Coryphopterus Glaucofraenum Research Articles

Host-parasite Interactions between a Copepod (Pharodes tortugensis) and Small Reef-associated Gobies (Coryphopterus) in the British Virgin Islands.

The effects of parasitic copepods on free-living hosts are infrequently documented, and the copepod Pharodes tortugensis has remained virtually unstudied since described. For the first time, we document its host range in the British Virgin Islands (BVI), the prevalence and intensity of infections on wild hosts, and its impacts on host morphology and performance. Infections were observed on four benthic gobies in the BVI (Coryphopterus glaucofraenum, C. venezuelae, C. dicrus and C. eidolon) but not on other host species previously reported from other parts of the western Atlantic. Infected gobies were widespread in the BVI (detected at 33 of 52 sites, prevalence from 1-25%) but extremely rare elsewhere in the Caribbean (detected at 2 of 16 sites, prevalence < 0.006%). As is typical of macroparasite infections, P. tortugensis was over-dispersed in BVI host populations (mean intensity = 4.7, range = 1-17). Infections were most common in juvenile and female hosts, and rarely found in larger male hosts. The copepods attach in the branchial chamber of the goby; female copepods show high attachment fidelity to the ventral surface of the chamber, while male copepods attached most often to the first two gill arches and in the branchial chamber adjacent to the female. Infections caused substantial damage to the host's branchial chamber and gill filaments. Parasitized gobies also had larger livers and smaller gonads than unparasitized individuals of similar length. The changes in organ mass of infected gobies were not sizeable enough to affect total body mass, and host condition (the body-length vs. body-mass relationship) was similar for gobies with and without infections. Parasitized gobies were, however, significantly smaller in body mass at a given age, reflecting slower overall growth. Effects of P. tortugensis on individual hosts were broadly similar to those of other parasitic copepods that infect fish gills and, for unknown reasons, the BVI appears to be a persistent hotspot of infections on these goby hosts.

Using DNA barcoding to identify host-parasite interactions between cryptic species of goby (Coryphopterus: Gobiidae, Perciformes) and parasitic copepods (Pharodes tortugensis: Chondracanthidae, Cyclopoida).

Previous work, using morphological characters, identified a generalist copepod parasite (Pharodes tortugensis) at high prevalence on two common gobies (Coryphopterus glaucofraenum and C. dicrus) in the British Virgin Islands (BVI). DNA barcoding subsequently revealed C. glaucofraenum to be three morphologically similar species (C. glaucofraenum, C. venezuelae and C. tortugae), casting doubt on host identities in the BVI and the classification of the parasite as a single species. Mitochondrial cytochrome c oxidase subunit I (COI) data from 67 gobies in the BVI showed that, in addition to C. dicrus, host gobies were a mix of C. glaucofraenum and C. venezuelae, while C. tortugae was unexpectedly absent from the study area. COI data (n = 70) indicated that the copepod infecting all three hosts was a single species, almost certainly P. tortugensis. The pharodes-coryphopterus interaction has a strong impact on host dynamics in the BVI, and a revised understanding of these dynamics must account for any differences among the three newly confirmed hosts in transmission of, and susceptibility to, the shared parasite. No other infected hosts were discovered at our sites, but P. tortugensis is reportedly widespread and infects 12 additional host species elsewhere. Further DNA barcoding is thus needed to test whether P. tortugensis is truly a widespread generalist, or instead represents a group of more specialized cryptic species.

Going against the flow: Barriers to gene flow impact patterns of connectivity in cryptic coral reef gobies throughout the western Atlantic

