Morphology and field behavior of pteropod molluscs: feeding methods in the families Cavoliniidae,Limacinidae and Peraclididae (Gastropoda: Thecosomata)

From 1983 to 1985 we studied the in-situ feeding behavior of fourteen species belonging to nine genera of thecosomatous pteropods, one in the family Limacinidae, seven in the family Cavoliniidae, and one in the family Peraclididae. All the euthecosomes we examined fed with a large spherical mucous web. Peraclis reticulata (D'Orbigny), however, uses a funnel-shaped mucous sheet, resembling that of other pseudothecosomes. Although the feeding mechanisms are similar in all the animals we examined closely, we found great differences in the size and morphology of the external part of the mantle. In species of Diacria and Cavolinia the external mantle attains its greatest complexity, and appears to be used for the sorting or rejection of food and for flotation. Species of the other five cavoliniid genera we studied have greatly reduced external mantles and sink slowly while feeding. Species of Limacina have no external mantle but appear to arrest sinking by setting their mucous webs. P. reticulata, which also appears to be neutrally buoyant, has an extensive external mantle that completely covers the shell. We conclude that feeding with a large mucous web explains the presence of fragments of large, fast moving prey in the stomach contents of both pseudothecosomes and euthecosomes. At present, it is impossible to decide whether thecosomes should be regarded as carnivorous trappers of prey or as suspension feeders. The use of an external mucous web for feeding is probably common to all thecosome pteropods and is the fundamental andaptation that enables them to live holoplanktonically.     

Development and functions of the shell sculpture of the marine snail Ceratostoma foliatum

The shell of the adult Ceratostoma foliatum (Gmelin) is characterized by three varices with foliations, and a tooth on the anterior portion of the outer lip. These features are derived gradually from the markedly different sculpture of shells of small juveniles (a network of fine axial and spiral cords). The sculpture changes as the thin, cord-like basic varix is elaborated, reinforced, and modified by the development of a secondary structure (the tooth) and as the number of varices per whorl decreases. Most muricid shell patterns can be derived from juvenile patterns similar to that of C. foliatum by quantitative variations in these four processes. Likely functions of the complex and varied muricid shell structures include stabilization in shifting substrates, defense against predators, and strengthening of the shell. Different functions and shell-growth patterns are likely for the different types of varices. Shell structures are most elaborate on shells of adults. A structure's functions are likely to change as the structure becomes more complex on each successive whorl. The functional period in an individual's lifespan is consequently restricted by the pattern of growth, the rate of structural development, and the rate of shell erosion.     

Scanning electron microscopy of metamorphosis in four species of barnacles (Cirripedia Thoracica Balanomorpha)

Metamorphosis and early juvenile development was followed in the laboratory in Balanus amphitrite and B. improvisus (family Balanidae) and in Semibalanus balanoides and Elminius modestus (family Archaeobalanidae) from cyprid settlement until 24 h after ecdysis. Stages of development were studied in vivo and with scanning electron microscopy. Events in metamorphosis and early juvenile development are very similar in all four species and can be interpreted in terms of a highly modified moult. Notably, there was no indication whatsoever of the amorphous decorticated settler previously described from metamorphosis of B. amphitrite. The shape of a juvenile barnacle with cirri and incipient shell plates is apparent immediately after the shedding of the cypris carapace, and rudimentary peduncle can be distinguished below the developing wall plates. A basal row of cuticular hairs encircles the peduncle in all species except S. balanoides. These hairs seem to serve a restraining function during early development, when the juvenile barnacle is only attached by the initially secreted cyprid cement. Similarly situated hairs are also present in very young juveniles of the lepadomorph Scalpellum scalpellum. In Semibalanus balanoides nothing indicates that the rostrum originates from the fusion of two latera as previously claimed, since this plate is single as soon as it can be distinguished.     

Ontogenetic change in the radula of Conus magus (Gastropoda)

Specimens of the Indo-Pacific piscivorous gastropod Conus magus Linnaeus, 1758 were either collected by SCUBA in the field in Palau (1983–1984) or raised in the laboratory from egg capsules. C. magus captures adult fish with a specially modified radula tooth. Radula morphology was analyzed in a size range of individuals from 4.1 to 43.7 mm shell length, which encompassed early postmetamorphic juveniles to adults. Post-metamorphic C. magus juveniles are too small to consume fish, and all individuals below 9 mm possess a juvenile radula tooth totally different from that of the adult and resembling that of some vermivorous Conus species. The only food remains found in the digestive tracts of juveniles were the setae of syllid polychaetes. All individuals above 10.5 mm possessed adult teeth and had only fish remains in the gut. Two specimens, 10.1 and 9.2 mm in shell length, had intermediate-type radula teeth.     

