Distribution of fish, benthic invertebrate, and algal communities in relation to physical and
chemical conditions, Yakima River Basin, Washington, 1990
Water-Resources Investigations Report 96-4280
By Thomas F Cuffney, Michael R Meador, Stephen D Porter, and Martin E. Gurtz
Full Report (PDF, 102 pages, 8 Mb)
Abstract
Biological investigations were conducted in the Yakima River Basin,
Washington, in conjunction with a pilot study for the U.S. Geological
Survey's National Water-Quality Assessment Program. Ecological surveys
were conducted at 25 sites in 1990 to (1) assess water-quality conditions
based on fish, benthic invertebrate, and algal communities; (2) determine
the hydrologic, habitat, and chemical factors that affect the distributions
of these organisms; and (3) relate physical and chemical conditions to
water quality. Results of these investigations showed that land uses and
other associated human activities influenced the biological characteristics
of streams and rivers and overall water-quality conditions.
Fish communities of headwater streams in the Cascades and Eastern Cascades
ecoregions of the Yakima River Basin were primarily composed of salmonids
and sculpins, with cyprinids dominating in the rest of the basin. The most
common of the 33 fish taxa collected were speckled dace, rainbow trout, and
Paiute sculpin. The highest number of taxa (193) was found among the invertebrates. Insects, particularly sensitive forms such as mayflies, stoneflies,
and caddisflies (EPT--Ephemeroptera, Plecoptera, and Trichoptera fauna),
formed the majority of the invertebrate communities of the Cascades and
Eastern Cascades ecoregions. Diatoms dominated algal communities throughout
the basin; 134 algal taxa were found on submerged rocks, but other stream
microhabitats were not sampled as part of the study. Sensitive red algae and
diatoms were predominant in the Cascades and Eastern Cascades ecoregions,
whereas the abundance of eutrophic diatoms and green algae was large in the
Columbia Basin ecoregion of the Yakima River Basin.
Ordination of physical, chemical, and biological site characteristics indicated
that elevation was the dominant factor accounting for the distribution of biota
in the Yakima River Basin; agricultural intensity and stream size were of
secondary importance. Ordination identified three site groups and three community
types. Site groups consisted of (1) small streams of the Cascades and Eastern
Cascades ecoregions, (2) small streams of the Columbia Basin ecoregions, and
(3) large rivers of the Cascades and Columbia Basin ecoregions. The small streams
of the Columbia Basin could be further subdivided into two groups--one where
agricultural intensity was low and one where agricultural intensity was moderate
to high. Dividing the basin into these three groups removed much of the influence
of elevation and facilitated the analysis of land-use effects. Community types
identified by ordination were (1) high elevation, cold-water communities associated
with low agricultural intensity; (2) lower elevation, warm-water communities
associated with low agricultural intensity, and (3) lower elevation, warm-water
communities associated with moderate to high agricultural intensity.
Multimetric community condition indices indicated that sites in the Cascades
and Eastern Cascades site group were largely unimpaired. In contrast, all but
two sites in the Columbia Basin site group were impaired, some severely.
Agriculture (nutrients and pesticides) was the primary factor responsible
for this impairment, and all impaired sites were characterized by multiple
indicators of impairment. Three sites (Granger Drain, Moxee Drain, and Spring
Creek) had high levels of impairment. Sites in the large-river site group
were moderately to severely impaired downstream from the city of Yakima. High
levels of impairment at large-river sites corresponded with high levels of
pesticides in fish tissues and the occurrence of external anomalies.
The response exhibited by invertebrates and algae to a gradient of agricultural
intensity suggested a threshold response for sites in the Columbia Basin site
group. Community condition declined precipitously at agricultural intensities
above 50 (non-pesticide agricultural intensity index) and showed little response
to higher levels of agricultural intensity. This pattern of response suggests
that mitigation efforts conducted at sites with high agricultural intensity may
not produce meaningful improvement in invertebrate and algal community conditions.
In contrast, relatively modest mitigation efforts at sites where the level of
agricultural intensity is near to the impairment threshold will probably produce
large improvements in community conditions at relatively modest costs. Because
the form of the response is critical to effective water-quality management,
future cycles of the National Water-Quality Assessment Program should be
designed to determine the form of the response that biota exhibit to the major
water-quality gradients in a basin.
Citation:
Cuffney, T.F., Meador, M.R., Porter, S.D., and Gurtz, M.E., 1997, Distribution of fish, benthic invertegrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, Washington, 1990: U.S. Geological Survey Water-Resources Investigations Report 96-4280, 94 p.
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