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Background Because the French grunt, Haemulon flavolineatum, is an ecologically important reef fish prized by both recreational anglers and public aquariums, the wild population requires limits on harvests. Yet, the environmental conditions conducive for French grunt spawning in aquarium settings is not well understood. Therefore, the goal of this study was to document the conditions leading to voluntary spawning and the number of eggs produced by French grunts without the use of hormones or artificial insemination. Methods We hypothesized and verified that it is possible for French grunts to spontaneously spawn in human care. Forty individuals were collected around the Florida Keys and haphazardly stocked in five recirculating seawater systems each containing two 250-L circular tanks. Over the course of 87 days, eggs were collected daily from each system and environmental parameters were monitored. Results Total daily number of eggs released ranged from 0 to 207,644 eggs. Of the observed environmental parameters, temperature and alkalinity had the greatest impact on number of eggs released. This study demonstrates that it is possible for French grunts to reproduce in captivity with little environmental manipulation, thus an ideal candidate to culture for the zoo/aquarium industry.

The role of parasites in trophic ecology is poorly understood in marine ecosystems. Stable isotope analyses (SIA) have been widely used in studies of trophic ecology, but have rarely been applied to study the role of parasites. Considering that some parasites are associated with altered host foraging patterns, SIA can help elucidate whether parasitism influences host trophic interactions. French grunt (Haemulon flavolineatum), an abundant Caribbean coral reef fish, contributes greatly to trophic connectivity. They typically depart the reef at dusk, feed overnight in seagrass beds, and return to the reef at dawn. The large parasitic isopod Anilocra haemuli commonly infects French grunt, and infected fish are less likely to complete their diel migration, and are in poorer condition than uninfected conspecifics. Brown chromis (Chromis multilineata) are diurnally feeding planktivores and infection by Anilocra chromis does not influence host condition. To determine if Anilocra infection influences host diet and foraging locality, we conducted stable carbon and nitrogen isotope analyses on scale, muscle, heart and gill tissues of infected and uninfected French grunt and brown chromis. We determined that all French grunt had δ13C values representative of seagrass habitats, but infected French grunt were significantly enriched in 13C and 15N compared to uninfected conspecifics. This suggests that compared to uninfected conspecifics, infected French grunt forage in seagrass, but on isotopically enriched prey, and/or are in poorer condition, which can elevate δ13C and δ15N values. For brown chromis, infection did not significantly influence any δ13C and δ15N values; hence they all foraged in the same environment and on similar prey. This is the first study to use SIA to examine differences in resource use by Caribbean coral reef fishes associated with parasitism and to evaluate how closely related parasites might have host-dependent effects on host trophic ecology.

A morphological review and molecular characterization of Anilocra haemuli Bunkley Williams & Williams, 1981, were completed using specimens collected from Haemulon flavolineatum Desmarest, 1823 (French grunt) and Epinephelus guttatus Linnaeus, 1758 (red hind). Molecular and morphological data suggest that the isopods parasitizing H. flavolineatum and E. guttatus are different species. The specimens collected from E. guttatus are recognized as a new species, Anilocra brillae sp. n. Differences between Anilocra brillae sp. n. and A. haemuli include but are not limited to the pleonites 1–3 of A. brillae sp. n. being wider than 4–5 and 4–5 subequal, whereas the pleonites 1–2 of A. haemuli are wider than 3–5, and 3–5 are subequal. The seventh pereopod of A. brillae sp. n. is proportionally larger, has more robust setae, and the setae are distributed more extensively over the articles when compared to A. haemuli. Additionally, this study provides the first genetic characterization of three Anilocra spp. from the Caribbean, and is based on mitochondrial cytochrome c oxidase subunit gene (COI) for A. haemuli from H. flavolineatum, A. brillae sp. n. from E. guttatus, and A. chromis Bunkley Williams & Williams, 1981 from Chromis multilineata Guichenot, 1853.

Caribbean seagrass habitats provide food and protection for reef-associated juvenile fish. The invasive seagrass Halophila stipulacea is rapidly altering these seascapes. Since its arrival in the Caribbean in 2002, H. stipulacea has colonized and displaced native seagrasses, but the function of this invasive seagrass as a juvenile fish habitat remains unknown. To compare diversity, community structure, and abundance of juvenile fish between H. stipulacea and native seagrass beds, fish traps were deployed in four nearshore bays around St. Thomas, U.S. Virgin Islands. Traps were deployed in Frenchman, Lindbergh, and Sprat Bays for 24 h intervals in patches of bare sand, patches of H. stipulacea and patches of the native Caribbean seagrasses Thalassia testudinum and Syringodium filiforme. Traps were then deployed in Brewers Bay for 12 h intervals in stands of H. stipulacea and S. filiforme. Relative and total abundances of juvenile fish, identified at least to family, were compared across treatment habitats for each trap deployment period. The catch from H. stipulacea, compared to native seagrasses, comprised a greater abundance of nocturnal carnivores Lutjanus synagris (family Lutjanidae) and Haemulon flavolineatum (family Haemulidae). Additionally, the herbivore species Sparisoma aurofrenatum (family Labridae) and Acanthurus bahianus (family Acanthuridae) and the diurnal carnivore species Pseudopeneus maculatus (family Mullidae) were relatively scarce in H. stipulacea. The catch from sand was much smaller, compared to vegetated habitats, and comprised only L. synagris, H. flavolineatum, and H. aurolineatum. These results provide evidence of reduced family diversity and altered juvenile fish assemblages in H. stipulacea, driven by an abundance of some nocturnal carnivores and scarcity of herbivores and diurnal carnivores. The findings from the present work underpin the need for further investigation and mitigation of this invasion, particularly where H. stipulacea is driving seascape-alterations of key juvenile fish habitats.

