7821

• UCREFRP Catalog Number: 7821
• Author: Hamilton, S. J., et al.
• Title: Evaluation Of Toxicity To Larval Razorback Sucker Of Selenium-Laden Food Organisms From Ouray NWR On The Green River, Utah.
• USFW Year: 1996.
• USFW - Doc Type: \
• Copyright Material: NO

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Study 1

All fish died in study 1 by 25 days of exposure (Figure 4, Appendix 3). No fish were
available for measurement of growth or selenium residue analysis. The survival curves and
median time to death were significantly different among locations (Table 9). Median time to
death was shortest in fish fed zooplankton from S 1 and longest in SR and NR.

Study 2

The majority of fish died in study 2 by 12 days of exposure, including fish fed
invertebrates from the SI reference site (Figure 5, Appendix 4). The survival curve and
median time to death for larvae fed zooplankton from S5 was significantly less than the other
five locations, which were not different from each other (Table 9). Concentrations of
selenium in zooplankton ranged from 2.5 I-Lg/g at SI to 911-Lg/g at SR (Table 5). Whole-
body residues of selenium in fish ranged from 8.7 to 94 I-Lg/g (Table to). Fish fed
invertebrates from the Sl reference site contained 14.3 I-Lg/g (Table to). The whole-body
concentrations of selenium in larvae from study 2 were somewhat variable, as shown by the
standard error, due in part to the very small-sized samples available (0.1 to 0.5 mg dry
weight) and the imprecision of weighing submilligram samples.

Study 3

Survival was 100% in all treatments through 9 days of exposure, but almost 50%
mortality or more occurred in the following 7 days (Figure 6, Appendix 5). The survival
curves and median time to death were not different between locations (Table 9).
Concentrations of selenium in zooplankton were 2.3 I-Lg/g in SI, 50 I-Lg/g in NR, and 87 I-Lg/g
in SR (Table 5). Whole-body residues of selenium in fish followed the same order of
progression as in invertebrates and were 3.7 I-Lg/ g in the S 1 treatment, 33 I-Lg/ g in the NR
treatment, and 39 I-Lg/ g in the SR treatment (Table 10). Fish length, weight, and condition
factor were not different between groups (Table 11).

Study 4

Survival was 100% through 7 days in the S3 and S4 treatments, but only through 5
days in the S5 treatment (Figure 7, Appendix 6). By day 20, survival was decreased to 22-
27 % . The survival curves and median time to death were not different between locations
(Table 9). Selenium concentrations in zooplankton ranged from 2.4 I-Lg/g in S4 to 12 I-Lg/g in
S5 (Table 5). Similar to study 3, whole-body residues in fish followed the same order as in
zooplankton and were lowest in treatment S4 (3.6 I-Lg/g), intermediate in S3 (3.9 I-Lg/g), and
highest in S5 (5.9 I-Lg/g) (Table to). Fish weight, but not length or condition factor, was
significantly reduced in larvae fed zooplankton from S5 (Table 11).

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