Patterns of colonization by macroinvertebrates were examined in two streams that differ in flow regime: a snowmelt system and a mesic groundwater system. Experiments were conducted during spring runoff, summer baseflow, and winter baseflow using artificial substrata. Colonization patterns reflected seasonal changes in benthic macroinvertebrate assemblages and life histories in each stream. The density and biomass of benthic organisms were approximately 3× greater in winter than in either spring or summer for both streams. Similarly, colonization was greater in winter than in spring or summer for both streams. In spring, colonization patterns were different between streams, with colonization being imperceptible in the snowmelt stream. Macroinvertebrate abundance fluctuated during the summer colonization experiment at both sites, resulting from a complex interplay among population emergence, recruitment, and/or movement. Assemblages in the snowmelt system primarily comprised mobile or ruderal taxa, such as Beatis tricaudatus and Chironomidae, whereas relatively sessile taxa, such as Glossoma nigrior, were predominant in the mesic groundwater system. Seasonal patterns of colonization differed among stream types primarily because of the profound interplay of flow regime and temperature on benthic community structure and organism life history.
Robinson, Christopher T.; Minshall, G. Wayne; and Van Every, Lynn
"Seasonal trends and colonization patterns of macroinvertebrate assemblages in two streams with contrasting flow regimes,"
Great Basin Naturalist: Vol. 53
, Article 1.
Available at: http://scholarsarchive.byu.edu/gbn/vol53/iss4/1