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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1986, Besser et al. 1993, Saiki 1986, Sandholm et al. 1973) and its dietary toxicity at low
concentrations (Bennett et al. 1986, Hamilton et al. 1990, Hilton et al. 1980, Hodson and
Hilton 1983). Low waterborne selenium concentrations have been documented to adversely
affect reproduction in fish in experimental field studies (Hermanutz et al. 1992, Schultz and
Hermanutz 1990) and in environmental situations in Colorado (Barnhart 1957), North
Carolina (Cumbie and Van Horn 1978), and Texas (Garrett and Inman 1984, Sorensen
1988) .

The objective of the study was to evaluate the survival, growth, and whole-body
residues of selenium and other inorganics in larval razorback sucker exposed to reference
water and food organisms with naturally occurring selenium collected at Ouray NWR, Utah.
Wetlands in floodplains such as those found at Ouray are believed to be important nursery
habitats for larval razorback sucker (Modde et al. 1995, Tyus and Karp 1990) because of
their high invertebrate production (Mabey 1993).

:METHOD AND MATERIALS

The on-site toxicity investigation was conducted at the Ouray NWR, Utah, from May
21 to June 26, 1994, in a mobile laboratory transported from the Ecotoxicology Research
Station (ERS), Yankton, SD, and parked at the Ouray Native Fish Facility (Figure 2). Two
lots of larval razorback sucker were used in a total of four studies. One lot of larvae were
from adults spawned at Grand Junction, CO, from brood stock from Etter Pond near
DeBeque, CO. Fertilized eggs from this lot were transported to Ouray Native Fish Facility
where they were held before testing, and used in studies 1 and 2, which are described below.
Study 2 was initiated when unexpected mortality occurred in study 1 in larvae fed
zooplankton from the reference site. Following unexpected mortality in study 2 in larvae fed
zooplankton from the reference site, studies 3 and 4 were initiated and are described below.
There were insufficient larvae available from the first lot of larvae to conduct studies 3 or 4.
Consequently, a second lot of larvae from adults spawned at Ouray Native Fish Facility from
brood stock from the Colorado River arm of Lake Powell, was used in studies 3 and 4.

Larvae were cultured at Ouray Native Fish Facility in filtered river water (hardness
488 mg/L as CaC03, alkalinity 191 mg/L as CaC03, pH 8.0). Larvae from the first lot were
fed live nauplii of brine shrimp (Artemia sp.; Aquarium Products, Glen Bumie, MD) prior to
testing in studies 1 and 2. Larvae from the second lot were fed a commercial diet (Biokyowa
B-250 diet, Biodiet Products, Warrenton, OR) ad libitum prior to testing in studies 3 and 4.

Study 1 was initiated with 5-day-old larvae, study 2 with lO-day-old larvae, study 3
with 24-day-old larvae, and study 4 with 28-day-old larvae. Ten fish were placed in each of
four replicate 2000-ml beakers containing 400 ml of filtered hatchery water and 400 ml of
Sheppard Bottom pond 1 (Sl) water to initiate acclimation. After 4 hours, an additional 800
ml of S 1 water was added. Thereafter, fifty percent of the water was removed and replaced
daily with Sl water. All Sl water was filtered through a 153-Jlm mesh plankton net to
remove debris and plankton. Water in exposure beakers was aerated continuously with

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