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

Grande sucker ("Cat ple") is at the upper
right of the assemblage near the end of the
environmental axis for potassium. The
occurrence of Rio Grande sucker near the
end of the potassium axis is due to the
species being in high relative abundance in
the lower Jemez River downstream from
Soda Dam. White suckers have been
introduced into some waters in the upper
Rio Grande-drainage (Sublette et al -,I 90);
but, they were not found at the sites
sampled in the Jemez River drainage.
Because the lower Jemez River sites were
outliers with respect to potassium, DCCA
separated the sucker species widely.
A number of authors have suggested that the
number of fish species increases as
elevation decreases (e.g., Sheldon, 1968;
Whiteside and McNatt, 1972; Cashner and
Brown, 1977). Given that elevation
appeared to be such an important
environmental variable for distinguishing
sites in the upper Rio Grande drainage of
New Mexico, a linear regression (Draper
and Smith, 1981) was carried out to
investigate the relationship between number
of fish species present and elevation. The
linear regression of number of fish species
on elevation for 28 sites in the upper Rio
Grande drainage is shown in Figure 19.
The regression indicated that within the
upper Rio Grande drainage, on average, an
additional fish species was added with each
drop of 1000 feet in elevation.
Chironomids
Data for chironomids have not yet been
analyzed by CCA and. DCCA. However,
the relationship between number of species
and elevation was investigated (Figure 20).
Linear regression of number of chironomid
species on elevation demonstrated no
significant relationship between number of
species and elevation.
Benthic Macroinvertebrates
A positive relationship between the number
of benthic macroinvertebrate taxa versus
elevation was evident based on collections
at 30 locations in the upper Rio Grande
--watershed, - As- the elevation increased, the
number of taxa increased (Figure 21). This
general relationship has been observed in
high mountain streams where upstream
fishless sections are present; fishless
sections contain more an and higher
standing crops (Jacobi, unpublished data).
This relationship is in contrast to the inverse
relationship between ntmzber of fish species
and elevation (Figure 19). The relationship
between number of fish species and number
of benthic macroinvertebrate taxa is further
evident in Figure 22A. As the number of
benthic macroinvertebrate taxa increased,
the number of fish species decreased.
Presently there is no linear relationship
between the number of chironomid species
and the number of benthic
macromvertebrate taxa at a site (Figure
22B). In this preliminary examination,
chironomid larvae were grouped as a subset
of the benthic macroinvertebrate collection;
no attempt was made to associate pupal
exuviae with the larval stages. A
relationship between number of benthic
macroinvertebrate taxa and the number of,
chironomid species may become apparent as
more samples are processed and additional
data are available.
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