ABSTRACT Lakes and ponds are abundant in the Arctic tundra. Global warming is altering these freshwater ecosystems, enriching the water column, increasing biomass of algae and plants, and having the potential to shift the composition, dominance, and timing of emergence and reproduction of zooplankton communities. Capitalizing on historic data collected in the 1970s, the goal of this study was to determine how zooplankton communities have responded to this environmental change over a 40‐year period. Environmental data and zooplankton assemblages from six Arctic tundra ponds near Utqiaġvik, Alaska (USA) were recorded weekly from mid‐June to mid‐August in 2010 to 2012 and compared to data collected from the same ponds in 1971 to 1973. The zooplankton community appeared to shift from one with high relative abundance of diaptomid copepods (from > 70% to 25%) over a 40‐year period. Changes in dominant species are likely attributable to warmer temperatures, increased food availability, as well as biotic interactions. Warmer spring temperatures were also associated with copepods reaching peak abundances earlier after overwintering. There were limited changes in species richness, although increased cover of vegetation expanding into the nearshore areas of the ponds likely led to increased abundance of plant‐associated zooplankton and may have played a role in limiting dispersal among ponds, resulting in greater dissimilarity among ponds through time. These changes in zooplankton abundance, timing of emergence, and spatial distribution may have important impacts on other components of the Arctic food web, including algae, as well as upper trophic levels that depend on zooplankton for food. Given that unprecedented warming is occurring and will likely continue into the future, these unique and abundant aquatic ecosystems must continue to be observed to predict, understand, and model future alterations, as these systems play critical ecological and biogeochemical roles in the Arctic ecosystem.
Lougheed et al. (Wed,) studied this question.