Current Science

Arvind Singh ¹, R. Ramesh ², Anna Godhe ¹

Affiliations
1 Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Goteborg, SE
2 Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, IN

Abstract

Phytoplankton are key components in primary production and their growth is determined mainly by the availability of nitrogen-nutrients in the ocean. The paradigm that phytoplankton prefer ammonium over nitrate when both substrates are present has been tested using ¹⁵N-labelled tracers on cultured diatoms and dinoflagellates isolated from two widespread geographical areas - the Baltic Sea and the Arabian Sea. We found contrary to the paradigm that both taxa preferred nitrate over ammonium and a significant within-species variation in N assimilation. Carbon uptake rates in the same experiments were estimated using ¹³C-labelled tracer.

Keywords

Carbon, Dinoflagellate, Diatom Species, Nitrogen, Stable Isotopes.

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Arvind Singh ¹, Benjamin Kurten ², Riaan Cedras ³, Michelle Fernandes ⁴, Nimit Kumar ⁵

Affiliations
1 Physical Research Laboratory, Ahmedabad 380 009
2 King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, SA
3 University of the Western Cape, Biodiversity and Conservation Biology Department, ZA
4 CSIR National Institute of Oceanography, Dona Paula, Goa, IN
5 ESSO-Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, IN

Abstract

The first International Indian Ocean Expedition (IIOE; conducted in the early 1960s) was one of the greatest international, interdisciplinary oceanographic research efforts. It involved 46 research vessels (under 14 different flags) that carried out an unprecedented number of hydrographic surveys (and repeat surveys) of the entire Indian Ocean (IO) basin from 1960 to 1965. One key to the successful qualitative and quantitative assessment of plankton organisms across the IO was the unification of zooplankton collections using the IO Standard Net.

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