Geology topics

Research about Lake Onalaska

Source-linked reports with geographic coverage including Lake Onalaska.

5 recordsLinked to original sources

USGS2011

Effects of fish predation on invertebrates associated with a macrophyte in Lake Onalaska, Wisconsin

We tested the effects of fish predation on the macroinvertebrates associated with Vallisneria americana (Michx) by using enclosure/exclosure experiments in lake Onalaska, Wisconsin. Four treatments were used: open water (cageless) controls, cage-effect controls (partially enclosed cages), exclosures (all fish removed), and enclosures (cages stocked with a known density of bluegills Lepomis macrochirus, Rafinesque). Bluegill predation at the density tested (one 70 mm fish per 0.37m 2 ) did not depress Vallisneria associated invertebrate density. Mean invertebrate abundance and biomass (number and dry weight of invertebrates per g dry plant weight) increased in both exclosures and enclosures relative to open water controls. The most likely explanation is that the cages excluded some vertebrate predator(s) from those two treatments and decreased predation pressure within the cages. Large invertebrates, such as Hyalella azteca, Enallagma sp., Gyraulus sp., and Physa sp., increased in abundance within cages, whereas, small invertebrates such as chironomid larvae decreased in abundance.

Wisconsin↗

USGS2011

Macroinvertebrate communities associated with three aquatic macrophytes (Ceratophyllum demersum, Myriophyllum spicatum, and Vallisneria americana) in Lake Onalaska, Wisconsin

The standing crop and species diversity of macroinvertebrates associated with wild celery (Vallisneria americana), Eurasian watermilfoil (Myriophyllum spicatum), and coontail (Ceratophyllum demersum) were examined in Lake Onalaska, Pool 7 of the upper Mississippi River, during summer 1983. Although Ceratophyllum generally supported the largest invertebrate standing crop (number per g plant dry weight), differences in invertebrate abundance among plant species were not consistent across time. However, the distribution of several taxa were significantly affected by plant species. Hyalella azteca (overall the most abundant species) and Enallagma spp. (the most abundant predator) were consistently most numerous in Ceratophyllum samples and least abundant in Vallisneria samples. Generally, invertebrate community composition differed significantly among plant species throughout the summer.

Wisconsin↗

USGS2008

Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments

The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region and Montana. It is important to limit the spread of the faucet snail; small fisheries equipment can serve as a method of snail distribution. Treatments with chemical disinfection, pH extremes, and heated water baths were tested to determine their effectiveness as a disinfectant for small fisheries equipment. Two treatments eliminated all test snails: (1) a 24-h exposure to Hydrothol 191 at a concentration of at least 20 mg/L and (2) a treatment with 50°C heated water for 1 min or longer. Faucet snails were highly resistant to ethanol, NaCl, formalin, Lysol, potassium permanganate, copper sulfate, Baquacil, Virkon, household bleach, and pH extremes (as low as 1 and as high as 13).

Wisconsin↗

USGS2006

Patterns of foraging and distribution of bluegill sunfish in a Mississippi River backwater: Influence of macrophytes and predation

We studied the trophic interactions and spatial distributions of bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides in a macrophyte bed in Lake Onalaska, a backwater lake in the upper Mississippi River. The diets of adult and age-0 bluegills were similar and changed seasonally probably in response to changes in life stages of macroinvertebrates (i. e. emergence of winged adults). Diets and diel patterns of abundance of bluegill suggest that age-O and adults were feeding in the vegetated, littoral zone. Predation by age-O largemouth bass appears to influence use of vegetated habitat by age-0 bluegills. In summer, when most age-O bluegills were vulnerable to predation by age-O largemouth bass, bluegill abundance was strongly correlated with vegetation biomass. In October and November, piscivory by age-O largemouth bass was limited by gape. Consequently, the relationship between the abundance of age-O bluegills and vegetation biomass was weakened because predation risk by age-O largemouth bass was reduced.

Wisconsin↗

USGS1996

Canvasback mortality from illegal hunting on the upper Mississippi River

To quantify the consequences of local hunting on illegal kill of canvasbacks ( Aythya valisineria ), we studied the behavior of hunters on a 646-ha area open to duck hunting (closed to canvasback hunting) on Lake Onalaska, Navigation Pool 7, Wisconsin, during the 1991 and 1992 waterfowl hunting seasons. Law enforcement officers observed 258 hunting parties for 419 hours. Of 94 hunting parties encountering canvasbacks, 41 (44%) shot at the ducks on 56 occasions, or 27% of 207 encounters observed, Based on a ratio estimator, there were 790 (95% CI = 376) attempts to shoot at canvasbacks on the Lake Onalaska study area during 1991 and 837 (95% CI = 390) during 1992. Mortality of canvasbacks, excluding crippling loss, was estimated to be 128 during 1991 and 166 during 1992. Thus, total canvasback losses may be higher than currently estimated on a flyway or national basis. This estimating technique offers a promising method for enumerating hunter take of protected and legal species.

Wisconsin↗