Spatial distribution and residency of green and loggerhead sea turtles using coastal reef habitats in southern Mozambique

Williams, Jessica L., Pierce, Simon J., Rohner, Chris A., Fuentes, Mariana M.P.B., and Hamann, Mark (2017) Spatial distribution and residency of green and loggerhead sea turtles using coastal reef habitats in southern Mozambique. Frontiers in Marine Science, 3.

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Abstract

Sea turtles spend the majority of their immature and adult lives in foraging grounds, yet few studies have examined their abundance and condition in these areas when compared to more accessible nesting beach habitats. Here, a 5-year dive log, photo-identification (photo-ID) and surface encounter datasets were used to investigate the abundance, individual movements and distribution of sea turtles along 40 km of coastal reefs in southern Mozambique. A generalized linear model (GLM) was constructed with turtle sightings as the response variable. Habitat type, year and day of the year, as well as underwater visibility, were significant predictors of turtle sightings. However, only 8% of the total variance was explained by the model, indicating that other variables have a significant influence on turtle movement and distribution. Photo-ID differentiated 22 individual green turtles Chelonia mydas and 42 loggerhead turtles Caretta caretta from 323 photo-ID encounters. A majority (64%) of the photos could be used to identify the individual. Although residency times of up to 1152 days were calculated for juvenile green turtles, a low overall resighting rate indicates that individual turtles either had large home ranges or were transient to the area. Surface encounter data revealed a preference for nearshore shallow waters and an increased abundance close to reef systems. Sea turtles' preferences for shallow, nearshore habitats are likely to increase the encounter risk with opportunistic and targeted artisanal fishers who catch sea turtles.

Item ID: 51573
Item Type: Article (Research - C1)
ISSN: 2296-7745
Keywords: marine turtle, citizen science, site fidelity, movement, photo-ID, Chelonia mydas, Caretta caretta
Additional Information:

This is the 6th publication in the series from the All Out Africa (AOA) Marine Research Unit.

Copyright © 2017 Williams, Pierce, Rohner, Fuentes and Hamann. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) [https://creativecommons.org/licenses/by/4.0/]. The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Date Deposited: 17 Nov 2017 01:21
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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