Tropical Atlantic reef fishes in the family Haemulidae (grunts) remain quiescent on reefs during the day and migrate to seagrass beds or sand flats at night. Hypothesized advantages of such nocturnal migrations are increased food availability and/or decreased predation risk. Here, we tested predictions of an alternative hypothesis that nocturnal migrations of French grunt, Haemulon flavolineatum (Desmarest, 1823), reduce exposure to blood-feeding gnathiid isopods. The departure of grunts from the reef coincides with increasing gnathiid activity. In field experiments, subadult fish placed in cages and deployed on the reef at night harbored significantly more gnathiids than those placed in the seagrass habitat. However, this was not the case during the day when gnathiid activity in all habitats is low. In another experiment, the timing of return to the reef was determined to coincide with the postdawn decrease in gnathiid activity. Estimates of cumulative gnathiid exposure at two sites revealed that grunts remaining in reef habitat at night would experience an average of 3 and 44 times more gnathiids than if they spent the night in the seagrass bed, and could reach more than 300 gnathiids on a single fish. In a final field experiment, even recently-settled (

Habitat selection by coral reef fish is influenced by a variety of biological and abiotic factors, but the relative importance of these factors is expected to change throughout ontogeny, espe- cially for species that utilize different habitats during their life cycle. In this study, 2 in situ choice ex- periments were designed to test the individual as well as the interactive effects of habitat structure and schooling (with conspecifics or heterospecifics) on refuge-seeking behavior of a coral reef fish. The experiments were conducted for 3 size-classes of the common reef fish Haemulon flavolineatum, a species that shows multiple habitat shifts throughout its ontogeny. We tested the hypothesis that, due to the additive effects of schooling and structure in providing suitable refuge, fish would be more attracted to a microhabitat with conspecifics or heterospecifics than to a microhabitat or conspecifics alone. In the habitat-only experiment, early juveniles (

Growth, survival, and abundance of young, and their connectivity to adult populations are four primary factors used to define nursery habitats. In the present study, we examined the relative quality of mangrove and seagrass habitats for juvenile French grunt, Haemulon flavolineatum (Desmarest, 1823), and schoolmaster, Lutjanus apodus (Walbaum, 1792), reef fish populations in St. Croix and Puerto Rico by using otolith microstructure to compare growth in these habitats. Mean daily otolith increment widths during the post-settlement period (30-60 d) of surviving late juvenile French grunts and schoolmaster collected in 2007 were compared between mangrove and seagrass habitats within each island. Increments widths were significantly wider during the post-settlement period in mangrove habitats at both study locations for both species. Our inferred growth interpretations indicate that mangroves may support faster growing fishes than seagrass habitats. However, due to the fact that the observed growth rates reflect the traits of the surviving cohorts among habitats, other factors, such as size-selective mortality/emigration and previous larval growth history, should also be considered in the interpretation of the observed growth patterns.

Ecosystems are intricately linked by the flow of organisms across their boundaries, and such connectivity can be essential to the structure and function of the linked ecosystems. For example, many coral reef fish populations are maintained by the movement of individuals from spatially segregated juvenile habitats (i.e., nurseries, such as mangroves and seagrass beds) to areas preferred by adults. It is presumed that nursery habitats provide for faster growth (higher food availability) and/or low predation risk for juveniles, but empirical data supporting this hypothesis is surprisingly lacking for coral reef fishes. Here, we investigate potential mechanisms (growth, predation risk, and reproductive investment) that give rise to the distribution patterns of a common Caribbean reef fish species, Haemulon flavolineatum (French grunt). Adults were primarily found on coral reefs, whereas juvenile fish only occurred in non-reef habitats. Contrary to our initial expectations, analysis of length-at-age revealed that growth rates were highest on coral reefs and not within nursery habitats. Survival rates in tethering trials were 0% for small juvenile fish transplanted to coral reefs and 24-47% in the nurseries. As fish grew, survival rates on coral reefs approached those in non-reef habitats (56 vs. 77-100%, respectively). As such, predation seems to be the primary factor driving across-ecosystem distributions of this fish, and thus the primary reason why mangrove and seagrass habitats function as nursery habitat. Identifying the mechanisms that lead to such distributions is critical to develop appropriate conservation initiatives, identify essential fish habitat, and predict impacts associated with environmental change.

Juvenile French grunt Haemulon flavolineatum and schoolmaster Lutjanus apodus were captured in mangrove and seagrass stations in St. Croix, and Puerto Rico in 2006 and 2007 to deter- mine whether areas for juvenile fish can be discriminated by means of otolith chemistry. Concentra- tions of 16 elements were determined in 0-group fish otoliths using laser ablation-inductively coupled plasma mass spectrometry. Two stable isotopes, δ 18 O and δ 13 C, in French grunt and schoolmaster otoliths were also analyzed. Multi-elemental signatures for both species differed significantly (p < 0.001) among mangrove and seagrass stations within both islands. Furthermore, concentrations of 6 el- ements (Sr, Ba, Cu, Mg, Co, Na) as well as δ 18 O and δ 13 C for both species within each year differed sig- nificantly among mangrove and seagrass stations within islands (p < 0.001). Classification success for French grunt and schoolmaster juvenile areas within St. Croix across years ranged from 87 to 92% and from 76 to 77%, respectively, whereas in Puerto Rico, classification success for French grunt and schoolmaster for the 2 years ranged from 80 to 84% and 84 to 87%, respectively. Classification success between mangrove and seagrass habitats (stations combined) in Puerto Rico for French grunt ranged from 84 to 91%, and for schoolmaster ranged from 94 to 99%. In St. Croix, classification success for French grunt was 95 to 96%, and for schoolmaster was 86 to 89%. The percentages of French grunt subadults collected from forereef stations in St. Croix, identified as having resided as juveniles in man- grove habitats in 2006 and 2007, were 40 and 68%, respectively, while for Puerto Rico, these percent- ages were 70 and 74%. By contrast, for schoolmaster almost 100% of all fish in both islands resided as juveniles in mangrove habitats in both years. This study contains the first direct evidence of postsettle- ment fish movement connecting mangrove habitats to the reef using otolith chemistry.

