COMMUNITY DYNAMICS AND METABOLISM OF BENTHIC ALGAE COLONIZING WOOD AND ROCK SUBSTRATA IN A FOREST STREAM

Autor: Sergi Sabater, James R. Sedell, Stan V. Gregory
Rok vydání: 1998
Předmět:
Zdroj: Journal of Phycology. 34:561-567
ISSN: 1529-8817
0022-3646
Popis: Colonization dynamics and metabolism of algal communities on wood (small pieces of Douglas fir) and artificial rock (tiles) substrata were investigated in an open reach in Mack Creek, Cascade Mountain Range, Oregon, for 42 days. Chlorophyll a concentration was not significantly different between the two algal communities (ANOVA, P= 0.119). Even though differences in cell densities were not significantly different between the two algal communities (ANOVA, P= 0.063), biovolume and diversity were greater in epixylic than in epilithic communities (ANOVA, P= 0.011 and 0.002, respectively). The same algal taxa occurred on both substrata, but some of them (e.g. Ceratoneis arcus Grun., Cymbella minuta Hilse ex Rabh., Zygnema sp.) were more numerous on wood, whereas a few others preferred tiles (e.g. Achnanthes lanceolata (Breb.) Grun.). Scanning electron microscopy revealed a much higher surface roughness on wood, which likely led to a patchy distribution of the algae and the development of stalked diatom species. However, adnate species adapted much better to the mainly flat surfaces of tiles. Net community primary productivity (NCPP) measured in 42-day-old substrata was moderate on tiles but negative on wood. Community respiration (CR) was significantly higher on wood than on tiles. Epixylic algal communities exhibited greater nitrogen demand than epilithic communities after ammonium addition. NCPP shifted to positive values on wood but did not increase on tiles. Despite metabolic differences, the variations between the two communities are more closely related to the physical characteristics of the substrata and the attachment abilities of the algal taxa.
Databáze: OpenAIRE
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