate limitation, and population density on somatic growth, fecundity, and offspring provisioning (larval length and energy reserves) in a planktivorous, territorial coral reef damselfish, Stegastes partitus. I manipulated food supply and adult S. part itus density on isolated patch reefs in the Bahamas and also made behavioral observations of S. partitus occurring on nearby natural reefs at a range of population densities. On the experimental reefs, females experienced density-dependent growth and fecundity; male reproductive success was density dependent, but male growth was not. Density-dependent growth and reproduction were not moderated by food supplementation, and density-dependent reproduction was not influenced by mate availability. On natural reefs, the frequency of aggressive interactions, particularly involving females, increased with population density, implicating aggression-related energetic costs as the source of both forms of density dependence in the experiments. Food supplementation increased female somatic growth and larval energy reserves, suggesting that females allocated surplus energy to future reproductive potential and enhanced offspring quality. Neither experimental treatment affected larval length. By altering patterns of reproduction, the interplay between spatial variation in food availability and population density may drive population dynamics in a broad range of benthic marine organisms. [ABSTRACT FROM AUTHOR]

The capacity for marine fishes to perform aerobically (aerobic scope) is predicted to control their thermal tolerance and, thus, the impact that rapid climate change will have on their populations. We tested the effect of increased water temperatures on the resting and maximum rates of oxygen consumption in five common coral reef fishes at Lizard Island on the northern Great Barrier Reef, Australia. All species exhibited a decline in aerobic capacity at elevated water temperatures (31, 32 or 33 °C) compared with controls (29 °C); however, the response was much stronger in two cardinalfishes, Ostorhinchus cyanosoma and O. doederleini, compared with three damselfishes, Dascyllus anuarus, Chromis atripectoralis and Acanthochromis polyacanthus. Aerobic scope of the two cardinalfishes was reduced by nearly half at 31 °C compared with 29 °C, and virtually all capacity for additional oxygen uptake was exhausted by 33 °C. In contrast, the three damselfishes retained over half their aerobic scope at 33 °C. Such differences in thermal tolerance between species, and possibly families, suggest that the community structure of reef fish assemblages might change significantly as ocean temperatures increase. Populations of thermally tolerant species are likely to persist at higher temperatures, but populations of thermally sensitive species could decline on low-latitude reefs if individual performance falls below levels needed to sustain viable populations. [ABSTRACT FROM AUTHOR]

1. The impact of environmental disturbance and habitat loss on associated species is expected to be dependent on a species’ level of specialization. We examined habitat use and specialization of coral reef fish from the diverse and ecologically important family Pomacentridae, and determined which species are susceptible to declines in coral cover due to disturbance induced by crown-of-thorns seastar (COTS, Acanthaster planci L.). 2. A high proportion of pomacentrid species live in association with live coral as adults (40%) or juveniles (53%). Adults of many species had strong affiliations with branching corals, while juveniles favoured plating growth forms, reflecting the sizes of refuge provided by coral types. 3. Juveniles of species that associated with coral had narrower niche breadths than adult conspecifics, due to associations with specific coral types. The especially high coral association and narrower niche breadth of juveniles suggest that the presence of live coral is crucial for many species during early life history, and that disturbance-induced coral loss may have serious flow-on effects on adult abundance. 4. Microhabitat availability was a poor predictor of fish species abundance. Significant correlations between coverage of coral types and abundance of five adults and two juvenile species were detected; however, these relationships explained <35% and <10% of the variation in abundance of adult and juvenile species, respectively. 5. Niche breadth explained 74% of the variation in species’ mean response to coral decline and it is clear that disturbance has a greater impact on resource specialists, suggesting that increasing frequency and intensity of coral loss will cause reef fish communities to become dominated by habitat generalists at the expense of coral-dwelling specialists. [ABSTRACT FROM AUTHOR]

