Negaprion Brevirostris Research Articles

Hooking injury, physiological status and short-term mortality of juvenile lemon sharks (Negaprion bevirostris) following catch-and-release recreational angling.

Sport fishing for sharks, including fishing with the intent to release, is becoming more prevalent within the recreational angling community. Common targets of recreational anglers are juvenile lemon sharks (Negaprion brevirostris) that frequent shallow tropical nearshore habitats. In this study, we captured 32 juvenile lemon sharks (530-875 mm total length) with conventional angling gear (i.e. spinning rods, dead fish bait and 5/0 barbed circle hooks) from the coastal waters of Eleuthera, The Bahamas, to determine the consequences of capture for individual sharks. Each shark was examined for hooking injuries, blood sampled to quantify physiological disturbance, assessed for reflex impairment and then monitored to assess post-release behaviour and mortality. Four sharks (12.5%) died following release during the 15 min tracking period. Principal components (PC) analysis revealed four axes describing 66.5% of the variance for blood physiology parameters, total length and water temperature. The PC1 and PC3 scores, characterized by positive factor loadings for indicators of exercise-induced stress and blood ion concentrations, respectively, were significantly related to fight time but were not associated with short-term mortality. Short-term mortality was significantly related to factor scores for PC4 that loaded heavily for water temperature and total length. Ten sharks (31%) exhibited impaired reflexes, with loss of bite reflex being most prevalent. Sharks that died had the following characteristics: (i) they had two or more impaired reflexes; (ii) they were hooked in the basihyal; (iii) they exhibited no movement after the initial bout of directional swimming; and (iv) they experienced high water temperatures (i.e. >31°C). Collectively, these results indicate that for juvenile lemon sharks inhabiting tropical flats, fight time can influence the degree of physiological disturbance, while water temperature contributes to the likelihood of survival following release.

Amino acid 15N trophic enrichment factors of four large carnivorous fishes

Ecosystem-based fisheries management strategies require knowledge of trophic relationships. Trophic position (TP) estimates from compound specific nitrogen isotopic analysis of amino acids (AA-CSIA) show promise as the method can disentangle confounding factors associated with changing δ15N values at the base of the food web, but it has yet to be tested in many organisms. This novel technique requires two empirically determined biological parameters: 1) β, the difference in δ15N values between glutamic acid (glu) and phenylalanine (phe) in primary producers and 2) trophic enrichment factor (TEF), the 15N enrichment of glu and phe at each trophic step. Values of β (3.4‰) and TEF (7.6‰) have been suggested for animals in aquatic environments; however recent observations indicate that TEF values may be variable, particularly among elasmobranchs where urea retention may alter nitrogen isotope fractionation between glu and phe. To test these uncertainties, we determined TEF values for three species of sharks, sand tiger (Carcharias taurus), lemon (Negaprion brevirostris), and leopard sharks (Triakis semifasciata), and one teleost species, opakapaka (Pristipomoides filamentosus) grown on controlled and well characterized diets for durations ranging from three (T. semifasciata) to over five years (P. filamentosus). TEF values for both elasmobranchs and opakapaka were ~2‰, significantly lower than TEFs previously reported. These results do not support the hypothesis that urea retention lowers 15N trophic enrichment between glu and phe in elasmobranchs. Rather, isotopic enrichment factors may be primarily driven by differences in dietary protein quality, leading to distinct TEFs for herbivores (~7.6‰) and carnivores (<7.6‰). We propose a method to calculate TP which integrates different TEF values for herbivores and carnivores.