Tropical marine habitats are often energetically linked through feeding migrations by fish. A widely accepted assumption is that species of Haemulidae (grunts) undertake nocturnal feed- ing migrations from coral reefs to seagrass beds. This has been based on studies investigating migra- tions between small patch reefs and surrounding seagrass beds located in lagoons. Due to the size and location of these patch reefs, we argue that this does not represent migration from coral reef to seagrass ecosystems, and a literature search shows limited proof for such migration. We hypothesised that the spatial arrangement of these habitats in the seascape may have profound effects on the degree to which such migrations occur. Haemulon flavolineatum caught from seagrass beds located in semi-enclosed embayments, and thus isolated to a high degree from adjacent reefs, showed a diet and stable isotope signature of muscle tissue that differed from those collected from the coral reef. In contrast, fishes from open seagrass systems without restricted access from the reef showed the same stable isotope signature as those collected from the coral reef, suggesting feeding from the same habitat, viz. the seagrass beds. Additional visual census data showed that semi-enclosed seagrass beds did not have elevated densities of large-sized fish at night, which would be expected if large individuals from the reef migrated to the seagrass beds to feed. The data thus show that interlinkages between coastal ecosystems, such as coral reefs and seagrass beds, by fishes may strongly depend on the spatial arrangement of habitats within the seascape.

Many of the most abundant fish species using mangroves in the Caribbean also use other habitat types through daily home range movements and ontogenetic habitat shifts. Few studies, however, have considered the structure of the surrounding seascape when explaining the spatial distribution of fish within mangroves. This study develops an exploratory seascape approach using the geographical location of mangroves and the structure of the surrounding seascape at multiple spatial scales to explain the spatial patterns in fish density and number of species observed within mangroves of SW Puerto Rico. Seascape structure immediately surrounding mangroves was most influential in determining assemblage attributes and the density of juvenile Haemulon flavolineatum, which were significantly higher in mangroves with high seagrass cover (>40%) in close proximity ( 40 and >15%, respectively) in close proximity ( 40%) of seagrass within 600 m of the mangrove edge. We argue that there is an urgent need to incorporate information on the influence of seascape structure into a wide range of marine resource management activities, such as the identification and evaluation of critical or essential fish habitat, the placement of marine protected areas and the design of habitat restoration projects.

Item does not contain fulltext Studies showing that tagged reef fish connect different habitat types are crucial for effective ecosystem management on a seascape-level, but are rare. Therefore we analysed movement of juvenile Haemulon flavolineatum and Haemulon sciurus among seagrass beds, mangroves and fossilised eroded coral shoreline. Fishes were tagged individually with external, short-term bead-tags (both species) or with internal, long-term coded wire tags (H. flavolineatum only). We also tested the hypothesis that in spatially continuous habitat types with many seemingly suitable resting sites, these fishes show high fidelity to only a small number of sites. The linear distribution range of daytime sites was 4–171 m for H. flavolineatum and 4–152 m for H. sciurus, but in agreement with our hypothesis, externally tagged fishes showed high fidelity to small spatial areas within this range: the percentage of resightings within a 10 m radius of the core area of presence (i.e. the site used most intensively) was 69% for bead-tagged H. flavolineatum, and 62% for H. sciurus during the 47-day study-period. Site fidelity was also present over a longer time span: of the 1114 coded wire tagged H. flavolineatum 51 were recaptured and 49 of them were still present at the tagging location after 163–425 days at liberty. Median linear movement within a day was small (5 m for H. flavolineatum and 8 m for H. sciurus), nonetheless, part of the bead-tagged Haemulidae moved from shoreline shelter habitats (mangroves and rocky shoreline) to adjacent seagrass beds (mean ± SD distance moved 23 ± 10 m) in the afternoon, likely to start feeding there during daylight. When comparing the habitat type occupied during the late afternoon (15:30–17:30 h) and morning (8:00–10:30 h) on two subsequent days, most movement occurred from seagrass beds back to shoreline habitats (mean distance moved 23 ± 10 m), indicating that in the morning these fishes had returned to shelter sites at the shoreline. The current study thus shows existence of connectivity between back-reef habitats through fish movement on a relatively small spatial scale.

The transition from a planktonic larval stage to a benthic or demersal juvenile stage is a crucial event in the life history of coral reef fishes, and recruitment success has a strong influence on reef-fish population size. Post-settlement predation is thought to limit recruitment success. Most studies on post-settlement predation have focused on piscivorous reef fishes. However, recent studies in the tropical Pacific Ocean suggest that blood-feeding ectoparasites may also be an important source of predation. Here we provide further evidence that a gnathiid ectoparasite is capable of such "micropredation" on settlement-stage fish in the eastern Caribbean Sea. On 12 occasions in May-August, 2014 and 2015, during plankton light-trap recovery, we observed post-settlement fishes from the families Apogonidae, Bothidae, Gobiidae, Labrisomidae, and Tripterygiidae with attached ectoparasitic juvenile gnathiid isopods. In one laboratory experiment in which 10 settlement-stage French grunt, Haemulon flavolineatum (Desmarest, 1823), were fed upon by an average of one gnathiid per fish, all fish died compared to none in the control group. In a subsequent experiment in which individual settlement-stage French grunt were exposed to 0–3 gnathiids each, all 50 fish that were fed upon by at least one gnathiid died, compared with only one of 78 that were not fed on by any gnathiids. Combined with observations on damselfishes from the Pacific Ocean, these findings suggest that gnathiids are capable of micropredation on larval fish at time of reef settlement and that micropredation should be further evaluated as a factor affecting success of settlement and thus recruitment success of coral reef fishes.

The extent of dispersal by pelagic larvae in marine environments, including coral reefs, is central for understanding local population dynamics and designing sustainable marine reserves. We present here the first example of a clear stepping-stone genetic structure throughout the Caribbean basin for a common coral reef species, the French grunt (Haemulon flavolineatum). Analysis of microsatellite DNA markers indicated that French grunt population structure may be characterized by overlapping populations throughout the Caribbean, influenced by independent population dynamics but with no fixed geographical boundaries. In addition, different spatial genetic patterns were found in different oceanographic regions. A second species, the bluehead wrasse (Thalassoma bifasciatum), has a much longer pelagic larval duration than French grunts and showed no explicit spatial pattern of genetic variation. This finding is concordant with the hypothesis of a positive relationship between larval dispersal and duration in the plankton. While the magnitude of the genetic signal of population structure in French grunts was very low (FST≈0.003), the pattern of isolation-by-distance throughout the Caribbean indicated considerable population structure with important ecological and conservation significance.