AbstractAimComplex oceanographic features have historically caused difficulty in understanding gene flow in marine taxa. Here, we evaluate the impact of potential phylogeographic barriers to gene flow and assess demography and evolutionary history of a coral reef goby species complex. Specifically, we test how the Amazon River outflow and ocean currents impact gene flow.LocationWestern Atlantic.TaxonThe bridled goby (Coryphopterus glaucofraenum) and sand‐canyon goby (C. venezuelae) species complex.MethodsWe used mitochondrial DNA and 2,401 genomic SNPs to investigate evolutionary history and test hypotheses of how major barriers impact species‐level differentiation. We used clustering algorithms and pairwiseFSTto assess population differentiation caused by minor barriers within and among regions. Finally, we tested alternate hypotheses of demographic history via coalescent simulations to determine the most plausible spread across the Western Atlantic.ResultsWe found two unique clades ofC. glaucofraenumalong the Brazilian coast and the oceanic island Atol das Rocas (AR) that are more closely related toC. venzuelae. Further genetic structure within the Caribbean and separately along the Brazilian coast led to at least two distinct populations in each Province. Coalescent simulations indicated that an ancestral population ofC. venezuelaesplit fromC. glaucofraenumin the Caribbean, dispersed to Brazil, then spread to AR.Main conclusionsSpecies‐level genetic differentiation has resulted from the Amazon River outflow and isolation of AR. Population differentiation within the Caribbean matched previous studies indicating an east‐west pattern of divergence. Brazilian population differentiation was impacted by the cold‐water upwelling filter at Cabo Frio. Overall, this research highlights how barriers to gene flow impact speciation and genetic structure within western Atlantic gobies and provides insight into the role oceanographic features have in the speciation process of fishes.

Cryptobenthic fish as clients of french angelfish Pomacanthus paru (Pomacanthidae) during cleaning behaviour

The French angelfish Pomacanthus paru (Pomacanthidae) is recognised as an important cleaner in tropical reef environments, yet its clients remain relatively undescribed in the literature. Here, we report observations of their cleaning behaviour when interacting with different species of cryptobenthic fish clients. The study was conducted in Bahia state, northeast Brazil. In this region, French angelfish were seen cleaning four different species of cryptobenthic species, respectively, Coryphopterus glaucofraenum, Scorpaena plumieri, Labrisomus cricota, and Scartella cristata. These records show the broad spectra of clients that cleaners interact with in coral reef systems, as well as give important insights into the poorly known cryptobenthic fishes habits and ecology.

Behavioral differences among mutualist species in a shrimp-goby association

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 510:101-106 (2014) - DOI: https://doi.org/10.3354/meps10905 Behavioral differences among mutualist species in a shrimp-goby association Patrick J. Lyons* Department of Ecology and Evolution, Stony Brook University, 650 Life Sciences Building, Stony Brook, New York 11794-5245, USA Present address: CIEE Research Station Bonaire, 26 Kaya Gobernador N. Debrot, Kralendijk, Bonaire, Caribbean Netherlands *Corresponding author: patrick.lyons5@gmail.com ABSTRACT: Alpheid shrimps and gobiid fishes engage in a mutualism in which shrimp construct burrows that are co-habited with gobies and used as refuge from predators by both. Gobies act as sentinels for shrimp. In the western Atlantic, different goby species have been hypothesized to have a facultative (Ctenogobius saepepallens) and obligate (Nes longus) association with the shrimp Alpheus floridanus. I compared various behaviors among these 2 gobies and another goby that occasionally associates with shrimp (Coryphopterus glaucofraenum). The putatively obligate goby had the greatest preference for shrimp burrows versus other shelters, had the greatest partner fidelity, and facilitated more emergence by shrimp by remaining for longer periods at shrimp burrow entrances. These findings provide evidence that in shrimp-goby mutualism, the more specialized and dependent mutualist gobies provide greater services to their shrimp partners. KEY WORDS: Mutualism · Coevolution · Obligate · Facultative · Shrimp-goby · Nes longus · Ctenogobius saepepallens Full text in pdf format PreviousNextCite this article as: Lyons PJ (2014) Behavioral differences among mutualist species in a shrimp-goby association. Mar Ecol Prog Ser 510:101-106. https://doi.org/10.3354/meps10905 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 510. Online publication date: September 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Antipredator responses to invasive lionfish, Pterois volitans: interspecific differences in cue utilization by two coral reef gobies

Understanding prey response to predators and their utilization of sensory cues to assess local predation risk is crucial in determining how predator avoidance strategies affect population demographics. This study examined the antipredator behaviors of two ecologically similar species of Caribbean coral reef fish, Coryphopterus glaucofraenum and Gnatholepis thompsoni, and characterized their responses to different reef predators. In laboratory assays, the two species of gobies were exposed to predator visual cues (native Nassau grouper predator vs. invasive lionfish predator), damage-released chemical cues from gobies, and combinations of these, along with appropriate controls. Behavioral responses indicate that the two prey species differ in their utilization of visual and chemical cues. Visual cues from predators were decisive for both species’ responses, demonstrating their relative importance in the sensory hierarchy, whereas damage-released cues were a source of information only for C. glaucofraenum. Both prey species could distinguish between native and invasive predators and subsequently altered their antipredator responses.

