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Last modified
7/14/2009 5:02:33 PM
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UCREFRP
UCREFRP Catalog Number
8172
Author
Jacobi, G. Z., J. E. Sublette, S. J. Herrmann, D. E. Cowley and M. D. Hatch.
Title
Final Report
USFW Year
1998.
USFW - Doc Type
Investigations of an Index of Biotic Integrity in New Mexico.
Copyright Material
NO
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macroinvertebrate _ taxa increases than the nature of the thin film habitat, thus <br />significantly as elevation increases. <br />accounting for their widespread occurrence. <br />The linear relationships between the number <br />of fish species and elevation and the number <br />of fish species and distance from the <br />headwaters (Figures 19, 28) were not <br />replicated by chironomid distributions <br />(Figure 20) in the Upper Rio Grande <br />drainage. For ._several -reasons, -when <br />additional lower elevation stations are <br />incorporated into the study, a stronger <br />relationship between chironomid <br />distribution and elevation is expected, since <br />studies in the literature clearly indicate a <br />positive relationship between the sequence <br />headwater to mid-stream to lower stream. <br />In New Mexico, a warm-water fish fauna <br />dominated by cyprinid, clupeid, ictalurid, <br />and centrtrchid species occurs below about <br />5500' elevation. In this region, we expect <br />to encounter a chironomid fanny dominated <br />by Chironominae with the Orthocladiinae <br />being of lesser importance. <br />One of the interesting aspects of this study <br />is the elucidation of a "widespread species" <br />group as shown in cluster 1 of Figure 12. <br />These. generalists species (euryecious) <br />tolerate a wide range of environmental <br />conditions. In clean water situations they <br />occur along with numerous other species, <br />but as water quality declines, or other <br />stressors occur, they become the survivors. <br />Large numbers of euryecious species <br />coupled with low species diversity are <br />expected to be one of the best measures of <br />habitat degradation. Many of the <br />widespread chironomid species of Figure 12 <br />are madricolous, that is, living in thin films <br />of water on rubble, gravel, bedrock, plant <br />surfaces or at the margins of streams or in <br />splash zones of riffle or cascades. The <br />substratum seems to be of less importance <br />Proposed Approach for IBI <br />Development <br />The ultimate purpose of the NMGF <br />Frsli/Macrobenthic project is to . develop <br />ffiIS• The fnst stage to fulfill that objective <br />will be to identify how the IBIS are to be <br />used and to what scale they are to be <br />applied. It must be determined if an IBI is <br />to have general utility, utility for sport fish <br />management, for genetic management of <br />stocks, or some outer purpose. It may be <br />difficult to develop an IBI to meet sport fish <br />and genetic objectives simultaneously. The <br />scope, or landscape scale to which the IBIs <br />are to be applied must be determined. Are <br />the IBIS intended for site classification <br />(acceptable versus unacceptable) or site <br />monitoring? Are they to be applied to <br />single sites, individual streams, a drainage, <br />or some larger region? <br />Karr (1993) provided a number of <br />observations relevant to the task at hand. <br />He noted that no single biological or <br />chemical attribute is sufficient to evaluate <br />ecological condition and complexity and that <br />a multivariate approach is mandatory. <br />Biotic indices are attractive because water <br />quality Parameters typically have high <br />variability and habitat assessment scores are <br />less consistent than biotic integrity analyses. <br />Thus, evaluating biotic integrity provides a <br />balance to conventional approaches <br />(chemical and physical evaluations) because <br />it allows the investigator to focus on the <br />resource rather than on a surrogate <br />variable(s). Karr (1993) noted two major <br />weaknesses with most past approaches: (1) <br />many projects have had a narrow conception <br />43
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