Nuanced connections between ice phenology and summer phytoplankton blooms

Northern hemisphere lakes have experienced a decrease in the duration, spatial extent, and quality of lake ice over the past century. There have been recent advances in the understanding of how ice conditions can drive some summer processes, however much is unknown regarding how changes in ice conditions will affect the timing and severity of summer phytoplankton blooms. To investigate this knowledge gap, we examined a 20-year data set, consisting of ice phenology and coverage data and summer water quality information for Lake Erie. We found significant correlations between the duration of ice coverage and both chlorophyll concentration and phytoplankton community composition. Chlorophyll was negatively correlated with the duration of ice cover, and percent ice coverage in Lake Erie’s western basin. In the central basin, chlorophyll was negatively correlated with the date of ice-on. In both the central and western basin, chlorophyll was positively correlated with date of ice-off, ice duration, and percent ice coverage. Phytoplankton community composition was also related with ice phenology and we found that dinoflagellate biomass was negatively correlated with ice duration and percent ice coverage in the western basin. In the central basin, the average chlorophyte biomass and the yearly chlorophyte maxima were negatively correlated with the date of ice off. These connections may help to elucidate not only the role that winter conditions play in summer dynamics, but also how the loss of lake ice may shape the severity of phytoplankton blooms.

Primary Presenter: Claire Stevens, Trent University (clairestevens@trentu.ca)

Authors:

Marguerite Xenopoulos, Trent University  (mxenopoulos@trentu.ca)