Chironomidae (Diptera) community succession in streams across a 200 year gradient in Glacier Bay National Park, Alaska, USA

In May 1997, 15 streams of contrasting stages of watershed development following glacial recession were investigated in Glacier Bay National Park, southeast Alaska, to examine chironomid community successional patterns in relation to physicochemical variables. A total of 54 taxa in five sub-families were identified; Diamesinae dominated in younger streams and Orthocladiinae in older streams. Chironominae and Tanypodinae were typically collected only in older streams. Canonical Correspondence Analysis with species and habitat data identified four distinct stream groupings (streams<50 years with lake influence; 50–100 years; 100–150 years and>150 years) based upon their chironomid community composition. CBOM, stream age and presence/absence of lakes in upper reaches of streams were the most significant habitat variables influencing communities. Total abundance decreased with stream age, whereas dominance, diversity and taxon richness were similar across the stream. Clear successional patterns were evident for several taxa. Diamesa spp. and Cricotopus tremulus dominated younger streams<100 years but were markedly less abundant in older streams. Paratrichocladius sp. and Eukiefferiella rectangularis were cosmopolitan, being found in most streams. Changes in chironomid communities over time exhibited similarities to chironomid succession found spatially along river continuums.