Summary of Abstract Submission

Abstract Submission No. IO50-13-0011PresentationOral

PRELIMINARY RESULTS FROM A DEMONSTRATION SURVEY THE SOUTHERN INDIAN OCEAN

Reidar Toresen*1, Francois Dufois1, Michelle Fernandes1, Patsy Theresine1, Bernerd Fulanda1, Ainhoa Bernal Bajo1, Melody Puckridge1, Cedras, Riaan1, Espen Bag°ien1, Alexander Christian Beck1, Indah Lutfiyati1, Nasirin1, Aina Le Don Nomenisoa1, Andria Asri Utama1, Pazy Simili1, Kristine Nilsen Torkildson1

1 Institute of Marine Research, Norway

ABSTRACT :

Between 26 June and 17th July 2015, the R/V Dr Fridtjof Nansen crossed the Southern Indian Ocean sampling along the 20 degree south latitude. The vessel is owned by the Norwegian Agency for Development Cooperation (Norad) but carries out scientific assessments for the EAF-Nansen Project of the Food and Agriculture Organization on the United Nations (FAO). The survey was the first of two legs that constitute a demonstration survey in a crossing from Indonesia to South Africa. There were sixteen scientists from ten countries in the team. The aim of the survey was to study ecological features of the southern Indian Ocean, and thematic teams looked at oceanographic features of the southern Indian Ocean gyre, primary and secondary plankton production, concentrations and behavior of meso-pelagic fish and occurrence and concentration of plastic particles in the water. Preliminary results show that the southern Indian Ocean gyre is complex, consisting of a number of smaller eddies with specific oceanographic features. The biological production in the gyre is low but relatively higher away from the centre and at both sides. The density of meso-pelagic fish in the gyre is also low, but tends to follow the biological production. The fish feed on plankton in the upper 100 m layer of the water column during night, migrating down to the oxygen maximum layer at 400 ┐ 500 m depth during daytime. Plastic particles were observed in almost all water samples collected throughout the survey. The concentrations of plastic particles varied and were higher on the eastern side of the gyre than within the gyre.