Rebecca Scott

Tropical marine areas represent rich and diverse ecosystems, however the ecological integrity of these systems are of heightening global concern due to increasing anthropogenic impacts (e.g. Halpern et al., 2008). One of the most direct and pervasive threats facing marine ecosystems is the global decline of large marine vertebrates such as sea turtles, due to the important roles these large consumers play in maintaining the structure and functioning of their habitats (e.g. Jackson et al., 2001). World-wide concern over the status of marine populations and ecosystems (Jackson et al., 2001 Halpern et al. 2008) calls for an urgent need for innovative approaches to guide marine conservation efforts. The complex life cycles of sea turtles are strongly influenced by ocean currents and typically involve various ontogenetic habitat shifts, long distance migrations and transoceanic juvenile dispersal phases. Their life history attributes thus renders turtle populations vulnerable to a range of threats at different life stages and notoriously difficult to study/conserve. Whilst a greater understanding of their complex life cycles has been gained through recent developments in the fields of genetics, biotelemetry and oceanography, the juvenile dispersal phase remains poorly understood.

Dispersal is a key life history trait amongst marine species. However many organisms, like hatchling sea turtles, are too small to be tracked. Here, we plan to develop novel autonomous oceanic turtle drifters that can be tracked via satellite to collect vital data on surface ocean currents and the impacts of active directional swimming on the dispersion of small organisms reliant on ocean currents for their survival and long distance dispersal. These observations will be analysed in-silico with currents and particle drift simulated using ocean models and key biological data.

Sea turtles fulfil vital roles maintaining the functioning and resilience of marine ecosystems but efforts to conserve populations are hindered by the lack of knowledge surrounding (and protection afforded to) cryptic juvenile life stages. Ocean modeling approaches, used to predict the dispersion of hatchling sea turtles, are limited by the paucity of data on their swimming behaviours and the omission of upper oceanic processes (e.g. Stokes drift: motion caused by wind/swell) from models. I propose an innovative study to: 1) collect in-situ data on hatchling swimming behaviours using miniature tracking technology, 2) measure surface ocean currents and Stokes drift using novel surface oceanic drifters alongside conventional surface drifter buoys, 3) model hatchling dispersal using operational ocean model products for ocean currents and Stokes drift and 4) validate the accuracy of models using our in-situ oceanographic data. This will be conducted at several proposed Marine Protected Areas (MPAs) in Gabon: the last global stronghold for leatherback sea turtles. Gabon´s government has committed to a new MPA network to improve capacity for sustainable development. MPA plans include adult sea turtle habitats and oil rigs located offshore from turtle nesting beaches. However, oil rigs (which have become artificial reefs) are potential death traps for hatchlings and it is now vital to assess their impact on turtles. Our unique interdisciplinary team including key collaborators in Gabon presents an ideal opportunity to study marine dispersal from oil platforms/proposed MPAs and advise conservation policy to improve the resilience of local marine populations and ecosystems.