Contains fulltext : 35368.pdf (Publisher’s version ) (Open Access) Mangroves and seagrass beds are considered nurseries for juvenile fish, but little experimental evidence exists to elucidate which factors make them attractive habitats. A multifactorial field experiment on the use of these habitats by juvenile reef fish and their behaviour was performed during daytime with experimental units (EUs: 1 �1 �0.8 m), each representing a unique combination of the factors structure, shade, and food, using artificial seagrass leaves (AS) and artificial mangrove roots (AM). Diurnally active herbivores were most abundant in EUs containing food, and grazed on algae growing on the structures, but were not attracted to structures in the absence of food. The most abundant diurnally active zoobenthivores (Eucinostomus spp.) were present in highest numbers in any EU with food, where they fed on zoobenthos or rested on the bottom. The nocturnally active zoobenthivore/zooplanktivore Ocyurus chrysurus and the diurnally active piscivore Sphyraena barracuda were primarily attracted to structure, in which they rested and were not observed to feed. Haemulon flavolineatum was mainly attracted to AS, Lutjanus mahogoni was attracted to AS or shade, whereas L. apodus, O. chrysurus and S. barracuda were found in AM as well as in AS. The data suggest that during daytime, herbivores and diurnally active zoobenthivores are probably attracted to mangroves and seagrass beds primarily by food, and nocturnally active zoobenthivores by structure (in interaction with shade) that offers shelter from predation. S. barracuda is also attracted primarily to structure, but the larger individuals probably use this for ambush predation rather than for protection. In conclusion, our experiment clarifies that presence of structure, food and shade significantly contribute to the attractiveness of mangroves and seagrass beds to juvenile reef fish.

The spatial size distribution of grunts and snappers have previously indicated the separation of juveniles in nursery habitats from the adults on the coral reef. This implies life cycle migrations from nursery habitats (such as seagrass beds and mangroves) to the coral reef. If diet shifts are related to such migrations, then the diets of these fish must change before or around the fish size at which such migrations take place. A wide size range of juveniles of two grunt species ( Haemulon sciurus and Haemulon flavolineatum ) and of two snapper species ( Lutjanus apodus and Ocyurus chrysurus ) were caught in seagrass beds and mangroves, and their gut contents identified and quantified. Regression analysis between fish size and dietary importance of small crustaceans showed a negative relationship in all four species. Positive relations were found for H. sciurus , L. apodus and O. chrysurus between fish length and the dietary importance of decapods, and for L. apodus and O. chrysurus between fish length and prey fish importance. Critical changes in the fish diets with fish size were examined by application of a Canonical Correspondence Analysis (CCA). The CCA yielded three clusters of size-classes of fishes with similar diets, and application of a Mantel test showed that each of these clusters had significantly different diets, and that each cluster diet was significantly specialised. The size at which a fish species ‘switched’ from one cluster to another was compared with size-at-maturity data and with the typical size at which these species migrate from the nursery habitats to the coral reef. H. sciurus and H. flavolineatum may be prompted to migrate from the nursery habitats to coral reef habitats because of dietary changes, or because of the development of the gonads. For L. apodus and O. chrysurus , a dietary changeover forms a more likely explanation for nursery-to-reef migrations than does sexual maturation because these species reach maturity at sizes much larger than the maximum size of individuals found in nursery habitats. Although other factors may theoretically initiate or promote the migration patterns, the results of this study indicate that ontogenetic dietary changes may crucially influence the nursery-to-coral reef migrations of these reef fish species.

Grunts are fish that are well known to vocalize, but how they produce their grunting sounds has not been clearly identified. In addition to characterizing acoustic signals and hearing in the French grunt Haemulon flavolineatum, the present study investigates the sound-production mechanism of this species by means of high-speed X-ray videos and scanning electron microscopy of the pharyngeal jaw apparatus. Vocalizations consist of a series of stridulatory sounds: grunts lasting ~47 ms with a mean period of 155 ms and a dominant frequency of ~700 Hz. Auditory capacity was determined to range from 100 to 600 Hz, with greatest sensitivity at 300 Hz (105.0±11.8 dB re. 1 μPa). This suggests that hearing is not tuned exclusively to detect the sounds of conspecifics. High-speed X-ray videos revealed how pharyngeal jaws move during sound production. Traces of erosion on teeth in the fourth ceratobranchial arch suggest that they are also involved in sound production. The similarity of motor patterns of the upper and lower pharyngeal jaws between food processing and sound production indicates that calling is an exaptation of the food-processing mechanism.

Various species of aquatic animals have complex life cycles and utilize differenthabitats during consecutive phases of their life cycles. For example, many marine fish speciesoccupy different habitat types during juvenile and adult life stages. Juveniles of some speciesrecruit to inshore nursery habitats such as mangroves and seagrass beds, whereas large adultstend to dominate coral reefs. The mechanisms underlying apparent cross-habitat distribution pat-terns by life stage remain uncertain for many species. Here, we investigated potential mecha-nisms that produce a 5-phase, and possibly even a 6-phase life cycle pattern in a common Carib-bean coral reef fish species Haemulon flavolineatum (French grunt) across multiple coastalhabitats. At each discrete life stage, individuals were faced with important and stage-specific eco-logical trade-offs that could significantly augment fitness. Pelagic larvae settled on rubble habitatsnear bay entrances where they reached an optimum between predation risk (survival) and foodabundance (growth). Individuals subsequently shifted to seagrass beds, likely as a result of in -creased food resources, followed by a shift to mangroves as predation refugia. Before the uni-directional movement between bays and coral reefs, some fishes shifted from mangroves to boul-der/notch habitats. Likely, this habitat serves as an intermediate stop before their final shift to thecoral reef, where they reach maturity and reproduce. This study reveals ecological linkages andflows among habitat types that are of direct conservation importance to these ecosystems. Further-more, the identification of mechanisms that give rise to cross-habitat distribution patterns of mar-ine fishes in general might lead to enhanced conservation management solutions to declines infisheries at larger scales.KEY WORDS: Ontogenetic habitat shifts · Life cycle · Nursery · Food abundance · Condition ·Maturation · Trade-offs

