Effects of chironomid (Insecta: Diptera) tube-building activities of stream diatom communities.
Abstract: Chironomid retreats, constructed out of sand grains upon submerged wood
debris, increase the surface area available for diatom colonization.
The three dimensional substratum afforded by chironomid tubes supports
up to twelve times the diatom biavolume found upon adjacent, unmodified
substratum in a northern Michigan stream. Diatom enumeration within
scrapings from small defined areas on artificial substrata, combined
with examination of intact natural substrata through scanning electron
microscopy (SEM), reveals distinct, microdistribution patterns. The
larval retreats of two major taxa of tube-dwelling chironomid's (Micropsectra sp. and Pseudodiamesa cf. pertinax
Garrett) display significantly different diatom communities relative to
adjacent masonite substratum. Substratum without chironomid tubes is
primarily colonized by Achnanthes minutissima Kütz. and Cocconeis placentula Ehr., exhibiting the lowest species diversity of microhabitats examined. The diatom flora upon sand tubes of Micropsectra sp. is dominated by Opephora martyi
Herib., as is the flora of sand grains collected from the stream
sediment load. These two micro-habitats exhibit a high community
similarity (SIMI). The SIMI index also suggests that the flora of P. pertinax tubes is highly similar to that of sand grains. Diversity, however, is almost three times greater on P. pertinax tubes and SEM observations reveal that this microhabitat is characterized by a more spatially complex flora; Nitzschia and Navicula spp. dominate the upperstory, and O. martyi
is located on underlying sand grains. Results indicate that
tube-building chironomids in Carp Creek affect diatom microdistribution
by: (1) stabilizing sand grains and associated flora within their
retreats, (2) providing a ‘refugium’ for upperstory diatom taxa from
the mayfly grazer, Baetis vagans McDunnough (Insecta: Ephemeroptera), and (3) through local nutrient enrichment.
Pringle, C.M. 1985. Effects of chironomid (Insecta: Diptera) tube-building activities of stream diatom communities. Journal of Phycology 21: 185-194.
Back to Literature Page
| Pringle's Home Page | University of Georgia | Odum School of Ecology |