Summary of Abstract Submission

Abstract Submission No. IO50-09-0025PresentationOral

COLD-CORE EDDIES WITH SHALLOW MIXED LAYERS IMPROVE THE NUTRITIONAL VALUE OF ZOOPLANKTON FOR ROCK LOBSTER LARVAE

Anya Waite*1, Eric J. Raes2, Lynnath Beckley3, Peter A. Thompson4, Andrew Jeffs5

1 Alfred Wegener Institute for Polar and Marine Research, Germany
2 The University of Western Australia, Australia
3 Murdoch University, Australia
4 CSIRO, Australia
5 University of Auckland, New Zealand

ABSTRACT :

During their 9-11 month oceanic phase, Western Rock Lobster larvae live in a sparse prey field in the eastern Indian Ocean, as they assimilate crucial lipid stores fuelling their transit to shore. The mechanisms determining their nutritional status at sea are therefore fundamental to their (highly variable) recruitment success. Earlier work showed that cold-core mesoscale eddies hosted larvae in better condition than those in warm core eddies, as indicated by higher lipid stores and protein content. Here we show that cold-core eddies with shallow mixed layers have higher primary production rates and a more negative (lighter) 13C of zooplankton. We argue that a more negative 13C is likely to indicate higher zooplankton lipid stores, such that in this context, negative 13C represents a positive health index. The 15N signatures also suggest that zooplankton in the centre of cold-core eddies are feeding about 1 trophic level lower than their counterparts in warm-core eddies. Our conceptual model for this system presents cold-core eddies as functional chemostats fuelled by continuous nutrient injection, and warm-core eddies as functional batch cultures, with productivity declining after initial nutrient injection at the time of eddy formation.