Patterns in the Composition of Arctic Tundra Pond Microcrustacean Communities

Abstract

On the basis of intensive collections of Microcrustacea (Cladocera, Copepoda, Anostraca, and Notostraca) from 11 sites in the Canadian arctic archipelago, patterns of species richness, distribution, and community composition were evaluated. Microcrustacean communities of pond habitats in the high arctic of Canada are much less diverse than communities at more mesic, subarctic sites. There is both a marked decline in species richness and a dramatic change in the composition of pond communities with increasing latitude and decreasing summer temperatures. Ponds in the low arctic have 3–4 times as many species as those in the high arctic and are dominated by calanoid copepods, a group largely absent from the high arctic. Sites with similar climatic conditions in Alaska have microcrustacean communities with higher species richness, a phenomenon correlated partially with the presence of glacial refuges throughout the Pleistocene. The failure of certain zooplankton taxa, especially calanoids, to colonize areas in the Canadian arctic remote from refuges in the 7000 yr since deglaciation suggests that their dispersal rates are low. Reestablishment of complete zooplankton communities in glaciated terrain with severe environmental conditions apparently requires long periods, although initial colonization by a few pioneer species may be rapid.

Genetic Consequences of Passive Dispersal in Pond-Dwelling Copepods

“…Many of the zooplankton taxa that have colonized these habitats rely on passive dispersal and seem to have encountered difficulty expanding into the vast areas vacated by the continental ice masses (Segerstrale, 1957;Ricker, 1959;Holmquist, 1966;Dadswell, 1974;Carter et aI., 1980;Hebert and Hann, 1986). Biogeographic studies on zooplanktonic crustaceans have revealed that some species are absent in regions that seem similar physically and climatically to those that are occupied (Dadswell, 1974;Hebert and Hann, 1986). For example, a deep-water lacustrine fauna is restricted in eastern North America to basins that were formerly occupied by glacial lakes and brackish seas (Dadswell, 1974).…”

“…For example, a deep-water lacustrine fauna is restricted in eastern North America to basins that were formerly occupied by glacial lakes and brackish seas (Dadswell, 1974). Similarly, the copepods have been cited as slow dispersers, because few taxa are present in regions distant from those that were unglaciated (Hebert and Hann, 1986).…”

Trends in Ostracoda and Cladocera distribution and water chemistry in subarctic Canada: Churchill (Manitoba) lakes and ponds revisited

“…2. Abundance of species in the study lakes and ponds and published presence/absence data in waters from Hudson Bay Lowlands (HBL; Shelford and Twomey, 1941;Hebert and Hann, 1986;Havel et al, 1990aHavel et al, , 1990bBoileau et al, 1992;Hann, 1995;Jeffery et al, 2011;Abbate and Sagri, 2012) and waters in the Yukon boreal forest (Yukon; Swadling et al, 2000;Bunbury and Gajewski, 2005). …”

“…For reasons of comparison, we focused on Cladocera and Ostracoda as both groups were subject of previously published (partly molecular biology) studies in HBL (Shelford and Twomey, 1941;Hebert and Hann, 1986;Havel et al, 1990aHavel et al, , 1990bBoileau et al, 1992;Hann, 1995;Weider et al, 1999aWeider et al, , 1999bMarková et al, 2007;Ng et al, 2009;Xu et al, 2009;Weider et al, 2010;Jeffery et al, 2011). In addition, both microcrustacean groups have potential value for paleoenvironmental assessment studies and this study is intentionally necessary to interpret future analyses of faunal assemblages in the HBL.…”

“…They are known to respond sensitively to environmental change and show distinct biogeographical distribution patterns (Jeffery et al, 2011;Rautio et al, 2011;Curry et al, 2012;Viehberg and MesquitaJoanes, 2012). Previous biological studies on cladocerans and ostracods in our study area (Shelford and Twomey, 1941;Hebert and Hann, 1986;Havel et al, 1990aHavel et al, , 1990bBoileau et al, 1992;Hann, 1995;Ng et al, 2009;Weider et al, 2010;Jeffery et al, 2011;Abbate and Sagri, 2012) enabled us to use this baseline information as a reference to compare against our most recent limnological survey completed in 2006. Our study aims to provide answers to fundamental questions related to modifications in faunal community composition, range (migration/dispersal) and biodiversity that are forced upon aquatic biota by the observed rapid ecoclimatic and environmental changes in the North.…”