Occurrence and detrimental effects of the bivalve-inhabiting hydroid <Emphasis Type="Italic">Eutima japonica</Emphasis> on juveniles of the Japanese scallop <Emphasis Type="Italic">Mizuhopecten yessoensis </Emphasis>in Funka Bay,Japan: relationship to juvenile massive mortality in 2003

In November 2003, we first observed prevalent occurrence of a hydroid, Eutima japonica, on soft body tissues of age zero Japanese scallop (Mizuhopecten yessoensis) juveniles cultured in large areas of Funka Bay, Hokkaido. The occurrence coincided with massive death of juvenile scallops. A major objective was to clarify ecological relationships between the symbionts, and to infer the relationship between symbiosis and the massive mortality. To do this, we investigated distributions of association rates of hydroids with juvenile scallops at 15–34 sites over 3 years (2003–2005), with age one adult scallops at 24 sites in 2003, and with mussels at 13 sites in 2004. We studied seasonal changes in association rates with juvenile scallops, and numbers of polyps per juvenile scallop at three sites from November 2003 to June 2004. We also quantified the hydroid impacts on juvenile scallop shell length growth and triglyceride accumulation in the digestive gland. The association rate of E. japonica polyps with juvenile scallops was high in large areas of Funka Bay in 2003, and overlapped the distribution of mussels bearing polyps. Association rates with age one adult scallops were very low in November 2003, even at the sites where polyps were very common on juvenile scallops. Levels of hydroid occurrence in juvenile scallops varies by year. We found that hydroids presence in juvenile scallops declined drastically in 2004 and 2005. The association rates with juvenile scallops, and numbers of polyps per juvenile scallop declined during winter, until they disappeared completely in the following June. Since polyps were rare in adult scallops, we believe that infection of juvenile scallops was probably initiated from the planulae produced by medusae released from polyps growing on Mytilus spp., especially M. galloprovincialis. Subsequently, the inhabitation spread intraspecifically and interspecifically. In juvenile scallops, inhabitation of polyps reduced shell length growth by 43%, and triglyceride accumulation in digestive glands by 24–47%. Inhabitation of E. japonica on juvenile scallop is best regarded as parasitism, rather than inquilinism or commensalism. Occurrence of polyps was probably not a direct lethal factor for juvenile scallops, because there were some sites where association rates were high, but mortalities were low. Massive mortalities in 2003 may have resulted from simultaneous impacts of heavy polyp load and stresses caused by the way in which the animals were handled (transferred from cages for pre-intermediate culture to cages for intermediate culture), because the massive mortality occurred within a month of the transfer. The presence of polyps in juvenile scallops does not affect the quality of the product in Funka Bay, because market size scallops are hydroid-free.     

Identification of settling and early postlarval stages of mussels (Mytilus spp.) from the Pacific coast of North America, using prodissoconch morphology and genomic DNA

 Detailed inventories of the benthos and field studies of the settlement and recruitment processes of marine benthic invertebrates require accurate identification of newly settled larvae and early juvenile stages. We provide morphological criteria, visible under a good quality dissecting stereomicroscope, by which to discriminate between species of the settling larval and early postlarval stages (∼250 to 700 μm shell length) of mussels of the genus Mytilus on the west coast of Vancouver Island and Southern California. Compared to the bay mussel (M. trossulus), the sea mussel (M. californianus) has: (i) a shallower and flatter umbo, the latter corresponding to a significantly less pronounced prodissoconch I (PI) curvature and (ii) a greater PI length; as well as (iii) a wider separation between the provincular lateral teeth (PLT). The PLT distance is a new term denoting the separation between the midpoint of two reddish pigment spots of the provinculum (larval hinge apparatus) region of settling larvae and early postlarvae of Mytilus spp. from the East Pacific Coast. These spots mark the larger provincular lateral teeth, situated at either end of the provinculum. We confirmed the validity of morphological criteria by comparing PCR products of genomic DNA of provisionally identified postlarvae. Furthermore, measurements of PI lengths and PLT distance from well-preserved postlarvae of sea mussels (M. californianus) and of bay mussels (M. galloprovincialis) from Southern California indicate that the PI morphology and morphometry, and PLT distance criterion apply for that region as well. The criteria presented here can also apply to the advanced (competent) veliger stages, as the latter may settle (i.e. become the “settling” stage) upon encountering a suitable substrate. Our present and previously published work provide economical and effective identification methods that can be used to discriminate among early life history stages (∼250 μm to 5.0 mm shell length) of Mytilus spp. along the west coast of North America. Received: 10 November 1999 / Accepted: 6 September 2000     

