HR: 1330h
AN: NB33T-08    [Abstracts]
TI: Natural and Anthropogenic Factors Affecting Benthic Macroinvertebrate Communities in Streams Across an Urban Gradient in the San Francisco Bay Area, California, USA
AU: * Cover, M R
EM: mcover@nature.berkeley.edu
AF: Department of Environmental Science, Policy and Management; University of California, Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720-3114 United States
AU: Taberski, K M
EM: KTaberski@waterboards.ca.gov
AF: San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street Suite 1400, Oakland, CA 94612 United States
AU: Moore, S M
EM: SMoore@waterboards.ca.gov
AF: San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street Suite 1400, Oakland, CA 94612 United States
AU: Resh, V H
EM: vresh@nature.berkeley.edu
AF: Department of Environmental Science, Policy and Management; University of California, Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720-3114 United States
AB: The development of biological criteria for streams requires an understanding of how both natural environmental factors and human disturbance affect biological communities. We used biological metrics, species traits, and multivariate ordinations to assess the relative importance of natural and anthropogenic factors on stream benthic macroinvertebrate communities in the San Francisco Bay Area, California. Upstream watershed land use was the dominant factor affecting macroinvertebrate assemblages. Urban sites exhibited uniformly low richness and functional diversity, and were dominated by four taxa: Chironomidae, Baetis sp., Simulium sp., and Oligochaeta. In contrast, the majority of sites draining rural residential land uses were compositionally similar to minimally disturbed conditions, while sites draining agricultural lands reflected an intermediate level of disturbance. Flow intermittency was the most important natural factor affecting the composition of benthic assemblages. Taxa richness was significantly lower in minimally disturbed intermittent streams (32) than perennial streams (46), as a result of the near absence of taxa with aquatic adult life stages and long life cycles, other than the hellgrammite Neohermes filicornis that survives for months in the moist streambed. Although flow intermittency is a critical factor influencing stream communities in mediterranean climates, urban land use has a much greater effect on benthic assemblages.
DE: 9810 New fields (not classifiable under other headings)
DE: 9902 NABS Student Award Applied Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly