Geology topics

David H. Wahl

Publications and source records attributed to David H. Wahl.

9 recordsLinked to original sources

USGS2023

Effect of feeding history on metabolic rate of largemouth bass (Micropterus nigricans): implications for bioenergetics models

Metabolic rate is a key parameter in fish energy budgets that strongly influences the output of bioenergetics models. In this study, we tested the hypothesis that metabolic rate varies with growth history of age-1 largemouth bass Micropterus nigricans Cuvier, 1828. Two groups of fish were fed alternating maintenance or ad libitum rations of fathead minnow Pimephales promelas Rafinesque, 1820, so that over a 9-week period, initial and ending size of fish was similar. After 9 weeks, oxygen consumption was measured using static, closed respirometry. Although final body weight was similar between the two groups (means, 104–108 g), specific oxygen consumption for fish fed maintenance rations (0.094 mg O 2 g −2 h −1 ) was 38% less than that measured for fish fed ad libitum (0.152 mg O 2 g −2 h −1 ). Bioenergetics estimates of food consumption were similar to observed values for fish fed ad libitum (∼7% error), but for fish fed maintenance rations, the model overestimated food consumption by 65%. By accounting for changes in metabolic rate owing to reduced feeding, error in model estimates of food consumption was reduced. These findings shed new insight into factors associated with consumption-dependent error in bioenergetics models and highlight the importance of feeding history on metabolic rate of fish. Incorporating growth-dependent metabolism into bioenergetics models can improve model accuracy and allow fisheries biologists to make more informed decisions regarding fish growth and energetics.

Canadian Journal of Zoology↗

USGS2018

Development of a quantitative PCR method for screening ichthyoplankton samples for bigheaded carps

Monitoring ichthyoplankton is useful for identifying reproductive fronts and spawning locations of bigheaded carps (Hypophthalmichthys spp.). Unfortunately, sorting and identifying ichthyoplankton to monitor for bigheaded carp reproduction is time consuming and expensive. Traditional methods require frequent egg-larvae sampling, sorting of all samples to obtain presumptively identified bigheaded carp, and genetic validation of presumptively identified eggs. Quantitative PCR (qPCR) has the potential to streamline this process by identifying samples that likely do or do not contain a target species. Our objective was to develop a genetic screening tool using qPCR with the duplex assays SCTM4/5 and BHTM1/2 to prioritize samples that have a higher likelihood of containing bigheaded carp eggs or larvae. We used tandem ichthyoplankton samples collected for monitoring bigheaded carps in the Upper Mississippi, Illinois, and St. Croix rivers to evaluate the effectiveness of qPCR as a screening tool. Samples with > 10,000 copies of DNA had 100% occurrence of bigheaded carp eggs or larvae in the traditionally sorted samples, whereas samples with < 10 copies of DNA had 0% occurrence of ichthyoplankton from these invasive species. We used a logistic regression model to calculate the probability of finding bigheaded carp eggs or larvae based upon the number of DNA copies; 406 copies corresponded with a 50% probability of having bigheaded carp ichthyoplankton present in a sample. These data can be used to inform management actions (i.e., control, containment) for these invasive fishes, and this tool could be adapted for monitoring for reproduction of other aquatic invasive species.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗

USGS2018

Using reverse-time egg transport analysis for predicting Asian Carp spawning grounds in the Illinois River

Identifying spawning grounds of Asian carp is important for determining the reproductive front of invasive populations. Ichthyoplankton monitoring along the Illinois Waterway (IWW) has provided information on abundances of Asian carp eggs in the IWW's navigation pools. Post-fertilization times derived from egg development stages and water temperatures can be used to estimate spawning times of Asian carp eggs, but estimating how far these eggs have drifted requires information on river hydraulics. A Fluvial Egg Drift Simulator (FluEgg) program was designed to predict the drift of Asian carp eggs in the riverine environment with egg growth considered. This paper presents a reverse-time particle tracking (RTPT) algorithm for back-casting the spawning location of eggs from their collection site. The RTPT algorithm was implemented as a module in FluEgg. The new version of FluEgg was coupled with an unsteady hydrodynamic model of the IWW to predict the spawning locations for 530 eggs that were collected in June 2015. The results indicate that tailwater sections below the Locks and Dams (L&Ds) in each navigation pool appear to be preferred spawning locations for Silver Carp. From the data analyzed, the most upstream spawning location for the June 2015 spawning period was in the upper Marseilles navigation pool, downstream of the Dresden Island L&D. The RTPT algorithm can efficiently estimate spawning locations for multiple egg samples.

