8282

• UCREFRP Catalog Number: 8282
• Author: Osmundson, B. C., T. W. May and D. B. Osmundson
• Title: Selenium Concentrations in the Colorado Pikeminnow ‎(Ptychocheilus lucius)‎
• USFW Year: 1999
• USFW - Doc Type: Relationship with Flows in the Upper Colorado River
• Copyright Material: YES

Se Concentrations in Colorado River R lucius
483
Table 4. Selenium concentrations (µg/g dry weight) in muscle plugs taken from Colorado pikeminnows captured during 1994 and recaptured
during 1995 and 1996 at Walter Walker State Wildlife area (rkm 263.1)
I
P
A

PIT Tag
No. 1994

Collection
Date
Fish
Weight
(g)

Selenium
W/O 1995

Collection
Date
Fish
Weight
(g)

Selenium
(µg/g) 1996

Collection
Date
Fish
Weight
(g)

Selenium
(µg/g)
0666 May 24 2,048 4.4 May 4 3,545 4.1
013161 Jun 13 7,936 4.4 Jun 13 6,500 5.1
OE65 May 24 2,950 6.4 Aug 4 3,500 8.3 May 14 3,400 8.0
184E May 24 1,890 20.4 May 25 2,025 15.0
19116 Jun 14 980 17.8 Jul 10 1,150 15.0 May 13 1,225 17.2
31217c May 24 1,110 7.1 Ju125 1,900 5.8
31328 May 24 1,840 13.7 Jul 10 2,450 6.5
3C6F May 24 1,260 29.1 May 4 1,818 19.0
5115 May 24 1,706 30.7 Jun 5 1,725 22.0 May 21 1,950 21.5
6531 May 24 1,897 16.6 May 4 2,545 10.0
6E7F May 24 1,663 25.9 Jul 10 2,200 18.0
a Fish captured at rkm 209.5 in 1994
b Fish captured at rkm 272.9 in 1994
Fish captured at rkm 263.9 in 1994
10
J
0) 8
Z
C
O
E! 6
C
U
C
U 4
E
N
N 2
35
30
0
Cameo 5th Street Fruita
Below GVC Redlands State Line
Fig. 2. Selenium concentrations (µg/L) in water sampled at six main
channel sites on the Colorado River heading from east to west in the
Grand Valley, July 1994 and July 1995 (data from Ugland et al. 1994;
Crowfoot et al. 1995). The Cameo and below Grand Valley Canal
(below GVC) sites are in the east Grand Valley and above the influence
of irrigation return water
three muscle plugs in 1995 were collected on May 4, right
before the high runoff flows in mid-May 1995. It is possible that
higher flows in 1995 than in 1994 played a role in reduced
selenium concentrations in muscle plugs of those fish collected
in June or later 1995. It should be noted that 10 of the 11
recaptured fish gained weight between 1994 and 1995 (Table 3).
To take into account possible dilution of selenium due to weight
gain on the nine fish, which had lower selenium concentrations
during 1995, a linear regression analysis was performed to
assess changes in selenium concentrations in muscle plugs due
to increase in body weight from 1994 to 1995. The resulting
25
N
20
N
0
Y 15
0
0
U_
10
-+r 1994 t 1995 $1996
5
0' '
OCT DEC FEB APR JUN AUG
NOV JAN MAR MAY JUL SEP
Fig. 3. Monthly mean discharge in cubic feet per second (cfs) in the
Colorado River at the US Geological Survey gauging station near the
Colorado-Utah state line during 1994-1996 (data from Ugland et al.,
1994; Crowfoot et al., 1995, 1996)
correlation coefficient was 0.32, the coefficient of determination
was 0.102 (p = 0.12). Thus, had the p value been significant
(larger sample size) only 10.2% of the reduction in selenium
concentrations in the nine fish could be attributed to increased
body weight.
In 1996, muscle plugs were taken from a total of 35 Colorado
pikeminnow captured at WWSWA (Table 3). The 1996 mean
selenium concentration from these samples was unchanged
from that in 1995 (Table 3). The magnitude of spring flows in
the Colorado River during 1996 was intermediate of that in
1994 and 1995 (Figure 3) (Crowfoot et al., 1996). As in 1994
and 1995, the mean selenium concentration in Colorado
pikeminnow captured at WWSWA in 1996 exceeded the 8 pg/g
DW toxic guideline for fish muscle tissue (Table 3).