RESPONSE OF ZOOPLANKTON TO UNUSUAL INCREASE IN TEMPERATURE AND SEA ICE MELTING IN COASTAL ANTARCTICA DURING AUSTRAL SUMMER

Zooplankton play a critical role in energy transfer across the Antarctic food web, where copepods are known to constitute the primary food supply for upper trophic level species, particularly at higher latitudes. Zooplankton samples were collected at five depth intervals, covering the area between the surface and 1000 m, by using a standard multiplankton sampler (mouth area: 0.25m²; mesh size: 200 µm) in the coastal Antarctica during January and February 2017. The sea surface temperature was slightly warmer than expected in the neritic zone, resulting in mixed layer depth was shallower in the neritic zone than in the ice-free domain of coastal Antarctica. Freshening of the surface water prevented both phytoplankton and zooplankton biomass in the seasonal ice zone, resulting in high zooplankton diversity in the subsurface layer. The high zooplankton biovolume in the neritic zone and ice fee zone was likely due to the presence of higher Chl-a concentrations than in the seasonal ice zone. Calanoids and cyclopoids composed the majority of the overall zooplankton biovolume, accounting for more than 81% of the total zooplankton count. Calanus simillimus and Calanus australis are important in the oceanic region, where Stephos longipes is an indicator species in the shelf region associated with floating sea ice. We assumed that the combination of provincial features, such as sea surface temperature, food availability, sea ice cover and freshening, would likely have the greatest impact on zooplankton abundance and species diversity in the coastal waters of eastern Antarctica.

Primary Presenter: Venkataramana Vankara, National Centre for Polar and Ocean Research (venkataramana.987@gmail.com)

Authors:

Venkataramana Vankara, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Head land Sada, Vasco-da-Gama, Goa 403 804, India  (venkataramana.987@gmail.com)

R.K Mishra, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Head land Sada, Vasco-da-Gama, Goa 403 804, India  (rajanimishra@ncpor.res.in)

Melena A Soares, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Head land Sada, Vasco-da-Gama, Goa 403 804, India  (melenaasoares@ncpor.res.in)

Sabu Prabhakaran, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Head land Sada, Vasco-da-Gama, Goa 403 804, India  (sabuprabakar@ncpor.res.in)

Amit Sarkar, Kuwait Institute for Scientific Research, Safat – 13109, Kuwait.  (amits@gmail.com)

Rahul Mohan, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Head land Sada, Vasco-da-Gama, Goa 403 804, India.  (rahulmohan@ncpor.res.in)