Morphological development of the larvae of the Ambon damselfish Pomacentrus amboinensis from the Great Barrier Reef, Australia, is described from 34 reared specimens (2·5–13·0 mm standard length), and two wild settlement-stage larvae (10·8–11·3 mm) captured in light traps. Reared larvae emerged from demersal eggs at c. 2·5 mm, underwent notochord flexion at 4·0–4·5 mm, and settled at 11–13 mm at 19–21 days after hatching (within the known range for wild larvae). Reared larvae grew at 0·3 mm day−1 (preflexion) to 0·5 mm day−1 (postflexion). Development was direct with few specializations for pelagic existence and was typical of pomacentrids. Head spination consisted of very weak spines on the preopercle, opercle, interopercle, subopercle and supracleithrum. Development of the olfactory system and retina are also described. A summary of published descriptions of early life-history stages of pomacentrid damselfishes is provided ( n= 15% of known species). Larvae of several genera ( e.g. Abudefduf, Chromis and Stegastes) are deeper-bodied and more ‘hunchbacked’ than P. amboinensis. Larvae of other genera ( e.g. Amblyglyphidodon, Chrysiptera and Neoglyphidodon) are similar to P. amboinensis. Larvae of only three other Pomacentrus species have been described, and they are similar to P. amboinensis in body morphology, pigmentation and head spination. [ABSTRACT FROM AUTHOR]

Most marine populations are sustained by the entry of juveniles that have survived the larval phase, during which time most die. The number of survivors depends strongly on the quality of the eggs produced by spawning females, but it is not known how the social conditions under which breeding occurs influence the quality of larvae produced. Here I show that the density of females interacting with breeding mothers directly influences the size of larvae produced, through a stress-related mechanism. On the Great Barrier Reef of Australia, breeding pairs of a damselfish, Pomacentrus amboinensis, were isolated on habitat patches, and additional females that could not access the spawning site were added at four densities (0, 1, 3, or 6 females). Additional females increased aggressive interactions by mothers and increased the levels of the stress hormone, cortisol, in their ovaries, leading to reduced larval size. Neither egg output nor yolk size of the larvae was influenced by female density. Pairs breeding in isolation produced the largest larvae; current theory suggests that these larvae should contribute most to subsequent population replenishment events. This social mechanism may influence which females effectively contribute to the next generation and may promote resilience in patchy or isolated populations. [ABSTRACT FROM AUTHOR]

A potential effect of parasitism on male egg loss while guarding was tested using damselfish Stegastes planifrons. Despite an apparent low energetic cost of the parasite on the male condition, there was a significant positive relationship between egg loss and parasite load. These data provide the first evidence that parasites could play a role in male guarding behaviour. The effect of the parasite could have resulted in low male condition compensated by an increase in filial cannibalism or in a lesser ability to protect the nest from predators. [ABSTRACT FROM AUTHOR]

TwoDascyllus reticulatuspopulations from Madang, Papua New Guinea exhibited diandric protogyny. In both populations, gonads began as undifferentiated, and then developed oocytes in the primary growth stage and an ovarian lumen. From this ovarian state or from more developed ovaries containing oocytes beyond the primary-growth stage, some gonads developed into testes. The first sign of testicular development was degeneration of oocytes, degeneration of oocytes in the primary growth stage in ovarian gonads and degeneration of oocytes of all growth stages present including the primary growth stage in ovaries, which was then followed by development of spermatogenic tissue. In both populations, most of the fish that had gonads with degenerating oocytes were smaller than the smallest mature females, indicating that development towards testes was mostly initiated in immature gonads containing only pre-vitellogenic oocytes. On some occasions, however, females as large as other mature females also had gonads with degenerating oocytes, suggesting that development towards testes may have occurred in mature ovaries as well. This latter notion is further strengthened by the discovery of a fish having a gonad that contained both degenerating vitellogenic oocytes and developing spermatogenic tissue. Taken together, these results suggest thatD. reticulatuscan exhibit diandric protogyny, because testes inD. reticulatusdeveloped from juvenile gonads as well as from mature ovaries. [ABSTRACT FROM AUTHOR]

We estimated the population consequences to an inferior competitor from interactions with a superior competitor that also is an indirect mutualist. The competitors are two damselfishes, three-spot dascyllus (Dascyllus trimaculatus) and orange-fin anemonefish (Amphiprion chrysopterus), that vie for shelter space on a sea anemone (Heteractis magnifica). Anemonefish have an indirect positive effect on dascyllus populations due to the faster growth that anemones experience when they are occupied by Amphiprion. A long-term experiment revealed that anemonefish depressed dascyllus density (number of individuals per area of anemone per area of reef) more than abundance (number of individuals per reef area) because anemonefish caused a greater net increase in anemone surface area. We calculated that the effect of competition alone would depress dascyllus populations to near zero. The indirect positive interaction compensated for &sim,67% of the direct negative effect. Failure to consider the indirect positive interaction in this system would lead to a gross underestimate of the strength of competition, and would not reveal the critical importance of the indirect mutualism in maintaining local populations of the inferior competitor. Indirect mutualisms are common in nature, and assessing how they mediate effects of other processes is crucial to a more accurate understanding of natural communities. [ABSTRACT FROM AUTHOR]