Physiological stress response, reflex impairment, and survival of five sympatric shark species following experimental capture and release

In many fisheries, some component of the catch is usually released. Quantifying the effects of capture and release on fish survival is critical for determining which practices are sus- tainable, particularly for threatened species. Using a standardized fishing technique, we studied sublethal (blood physiology and reflex impairment assessment) and lethal (post-release mortality with satellite tags) outcomes of fishing stress on 5 species of coastal sharks (great hammerhead, bull, blacktip, lemon, and tiger). Species-specific differences were detected in whole blood lactate, partial pressure of carbon dioxide, and pH values, with lactate emerging as the sole parameter to be significantly affected by increasing hooking duration and shark size. Species-spe- cific differences in reflex impairment were also found; however, we did not detect any significant relationships between reflex impairment and hooking duration. Taken together, we ranked each species according to degree of stress response, from most to least disturbed, as follows: hammer- head shark > blacktip shark > bull shark > lemon shark > tiger shark. Satellite tagging data revealed that nearly 100% of all tracked tiger sharks reported for at least 4 wk after release, which was significantly higher than bull (74.1%) and great hammerhead (53.6%) sharks. We discuss which mechanisms may lead to species-specific differences in sensitivity to fishing and suggest that observed variation in responses may be influenced by ecological and evolutionary phenom- ena. Moreover, our results show that certain species (i.e. hammerhead sharks in this study) are inherently vulnerable to capture stress and mortality resulting from fisheries interactions and should receive additional attention in future conservation strategies.

Long-Term Changes in Species Composition and Relative Abundances of Sharks at a Provisioning Site

Diving with sharks, often in combination with food baiting/provisioning, has become an important product of today’s recreational dive industry. Whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. In this study, changes in species composition and relative abundances were determined at the Shark Reef Marine Reserve, a multi-species shark feeding site in Fiji. Using direct observation sampling methods, eight species of sharks (bull shark Carcharhinus leucas, grey reef shark Carcharhinus amblyrhynchos, whitetip reef shark Triaenodon obesus, blacktip reef shark Carcharhinus melanopterus, tawny nurse shark Nebrius ferrugineus, silvertip shark Carcharhinus albimarginatus, sicklefin lemon shark Negaprion acutidens, and tiger shark Galeocerdo cuvier) displayed inter-annual site fidelity between 2003 and 2012. Encounter rates and/or relative abundances of some species changed over time, overall resulting in more individuals (mostly C. leucas) of fewer species being encountered on average on shark feeding dives at the end of the study period. Differences in shark community composition between the years 2004–2006 and 2007–2012 were evident, mostly because N. ferrugineus, C. albimarginatus and N. acutidens were much more abundant in 2004–2006 and very rare in the period of 2007–2012. Two explanations are offered for the observed changes in relative abundances over time, namely inter-specific interactions and operator-specific feeding protocols. Both, possibly in combination, are suggested to be important determinants of species composition and encounter rates, and relative abundances at this shark provisioning site in Fiji. This study, which includes the most species from a spatially confined shark provisioning site to date, suggests that long-term provisioning may result in competitive exclusion among shark species.

Modeling the population dynamics of lemon sharks

BackgroundLong-lived marine megavertebrates (e.g. sharks, turtles, mammals, and seabirds) are inherently vulnerable to anthropogenic mortality. Although some mathematical models have been applied successfully to manage these animals, more detailed treatments are often needed to assess potential drivers of population dynamics. In particular, factors such as age-structure, density-dependent feedbacks on reproduction, and demographic stochasticity are important for understanding population trends, but are often difficult to assess. Lemon sharks (Negaprion brevirostris) have a pelagic adult phase that makes them logistically difficult to study. However, juveniles use coastal nursery areas where their densities can be high.ResultsWe use a stage-structured, Markov-chain stochastic model to describe lemon shark population dynamics from a 17-year longitudinal dataset at a coastal nursery area at Bimini, Bahamas. We found that the interaction between delayed breeding, density-dependence, and demographic stochasticity accounts for 33 to 49% of the variance in population size.ConclusionsDemographic stochasticity contributed all random effects in this model, suggesting that the existence of unmodeled environmental factors may be driving the majority of interannual population fluctuations. In addition, we are able to use our model to estimate the natural mortality rate of older age classes of lemon sharks that are difficult to study. Further, we use our model to examine what effect the length of a time series plays on deciphering ecological patterns. We find that—even with a relatively long time series—our sampling still misses important rare events. Our approach can be used more broadly to infer population dynamics of other large vertebrates in which age structure and demographic stochasticity are important.ReviewersThis article was reviewed by Yang Kuang, Christine Jacob, and Ollivier Hyrien.

