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Rincon-Diaz M.P.,University of Puerto Rico at San Juan | Van Dam R.P.,Chelonia Inc. | Sabat A.M.,University of Puerto Rico at San Juan
Journal of Herpetology | Year: 2011

Recent literature on foraging in Hawksbill Sea Turtles in the Caribbean region concludes that prey selectivity is a combination of preference for certain prey species and their local abundance. In this study, prey selectivity patterns were measured in five juvenile Hawksbill Sea Turtle (Eretmochelys imbricata) aggregations in the Culebra Archipelago, Puerto Rico, and the hypothesis that juvenile Hawksbill Sea Turtles exhibit selectivity for certain prey items independent of their environmental availability was tested. Hawksbill Sea Turtles showed positive selection for the corallimorph Ricordea florida, which was rare in all four study sites, and for the alga Lobophora variegata, that was abundant in one site. Turtles exhibited low preference for the sponge Chondrilla nucula, the most common prey item in both diet samples and the environment at all study sites. Low preference for this sponge corresponds to its high availability in the environment. Turtles also exhibited low preference for the sponge Cinacyrella sp. and the branching anemone Lebrunia danae. That juvenile hawksbills exhibited strong positive selectivity for rare items indicates that diet selection is not necessarily related to the abundance of the items in the environment. In addition, spatial variability in diet composition among Hawksbill Sea Turtles in the Culebra Archipelago indicates plasticity in their foraging habits. © 2011 Society for the Study of Amphibians and Reptiles.

Temple A.J.,Northumbria University | Tregenza N.,Chelonia Inc. | Amir O.A.,Ministry of Livestock and Fisheries | Jiddawi N.,University of Dar es Salaam | Berggren P.,Northumbria University
PLoS ONE | Year: 2016

Understanding temporal patterns in distribution, occurrence and behaviour is vital for the effective conservation of cetaceans. This study used cetacean click detectors (C-PODs) to investigate spatial and temporal variation in occurrence and foraging activity of the Indo- Pacific bottlenose (Tursiops aduncus) and Indian Ocean humpback (Sousa plumbea) dolphins resident in the Menai Bay Conservation Area (MBCA), Zanzibar, Tanzania. Occurrence was measured using detection positive minutes. Inter-click intervals were used to identify terminal buzz vocalisations, allowing for analysis of foraging activity. Data were analysed in relation to spatial (location) and temporal (monsoon season, diel phase and tidal phase) variables. Results showed significantly increased occurrence and foraging activity of dolphins in southern areas and during hours of darkness. Higher occurrence at night was not explained by diel variation in echolocation rate and so were considered representative of occurrence patterns. Both tidal phase and monsoon season influenced occurrence but results varied among sites, with no general patterns found. Foraging activity was greatest during hours of darkness, High water and Flood tidal phases. Comparisons of echolocation data among sites suggested differences in the broadband click spectra of MBCA dolphins, possibly indicative of species differences. These dolphin populations are threatened by unsustainable fisheries bycatch and tourism activities. The spatial and temporal patterns identified in this study have implications for future conservation and management actions with regards to these two threats. Further, the results indicate future potential for using passive acoustics to identify and monitor the occurrence of these two species in areas where they co-exist. © 2016 Temple et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Rincon-Diaz M.P.,University of Puerto Rico at San Juan | Van Dam R.P.,Chelonia Inc. | Sabat A.M.,University of Puerto Rico at San Juan
Chelonian Conservation and Biology | Year: 2011

Habitat features influence the distribution and abundance of marine animals and are used to identify critical areas to protect threatened marine species. In this study, we surveyed juvenile hawksbill turtles in 5 localities of the Culebra Archipelago, Puerto Rico; described the habitats using cover of benthic features; and related relative abundance of turtles among localities with food availability. We tested the hypothesis that variability in turtle abundance among study sites was related to spatial variability in the availability of diet items. Our results point out that spatial variability in turtle abundance is not related to food availability by itself; rather, the structural complexity and types of benthic structure played a more important role in explaining the turtles' local abundance. The importance of structural complexity is most likely related to sheltering. © 2011 Chelonian Research Foundation.

Cuevas E.,CINVESTAV | Abreu-Grobois F.A.,National Autonomous University of Mexico | Guzman-Hernandez V.,Area de Proteccion de Flora y Fauna Laguna de Terminos | Liceaga-Correa M.A.,CINVESTAV | van Dam R.P.,Chelonia Inc.
Endangered Species Research | Year: 2010

The Yucatan Peninsula harbors the largest nesting population of hawksbill turtle Eretmochelys imbricata in the Atlantic Basin. In Mexico, one of the most significant conservation problems for this species is the lack of knowledge on migratory patterns and the location of feeding grounds for post-nesting hawksbill females. The main goal of this study was to gather information on the hawksbill's migratory patterns and the location of their feeding grounds by tracking 3 post-nesting females from Campeche state, Mexico. We attached satellite transmitters and tracked the 3 turtles for 166, 446 and 510 d, respectively. The turtles remained within Mexican territorial waters, reaching separate foraging grounds off the coast of Campeche and in the Mexican Caribbean. No significant relationships were observed between turtles' migrating behavior and sea-surface temperature or geostrophic currents. Spatial analysis of the data recorded in this study has generated novel information on hawksbill turtle migratory patterns and feeding grounds, which will aid in decisionmaking for hawksbill turtle conservation in the Yucatan Peninsula. © Inter-Research 2008.

Patricio A.R.,University of Puerto Rico at San Juan | Velez-Zuazo X.,University of Puerto Rico at San Juan | Diez C.E.,Programa de Especies Protegidas | Van Dam R.,Chelonia Inc. | Sabat A.M.,University of Puerto Rico at San Juan
Marine Ecology Progress Series | Year: 2011

Inshore bays are key foraging grounds for immature green turtles Chelonia mydas. At these confined areas, capture-mark-recapture (CMR) programs generate valuable information that can be used to estimate vital rates, essential for the effective conservation of this endangered species. We compiled the CMR history profiles of 273 individuals from 13 yr of in-water surveys and employed the Cormack-Jolly-Seber model to estimate the survival probabilities of green turtles in 2 neritic bays at Culebra municipality, Puerto Rico. The CMR profiles were grouped into 2 size classes: juvenile and subadult. No adults were captured during the study. We found no significant differences in survival probability between the green turtles occupying each bay. We also assessed the survival probability of fibropapillomatosis (FP)-afflicted turtles versus FP-free turtles and found no significant differences among these groups. However, there was a significant difference in survival between the 2 size classes. Juveniles showed a higher survival probability (0.8322, 95% CI = 0.7875 to 0.8690) than subadults (0.5290, 95% CI = 0.3851 to 0.6682). The low survival of subadults is potentially biased by the permanent emigration of some of these individuals. Previous studies have shown that larger immatures leave shallow protected bays and occupy deeper open waters, sometimes associated with adults. Juveniles seem to be resident, and their survival rate can serve as a reference value for viability analysis. This is the first study on the survival of green turtles in the West Indies. © 2011 Inter-Research.

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