Abstract Mutualistic interactions are not believed to promote coexistence of competitors because mutualisms produce positive feedbacks on abundances whereas coexistence requires negative feedbacks. Here we show that a mutualism between an anemonefish (Amphiprion ) and its sea anemone host mediates the effect of asymmetrical competition for space between the anemonefish and another damselfish (Dascyllus ) in a manner that fosters their coexistence. Amphiprion stimulates increases in host area, the shared resource, but social interactions cap the number of anemonefish to two adults per host. Space generated by the mutualism becomes differentially available to Dascyllus because the effectiveness of an anemonefish in excluding its competitor declines with increases in the area it defends. This alters Amphiprion 's ratio of per capita intra- to interspecific effects and thus facilitates coexistence of the fishes. This mechanism may be prevalent in nature, adding another major pathway by which mutualism can enhance diversity. [ABSTRACT FROM AUTHOR]

Settlement-stage damselfish (Pomacentridae) larvae of 13 species in seven genera were obtained from light traps at Lizard Island, Great Barrier Reef, Australia. Behaviour, observed in situ by SCUBA divers, of 245 larvae (6–13 mm, LS; 5–60 individuals per species) released individually within a few m of reefs during the day differed markedly among species. From 0–28% (range among 13 species) of individuals of each species swam away from the adjacent reefs without swimming to the reefs. Of those that swam to a reef, 0–75% settled. For three species, sufficient data were available to test the hypothesis that these percentages did not differ amongst reefs: the hypothesis was rejected in one species. From 0–75% of larvae that reached the reef were eaten, 0–63% subsequently left the reef and 0–60% were still swimming over the reef at the end of the observation period. Swimming speeds of all but one species were greater when swimming away from the reef than toward it. Most species exceeded average current speeds when swimming away from reefs, but not when swimming toward and over them. Average swimming depths were in the upper half of the water column for most species, and were somewhat greater where the water depths were greater. The time the larvae swam over the reef before settling and the distance swum varied greatly among species from 0 to a mean of 5·5 min and 43 m. Settlement habitats chosen differed amongst species, and in some species, they were very specific. Average settlement depth varied among species from 6–13·5 m. In one species, settlement depth varied between reefs. About half of the 53 observed interactions between larvae and reef resident fishes were predation attempts: fishes of eight species (six families) attacked larvae. The other interactions were aggressive approaches by 11 species of resident fishes, all but one of which were pomacentrids. Many of these aggressive interactions discouraged settlement attempts. Larvae of some species experienced no predatory or aggressive interactions, whereas in other species interactions averaged >0·6 per released larva. Species that swam more-or-less directly to settlement sites near the reef edge experienced more interactions. Even within the same family, settlement behaviour differed among species in nearly all measures. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Nesting male demoiselles Chromis dispilus were captured and blood sampled under water by divers, and plasma levels of reproductive hormones correlated with behavioural status at the time of capture. Plasma gonadotropin-II (dGtH-II) was measured using a heterologous assay based on carp GtH-II standards and an antibody to the β-subunit of cGtH-II. Plasma samples diluted parallel to standards in the assay, and there was a significant transient increase in dGtH-II in response to treatment with gonadotropin releasing hormone analogue (GnRHa). Male demoiselles had elevated plasma levels of dGtH-II during periods of reproductive display, but low levels of dGtH-II during periods of brooding, irrespective of egg stage. Plasma testosterone levels followed a similar pattern whereas plasma 11-ketotestosterone and 17,20β-dihydroxy-4-pregnen-3-one levels tended to remain elevated during the early phases of egg brooding. The results are consistent with earlier studies showing that reproductive hormone levels in demoiselles are behaviourally mediated, and support the view that behavioural alterations of reproductive endocrine status in fishes are mediated through the action of GnRH. [Copyright &y& Elsevier]

