Summary of Abstract Submission

Abstract Submission No. IO50-09-0008PresentationPoster


Lara S. Garcia-Corral*1, Lorena Vigoya1, Carlos M. Duarte2, Susana Agusti2

1 University of Western Australia, Australia
2 King Abdullah University of Science and Technology , Saudi Arabia


Plankton communities play a key role in the biochemical cycles on marine ecosystems. Trough their metabolic processes, they control part of the gas exchange of CO2-O2 between the surface ocean and the atmosphere. Measurements of plankton metabolic rates in Indian Ocean are however still very limited. In this study we experimentally assessed the metabolic rates of plankton communities at the surface waters along the coastal line of the Eastern basin (Western Australian coast) and across the subtropical gyre. We quantified the gross primary production (GPP), the community respiration (CR) and the balance between both processes, the net community production (NCP=GPP-CR). We found consistent differences between coastal communities, and the open ocean waters. Coastal waters were net autotrophic systems, acting as a sinks of CO2, whereas the open ocean areas of the subtropical gyre showed a balanced net metabolism (NCP=0). The net metabolism of the coastal area was influenced by the distribution of the warm and nutrient rich waters of the Leeuwin current and by nutrients inputs from land. The seasonal variation of the metabolic rates was also evaluated in a coastal area closed to the city of Perth, during an annual cycle. Net autotrophic metabolism (NCP>0) was observed during the austral winter contrasting with net heterotrophic (NCP<0) during the summer. NCP decreased with seawater temperature increase, but was positively related to chlorophyll a concentrations and GPP increase, indicating the dominance of phytoplankton processes in determining the metabolic balance.