Illinois↗

USGS2009

Maintaining the competitiveness of the American Fisheries Society journals: An assessment based on influence and cost-effectiveness

Recent changes in the landscape of scientific publishing prompted the Publications Overview Committee of the American Fisheries Society (AFS) to review the Society's portfolio of scientific journals. We evaluated journals based on metrics in two categories: (1) citation-based measures of the influence of a journal on the scientific literature, and (2) measures of the cost-effectiveness of a journal (citation rate adjusted for subscription cost). Over the long-term, we found that ecology journals had far stronger citation-based influence than fisheries and aquatic sciences journals, and that journals publishing primarily basic research had stronger influence than journals publishing applied research (including four AFS journals and Fisheries magazine). In evaluating the current status of fisheries and aquatic sciences journals, we found that metrics of influence and cost-effectiveness provided considerably different portrayals of journals relative to their peers. In terms of citation-based influence, we found that the AFS journal Transactions of the American Fisheries Society (TAFS) and Fisheries magazine were competitive with highly regarded peer fisheries journals, but that North American Journal of Aquaculture (NAJA) and Journal of Aquatic Animal Health (JAAH) were less influential than their peers. The citation-based influence of North American Journal of Fisheries Management (NAJFM) was intermediate between TAFS/Fisheries and NAJA/JAAH . For journals like NAJFM and NAJA , we expect that much of the scientific influence on policy and management is not captured by citations in the primary literature, and alternative methods of evaluation may be needed. All of the AFS journals ranked highly with regard to cost-effectiveness because their subscription costs are low, and these rankings are in accordance with membership needs and the strategic mission of AFS to provide broad and timely dissemination of scientific information. We conclude by suggesting ways to increase the influence of AFS journals without compromising their accessibility and affordability, and offer advice about methods and frequency for future journal evaluations.

Fisheries↗

USGS2004

Phenotypic variation and vulnerability to predation in juvenile bluegill sunfish (Lepomis macrochirus)

Bluegill sunfish (Lepomis macrochirus) are known to diversify into two forms specialized for foraging on either limnetic or littoral prey. Because juvenile bluegills seek vegetative cover in the presence of largemouth bass (Micropterus salmoides) predators, natural selection should favor the littoral body design at size ranges most vulnerable to predation. Yet within bluegill populations, both limnetic and littoral forms occur where vegetation and predators are present. While adaptive for foraging in different environments, does habitat-linked phenotypic variation also influence predator evasiveness for juvenile bluegills? We evaluate this question by quantifying susceptibility to predation for two groups of morphologically distinct bluegills; a limnetic form characteristic of bluegills inhabiting open water areas (limnetic bluegill) and a littoral form characteristic of bluegills inhabiting dense vegetation (littoral bluegill). In a series of predation trials, we found that bluegill behaviors differed in open water habitat but not in simulated vegetation. In open water habitat, limnetic bluegills formed more dense shoaling aggregations, maintained a larger distance from the predator, and required longer amounts of time to capture than littoral bluegill. When provided with simulated vegetation, largemouth bass spent longer amounts of time pursuing littoral bluegill and captured significantly fewer littoral bluegills than limnetic fish. Hence, morphological and behavioral variation in bluegills was linked to differential susceptibility to predation in open water and vegetated environments. Combined with previous studies, these findings show that morphological and behavioral adaptations enhance both foraging performance and predator evasiveness in different lake habitats.

Oecologia↗

USGS2003

Piscivory in juvenile walleyes: Relative importance of prey species, timing of spawning of prey fish, and density on growth and survival

We examined the effect of the timing of spawning by prey fish and the species of prey fish on the growth and survival of juvenile walleye Stizostedion vitreum. We expected that age-0 walleyes would grow more in ponds when stocked about the same time as the spawning of gizzard shad Dorosoma cepedianum than when stocked about 6 weeks after spawning. We found, however, that the timing of larval gizzard shad presence did not affect walleye growth or survival. Also contrary to our expectations, walleyes from ponds with bluegill Lepomis macrochirus grew more (by 9% in total length and 38% in mass) than those from ponds with gizzard shad. However, the density of gizzard shad was lower than that of bluegills, particularly after the first few weeks of the experiment. Bluegills remained within the gape limits of walleyes throughout the experiment, whereas gizzard shad outgrew their vulnerability to predation. Late-spawned gizzard shad remained vulnerable to walleye predation only slightly longer than did those from early spawned ponds. The survival of age-0 walleyes was unaffected by water temperature, the timing of spawning by prey fish, prey species, or density. Our results suggest that even though walleyes typically grow faster in systems with gizzard shad as prey than in those with bluegills, juvenile walleyes can still grow well in bluegill-dominated systems. In some systems, high densities of a less beneficial prey (e.g., abundant bluegills rather than less abundant gizzard shad) may overcome the growth differences of juvenile walleyes that would be expected based on the differences in prey species alone. A wide variation in individual walleye growth in our ponds, even within prey treatments, indicated the complexity of interactions among the factors affecting juvenile walleye growth.