First records of the sicklefin lemon shark, Negaprion acutidens, at Palmyra Atoll, central Pacific: a recent colonization event?

The range of the sicklefin lemon shark (Negaprion acutidens) is expanded to include Palmyra Atoll, in the Northern Line Islands, central Pacific. Despite the fact that researchers have been studying reef and lagoon flat habitats of the Atoll since 2003, lemon sharks were first observed in 2010, suggesting a recent colonization event. To date, only juveniles and sub-adult sharks have been observed.

Sharks Love Their Country

Ecology![Figure][1] CREDIT: ALBERT KOK/WIKIMEDIA COMMONS The return of individuals to the place of their birth to reproduce is called philopatry, and it occurs in many vertebrate species. Understanding the level, and details, of philopatry within a given species is important for conservation planning, particularly when it involves large, imperiled, and difficult-to-handle marine vertebrates, such as sharks. Feldheim et al. have undertaken an at-times arduous, 19-year survey of the coastal lemon shark, Negaprion brevirostris , around Bimini in the Bahamas. Previous genetic data hinted that this late-maturing species shows philopatry, and this study gathered direct evidence: Six recaptured mature female sharks were all, without exception, faithful to one nursery site or the other over multiple reproductive events. Such strong local fidelity would be expected to result in some degree of population isolation at very local scales, indicating a requirement for local conservation measures to match this faithfulness. Mol. Ecol. 10.1111/mec.12583 (2013). [1]: pending:yes

Two decades of genetic profiling yields first evidence of natal philopatry and long‐term fidelity to parturition sites in sharks

Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed ('natal philopatry'), which would have important conservation implications. Genetic profiling of lemon sharks (Negaprion brevirostris) from 20 consecutive cohorts (1993-2012) at Bimini, Bahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993-1997 cohorts returned to give birth 14-17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long-term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.

Homing in the New Zealand eagle ray, Myliobatis tenuicaudatus

Homing after experimental displacement is widespread among bony fishes but has only been documented in two species of elasmobranchs, lemon sharks, Negaprion brevirostris, and Port Jackson sharks, Heterodontus portusjacksoni. To test if a species of batoid was capable of homing, New Zealand eagle rays, Myliobatis tenuicaudatus, were experimentally displaced 1.3–9.4 km from the Whangateau Estuary, where they feed, rest and are protected from predators. Significantly more rays returned to the estuary than expected by chance (seven out of eleven rays). The present study demonstrated for the first time that rays are capable of homing after experimental displacement. Homing success was not predicted by day or night capture, displacement distance, ray size, water depth at the displacement site or time in captivity. The homing rates and speeds of the rays were lower than those recorded for sharks, possibly due to a disparity in motivation and behavioural differences. Analysis of active tracks for associations with potential navigational stimuli may indicate which stimuli the rays use to home.

A revised estimate of daily ration in the tiger shark with implication for assessing ecosystem impacts of apex predators