Eight species of prospective cleaners, four fishes (sharknosed goby Gobiosoma evelynae, and juveniles of bluehead (wrasse) Thalassoma bifasciatum, Spanish hogfish Bodianus rufus and gray angelfish Pomaccanthus arcuatus) and four shrimps (cleaner shrimp Lysmata grabhami, Pederson cleaner shrimp Periclimenes pedersoni, banded coral shrimp Stenopus hispidus and golden coral shrimp Stenopus scutellatus) were evaluated in aquaria for their ability to remove newly settled juveniles of the fish-parasitic cymothoid isopod Anilocra haemuli from French grunts Haemulon flavolineatum. Periclimenes pedersoni removed all isopods almost immediately. No other cleaners removed any isopods over a 24 hr challenge period. This study is the first evidence that cleaner shrimps can remove juvenile cymothoid isopods.

Habitat-specific cues play an important role in orientation for animals that move through a mosaic of habitats. Environmental cues can be imprinted upon during early life stages to guide later return to adult habitats, yet many species must orient toward suitable habitats without previous experience of the habitat. It is hypothesized that multiple sensory cues may enable animals to differentiate between habitats in a sequential order relevant to the spatial scales over which the different types of information are conveyed, but previous research, especially for marine organisms, has mainly focused on the use of single cues in isolation. In this study, we investigated novel habitat selection through the use of three different sensory modalities (hearing, vision, and olfaction). Our model species, the French grunt, Haemulon flavolineatum, is a mangrove/seagrass-associated reef fish species that makes several habitat transitions during early life. Using several in situ and ex situ experiments, we tested the response of fish toward auditory, olfactory, and visual cues from four different habitats (seagrass beds, mangroves, rubble, and coral reef). We identified receptivity to multiple sensory cues during the same life phase, and found that different cues induced different reactions toward the same habitat. For example, early-juvenile fish only responded to sound from coral reefs and to chemical cues from mangroves/seagrass beds, while visual cues of conspecifics overruled olfactory cues from mangrove/seagrass water. Mapping these preferences to the ecology of ontogenetic movements, our results suggest sequential cue use would indeed aid successful orientation to novel key habitats in early life.

Dispersal of marine fishes mainly depends on passive transport of planktonic larvae driven by ocean currents. It allows populations to be connected through thousands of kilometers but also make them sensitive to factors limiting larval dispersion. In this regard it is known that there are several physical and biological factors that determine the distribution of marine species larvae and therefore population connectivity.The present work aims to study the effects of geographic traits of Cuban archipelago and biological characteristics of reef fishes inhabiting it on the genetic structure of their populations. Three different species with distinct biological characteristics and broadly distributed within the Caribbean were selected: Stegastes partitus, Haemulon flavolineatum and Acanthurus tractus. Individuals were sampled from five localities distributed around Cuba during the time period from 2005 to 2010. We analyzed mitochondrial DNA (mtDNA) polymorphism: a fragment of the non coding region (NCR) for the three species and cytb for A. tractus. The polymorphism of nuclear microsatellite loci was studied for S. partitus and H. flavolineatum.Genetic diversity, assessed by means of Ho and He have high values when analysing microsatellite loci. These molecular markers revealed the presence of contrasting geographic structure patterns for the two species. Low but significant pairwise FST estimates were obtained for S. partitus while H. flavolineatum was genetically homogenous. These results were supported by mtDNA analyses. Likewise, A. tractus showed no evidence of significant genetic differentiation at the level of the NCR and cytb gene. Differences in population genetic structure of surveyed species could be the result of extant marine currents acting distinctly on species dispersion according to their reproductive behaviour (i.e. spawning sites, benthonic or pelagic eggs and capacity of larvae to staying close to the natal reef or being driven away from it). Mitochondrial markers showed high levels of haplotypic diversity for the three species and contrasted nucleotide diversity, low for S. partitus, intermediate for H. flavolineatum and high for A. tractus. According to these observations and results of neutrality tests and mismatch distribution analyses, it is suggested that recent population expansion occurred in these species. However differences in population parameter estimations suggest that the time and the rate of population expansion were different for the different species.The analysis of A. tractus cytb haplotype relationships grouped some Cuban individuals with two haplotypes previously described as A. bahianus. This latter species has been recently proposed as restrict to South Atlantic and separated from A. tractus by the Amazon-Orinoco outflow barrier. The presence of mtDNA haplotypes from the southern region in Cuba suggests that A. bahianus may be able to overcome this barrier., La dispersion des poissons des récifs coralliens dépend, pour une large part, de l’existence de larves pélagiques qui peuvent être transportées au sein des courants marins loin de la population source. De l’efficacité de ce transport dépendra l’existence de populations formant un continuum, plus ou moins connectées, tout le long des zones de récifs. Toutefois, ce phénomène de dispersion est complexe et il implique aussi d’autres facteurs, physiques et biologiques, qui influent sur la dispersion de ces organismes.L’objectif de cette thèse a été d’étudier les effets des caractéristiques géographiques de l’archipel cubain et de la biologie des espèces sur la structure génétique et la connectivité des populations de poissons de récifs en utilisant comme modèle trois espèces présentant des traits d’histoire de vie différents : Stegastes partitus, Haemulon flavolineatum et Acanthurus tractus.Nous avons échantillonné des individus adultes dans cinq localités situées autour de l´archipel cubain pendant la période 2005-2010. Le polymorphisme de marqueurs microsatellites a été étudié chez S. partitus et H. flavolineatum, celui de la région non codante de l’ADNmt chez les trois espèces et celui du gène cytb chez A. tractus.L’analyse de la diversité génétique des locus microsatellites révèle des taux d’hétérozygotie observés (Ho) et attendus (He) élevés à chaque locus et pour les deux espèces, mais elles présentent différents patrons d’organisation de la diversité génétique. Chez S. partitus, la comparaison des localités prises deux à deux nous montre une différentiation exprimée par des valeurs de FST très faibles mais significatives, alors que chez H. flavolineatum aucune structuration géographique n’est observée. Ces résultats sont confirmés au niveau de l’ADN mitochondrial, lequel indique aussi une absence de différentiation d’A. tractus pour l’ensemble des localités étudiées. Les différences de structuration génétique des espèces étudiées pourraient être le résultat des effets des courants marins autour de l’ile qui agissent de façon différente sur la dispersion des espèces en fonction de leur comportement reproducteur (e.g. sites de fraie, œufs pélagiques ou benthiques et capacité des larves de rester prêt des récifs natals ou d’être transportés au loin).Pour les marqueurs mitochondriaux, nous avons obtenu des valeurs élevées de diversité haplotypique pour les trois espèces, mais la diversité nucléotidique est très différente selon les espèces, faible chez S. partitus, grande chez H. flavolineatum, et très grande chez A. tractus. La distribution du nombre de différences entre les séquences suggère que ces populations sont passées par des périodes d’expansion démographique. Ceci est confirmé par les estimations des paramètres de tests de neutralité. Les paramètres caractérisant la croissance des populations qui ont été obtenus pour les trois espèces ne sont pas semblables, ce qui suggère que le temps et l’ampleur des événements d’expansion ont été différents pour les trois espèces.L’analyse du gène cytb nous a permis d’identifier des haplotypes chez A. tractus qui n’avaient été observés préalablement que chez A. bahianus. L’aire de répartition de cette dernière espèce a été récemment restreinte à l’Atlantique Sud sur la base de la divergence génétique avec A. tractus et de la séparation géographique qui est maintenu par la barrière que constitue l’embouchure des rivières Orénoque et Amazone. La présence d’haplotypes du sud à Cuba suggère que des individus du sud ont été capables de traverser cette barrière.