Induced triploidy in the soft-shelled clam Mya arenaria: energetic implications

Given that triploid adult bivalves reportedly grow larger and faster than their diploid siblings, such differences should be traceable to variation in energy allocation. In one proposed mechanism, retarded gametogenesis found in triploid adults may allow them more energy for somatic growth. Another hypothesis states that triploids are more heterozygous; increased heterozygosity has been positively correlated with enhanced growth. Juvenile soft-shelled clams, Mya arenaria, were treated with cytochalasin B to induce triploidy and examined with respect to components of a balanced energy equation (C=P+R+E). The variables measured were oxygen uptake (V _{o 2}), filtration rate (FR), dry tissue weight, shell length, shell height and shell inflation. Energy budgets were constructed and diploid and triploid groups compared. Few significant differences were found between diploid and triploid juvenile clams with respect to energy budget components. However, at seven loci assayed electrophoretically the triploid individuals were nearly twice as heterozygous as their diploid siblings. Moreover, tripoloid variances were less than diploid variances for every variable measured. Increased heterozygosity has been correlated with the decreased variance of morphological parameters. This study is believed to be the first to show decreased variance of physiological properties as well as morphological characters. Overall the data clearly indicate that energy allocation in juvenile M. arenaria is not related to ploidy.     

Passing the gut of juvenile flounder, Platichthys flesus: differential survival of zoobenthic prey species

We studied the resistance of benthic prey organisms (Ostracoda, Hydrobia spp., Macoma balthica) to digestion by juvenile flounder, Platichthys flesus (L.), in a series of aquarium experiments. Results showed that some food species are able to survive the gut passage (Ostracoda 53 to 75%, Hydrobia spp. 46 to 92%). This has ecological implications, as increasing eutrophication of the Baltic Sea favours prey species that are nondigestible for the juvenile flounder. Thus, seemingly small changes in food-web structure may have unpredictable effects for the predatory fish. Received: 8 March 1997 / Accepted: 14 March 1997     

Development of the echinothurid sea urchin Asthenosoma ijimai

Development of an echinothurid sea urchin is described for the first time; eggs of Asthenosoma ijimai (Yoshiwara) have been fertilized in the laboratory, and development has been followed light-microscopically up to the early juvenile stage. The eggs, which are orange and float, are 1.2 mm in diameter, by far the largest echinoid eggs on record. The embryos, larvae and early juveniles are lecithotrophic, and no exogenous food is needed for development. The embryonic stages include a remarkable biscuit-shaped late blastula, which has never been described for any echinoid before. The larva, with its para-arms unsupported by skeletal ossicles, is unlike the echinoid prism or pluteus and more resembles the early bipinnaria or early auricularia of asteroids and holothurians, respectively. All stages through late larvae float just beneath the surface until settlement occurs during the third and fourth weeks at 20°C. Metamorphosis from late larva to juvenile is gradual and no part of the larval body appears to be cast off.This paper is dedicated to Professor Juro Ishida on the occasion of his seventieth birthday.     

Purification of multiple vitellogenins in grey mullet (<Emphasis Type="Italic">Mugil cephalus</Emphasis>)

Coralliophila abbreviata (Lamarck) is a corallivorous gastropod that lives and feeds on several species of scleractinian coral in the Western Atlantic and Caribbean. Previous studies of C. abbreviata have revealed that snails on branching acroporid corals are larger and consume more tissue than those on massive and plating corals. To ascertain whether snail life-history and fitness are differentially affected by the coral host, an analysis of the age structure and female reproductive output of snail populations on three coral host taxa (Acropora palmata, Diploria spp., and Montastraea spp.) was conducted at four shallow (2–7 m depth) reef sites off Key Largo, Florida in June through August, 2004. Snails were, on average, almost twice as large on A. palmata than on Diploria spp. and Montastraea spp., averaging 30.3 mm shell length, compared to 17.2 and 17.6 mm, respectively. Brood size increased as a power function with female shell length. Females on A. palmata were significantly larger than females on the other two hosts and, therefore, produced more offspring per female. The number of growth striae on the inner surface of the operculum was used to estimate snail age. Estimates of growth rate were obtained by fitting the Gompertz growth function to size-at-age plots and mortality was estimated using growth parameters and size-frequency data. The data suggest that C. abbreviata inhabiting A. palmata are larger than on alternative hosts due to a combination of a faster growth rate and longer life-span. The species is believed to be a protandrous hermaphrodite. The timing of sex change varied among hosts; snails on A. palmata changed sex later at larger sizes relative to those on the other two hosts. Based on these results, it seems probable that C. abbreviata has developed reaction norms for life-history traits, allowing snails to adjust and maximize fitness in the different environments associated with various coral hosts.     

