CHARACTERIZING TEMPORAL AND SPATIAL ECOSYSTEM VARIABILITY WITH OBJECTIVELY DEFINED BIOMES IN A TWENTY-PLUS YEAR TIME SERIES FROM THE WEST ANTARCTIC PENINSULA
The marine environment of the West Antarctic Peninsula experiences high interannual variability as a result of its oceanographic setting. To better understand variations in the physico-chemical conditions that underpin ecological change along the WAP, we developed a biome classification scheme based on nutrient and hydrographic data collected by the Palmer Long-Term Ecological Research (PAL-LTER) project. Data from 20 PAL-LTER cruises were used to construct an emergent self-organizing map (ESOM); k-means clustering identified 8 topological features in the ESOM corresponding to 8 biomes. To evaluate the distribution of biomes in space and time we used the ESOM to classify kriging surfaces at standard depths for all cruises. This approach reproduced major ecological events over the last 20 years, including strong phytoplankton blooms in several years. By connecting these high-chlorophyll events with diagnostic nutrient and hydrographic signatures we could distinguish between two bloom types associated with distinct biomes. The more widely distributed of these biomes had a nutrient signature suggestive of a mixed phytoplankton bloom, and temperature-salinity values consistent with a high input of glacial meltwater. Through linear modeling we observed a link between the extent of this biome and spring and summer sea ice conditions, with November and January ice conditions together explaining 36 % of the variance in this biome. These results confirm that physico-chemical biomes provide a strategy for understanding variability in complex ecological systems.
Bowman, J. S., Scripps Institute of Oceanography, USA, email@example.com
Kavanaugh, M., Woods Hole Oceanographic Institution, USA, firstname.lastname@example.org
Doney, S., Woods Hole Oceanographic Institution, USA, email@example.com
Ducklow, H. W., Lamont-Doherty Earth Observatory, USA, firstname.lastname@example.org
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