Coral reef populations of a variety of fish and invertebrate species are replenished by individuals that use inshore coastal habitats as temporary juvenile habitats. These habitats vary greatly in their architecture, and different characteristics of structure could play a role in their selection and utilization by resident fauna. To solely investigate the role of structural complexity in microhabitat selection, in situ habitat preference of 48 individuals of the early juvenile stage of a common reef fish (Haemulon flavolineatum) was studied for 4 structurally very different lagoonal microhabitats (i.e. mangrove, seagrass, rubble, coral), using a multiple-choice experiment in field enclosures. This fish species was selected as it utilizes these habitats during different parts of its life cycle. The structural complexity of each microhabitat was changed in each replicate experiment and assessed on the basis of 7 commonly used measures of structure using digitized photographs. We tested the hypothesis that in isolation of other factors, fish prefer the structurally most complex microhabitat that is available, independent of habitat type. However, fish always preferred seagrass and coral microhabitats even when offered at low complexity, and this choice was rather consistent over a 24 h time period. Structural characteristics appeared to be marginally important for the seagrass microhabitat only. Therefore, the differential preference for distinct lagoonal microhabitats does not appear to be driven by measures of structural complexity that are known to be important at the level of individual habitat types. In this light, continuing loss of coral and seagrass habitats in lagoonal environments due to anthropogenic effects is alarming as it affects preferential habitat of certain stages of the life cycle of fishes.

An important process thought to drive habitat selection during (post-)settlement of coral reef fish is predation. It is assumed that in back-reef habitats such as seagrass beds and mangroves predation is lower than on coral reefs. However, recent studies have suggested that significant piscivore assemblages are present in back-reef habitats. The assumption of reduced predation pressure in back-reef habitats can therefore be debated. We compared piscivore assemblages along the coast of a Caribbean island using underwater visual census surveys in a spatial gradient of coral reefs, seagrass beds and mangroves. We also performed predation experiments in combination with video observations in these habitats using tethered recently settled Haemulon flavolineatum. High piscivore densities and reduced survival showed the presence of significant piscivore assemblages in both reef and back-reef habitats. Both reef-associated piscivores and piscivores that use back-reef habitats as a juvenile habitat contributed to the piscivore assemblage in the investigated gradient. Habitat type had a significant effect on the composition of the piscivore assemblage, density, and prey survival. Piscivore density was highest on the reef, mangroves and notches, all of which are habitats with a high structural complexity. On the contrary, seagrass beds showed lowest piscivore density. Tethering experiments showed lowest survival on the reef but also reduced survival on back- reef habitats located close to the coral reef. Seagrass beds and mangroves located farther away from the reef into the bay showed highest survival. The present study shows that the concept of reduced predation in back-reef habitats used by juvenile fish does not apply to all habitats, since these habitats can harbour significant piscivore assemblages. However, depending on the spatial setting in the seascape (distance to the reef and presence of other habitat types), some Caribbean seagrass beds show low densities of piscivores and increased survival when compared to other habitats.

Environmental cues like sound, magnetic field, oceanic currents, water chemistry or habitat structure are believed to play an important role in the orientation of reef fish towards their settlement habitat. Some species of coral reef fish are known to use seagrass beds and mangroves as juvenile habitats. Once oceanic larvae of these fish have located a coral reef from the open ocean, they still have to find embayments or lagoons harbouring these juvenile habitats. The sensory mechanisms that are used for this are still unknown. In the present study, experiments were conducted to investigate if recruits of the French grunt (Haemulon flavolineatum) respond to habitat differences in water type, as mangrove/seagrass water may differ in biotic and abiotic compounds from coral reef water. Our results show that post-larvae of a reef fish that is highly associated with mangroves and seagrass beds during its juvenile life stage, choose significantly more often for water from mangroves and seagrass beds than for water from the coral reef. These results provide a more detailed insight in the mechanisms that play a role in the detection of these juvenile habitats.

Mangroves and seagrass beds have received considerable attention as nurseries for reef fish, but comparisons have often been made with different methodologies. Thus, relative importance of different habitats to specific size-classes of reef fish species remains unclear. In this study, 35 transects in 11 sites of mangroves, seagrass beds and coral reef were surveyed daily, in and in front of a marine bay on the island of Curacao (Netherlands Antilles). The density and size-frequency of nine reef fish species (including herbivores, zoobenthivores and piscivores) was determined during a five-month period using a single methodology, viz. underwater visual census. All species were ‘ nursery species ’ in terms of their high densities of juveniles in mangroves or seagrass beds. Relative density distribution of the size-classes of the selected species over mangroves and seagrass beds suggested high levels of preference for either mangroves or seagrass beds of some species, while other species used both habitats as a nursery. Spatial size distribution of the nine species suggested three possible models for Post-settlement Life Cycle Migrations (PLCM). Haemulon sciurus, Lutjanus griseus, L. apodus, and Acanthurus chirurgus appear to settle and grow up in bay habitats such as mangroves and seagrass beds, and in a later stage migrate to the coral reef (Long Distance PLCM). Juveniles of Acanthurus bahianus and Scarus taeniopterus were found only in bay habitats at close proximity to the coral reef or on the reef itself, and their migration pattern concerns a limited spatial scale (Short Distance PLCM). Some congeneric species carry out either Long Distance PLCM or Short Distance PLCM, thereby temporarily alleviating competition in reef habitats. Haemulon flavolineatum, Ocyurus chrysurus and Scarus iserti displayed a Stepwise PLCM pattern in which smallest juveniles dwell in the mouth of the bay, larger individuals then move to habitats deeper into the bay, where they grow up to a (sub-) adult size at which they migrate to nearby coral reef habitats. This type of stepwise migration in opposite directions, combined with different preference for either mangroves or seagrass beds among (size-classes of) species, shows that reef fish using in-bay habitats during post-settlement life stages may do so by choice and not merely because of stochastic dispersal of their larvae, and underline the necessity of these habitats to Caribbean coral reef systems.

Juvenile French grunts (Haemulon flavolineatum) form extremely site-specific and long-lasting diurnal resting shoals (Helfman and Schultz, 1984). Although the resting shoals often congregate near reef structures such as coral heads or grassbeds, when threatened by a potential predator, they rarely enter shelter holes. Instead, they begin schooling and perform antipredator behavior typical of fish schools (Pitcher and Wyche, 1983; Pitcher and Parrish, 1993). This behavior differs from many other species of coral reef fishes which shelter in crevices in

The effect of collecting trauma on the metazoan parasites in the alimentary canal of French grunts, Haemulon flavolineatum (Desmarest) (Perciformes: Haemulidae), was evaluated by comparing the number and species of parasites in 10-fish lots that were identical except for collecting technique. Collecting techniques included speared (dead), speared through the caudal peduncle (live), trapped, dipnetted at night, and ostracitoxin exposed. Dead, trapped, and toxin-stressed fish had no alimentary canal parasites, whereas speared-live and night-dipnetted fish had comparable numbers of parasites. Fish collected by using apparently traumatic techniques quickly expelled their alimentary canal metazoan parasites. Our results cast doubt on the reliability of traditional fish parasite surveys, studies on population dynamics of fish parasites, and experiments that employ these traumatic collecting methods.

Coral reefs occur in a variety of situations in the Atlantic, Pacific and lndian Oceans, which involve great differences in the degree of isolation from surrounding shallow-water environments, e.g. seagrass beds, mangroves and unvegetated sediments. Mangroves and seagrass beds appear to offer attractive habitat for fishes including species commonly found on reefs especially for settling postlarvae and developing juveniles. These habitats probably intercept large numbers of recruits, and may offer some advantages over coral reefs for early survival of young juveniles. They may act as accumulators of excess recruits, which could tend to smooth out the temporal patchiness of recruits available to reefs directly from the plankton. However, there is no clear evidence that, in general, reefs situated favorably to the shallow-water, vegetated habitats experience enhancement of these early life stages, by comparison with more remote reefs There are a few demonstrated mechanisms for movement of plant and animal material (alive, dead or reprocessed) between these shallow-water habitats. including recycling of reef organic production through an adjacent habitat and back to the reef. The absolute values of such fluxes assimilated by (or returned to) the reef may be small, but the means by which the material is exchanged may be particularly suitable to enhance fish populations. Relative trophic patterns among the various shallow-water, demenal habitats and among the oceans of the world are not entirely clear. This is partly because quantitative fish community studies and trophic studies in seagrass and mangrove habitats are inadequate. Among fish, carnivores appear to dominate in all habitats in almost all situations; usually benthic invertebrates are the major prey group. In a few reported situations, primarily in the Pacific, planktivory appears to be the dominant feeding mode. Algivory is important in all situations, but almost never dominant, and its importance varies widely within (as well as between] oceans and types of situations. I t may be most significant on the open coasts of some isolated islands and atolls. Seagrass is a minor direct food source in all oceans and is best documented in the Atlantic. If important linkages occur among the shallow-water, adjacent, tropical habitats, they most likely involve fish recruitment and/or trophic processes involving invertebrates. Both are little-known subjects in these environments, that will require additional, focused research to clarify the nature and magnitude of any interactions that influence marine resources.

Juvenile french and white grunts (Haemulorlflavolineatum and Haemulonplumieri) form diurnal resting schools over colonies of Porites furcata and Acropora palmata in St. Croix. We studied the effect of these grunts on the tissue composition and growth rate of corals. Porites furcata colonies with grunts had significantly more tissue cm- *, N cm-* and zooxanthellae cm-* than colonies without grunts. Acropora palma after removal growth rates were lower or not significantly different. These data demonstrate that schools of resident fishes can stimulate coral growth, perhaps by providing nitrogen supplements.

Juvenile french and white grunts (Haemulon jlavolineatum and Haemulon plumierl) rest over coral colonies during the day and feed only at night in surrounding seagrass beds. We examined the amount of nitrogen, phosphorus, particulate organic carbon, and calories which these fishes deposited over the coral colonies that were their resting sites. Weight-specific rates of nitrogen excretion by grunts decreased with increasing fish size. Rates of phosphorus excretion were not related to fish size. Excretory products were rich in nitrogen (molar N:P = 48), primarily ammonium, whereas fecal material was richer in phosphorus (N:P = 8). Feces leached over half of their phosphorus content within the first day. Half of the daily excretion and defecation occurred during the first 4 h after grunts returned to the reef, in which time they doubled the amount of NH.,+ available to corals under calm conditions. Seasonal patterns of nutrient and particulate organic carbon (caloric) input to coral colonies varied with grunt biomass on the colony. The maximum input to colonies of Porites jiircata from grunts occurred during August, which coincided with the time of highest coral growth rate. Grunts deposited an average of 164 and 251 mg m-2 d-’ of particulate organic carbon (feces) on the P. furcata and Acropora palmata colonies over which they rested, an energy supplement to the colonies of 0.8 and 1.2 kcal m-2 d-l. Rates of nutrient and organic matter input from grunts are comparable to or greater than rates observed in other naturally or artificially enriched ecosystems.