Assessment of the nutritional condition of larval and early juvenile tuna and Spanish mackerel (Pisces: Scombridae) in the Panamá Bight

The nutritional condition of first-feeding and late larval/early juvenile scombrids was investigated in waters of the northwestern Panamá Bight from May through early November 1988. Wild-caught larvae and juveniles of three taxa, black skipjack tuna (Euthynnus lineatus), bullet and/or frigate tuna (Auxis spp.) and sierra (Scomberomorus sierra), were examined histologically to determine nutritional condition. The incidence of malnourishment in wild-caught preflexion (first feeding—prior to notochord flexion) larvae of all taxa was high. Starvation rates for E. lineatus and Auxis spp. preflexion larvae ranged from 62 to 63% d^-1, while the percentage of larvae actually dying of starvation was estimated at 41 to 43% d^-1. The nutritional point-of-no-return for preflexion larvae was estimated at 1 to 2 d maximum. The cellular condition of liver hepatocytes, particularly the relative amount of vacuolation related to storage of glycogen and lipid, proved to be a sensitive indicator of nutritional condition. In laboratory trials, late larval (postflexion) and early juvenile black skipjack exhibited a nutritional point-of-no-return of 2 to 3 d. Although postflexion larvae were moderately vulnerable to malnourishment in laboratory trials, <13% of wild-caught postflexion larvae exhibited even mild nutritional stress, and no postflexion larvae or juveniles showed signs of severe malnourishment. This pattern of starvation incidence suggests that tropical scombrids undergo stagespecific starvation mortality. Preflexion larvae can suffer significant daily losses due to starvation, while postflexion larvae and early juveniles seem to experience a rapid improvement in feeding ability and/or food availability.     

Observations sur les larves et les adultes de Carinariidae (Mollusca: Heteropoda) de l'Océan Atlantique Nord

Three species of Carinariidae were collected from the North Atlantic Ocean during the KN-38 cruise of the R.V. “Knorr”: Carinaria lamarcki Péron and Lesueur, 1810, Cardiapoda placenta (Lesson) 1830, and Cardiapoda richardi Vayssière, 1904. The characteristics of living specimens of larvae from all three species are described; shell morphology has been studied with the scanning electron microscope and internal anatomy from histological sections. The observations on C. placenta and C. richardi larvae are new. The specific characteristics of these larvae are tabulated. Particular attention is given to the morphology of an adult C. placenta and a juvenile C. richardi, with special emphasis on the shell and radula as studied with the scanning electron microscope.     

Fish predators and scavengers of the sea urchin Paracentrotus lividus in protected areas of the north-west Mediterranean Sea

Direct observations of predation on 436 individuals of the sea urchin Paracentrotus lividus (Lamarck) were carried out in infralittoral rocky bottoms (between 5 and 20 m deep) in three Mediterranean marine reserves. The predator guild was composed of six fish species, the sparids Diplodus sargus and D. vulgaris being the main predators, and the labrid Coris julis a major predator of juvenile sea urchins. Four species attempted but failed to open sea urchins. The scavenger guild was most rich in species, with 17 species observed. Predation was size-dependent; the size of predators increased with increasing size of the sea urchins. The presence of two feeding guilds is suggested, one composed of sparids (Diplodus spp.), able to kill juvenile and adult sea urchins, and the other composed of labrids (mainly C. julis), which feed on juvenile sea urchins. To avoid the extension of overgrazed, barren areas created by P. lividus populations, fisheries' regulations should focus on major sea-urchin predators, chiefly D. sargus, D. vulgaris and C. julis. Received: 23 April 1997 / Accepted: 30 May 1997     

