- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-05-0267 |
| Title of Abstract | Planktonic protist diversity and complexity along 110°E |
| Authors | Ruth Eriksen*, Claire Davies, Michaela Larsson, Madeline Anderson, Martina Doblin |
| Organisation | CSIRO |
| Address | CSIRO Oceans and Atmosphere, Castray Esplanade Hobart, Tasmania, Australia Pincode: 7000 Mobile: 431047648 E-mail: ruth.eriksen@csiro.au |
| Country | Australia |
| Presentation | Oral |
| Abstract | Marine planktonic protists have an integral role in the food-webs of the Indian Ocean, and their productivity regulates biogeochemistry, higher trophic levels, and fisheries in one of the world?s most populous ocean basins. Yet the region remains under-sampled and understudied with respect to protist species diversity, their nutritional strategies, and their influence on marine ecology.We analysed 20 Vertical Net Tow samples collected during the Australian contribution to IIOE2, along the 110°E line from 39.5 S to 11.5S, in May 2019 (austral autumn). Using light, fluorescence, and electron microscopy, we observed more than 250 taxa in the 10 - 1000 µm size range. Diatoms and dinoflagellates were the most species-rich taxonomic groups, followed by loricate (tintinnid) ciliates and coccolithophorids. Forams, appendicularians and radioalarians were sometimes abundant, but were rarely identified to species.Abundances increased towards the equator for diatoms, radiozoans and tintinnids, whilst dinoflagellate abundances were relatively constant from south to north (although taxa present along the transect changed for all taxonomic groups). Silicoflagellates and coccolithophorid abundances decreased from south to north. We compare protist distributions and abundances to standard oceanographic variables (temperature, salinity, nutrients, oxygen, chlorophyll) and assigned trophic type (photo/autotrophy, mixotrophy, osmo/heterotrophy, and variations within) to refine our understanding of environmental filtering of functional types and "who is where".This taxonomic work forms part of a larger effort to understand the drivers of the diverse nutritional strategies employed by microorganisms in this sector of the Indian Ocean, and the development of new indices to better understand the complex role of lower trophic levels in our changing oceans. |