NOAA, National Marine Fisheries Service, Southeast FisheriesScience Center, 3500 Delwood Beach Road, Panama City, Florida 32408, USAApex predators may impact ecosystem structure and func-tion through trophic cascades (Estes, Tinker & Williams1998). Studies of diets, feeding patterns and food webdynamics can contribute to an understanding of commu-nity structure and ecological interactions (Winemiller 1989;Krebs 1998). Thus, understanding trophodynamics isimportant for developing ecosystem models for predictingcommunity responses to anthropogenic changes (Walters,Christensen & Pauly 1997). Studies of this kind are espe-cially critical in the case of large sharks, given that severalspecies are experiencing varying levels of populationdeclines on a global scale (Dulvy et al. 2008; Camhi et al.2009). Accordingly, there is mounting concern – andincreasing effort – to predict the consequences of largeshark declines for food web dynamics (Estes et al. 2011).In a recent study, Hammerschlag et al. (2012) investi-gated the movement patterns of an apex marine predator,the tiger shark (Galeocerdo cuvier), in relation to an eco-tourism provisioning site. The authors rejected the nullhypothesis that sharks displayed restricted long-term habi-tat use at the site. However, they speculated that theobserved long-term and large-scale shark movements maybe related to cryptic, lesser-understood aspects of Atlantictiger shark life history (i.e. reproduction, mating, foragingforays).As part of their discussion, Hammerschlag et al. (2012)considered the daily ration of 210-kg adult female tigersharks. However, no published studies exist that havequantified this aspect of tiger shark food-consumptiveneeds. To get a broad approximation of daily ration, theauthors averaged values derived from two other species ofsharks found in the subtropical Atlantic: the lemon shark(Negaprion brevirostris), daily ration estimate of 2 1%body weight (Cortes & Gruber 1990); and shortfin makoshark (Isurus oxyrinchus), daily ration estimate of 4 6%body weight (Wood et al. 2009). The species used in thecalculation here were chosen in part because of theirbehavioural and geospatial overlap with the tiger sharkmovements found in Hammerschlag et al. (2012). How-ever, the resulting approximation of the daily ration valuefor an adult tiger shark (3 7%) is likely inflated for twoprimary reasons: (i) using values derived from juvenile spe-cies, although daily ration in sharks is known to decreasewith size (Wetherbee & Cortes 2004) and (ii) averaging val-ues from two species, one of which, the shortfin mako, isregionally endothermic, while tiger sharks are ectothermic(Carlson, Goldman & Lowe 2004).Here we present a different, more traditional approachto estimate the daily ration for tiger sharks followingWinberg (1956). Accordingly, daily ration (kcal day

Genetic network and breeding patterns of a sicklefin lemon shark (Negaprion acutidens) population in the Society Islands, French Polynesia.

Human pressures have put many top predator populations at risk of extinction. Recent years have seen alarming declines in sharks worldwide, while their resilience remains poorly understood. Studying the ecology of small populations of marine predators is a priority to better understand their ability to withstand anthropogenic and environmental stressors. In the present study, we monitored a naturally small island population of 40 adult sicklefin lemon sharks in Moorea, French Polynesia over 5 years. We reconstructed the genetic relationships among individuals and determined the population’s mating system. The genetic network illustrates that all individuals, except one, are interconnected at least through one first order genetic relationship. While this species developed a clear inbreeding avoidance strategy involving dispersal and migration, the small population size, low number of breeders, and the fragmented environment characterizing these tropical islands, limits its complete effectiveness.

Monogenoid Infection of Neonatal and Older Juvenile Lemon Sharks,Negaprion brevirostris(Carcharhinidae), in a Shark Nursery

Fifty lemon sharks, Negaprion brevirostris , were captured in a shallow, mangrove-fringed shark nursery at Bimini, Bahamas and examined for the presence of skin-dwelling ectoparasitic monogenoids (Monogenoidea). Sixteen sharks were infected by Dermophthirius nigrellii (Microbothriidae); the youngest host was estimated to be 3- to 4-wk-old. Infection prevalence, mean intensity, and median intensity (0.32, 2.63, and 2.0, respectively, for all sharks) were not significantly different between neonates (estimated ages 3- to 10-wk-old) and non-neonatal juveniles (estimated ages 1- to 4-yr-old), suggesting that soon after parturition lemon sharks acquire infection levels of D. nigrellii matching those of juvenile conspecifics. Monogenoids were only found on the trailing portion of the first and second dorsal fins and upper lobe of the caudal fin. The prevalence of D. nigrellii was highest on the first dorsal fin; however, the mean and median intensities of D. nigrellii were similar between fins in all but 1 case. These results raise important husbandry implications regarding the practice of preferentially seeking neonatal and other small lemon sharks for captivity.