Transactions of the American Fisheries Society↗

USGS2001

Patterns in abundance of fishes in main channels of the upper Mississippi River system

Abundance of fishes of the main channels of the upper Mississippi River system and of other large North American rivers is largely unknown because historic sampling methods have been inadequate. We used a bottom trawl to estimate spatial and temporal patterns in abundance in the navigation channels of Pool 26 of the Mississippi River and the lower Illinois River. Total biomass density averaged 21 and 29 kg·ha -1 in the navigation channels of Pool 26 and the lower Illinois River, respectively. We identified spatial and temporal patterns in catches of key species using a generalized linear model based on the negative binomial distribution. Some species, including shovelnose sturgeon (Scaphirhynchus platorynchus), are persistent residents of the main channel. Multiple-season residents, including freshwater drum (Aplodinotus grunniens), rely heavily on the main channel during most of the year but leave it briefly, for example to seek thermal refugia in backwaters during winters. We suggest revision of the prevailing notion that main channels of large temperate rivers serve mainly as corridors for movement among other habitat types.

Mississippi River↗

USGS2001

Life in the fast lane: Fish and foodweb structure in the main channel of large rivers

We studied the main channel of the lower Illinois River and of the Mississippi River just upstream and downstream of its confluence with the Illinois River to describe the abundance, composition, and/or seasonal appearance of components of the main-channel community. Abundance of fishes in the main channel was high, especially adults. Most adult fishes were present in the main channel for either 3 or 4 seasons/y, indicating that fishes regularly reside in the main channel. We documented abundant zooplankton and benthic invertebrates in the main channel, and the presence of these food types in the diets of channel catfish and freshwater drum. All trophic levels were well represented in the main channel, indicating that the main channel supports a unique food web. The main channel also serves as an important energetic link with other riverine habitats (e.g., floodplains, secondary channels, backwater lakes) because of the mobility of resident fishes and because of the varied energy sources supplying this food web. It may be more realistic to view energy flow in large-river systems as a combination of 3 existing concepts, the river continuum concept (downstream transport), the flood pulse concept (lateral transport to the floodplain), and the riverine productivity model (autochthonous production). We urge additional research to quantify the links between the main channel and other habitat types in large rivers because of the apparent importance of main-channel processes in the overall structure and function of large-river ecosystems.

Illinois↗

USGS2000

Growth and food consumption by tiger muskellunge: Effects of temperature and ration level on bioenergetic model predictions

We measured growth of age-0 tiger muskellunge as a function of ration size (25, 50, 75, and 100% C max ) and water temperature (7.5–25°C) and compared experimental results with those predicted from a bioenergetic model. Discrepancies between actual and predicted values varied appreciably with water temperature and growth rate. On average, model output overestimated winter consumption rates at 10 and 7.5°C by 113 to 328%, respectively, whereas model predictions in summer and autumn (20–25°C) were in better agreement with actual values (4 to 58%). We postulate that variation in model performance was related to seasonal changes in esocid metabolic rate, which were not accounted for in the bioenergetic model. Moreover, accuracy of model output varied with feeding and growth rate of tiger muskellunge. The model performed poorly for fish fed low rations compared with estimates based on fish fed ad libitum rations and was attributed, in part, to the influence of growth rate on the accuracy of bioenergetic predictions. Based on modeling simulations, we found that errors associated with bioenergetic parameters had more influence on model output when growth rate was low, which is consistent with our observations. In addition, reduced conversion efficiency at high ration levels may contribute to variable model performance, thereby implying that waste losses should be modeled as a function of ration size for esocids. Our findings support earlier field tests of the esocid bioenergetic model and indicate that food consumption is generally overestimated by the model, particularly in winter months and for fish exhibiting low feeding and growth rates.

Transactions of the American Fisheries Society↗