Experimental evidence for density‐dependent reproductive output in a coral reef fish

AbstractWe tested for density‐dependent reproduction in a small coral reef fish using field manipulations of density and observational data. Males of the study species, the bridled goby (Coryphopterus glaucofraenum Gill), defend benthic nest sites, within which they spawn with females, and females can spawn repeatedly over an extended breeding season. In small areas, usually only a single male nested at any one time regardless of how many males were present, so the probability of nesting was inversely proportional to density. Nesting males were almost always the largest in the vicinity, suggesting that, for males whose home ranges overlap, social interactions dictate opportunities to nest. Both the per capita rate at which clutches were laid and the number of eggs produced per clutch declined with increasing density, so the per capita rate of egg production was also density dependent. All three measures of fecundity were better predicted by numerical density (numbers per unit area) than biomass (mass of fish per unit area), and were well described as an inverse function of the number of gobies in the vicinity. A simple hypothesis consistent with these results is that a constant number of females spawn, regardless of density. Alternately, the effect of crowding may depend primarily on the number of interacting individuals and affect all females relatively equally. This density dependence could thus contribute to population regulation at the spatial scale over which populations become reproductively closed.

Using an individual-based model to quantify scale transition in demographic rate functions: Deaths in a coral reef fish

Scientifically informed population management requires quantitatively accurate demographic rate functions that apply at the spatial scale at which populations are actually managed, but practical constraints confine most field measurements of such functions to small study plots. This paper employs an individual-based population growth model to extrapolate the death rate function in a well-studied coral reef fish, the bridled goby Coryphopterus glaucofraenum, from the scale of 2 m × 2 m coral reef “cells” at which it was measured to the larger scale of an entire coral reef. Density dependence in the whole-reef function actually proves stronger than in the local function because high goby density occasionally arises in local patches with few refuges from predators, producing very high mortality there. This IBM-based approach extends the reach of scale transition theory by examining considerably more realistic models than standard analytical methods can presently handle.

Aspects of Spawning Behaviour in Five Gobiids of the Genus Coryphopterus (Pisces: Gobiidae) in the Caribbean Sea

Sand dwelling species of Coryphopterus live in shared habitats and were reported to have a similar ecology. Species lineages within the western Atlantic Coryphopterus have recently been reconciled; fish which according to the common keys had formerly been identified as Coryphopterus glaucofraenum could in fact be C. glaucofraenum, C. tortu- gae or C. venezuelae and can genetically be clearly separated into different clades. Based on the new taxonomic key, eco- logical data for five Coryphopterus species are provided; size-sex distribution, number of eggs deposited, inter spawning intervals and courtship behaviour of Coryphopterus dicrus Bohlke and Robins, Coryphopterus eidolon Bohlke and Rob- ins, Coryphopterus thrix Bohlke and Robins, Coryphopterus tortugae Jordan, and Coryphopterus venezuelae Cervigon, were examined in Curacao, Netherland Antilles. For the first time ecological data on C. tortugae and C. venezuelae are provided, which had been previously questioned as distinct species from Coryphopterus glaucofraenum. In all species males reached a greater total length than females. Clutch sizes varied between 423 - 5872 eggs and inter- spawning intervals were between 5 - 14 days; no preferences for spawning at a particular lunar phase was found.

Musical chairs mortality functions: density-dependent deaths caused by competition for unguarded refuges

Structural refuges within which prey can escape from predators can be an important limiting resource for the prey. In a manner that resembles the childhood game of musical chairs, many prey species rapidly retreat to shared, unguarded refuges whenever a predator threatens, and only when refuges are relatively abundant do all prey individuals actually escape. The key feature of this process is that the per capita prey mortality rate depends on the ratio of prey individuals to refuges. We introduce a new class of mortality functions with this feature and then demonstrate statistically that they describe field mortality data from a well-studied coral reef fish species, the Caribbean bridled goby Coryphopterus glaucofraenum, substantially better than do several mortality functions of more conventional form.

SPATIAL DENSITY DEPENDENCE SCALES UP BUT DOES NOT PRODUCE TEMPORAL DENSITY DEPENDENCE IN A REEF FISH.