Electrochemical properties of lanthanide metals in relation to their application as shark repellents

Sharks comprise a large portion of unwanted bycatch in longline fisheries worldwide and various technologies have been proposed to reduce elasmobranch bycatch without impacting the catch of target species. Recently, the naturally electrogenic lanthanide metals have been introduced as an elasmobranch-specific repellent. We quantified the voltage produced by six lanthanide metals in seawater, compared their dissolution rates, and performed a behavioral assay to determine their efficacy against two coastal shark species. We found that there was no difference in the voltage produced by the six tested metals and the voltage decayed as a power function (approximately x−1.5) with distance from the metal sample. We calculated that sharks should detect a sample of neodymium from a distance of 65–85cm in seawater. Voltage was greatest in freshwater and decreased logarithmically with increasing salinity but did not differ above salinities greater than 10ppt. The dissolution rate for the lanthanides varied from −1.6 to −0.2gh−1 and as the metals dissolved, the voltage remained constant. In a behavioral assay, neodymium was ineffective at repelling bonnethead sharks (Sphyrna tiburo) tested individually and in groups, and juvenile lemon sharks (Negaprion brevirostris) in groups.

Two new species and a new phyllobothriid cestode genus from sharks of the genus Negaprion Whitley (Carcharhiniformes)

Alexandercestus n. g. (Cestoda: Tetraphyllidea) is erected for two cestode species found parasitising the two known species of lemon sharks (Carcharhiniformes: Negaprion spp.). This new genus differs from all other phyllobothriid genera except for Hemipristicola Cutmore, Theiss, Bennett & Cribb, 2011, Marsupiobothrium Yamaguti, 1952, Nandocestus Reyda, 2008, Orectolobicestus Ruhnke, Caira & Carpenter 2006, Orygmatobothrium Diesing, 1863, Paraorygmatobothrium Ruhnke, 1994 and Phyllobothrium van Beneden, 1849 in possessing uniloculate bothridia with an apical sucker and neck scutes. Alexandercestus differs from Orectolobicestus and Nandocestus in lacking marginal loculi on the bothridia, from Paraorygmatobothrium in possessing uninterrupted vitelline follicles at the level of the ovary and from Phyllobothrium in being euapolytic as opposed to anapolytic and in lacking posteriorly bifid bothridia. The new genus lacks the central accessory bothridial organ seen in specimens of Orygmatobothrium, and lacks the central bothridial accessory sucker of specimens of Marsupiobothrium. Alexandercestus spp. compare most favourably with specimens of Hemipristicola, especially with respect to aspects of proglottid morphology, but differ in possessing aristate gladiate spinitriches rather than serrate gladiate spinitriches on the proximal bothridial surface. In addition, the bothridia of Alexandercestus spp. are comparatively more fleshy and foliose than those in specimens of Hemipristicola. Two new species of Alexandercestus n. g. are described, Alexandercestus gibsoni n. sp. from Negaprion acutidens, collected from off northern Australia and the Marshall Islands, and Alexandercestus manteri n. sp. from N. brevirostris, collected off the islands of Bimini and the Florida Keys. The two new species differ in total length and vitelline follicle distribution. Bayesian inference and parsimony analysis of the D1-D3 region of the large nuclear ribosomal DNA of 17 published and seven novel sequences placed A. gibsoni as the sister taxon to a clade containing Hemipristicola gunterae Cutmore, Theiss, Bennett & Cribb, 2011 and species of Paraorygmatobothrium. This result supports the erection of Alexandercestus as a genus separate from Hemipristicola and Paraorygmatobothrium. At the present time, species of Alexandercestus are known only from hosts of the carcharhinid genus Negaprion Whitley; examination of extensive survey data suggests this may be the extent of the host distribution of this genus.

Spatial behaviour and site fidelity of the sicklefin lemon shark Negaprion acutidens in a remote Indian Ocean atoll

Understanding the movement behaviour of any species is important for developing species-specific management and conservation measures. In recent years, the sicklefin lemon shark Negaprion acutidens has shown rapid range reductions and has even disappeared altogether in certain areas. In this study, the area use patterns and site fidelity of the N. acutidens were assessed at the St. Joseph Atoll in the Seychelles. Passive acoustic telemetry methods were employed to monitor the movements of 19 tagged individuals for 1 year. Area use within the lagoon of the atoll was found to be highly restricted, with individuals typically utilising a small portion of the available area throughout the year. A high-use zone was apparent in the south-east of the atoll’s lagoon, which was shared by many of the monitored individuals. Fidelity to the study site was found to be extremely high, with the 79 % of tagged N. acutidens still present in the atoll at the end of the study. Individuals displayed both diel and tidal movements between the lagoon and surrounding habitats. The restricted area use and high site fidelity observed in this study highlight both the vulnerability of this species to rapid over exploitation and importance of remote habitats such as the St. Joseph Atoll in their future conservation. The results obtained here can be used to inform management decisions regarding the development and utilisation of similar atoll environments throughout the species’ range.

