Multidisciplinary study of the Antarctic pelagic marine ecosystem

The last weeks of January 2019 were spent monitoring the surrounding marine environment north of the Antarctic Peninsula. On board the “Oncle Max” Polar Ship, we work in shifts of 12 hours in order to maximize the navigation and sampling time of this remote region. The water column has been sampled almost every day since the beginning of the work, to investigate the distribution of biomass and composition of phytoplankton communities, including the biogeochemically important coccolithophores.

The view of the deck from our phytoplankton laboratory, where the CTD-Rosette system is operated, with the Antarctic landscape in the background.

The view of the deck from our phytoplankton laboratory, where the CTD-Rosette system is operated, with the Antarctic landscape in the background.

In addition to the vertical profiles of temperature, salinity, oxygen and fluorescence of the seawater column obtained through CTD (Conductivity, Temperature, Density), we are also collecting water for the study of macronutrients, as well as underway measurements of pH and CO2 fluxes between the atmosphere and the surface of the ocean. In key regions, the MultiNet system is used to collect samples of marine zooplankton.

Sampling of zooplankton with the "MultiNet" system by Claus Inck and Vanessa Agostini (left and above), both FURG oceanographers. Sample of krill, by the hand of Camila Signori (Oceanographer, USP).

Sampling of zooplankton with the "MultiNet" system by Claus Inck and Vanessa Agostini (left and above), both FURG oceanographers. Sample of krill, by the hand of Camila Signori (Oceanographer, USP).

In addition to the physics, chemistry and phyto- and zooplankton teams, the INTERBIOTA team also has a group of oceanographers specialised in the study of whales and dolphins. Along with their long vigils under the cold at the bow of the ship to observe/quantify the different species that inhabit this highly productive region, our "whalers" (as we affectionately call them) also venture into the open sea. When the conditions of swell and visibility are favorable, the fearless team leaves the ship to observe these magnificent marine mammals more closely, to record their sounds, and to collect biopsies of the skin and fat for later performing studies of their genetics, taxonomy, stable isotopes and concentration of contaminants (see Seyboth et al., 2018).

Our team of "whale-watchers" in action for another boat outing. In the upper right corner (from left to right), oceanographers Renan Lima (FURG), Jonatas Prado (Instituto Baleia Franca), Manuela Bassoi (Federal University of Rio Grande do Norte) and Elisa Seyboth (University of Cape Town).

Our team of "whale-watchers" in action for another boat outing. In the upper right corner (from left to right), oceanographers Renan Lima (FURG), Jonatas Prado (Instituto Baleia Franca), Manuela Bassoi (Federal University of Rio Grande do Norte) and Elisa Seyboth (University of Cape Town).

One of the most recent GOAL findings reports to an increase in the abundance of cryptophytes (nanoflagellate phytoplankton) rather than diatoms (e.g. Mendes et al., 2018) over the last years. As diatoms are the preferred food for krill, which is in turn the main source of food for whales, their reduction to the benefit of cryptophytes has the potential to alter the entire pelagic marine trophic web in the Antarctic Peninsula. One of the aims of this expedition is precisely to investigate the relationship between the biomass of cryptophytes and the thaw-driven increase of water column stratification, for evaluating the persistence of these trends observed in previous expeditions. This is also the most interesting part of working together with GOAL, as they deal with the impact of climate change on the marine pelagic ecosystem as a whole, from primary producers to marine mammals. This interdisciplinary approach is crucial to developing a holistic perspective of the biogeochemical, ecological and oceanographic processes that are in force here, both spatially and over time.

Some Aspects of the methodology used by our "whalers": Joni and Elisa holding the cross-bow with which they sample skin and whale fat (above, left); Elisa holding a sample of whale fat (bottom right).

Some Aspects of the methodology used by our "whalers": Joni and Elisa holding the cross-bow with which they sample skin and whale fat (above, left); Elisa holding a sample of whale fat (bottom right).

Some images of Humpback whales and a fin whale swimming (left upper corner) in an icy sea. Pictures taken by Manuela Bassoi, in the framework of the Brazilian project Interbiota.

Some images of Humpback whales and a fin whale swimming (left upper corner) in an icy sea. Pictures taken by Manuela Bassoi, in the framework of the Brazilian project Interbiota.