Macroinvertebrates and Excessive Fine Sediment Conditions in Oregon Coastal Streams

Abstract

The Pacific Coastal ecoregion contains large tracts of economically important forestlands that also serve as critical stream habitat for endangered Salmonids. Excessive fine sediment deposition in streams of this region is a major environmental concern in the region but difficult to measure directly. The use of stream invertebrates to monitor fine sediment conditions in streams requires careful consideration of several important factors that complicate their use as bioindicators including high spatial and temporal variability and covariance with other environmental variables.To evaluate the use of stream invertebrates as bioindicators of excessive fine sediment, three hypotheses were tested. The first hypothesis was that invertebrates would be related to broad-scale climate variables (Chapter 2). The second hypothesis was that functional aspects of the invertebrate community would serve as useful indicators of excessive fine sediment condition. (Chapter 3). The third hypothesis was that invertebrates in streams with naturally high levels of sediment would be tolerant to fine sediment (<2 mm, Chapter 4). Hypotheses were tested using a temporal data set at two streams in western Oregon, spatial data from 214 sites across the Oregon Coast Range, and in-situ experiment conducted in streams with erosive or resistant geologies.In the temporal study, both invertebrate density and functional traits were iii Acknowledgements

Assessment of multi-stressors on compositional turnover of diatom, invertebrate and fish assemblages along an urban gradient in Pacific Northwest streams (USA)

“…All the assemblages had some taxa that responded positively to increases in substrate size (e.g., sensitive native taxa) and some taxa responded negatively. These responses illustrate the critical importance of substrate size as a medium for stream biota and of the potential impacts of small increases in fine sediment to organisms evolved for relatively clean, high-gradient PNW streams (Munn et al, 2009;Edwards, 2014;Hubler et al, 2016). Dissolved oxygen is another critical factor affecting all biology in streams and the three assemblages sampled in this study all showed assemblage level response as minimum daytime DO values increased above ca.…”

“…6). Substrate size is a well-known important determinant of invertebrate abundance and diversity, with highest diversity in the mid-size ranges (large gravels to cobbles) and the lowest abundance and diversity near the two extremes, sand and bedrock (Minshall, 1984;Munn et al, 2009;Relyea, et al, 2012;Edwards, 2014;Waite, 2014;Hubler et al, 2016).…”

Impacts of sediment derived from erosion of partially-constructed road on aquatic organisms in a tropical river: The Río San Juan, Nicaragua and Costa Rica

“…At least 16 EPT genera of macroinvertebrates occur in this region (Supporting Information S3 Table). As these taxa are sensitive to suspended sediment increase and fine sediment deposition (nine of them highly sensitive), they are often considered as indicators of good water quality, and sensitive to environmental changes [35,42] such as fine sediment deposition [43]. These taxa occurred with higher abundance on north-bank deltas than on south-bank deltas, although the differences were not significant.…”