Factors affecting recruitment and early survivorship of juvenile coral reef fishes were studied on St. Croix, United States Virgin Islands. The faunal assemblage studied included diurnally active fishes found in the rubble/sand habitat. The most abundant members were: beaugregory {Ste- gastes leucostictus), foureye butterflyfish {Chaetodon capistratus), mahogany snapper {Lutjanus ma- hogoni), surgeonfishes {Acanthurus bahianus and A. chirurgus) and French grunt {Haemulon flavoli- neatum). During the period 1978-1981, sets of experimental reefs constructed from Strombus gigas shells were built in various locations relative to a major reef. Recruitment of juveniles of almost all species in the rubble/sand fish assemblage occurred more heavily on reefs that were built 20-40 m away from the main reef (into the lagoon) than on those built at the edge ofthe backreef. A series of experiments revealed that this is probably due to two factors: differences in available shelter and differences in encounter rates with predators. Seagrass and algae, which provide shelter to very small juvenile fishes, are absent in a "halo" zone close to the reef due to the feeding activities of reef-associated grazers (fishes and urchins). Experiments with artificially produced halos and artificial seagrass and algae showed that part of the explanation for the observed spatial pattern of fish recruitment is the spatial pattern of the shelter provided by seagrass and algae. Experiments in which potential prey fish were tethered demonstrated that the risk of predation for small juvenile fishes was considerably higher close to the reef than it was 20 m away. The results of these experiments suggest that patterns of settlement and juvenile survivorship of coral reef fishes are affected by complex interactions with other reef organisms (in this case, the activities of reef-associated grazers that modify available shelter) and by the frequency of encounters with predators. If they survive, all of the juveniles, regardless of where they initially settle, eventually migrate to a nearby reef. The species studies here differed in the degree to which juveniles use the sea-grass/algal habitat as a refuge from predation; these differences suggest that spatial patterns of recruitment, interacting with predation, may influence both population abundances and species com? position of older juveniles on the reef.

Traditional behaviours involve the non-genetic transmission of social information across age classes or generations. French grunts (Haemulon flavolineatum) exhibit social traditions of daytime schooling sites and twilight migration routes. Individuals transplanted to new schooling sites and allowed to follow residents at the new sites used the new migration routes and returned to the new sites in the absence of resident fish. Control fish with no opportunity to learn showed no such directionality or return. This is the first demonstration of apparent pre-cultural behaviour in free-living fish. Our observations suggest additional classes of behaviour and taxonomic groups in which pre-cultural activities are likely to have evolved.

Day-night changes in fish communities were quantified in 6 associated shallow-water biotopes within a single bay: mangroves, seagrass beds, algal beds, channel, fossil reef boulders, and notches in fossil reef rock. All biotopes, except the algal beds, showed a strong reduction in fish density and species richness at night, caused by absence of diurnally active fishes and migrations of Haemulidae and Lutjanidae to the seagrass beds. The fish fauna of the different biotopes showed a relatively high dissimilarity between day and night. This dissimilarity is largely caused by absence of Acanthuridae, Chaetodontidae, Labridae, Pomacentridae, Scaridae and Sparidae at night. These fishes seek shelter at night in, amongst others, the channel, notches and boulders. The balloonfish Diodon holocanthus utilised almost all biotopes as shelter as well as feeding sites. The wide distribution of its preferred food (molluscs) probably explains its distribution in most biotopes at night. The nocturnally active Haemulidae and Lutjanidae, on the other hand, migrated from their daytime shelter sites to the seagrass beds at night to feed. Some of these fishes also migrated to the algal beds to feed. The preference of Haemulidae and Lutjanidae for the seagrass bed as a feeding biotope, instead of other bay biotopes, appears to be related to the relatively high availability of their preferred food (Tanaidacea and Decapoda) as determined by digestive tract analysis. Other bay biotopes showed much lower densities of such food items compared to the seagrass beds.

Varias especies de peces que habitan los arrecifes de coral están asociadas con los hábitats que funcionan como viveros, por ejemplo los manglares y áreas de pastos marinos, durante la etapa juvenil de su vida (i.e., ?especies de vivero?). Sin embargo, poco se sabe de si pueden utilizar otros tipos de hábitat en esta etapa. En este estudio investigamos si algunas ?especies de vivero? pueden utilizar hábitats alternativos durante la etapa juvenil, cuando se les dificulta el acceso a manglares y pastos marinos. Se llevaron a cabo censos visuales en seis tipos de hábitat costero en la Isla Bermuda (Atlántico Oeste), y las densidades de los jóvenes tempranos ( < 4 cm) de cuatro ?especies de vivero? fueron cuantificadas y comparadas con cuatro especies que no son de viveros. Los jóvenes tempranos de las especies de vivero, Haemulon flavolineatum y Scarus iserti, fueron observados en una variedad de tipos de hábitats, entre los cuales se encontraban los hábitats comunes para los jóvenes (manglares, parches de pastos marinos y debajo de cornisas de rocas grandes), así como hábitats que no son típicos para los jóvenes (parches arrecifales). Otras dos especies de vivero, Haemulon sciurus y Lutjanus griseus, solo se encontraron en manglares, pastos marinos y rocas. Todas las especies que no son de vivero fueron observadas solamente en los parches arrecifales. Estos resultados sugieren que algunas especies de vivero son flexibles a la hora de elegir un hábitat en la etapa de jóvenes tempranos, mientras que otras tienen una mayor dependencia de los manglares y los parches de pastos marinos, aun cuando estos hábitats son escasos.