Abstract The phylogeographical and systematic relationships among species in the tropical marine fish genus Dascyllus were inferred using mitochondrial DNA (mtDNA) sequence data. Although our results were generally consistent with previously published phylogenies based on both morphological and mitochondrial data, our broad taxonomic and geographical sampling design revealed novel insights into the phylogenetic history of Dascyllus that had escaped previous notice. These results include: (a) the polyphyletic nature of D. reticulatus mtDNAs, representing two divergent and geographically separated lineages, one shared with D. flavicaudus and the second forming the sister lineage of D. carneus ; (b) the paraphyly of D. trimaculatus relative to the closely related D. abisella ; and (c) phylogeographical structure within the widespread taxa D. aruanus and D. trimaculatus . Application of a molecular clock permits us to posit a causative role for tectonic and oceanic changes regarding some Dascyllus speciation events. Finally, we mapped body size and the presence or absence of protogynous sex change on the mtDNA tree, and tested published hypotheses regarding determinants of the evolution of mating system and protogyny in the genus. Our data rejected a model based on body size but not one based on phylogenetic inertia. The ability to change sex arose once in the ancestor to the entire genus, and was lost once in the ancestor of the D. trimaculatus complex. For taxa that are as geographically widespread as many Indo-Pacific genera, this study highlights the importance of adequate geographical sampling when inferring patterns of species diversification and life history evolution. [ABSTRACT FROM AUTHOR]

Populations of coral reef fishes are often thought to saturate habitable space and to be limited by its availability, particularly those fishes that defend space. In Panama, individual adults of the common Caribbean damselfish Eupomacentrus planifrons defend permanent, all-purpose territories . A territory contains a mass of coral from which the fish derives required substrate-based resources: shelter from predators, a nest site (males only), and food (from a distinct mat of algae). Two experiments tested whether an excess of suitable substrate was present in two of the main habitats of E. planifrons. (1) Coral substrate that contained algal mats was removed from small areas (up to 45 m2) in habitats composed of Agaricia and Acropora corals. After 3 mo new algal mats were established on previously mat-free parts of the experimental areas, and the density of adult E. platnifrons increased in the experimental areas. (2) The area of habitat of three small patch-reefs was reduced by one-half through the removal of coral substrate. One year later, the density of E. planifrons adults had increased on the remaining halves of those reefs. The results of both experiments indicated that a surplus of suitable substrate existed in the experimental areas and that E. planifrons was not generally limited by the availability of habitable space. Compared to control fish of the same length, experimental E. planifrons were similar in mass, in the amounts of fat reserves, and, in the case of females, in activity of their ovaries. Both experimental and control fish were breeding at the end of the experiment. Thus the experimental increase in population density did not appear to be detrimental to the physiological condition or reproductive capacity of the fish. We conclude that E. planifrons is probably not at the carrying capacity of the habitats it occupies [ABSTRACT FROM AUTHOR]

Neopomacentrus filamentosus, a common damselfish on the Indo–Australian archipelago, undergoes significant shifts in size and mitochondrial genetic structure upon larval settlement and metamorphosis to juvenile stages. We characterized five polymorphic microsatellite loci in order to study temporal genetic shifts within a single generation of N. filamentosus sampled first as larval settlers then again as demersal juvenile recruits. All loci were extremely polymorphic and exhibited high levels of heterozygosity. While all loci from the larval samples conformed to Hardy – Weinberg expectations, significant heterozygote deficiencies were seen in two loci in the juvenile samples, likely due to extreme size-selective mortality imposed post-settlement. [ABSTRACT FROM AUTHOR]

We describe 15 polymorphic dinucleotide microsatellite loci in the black-and-gold chromis, Neoglyphidodon nigroris (Cuvier: Teleostei: Pomacentridae). Microsatellites were isolated from a partial genomic library that was enriched for CA repeat motifs. The 15 loci yielded between two and 23 alleles per locus in a sample of 16 fish from two forereef sites off the island of Hoga, Wakatobi National Park, Indonesia. Observed and expected heterozygosities varied from 0.13 to 1.00 and 0.24 to 0.98, respectively. These markers should allow us to discriminate between closely related individuals and also to assess the connectedness of populations of N. nigroris that inhabit different reefs. [ABSTRACT FROM AUTHOR]

The extent of dispersal between populations of Caribbean reef fish remains largely unknown. Resolution of this issue is critical for managing populations and designing marine reserves. As part of a larger study of reef fish dispersal, we developed and characterized 11 polymorphic microsatellite loci for the bicolor damselfish ( Stegastes partitus), an abundant reef fish found throughout the Caribbean. These loci will be useful for population genetic and relatedness studies of this species and also appear to be useful in other Caribbean members of the Pomacentridae. [ABSTRACT FROM AUTHOR]