Field experiments provide rigorous tests of ecological hypotheses but are typically of short duration and use small spatial replicates. We assessed empirically whether the results of experiments testing for density dependence applied at larger spatial domains and explained temporal population dynamics. We studied a small coral reef fish, the goldspot goby (Gnatholepis thompsoni), in the Bahamas. We assessed the effects of interactions with conspecifics and with an ecologically similar species, the bridled goby (Coryphopterus glaucofraenum). Two density manipulations on small reef patches revealed that goldspot goby mortality over one month increased as conspecifics became crowded. On five large natural reefs, we correlated the initial year-class density of both species (annual larval settlement) with the subsequent decline of goldspot goby year-classes for five years. Mortality was correlated with conspecific density among reefs for all years, but not among years for all reefs. Thus, spatial density dependence in mortality scaled up qualitatively from small patches to entire reefs but was not associated with temporal density dependence. Our results support the conclusion that field experiments may be extrapolated to larger spatial domains with care, but that using small spatial comparisons to predict temporal responses is difficult without knowing the underlying biological mechanisms.

Settling larvae of a small coral‐reef fish discriminate reef features at large, but not small, spatial scales

Larval settlement of a small coral‐reef fish, the bridled goby (Coryphopterus glaucofraenum), to five entire reefs over 4 yr decreased with increasing cover of hard substrate (rock and coral). Experimentally increasing rock cover on these large reefs caused a reduction in settlement that lasted 3 yr, confirming that settling coral‐reef fish discriminate among sites at the mesoscale (hundreds of meters to tens of kilometers). Counterintuitively, a small‐scale manipulation of rock cover and an observational study both suggest that settlers show no response to rock cover at the microscale (few to tens of meters). Habitat selection at settlement can, thus, set initial benthic population size at much larger spatial scales than previously recognized, a finding consistent with the good swimming and sensory capabilities of late‐stage larvae.

A Comparison of Fish Assemblages Among Five Habitat Types Within a Caribbean Lagoonal System

Fish assemblages associated with patch reefs, rubble, seagrass, algal plain, and sandy habitats types were studied at St. Croix's Southeastern barrier reef lagoon using underwater visual census techniques. Higher species richness and fish density were observed over patch reefs/rubble habitat followed by seagrass, algal plain, and unvegetated sandy habitat types. Thalassoma bifasciatum, Haemulon flavolineatum, and Acanthuras chirurgus were the most common fishes in highly structured habitat types (patch reef, rubble). Halichoeres bivittatus, Sparisoma radians, newly settled grunts (l.e., Haemulon spp.), and juveniles of Ocyurus chrysurus were mainly associated with vegetated habitat types (seagrass, algal beds), while Xyrichtys martinicensis and Coryphopterus glaucofraenum were common over unvegetated sandy habitat types. Cluster analysis among backreef lagoon habitat types based on the entire fish density data showed distinct associations of fish assemblages by habitat type, regardless of season. Fish assemblages in the more structured habitat types were similar to each other but different from unstructured vegetated, and unvegetated habitat types. These results suggest that differences in fish species richness and density in the backreef lagoon are related to habitat type. The ecological importance and need for protection of backreef lagoon habitat types are discussed in relation to their potential role as nurseries for many fish species.

PARASITISM AND A SHORTAGE OF REFUGES JOINTLY MEDIATE THE STRENGTH OF DENSITY DEPENDENCE IN A REEF FISH

Various predator-prey, host-pathogen, and competitive interactions can combine to cause density dependence in population growth. Despite this possibility, most empirical tests for density-dependent interactions have focused on single mechanisms. Here we tested the hypothesis that two mechanisms of density dependence, parasitism and a shortage of refuges, jointly influence the strength of density-dependent mortality. We used mark-recapture analysis to estimate mortality of the host species, the bridled goby (Coryphopterus glaucofraenum). Sixty-three marked gobies were infected with a copepod gill parasite (Pharodes tortugensis), and 188 were uninfected. We used the spatial scale at which gobies were clustered naturally (approximately 4 m2) as an ecologically relevant neighborhood and measured goby density and the availability of refuges from predators within each goby's neighborhood. Goby survival generally declined with increasing density, and this decline was steeper for gobies with access to few refuges than for gobies in neighborhoods where refuges were common. The negative effects of high density and refuge shortage were also more severe for parasitized gobies than for gobies free of parasites. This parasite has characteristics typical of emerging diseases and appears to have altered the strength of a preexisting density-dependent interaction.

