Data from: Phytoplankton community interactions and environmental sensitivity in coastal and offshore habitats

Assessing the relative importance of environmental conditions and
community interactions is necessary for evaluating the sensitivity of
biological communities to anthropogenic change. Phytoplankton communities
have a central role in aquatic food webs and biogeochemical cycles,
therefore, consequences of differing community sensitivities may have
broad ecosystem effects. Using two long-term time series (28 and 20 years)
from the Baltic Sea, we evaluated coastal and offshore major phytoplankton
taxonomic group biovolume patterns over annual and monthly time-scales and
assessed their response to environmental drivers and biotic interactions.
Overall, coastal phytoplankton responded more strongly to environmental
anomalies than offshore phytoplankton, although the specific environmental
driver changed with time scale. A trend indicating a state shift in annual
biovolume anomalies occurred at both sites and the shift's timing at
the coastal site closely tracked other long-term Baltic Sea ecosystem
shifts. Cyanobacteria and the autotrophic ciliate Mesodinium rubrum were
more strongly related than other groups to this trend with opposing
relationships that were consistent across sites. On a monthly scale,
biotic interactions within communities were rare and did not overlap
between the coastal and offshore sites. Annual scales may be better able
to assess general patterns across habitat types in the Baltic Sea, but
monthly community dynamics may differ at relatively small spatial scales
and consequently respond differently to future change.