The effects of temperature on the growth of juvenile scleractinian corals

Tropical reef corals are well known for their sensitivity to rising temperature, yet surprisingly little is known of the mechanisms through which temperature acts on intact coral colonies. One such mechanism recently has been suggested by the association between the growth of juvenile corals and seawater temperature in the Caribbean, which suggests that temperature causes a transition between isometric and allometric growth scaling in warmer versus cooler years, respectively (Edmunds in Proc R Soc B 273:2275–2281, 2006). Here, this correlative association is tested experimentally for a cause-and-effect relationship. During April and May 2006, juvenile colonies (8–35 mm diameter) of massive Porites spp. from Moorea, French Polynesia, were incubated at warm (27.8°C) and cool (25.7°C) temperatures for 15 days, and their response assessed through the scaling of growth (change in weight) with colony size. The results reveal that the scaling of colony-specific growth (mg colony⁻¹ day⁻¹) was unaffected by temperature, although growth absolutely was greater at the cool compared to the warm temperature, regardless of colony size. This outcome was caused by contrasting scaling relationships for area-specific growth (mg cm⁻² day⁻¹) that were negatively allometric under warm conditions, but independent of size under cool conditions. In April 2007, a 22 days field experiment confirmed that the scaling of area-specific growth in juvenile Porites spp. is negatively allometric at a warm temperature of 29.5°C. Based on strong allometry for tissue thickness, biomass, and Symbiodinium density in freshly collected Porites spp., it is hypothesized that the temperature-dependency of growth scaling in these small corals is mediated by the interaction of temperature with biomass.     

Post-larval development of the common north-west European brittle stars Ophiura ophiura,O. albida and Acrocnida brachiata (Echinodermata: Ophiuroidea)

The post-larval skeletal plate ontogeny of the ophiuroids Ophiura ophiura (Linnaeus) and Acrocnida brachiata (Montagu) from the recently metamorphosed 0.3 mm disc diameter size to a juvenile size of 2.0 mm disc diameter has been examined using scanning electron microscopy. Post-larval development of O. albida Forbes is briefly described for sizes between 1.0 and 2.0 mm disc diameter. Early post-larval development in the 0.2 to 1.0 mm discsize range involves considerable morphogenetic change and necessitates the use of a developmental series in the identification of newly settled ophiuroids. Comparison of these ophiuroids with other closely related species reveals that the post-larvae are readily distinguishable at even the smallest sizes by their transient post-larval morphologies. Abbreviated larval development in A. brachiata is suggested from the egg size and post-larval form. The ophiuroid post-larvae were collected from the shallow sublittoral of Oxwich Bay, Bristol Channel, UK, during the years 1980 to 1982.     

Characterizing temperate rocky shores from the perspective of an early juvenile snail: the main threats to survival of newly hatched Nucella emarginata

Mortality factors most likely to constitute substantial selective pressures for early juvenile gastropods on temperate rocky shores were identified by examining the vulnerability of hatchlings of an intertidal snail, Nucella emarginata, to heat stress, desiccation, and predation in 1992 and 1993. The highest temperature of substrata measured at tidal heights colonized by N. emarginata in Barkley Sound, British Columbia, Canada, was 28.5°C. This temperature was not lethal to hatchlings in laboratory tests. In laboratory and field desiccation experiments, all hatchlings died within 6 h of emersion. Early juveniles could not survive direct exposure to even moderate drying conditions for the duration of a low tide. Hence, intertidal microhabitats which dry up even for short periods during low tides would prove lethal. Of 45 intertidal animal species to which hatchlings were exposed in the laboratory, small decapod crustaceans were the only organisms to cause substantial hatchling mortality. Of these, Pagurus hirsutiusculus and Hemigrapsus nudus were by far the most abundant in the field, and are probably the only important predators of early juvenile N. emarginata at most sites. Total predator densities in the field were as high as 438 individuals m^–2, suggesting that predation pressure may be intense. Desiccation and predation by decapod crustanceans appear to be the most significant threats to early juvenile N. emarginata. These factors commonly occur on most temperate rocky shores and undoubtedly constitute major selective agent influencing population parameters and shaping life-history strategies and early juvenile traits of intertidal invertebrates.     