PREDATORS, PREY REFUGES, AND THE SPATIAL SCALING OF DENSITY-DEPENDENT PREY MORTALITY

We tested the biological cause of density-dependent mortality in the bridled goby (Coryphopterus glaucofraenum), a small coral reef fish, and evaluated whether this knowledge allowed us to detect density dependence at different spatial scales in natural habitats. To identify the biological cause of density dependence, we manipulated both population density and the availability of shelter (crevices used as refuges from predators) in small plots of continuous reef. We detected strong density-dependent mortality in plots with few refuges, but mortality was density independent in plots with abundant refuges, indicating that limited shelter causes density dependence. Predator density was unrelated to the density of gobies and refuges, suggesting that predators displayed a type III functional response in patches with few refuges. In a second experiment, we manipulated goby density within replicate plots of three sizes (4, 16, and 64 m2) that varied naturally in the availability of refuges. If refuge availability was ignored, mortality appeared to be density independent at all scales. If, however, plots were grouped by refuge availability, mortality was density dependent in plots with few refuges, but low and density independent in plots with many refuges at all spatial scales. Understanding the mechanism of density dependence (refuge shortage) was thus required to measure the strength of density dependence in natural, spatially variable, habitat. We suggest that density dependence was detectable in plots of different sizes because the relationships between the densities of gobies, refuges, and goby predators were similar across the spatial scales we studied. Our work demonstrates that identifying the biological interactions that cause density dependence, and characterizing the spatial domains at which those interactions operate, will be important to accurately assess the effects of density dependence on population dynamics.

Impact of ectoparasites on the demography of a small reef fish

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 248:305-309 (2003) - doi:10.3354/meps248305 Impact of ectoparasites on the demography of a small reef fish Rachel J. Finley*, Graham E. Forrester Department of Biological Sciences, 100 Flagg Road, University of Rhode Island, Kingston, Rhode Island 02881-0816, USA *Email: rpet3012@postoffice.uri.edu ABSTRACT: In marine systems, empirical studies demonstrating effects of macroparasites on host population dynamics are relatively few. We tested the effects of a copepod macroparasite infecting the gills of a small coral reef fish, the bridled goby Coryphopterus glaucofraenum. Fish that were naturally infected and uninfected were tagged as individuals and tracked in the field for 5 mo. Parasitism was associated with an increase in gill ventilation rate, and a reduction in feeding. More importantly, parasitized fish showed significantly reduced growth (by 66%) and gonad mass (by 68%) compared to uninfected fish, and parasitism increased instantaneous mortality by a factor of 1.8. Since the prevalence of infection was higher in areas of high goby density, parasite-induced mortality is a possible cause of host density dependence. These results imply a major effect of parasitism on host population dynamics and suggest that parasitism warrants closer attention by marine ecologists. KEY WORDS: Pharodes tortugensis · Coryphopterus glaucofraenum · Host-parasite interaction · Parasitic gill copepod Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 248. Online publication date: February 20, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

VARIATION IN THE PRESENCE AND CAUSE OF DENSITY-DEPENDENT MORTALITY IN THREE SPECIES OF REEF FISHES

Determining the mechanisms by which natural populations are regulated is a key issue in ecology. Identifying the biological causes of density dependence has, however, proved difficult in many systems. In this study we tested whether adults of three species of reef fish (all gobies) suffered density-dependent mortality, and whether the density-dependent component of mortality was caused by predation. We used field experiments to test for density dependence in each prey species, manipulating the presence of predators and prey density in a factorial design. Prey were stocked on replicate patches of reef constructed of natural materials, with each reef receiving a different density of gobies. Predatory fishes were excluded from half of the reefs using a combination of removals and exclusion cages. Survival of the first species, Lythrypnus dalli, was high and density-independent on reefs free of predators, but declined rapidly with increasing density on reefs to which predators had access. Density dependence in L. dalli was thus a result of mortality inflicted by predatory fishes. In the second species, Coryphopterus nicholsii, predators caused a large reduction in the survival in one experiment but had a negligible effect in a second experiment. More importantly, though, survival of C. nicholsii was always independent of its density, regardless of predator presence. In the final species, Coryphopterus glaucofraenum, two separate experiments showed that natural changes in adult abundance (experiment 1) and survival of stocked adults (experiment 2) were density-dependent regardless of predator presence. Both experiments thus indicated that the density-dependent component of loss in C. glaucofraenum was caused, at least in part, by an interaction other than predation. The presence, intensity, and biological cause of density-dependent survival were thus strikingly different for each of these three fishes, despite the fact that they are taxonomically closely related and ecologically similar. These findings suggest a need for further studies aimed at predicting under what circumstances different mechanisms of population regulation will operate.

