In Antarctica a primary source of nutrients to the nearshore comes from aquatic mammals and birds, such as penguins, that deposit marine-derived nutrients on the land, which subsequently runs off into the ocean. Changes in primary producer biomass or composition due to increased nutrient inputs from penguin colonies may impact the composition of trophic levels, and the functioning of the Antarctic aquatic ecosystem. Looking at the penguin density in relationship to the phytoplankton communities, and nutrient levels will help in understanding these important ecological dynamics. During the austral summer (December 2007), samples were collected from 8 different sites spanning from the South Shetland Islands to the northern continental tip of the Antarctica peninsula. The site locations contained penguin abundances ranging from 0 to 5,800 nesting pairs, and were sites commonly visited by tourist vessels. In related work, we have found that these higher penguin abundances lead to an enrichment of the water column nutrients and higher algal biomass. Several liters of water were collected from the nearshore zone, algae was settled and preserved in Lugol's solution. Species will be identified and enumerated until 300 individuals are counted; however, only preliminary counts of approximately 100 individuals are reported here. Jaccard's index was calculated to describe similarity in species composition among sites.

Results/Conclusions

From these counts, we found that sites with no or few penguins had algal compositions that were more similar to each other, while sites with higher penguin densities tended to have unique algal species compositions (p<0.05). Interestingly, the 2 sites with the highest penguin abundances were dominated by different species, gentoo (Pygoscelis papua) or chinstrap (P. antarcticus) penguins, while another site had a moderate-sized population of Adélie penguins (P. adeliae). It is possible that the different feeding strategies and behaviors of these penguins have contributed micronutrients to the environment that favor the growth of different algal taxa. GIS will be utilized to map the spatial distribution of the phytoplankton community in relation to penguin colonies in the Antarctic peninsula region.