8172

• 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

species. Distances' between sites were weighted rare and common s
pecies equally
computed as the percent
disagreement, i.e.,
%D= number of discordant
airs/
b .
Analysis of presence/absence data was
p
num
er of determined to be the preferred approach for
species. The cluster analysis tree was
constructed using Ward's method
Th obtaining fish faunal regions because it
.
e
utility of other clustering methods was also provided a coarser scale view of fish faunal
regions (Hawkes et al., 1986).
investigated, including single linkage,
complete linkage, unweighted pair-group For relative abundance data, cluster analysis
method using arithmetic averages
(UPGMA); and -weighted pak-group method - was performed on Euclidean distances
--between sit
-
i
'

using weighted averages (WPGMA). In es
us
ng Ward
s method. The
relative abundance data provided a fine

general, Ward's method consistently
provided mor
i r
scale view of site similarity because it
e
nterpretable trees than did
the other clustering algorithms
Oth grouped sites based on their most abundant
.
er
distance metrics evaluated, but not species of fish. As a result, relative
abundance data had less utility in defining
considered further for presence/absence
data, included Euclidean distance, squared fish faunal regions than did
presen Wabsence data
Whil

Euclidean distance, and one minus the ,
e relative
abundance data had less utility in defining
Pearson correlation coefficient. Similarity fish faunal regions, it should have greater
among upper Rio Grande drainage sites was utility for development of an IBI because it
also assessed using presence/absence for 59 can distinguish sites that are dominated by
benthic macromvertebrate taxa (generally an undesirable species such as white sucker`
family or subfamily). Cluster analysis for from sites with a more desirable array of
benthic macroinvertebrate taxa was species.
performed using Ward's method (Ward,
1963). on percent disagreement distances
between sites. Associations of Benthic Maeroinvertebrate
Taxa and Ch&vnomid Species
Site Similarity Based on FUh Species (fth
Faunal Regions)
One of the objectives of the present study
was to define species or taxonomic
associations. Herein, the term association is
Fish-faunal regions in the upper Rio Grande taken to mean a group of taxa that tend to
drainage were elucidated using cluster be found together at the same site(s).
analysis on presence/absence data and Cluster analysis on presence/absence data
cluster analysis on relative abundance data. was used to define associations, or
For presence/absence data, cluster analysis assemblages, of chironomid species and of
was performed on percent disagreement benthic macroinvertebrate taxa. The cluster
distances between sites using Ward's analyses were conducted on percent
method. This analysis grouped sites based
on their fish species diversity and it
7 In this report, "distance" refers to a statistical difference; it should not be interpreted as a
physical separation in the geographic sense.
` Where it exists as an introduced taxon and it has a repressive effect on other species.
23
r,