Variation in the Presence and Cause of Density-Dependent Mortality in Three Species of Reef Fishes

Determining the mechanisms by which natural populations are regulated is a key issue in ecology. Identifying the biological causes of density dependence has, however, proved difficult in many systems. In this study we tested whether adults of three species of reef fish (all gobies) suffered density-dependent mortality, and whether the density-dependent component of mortality was caused by predation. We used field experiments to test for density dependence in each prey species, manipulating the presence of predators and prey density in a factorial design. Prey were stocked on replicate patches of reef constructed of natural materials, with each reef receiving a different density of gobies. Predatory fishes were excluded from half of the reefs using a combination of removals and exclusion cages. Survival of the first species, Lythrypnus dalli, was high and density-independent on reefs free of predators, but declined rapidly with increasing density on reefs to which predators had access. Density dependence in L. dalli was thus a result of mortality inflicted by predatory fishes. In the second species, Coryphopterus nicholsii, predators caused a large reduction in the survival in one experiment but had a negligible effect in a second experiment. More importantly, though, survival of C. nicholsii was always independent of its density, regardless of predator presence. In the final species, Coryphopterus glaucofraenum, two separate experiments showed that natural changes in adult abundance (experiment 1) and survival of stocked adults (experiment 2) were density-dependent regardless of predator presence. Both experiments thus indicated that the density-dependent component of loss in C. glaucofraenum was caused, at least in part, by an interaction other than predation. The presence, intensity, and biological cause of density-dependent survival were thus strikingly different for each of these three fishes, despite the fact that they are taxonomically closely related and ecologically similar. These findings suggest a need for further studies aimed at predicting under what circumstances different mechanisms of population regulation will operate.

Microstructure of settlement-marks in the otoliths of tropical reef fishes

The morphology and ultrastructure of the otolith settlement-mark was examined in 44 tropical reef-fish species spanning nine families. A classification scheme based on similar otolith characteristics is presented. Three major categories are identified based on changes in increment width and optical qualities of the settlement-mark. Of the 44 species examined, 39 possessed “abrupt” settlement-marks (Type I) characterised by a rapid decrease in increment width (up to 50% reduction) over settlement. Type I settlement-marks were found in all nine families examined. The 39 species spanned the whole range of possible larval durations (Pomacentrus moluccensis, 15 d ± 0 SE; Naso hexacanthus, 91.2 d ± 2.97 SE). Four of the 44 species possessed “zonal” settlement-marks (Type II), featuring a band of increments that are wider than pre-settlement increments. Species in this category are the labrids Corisaygula, Thalassoma bifasciatum, T. lunare and an unidentified acanthurid (Acanthurus sp. 2). One species of acanthurid (N. brevirostris) possessed a “gradual” settlement-mark (Type III), manifest as a gradual decrease in increment width during the settlement period. A possible fourth type was identified from the literature. Gnatholepis thompsoni and Coryphopterus glaucofraenum possessed a settlement-mark with increment widths that increased post-settlement. Available data suggest a poor relationship between the structure of the settlement-mark and the magnitude of metamorphosis (previously reported as internal and external morphological change). Evidence suggests that the increment profile over early development and the increment transitions associated with the settlement event are taxon-specific and may enable late-larval stage fishes to be identified to species level.

The influence of adult density on larval settlement in a coral reef fish Coryphopterus glaucofraenum

For marine species with open populations, patterns of larval settlement can have important consequences for performance and abundance at later life-stages. In this study, I tested whether larvae of a reef-dwelling goby (Coryphopterus glaucofraenum) settled differentially to reefs occupied by varying numbers of adults. I monitored settlement daily to reefs on which the density of adult gobies varied naturally, or was manipulated experimentally. Rates of settlement were constant across a broad range of adult densities, suggesting that larvae do not choose settlement sites based on the number of adults in their immediate vicinity.