| Summary: | This thesis has already been submitted to Graduate Program Services in hard copy and approved, however I was advised that I could upload it for electronic distribution as well. Climate change can affect northern aquatic systems causing changes in the composition of resident species through either evolutionary or ecological processes. Rock pools near Churchill, Manitoba, Canada provide an ideal study system for studying the effect of environmental change in a metacommunity context, since salinity of the pools has increased significantly over the past quarter century, and dispersal between habitats is important in this landscape. I used a field experiment to study how zooplankton communities respond to increased salinity with two levels of dispersal limitation and three seasonal levels. I found that experimental zooplankton communities shifted from freshwater to more saline communities after a time lag of three weeks, and that highly connected pools became more similar to saline control communities faster than isolated pools. Moreover, freshwater communities manipulated later in the season changed faster to saline communities. This study highlights the metacommunity concept as a useful tool for studying environmental change.
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