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Spring bloom development of microbenthic algae and associated invertebrates in two reaches of a small lowland stream with contrasting sediment stability
Author(s) -
IVERSEN TORBEN MOTH,
THORUP JENS,
KJELDSEN KARINA,
THYSSEN NIELS
Publication year - 1991
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1991.tb01728.x
Subject(s) - biomass (ecology) , invertebrate , sediment , ecology , biology , algae , fauna , algal bloom , environmental science , phytoplankton , nutrient , paleontology
SUMMARY.1 The microbenthic algal biomass and the invertebrate fauna were quantified during an algal spring bloom in two reaches of a small Danish lowland stream which, although similar with regard to stream velocity, water chemistry and irradiance, differed with regard to substrata and sediment stability. Due to channelization, one reach (Ellerup I) had low variation in depth, unstable sand midstream and mud along the banks; the other reach (Ellerup II) had more variable depth and more different and stable substrata. 2 At Ellerup I, maximum mean algal biomass was 74 ± 28 mg chl m −2 . Algal biomass primarily developed in muddy areas near the banks, whereas midstream algal biomass remained low. 3 At Ellerup II, maximum mean algal biomass was 161 ± 41 mg chl m −2 on fine‐grained sediments and 64 ± 21 mg chl m −2 on stones. Algal biomasses near the banks and midstream were similar, but seasonal development on the two main substrata was significantly different, suggesting that algal development on the two substrata was regulated by different factors. 4 At Ellerup I, the invertebrate fauna was dominated by Oligochaeta and invertebrate density and diversity were generally higher near the banks than midstream. Such differences did not occur at Ellerup II, where total invertebrate density was significantly higher than at Ellerup I and the fauna was dominated by Orthocladiinae, Simuliidae and Baetis sp. 5 It was concluded that stream channelization and maintenance, through their effects on sediment variation and stability, profoundly affect algal biomass distribution and development and invertebrate distribution, density and community structure.