Otolith record of age, growth, and ontogeny in larval and pelagic juvenile Stephanolepishispidus (Pisces: Monacanthidae)

Juveniles of the planehead filefish Stephano-lepishispidus (Pisces: Monacanthidae) (Linnaeus, 1766) are a major component of the Sargassum spp. community, yet little is known of their ecology. In this study, the otolith record of age, growth, and ontogeny in S. hispidus was examined. Juveniles caught off Beaufort Inlet, North Carolina (USA) on 30 June 1996 were marked with alizarin complexone and reared in a flow-through, outdoor tank for up to 19 days. Examination of marked otoliths at several time intervals showed that increment formation was not significantly different than one increment per day, and thus, increment number was used to estimate age. Depth-distribution, morphology, and meristics of larvae and juveniles collected (1990–1992) between Cape Romain, South Carolina, and Cape Hatteras, North Carolina, were examined to identify the timing of the larval to juvenile transition. All indicators suggested the transition occurred between 17 and 20 days. Mean otolith increment widths exhibited a marked change at about 20 days, coinciding with the timing of the larval to juvenile transition and a change in the depth distribution from bottom to surface waters. Increment width of individual juveniles, however, did not exhibit the same pattern; only 40% conformed to the pattern identified for all fish. Thus, the record of the larval to juvenile transition is clear at the population level, but unresolved at the individual level. Received: 1 November 1999 / Accepted: 18 December 2000     

Biomineralization markers during early shell formation in the European abalone <Emphasis Type="Italic">Haliotis tuberculata</Emphasis>, Linnaeus

Larval shell formation was investigated in the European abalone Haliotis tuberculata. Stages of mineralization as well as enzymatic and endocrine biomarkers were monitored throughout larval development, from hatching to post-larval stages. Polarized light microscopy and infrared spectroscopy analyses revealed the presence of crystallized calcium carbonate arranged in aragonite polymorphs from the late trochophore stage. A correlation between the main steps of shell formation and enzymatic activities of alkaline phosphatase and carbonic anhydrase was seen. The variations of these biologic activities were related to the onset of mineralization, the rapid shell growth, and the switch from larval to juvenile shell following metamorphosis. Furthermore, a strong increase in the level of calcitonin gene-related molecules was measured in post-larvae, suggesting that endocrine control takes place after metamorphosis. The changes measured for the three biomineralization markers together with mineralogical analysis allowed us to correlate physiologic mechanisms with early steps of abalone shell formation.     

Defining length-at-metamorphosis in fishes: a multi-character approach

The present study attempts to highlight the value of multi-character approaches for defining thresholds in fish ontogeny, like the onset of the juvenile period. We developed techniques to objectively define the transition from larval to juvenile development using morphometric as well as morphological characters and exemplify the multi-character approach on newly settled white sea-breams (Diplodus sargus sargus) collected from the eastern Mediterranean. The morphometric analysis was based on principles of multivariate allometry whereas the analysis of morphology, on assigning a suite of selected characters (here related to external morphology and osteological development) into larval, transforming and juvenile states. The size-at-change in multivariate allometric growth (L _m) is considered here to denote mean length-at-metamorphosis. An almost perfect match is demonstrated between L _m (‘multivariate morphometry’) and mean size-at-morphological change (‘multivariate morphology’) in white sea-bream.     

Movement patterns of young Caribbean reef sharks, Carcharhinus perezi, at Fernando de Noronha Archipelago, Brazil: the potential of marine protected areas for conservation of a nursery ground

The movement patterns and long-term site-fidelity of primarily juvenile Caribbean reef sharks, Carcharhinus perezi, were investigated using tag-recapture and automated telemetry at an insular nursery area, the Fernando de Noronha Archipelago, Brazil. Of the 143 externally tagged juvenile sharks (<110 cm), 22 (15.3%) were recaptured between 0 and 5 km from the site of tagging after 5–800 days at liberty, suggesting some site-fidelity in young individuals of this species. Site-fidelity and movement patterns of ten juvenile sharks ranging from 78 to 110 cm total length (TL) and one opportunistically captured adult female (224 cm TL) were also investigated for periods of up to 2 years with an array of automated telemetry receivers. Tagging and telemetry data from both inside and outside a marine protected area (MPA) show that shark abundance and activity is greatest along the part of the archipelago’s coastline least disturbed by human activity. Telemetry tracking also showed that juvenile reef sharks demonstrated a high degree of site-fidelity and occupied specific locations along the coast throughout the year, with some evidence of an increase in activity space with ontogeny. Sharks appeared to range more widely at night and there were no seasonal variations in habitat use. Our results suggest that MPAs may be a useful conservation tool to protect young C. perezi and potentially other reef-dwelling carcharhinid sharks during their early life history.