Aerial Survey as a Tool to Estimate Abundance and Describe Distribution of a Carcharhinid Species, the Lemon Shark,Negaprion brevirostris

Aerial survey provides an important tool to assess the abundance of both terrestrial and marine vertebrates. To date, limited work has tested the effectiveness of this technique to estimate the abundance of smaller shark species. In Bimini, Bahamas, the lemon shark (Negaprion brevirostris) shows high site fidelity to a shallow sandy lagoon, providing an ideal test species to determine the effectiveness of localised aerial survey techniques for a Carcharhinid species in shallow subtropical waters. Between September 2007 and September 2008, visual surveys were conducted from light aircraft following defined transects ranging in length between 8.8 and 4.4 km. Count results were corrected for “availability”, “perception”, and “survey intensity” to provide unbiased abundance estimates. The abundance of lemon sharks was greatest in the central area of the lagoon during high tide, with a change in abundance distribution to the east and western regions of the lagoon with low tide. Mean abundance of sharks was estimated at 49 (±8.6) individuals, and monthly abundance was significantly positively correlated with mean water temperature. The successful implementation of the aerial survey technique highlighted the potential of further employment for shark abundance assessments in shallow coastal marine environments.

Effects of species biology on the historical demography of sharks and their implications for likely consequences of contemporary climate change

Climate variation is an important factor shaping the demographic histories of many marine species, though impacts likely differ depending on species life history, habitat preferences and ecology. Investigating how species responded to historic climate fluctuations may provide critical insights into a species’ response to current climate change. Despite their ecological diversity, shark species share many similar life history characteristics and may be especially vulnerable to anthropogenic and climate impacts. We compared patterns of genetic variability, mismatch distributions and demographic reconstructions from coalescence approaches among temperate and tropical shark species with differing ecological characteristics, to investigate the effect of the past glaciation cycles on population abundance. Genetic diversity at two mitochondrial DNA regions (ND2 and control region) was assayed in four North Pacific species, Pacific spiny dogfish, Pacific sleeper sharks, salmon shark, and bluntnose sixgill shark. In addition, control region sequences acquired from GenBank for five shark species [tope shark (California/Australia), white shark (California), blacktip shark (eastern and western Gulf of Mexico), lemon shark (Bahamas), and whale shark] were analyzed. General patterns in genetic diversity, mismatch analyses and Bayesian skyline plots supported our hypothesis that species biology affected the impact of climate variation on demographic history. Consequently, our results suggest that effects of contemporary climate change on sharks may be to some degree predictable from species biology, distribution, habitat and the impact of past climate events.

Social learning in juvenile lemon sharks, Negaprion brevirostris

Social learning is taxonomically widespread and can provide distinct behavioural advantages, such as in finding food or avoiding predators more efficiently. Although extensively studied in bony fishes, no such empirical evidence exists for cartilaginous fishes. Our aim in this study was to experimentally investigate the social learning capabilities of juvenile lemon sharks, Negaprion brevirostris. We designed a novel food task, where sharks were required to enter a start zone and subsequently make physical contact with a target in order to receive a food reward. Naive sharks were then able to interact with and observe (a) pre-trained sharks, that is, 'demonstrators', or (b) sharks with no previous experience, that is, 'sham demonstrators'. On completion, observer sharks were then isolated and tested individually in a similar task. During the exposure phase observers paired with 'demonstrator' sharks performed a greater number of task-related behaviours and made significantly more transitions from the start zone to the target, than observers paired with 'sham demonstrators'. When tested in isolation, observers previously paired with 'demonstrator' sharks completed a greater number of trials and made contact with the target significantly more often than observers previously paired with 'sham demonstrators'. Such experience also tended to result in faster overall task performance. These results indicate that juvenile lemon sharks, like numerous other animals, are capable of using socially derived information to learn about novel features in their environment. The results likely have important implications for behavioural processes, ecotourism and fisheries.

