PHYTOPLANKTON DYNAMICS AFFECTED BY THE COASTAL UPWELLING EVENTS IN THE GULF OF FINLAND IN JULY-AUGUST 2006

Inga Lips (1) , Urmas Lips (1)

1 MSI - Marine Systems Institute

The response of phytoplankton to the observed coastal upwelling events in the central Gulf of Finland in July-August 2006 is described on the basis of chlorophyll a and phytoplankton community/biomass data. Due to the nutrient supply, advection, replacement/mixing of water masses and changes in water temperature not only single phytoplankton species were affected but the entire phytoplankton community was changed several times during a two month period. Faster response of nanoplanktonic species to the upwelled nutrients and high biomass of photosynthetic ciliate Myrionecta rubra was observed in the upwelling waters. The highest phytoplankton biomass was observed in the area of domed isopycnals on the background of developing downwelling three weeks after a relatively weak upwelling near the northern coast of the Gulf of Finland. An increase of biomass was observed also after the relaxation of a major upwelling event near the southern coast. MDS analysis matches this relatively high biomass community with the communities observed outside the area of upwelling influence two weeks earlier. We suggest that the observed biomass increase could be connected to the relaxation of upwelling and subsequent reversal movement of surface water masses together with the utilization of mostly regenerated but also stored nutrients.

Mots clés: Life Sciences

Inga Lips, Urmas Lips. PHYTOPLANKTON DYNAMICS AFFECTED BY THE COASTAL UPWELLING EVENTS IN THE GULF OF FINLAND IN JULY-AUGUST 2006. Journal of Plankton Research, 2010, 32 (9), pp.1269. ⟨10.1093/plankt/FBQ049⟩. ⟨hal-00589426⟩