Defining the potential ecological roles of three benthic-foraging sea turtle species (Caretta caretta, Chelonia mydas and Eretmochelys imbricata) along the eastern seaboard of South Africa

Student: Ryan Rambaran
Supervisors: Dr Ronel Nel, Dr Toufiek Samaai, Dr Steve Kirkman
Collaborating Institutions: Nelson Mandela University Coastal and Marine Research Unit, Department of Environmental Affairs: Oceans and Coasts
Email contact: Ronel Nel

Turtle sex ratios

Sea turtles were once considered as key species, driving ecosystem processes and energy flows. However, the past decline in sea turtle abundance and subsequent loss of their ecological roles has resulted in reduced ecosystem functionality through drastic food web shifts and trophic cascades. Therefore defining the past and present ecological roles of sea turtles is identified as one of the global research priorities for sea turtle management and conservation.

While South African sea turtles are relatively well-protected through the combination of a successful, long-term turtle conservation program established in 1963 and a series of coastal marine protected areas, the ecological roles of these turtles have never been investigated. This study aims to evaluate the ecological roles of three species that display high site fidelity to nesting and foraging regions, as well as form aggregations in the neritic environment along the eastern seaboard of South Africa. These species include loggerheads (Caretta caretta), green turtles (Chelonia mydas), and hawksbills (Eretmochelys imbricata).

A multi-technique approach that incorporates the use of satellite telemetry, stable isotope analysis, dietary analyses and direct in situ behavioural observations will be used to examine key ecological features of these species such as habitat use and movements, trophic position, diet and in-water behaviour and interactions. This is a novel study for sea turtle research in South Africa and will, for the first time, specifically highlight ecological traits such as diet, habitat use and trophic interactions. The results obtained from this study will be used to help add to and further pre-existing knowledge, strengthen the on-going conservation efforts and provide a framework for future studies in the region.

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