Reef sharks and inshore habitats: patterns of occurrence and implications for vulnerability

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 460:115-125 (2012) - DOI: https://doi.org/10.3354/meps09722 Reef sharks and inshore habitats: patterns of occurrence and implications for vulnerability Andrew Chin1,*, Andrew Tobin1, Colin Simpfendorfer1, Michelle Heupel1,2 1Fishing and Fisheries Research Centre, School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia 2Australian Institute of Marine Science, Townsville, Queensland 4810, Australia *Email: andrew.chin@jcu.edu.au ABSTRACT: Reef sharks play important roles in tropical reef environments, but population declines have occurred in various locations including the Great Barrier Reef (GBR). While many reef shark studies focus on coral reefs, some reef sharks have been found across a range of inshore and coastal habitats. This study analyses fisheries observer data across large spatial scales (19314 km2) to investigate the occurrence of reef sharks amongst a mosaic of inshore habitats in the GBR lagoon. Six reef shark species were recorded, but comprised a relatively small proportion (1.8% by number) of the elasmobranch catch. The blacktip reef shark dominated the catch of reef sharks (60.2% by number), with lemon sharks, zebra sharks, grey carpet sharks, whitetip reef sharks and grey reef sharks less frequently encountered. Reef sharks occur in several habitat types, and logistic regression models suggest that they are most likely to occur in reef habitats and shallow shore habitats. The presence of a reef within 2 km increased the encounter probability in all habitat types. While the use of these different habitats by reef sharks is not well understood, these habitat use patterns affect the exposure of these species to risks, including some risk factors not considered previously, and could also lead to cumulative impacts. These habitats may also perform important ecological functions in sustaining reef shark populations. Habitat use patterns should be considered in risk assessments and management and have important implications for method selection and survey design in field studies of reef sharks and other mobile reef species. KEY WORDS: Habitat use · Vulnerability · Cumulative impact · Reef shark · Great Barrier Reef · Coastal habitat Full text in pdf format Supplementary material PreviousNextCite this article as: Chin A, Tobin A, Simpfendorfer C, Heupel M (2012) Reef sharks and inshore habitats: patterns of occurrence and implications for vulnerability. Mar Ecol Prog Ser 460:115-125. https://doi.org/10.3354/meps09722 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 460. Online publication date: July 24, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Assessment of the aquatic biodiversity of a threatened coastal lagoon at Bimini, Bahamas

Coastal biodiversity is threatened worldwide by both direct and indirect anthropogenic activities. To more effectively manage and protect coastal biodiversity, accurate assessments of genetic, species, and ecosystem level diversity are required. We present the results from an assessment of the aquatic species diversity of a small (3 km2), shallow, mangrove-fringed Bahamian lagoon (the North Sound) subject to ongoing anthropogenic development. The assessment was conducted through a collation of field observations and data in published literature. We found that eight angiosperm species, 30 macroalgal species, and 370 animal species (including 95 fishes, 69 arthropods, 56 birds, and 45 mollusks) were documented within the lagoon. At least 11 of these species are of conservation concern, such as the critically endangered smalltooth sawfish (Pristis pectinata) and hawksbill turtle (Eretmochelys imbricata). Comparisons of community similarity indicated that the North Sound has a relatively distinct fauna and flora, but available data suggest that the species found there are most similar to those found in nearby habitats in Cuba. The lagoon forms a key nursery habitat for many species, including lemon sharks (Negaprion brevirostris), Caribbean spiny lobsters (Panulirus argus), and queen conch (Strombas gigas). Recently, the lagoon was included as part of a new marine protected area (MPA), but much of the habitat has already experienced considerable anthropogenic disturbance and the MPA boundaries have yet to be established. We have therefore analyzed the lagoon biodiversity and expect the data presented here to serve as a baseline for future comparisons.