Steven R. Chipps

Bioenergetics Modeling in the 21st Century: Reviewing New Insights and Revisiting Old Constraints

Abstract The development and application of fish bioenergetics models have flourished in recent years, due in part to the complexity of the issues being faced by fisheries biologists. As with any model, the accuracy of bioenergetics models can be hampered by uncertainty in model parameters. A review of the literature showed that field and laboratory tests of bioenergetics models often result in poor agreement between model predictions and independent data. Nonetheless, bioenergetics modeling continues to be used to make important management decisions. Recent tests of model predictions have shown that parameter uncertainty is influenced by factors such as feeding rate, physiological adaptations, and prey composition and abundance. In an attempt to reduce the uncertainty in modeling applications, we propose a framework that highlights the importance of (1) model evaluation, (2) hypothesis-based parameter testing, and (3) improved communication between model developers and model users. Adherence to this fram...

Zooplanktivory and Nutrient Regeneration by Invertebrate (Mysis relicta) and Vertebrate (Oncorhynchus nerka) Planktivores: Implications for Trophic Interactions in Oligotrophic Lakes

Abstract We investigated zooplanktivory and nutrient regeneration by the opossum shrimp Mysis relicta and kokanee Oncorhynchus nerka to assess the relative roles of these planktivores in oligotrophic food webs. Using bioenergetic models and clearance rate estimates, we quantified phosphorus (P) excretion rates and consumption of cladoceran prey by Mysis and kokanees in Lake Pend Oreille, Idaho, from 1995 to 1996. Consumption of cladoceran prey by Mysis was 186 kg·ha−1·year−1, whereas consumption by kokanees was less than one quarter as much, at 45 kg·ha−1·year−1. Similarly, Mysis excreted approximately 0.250 kg P·ha−1·year−1 during nighttime migrations into the upper water column, whereas P excretion by kokanees was less than one third as much, at approximately 0.070 kg P·ha−1·year−1. On a volumetric basis, nocturnal excretion by Mysis ranged from 0.002 to 0.007 μg P·L−1·d−1 and accounted for less than 1% of the soluble reactive P typically measured in the upper water column of the lake. Hence, nutrient r...

Association between wetland disturbance and biological attributes in floodplain wetlands

We quantified the influence of agricultural activities on environmental and biological conditions of floodplain wetlands in the upper Missouri River basin. Seasonally-flooded wetlands were characterized as low impact (non-disturbed) or high impact (disturbed) based on local land use. Biological data collected from these wetlands were used to develop a wetland condition index (WCI). Fourteen additional wetlands were sampled to evaluate the general condition of seasonally-flooded floodplain wetlands. Structural and functional attributes of macrophyte, algae, and macroinvertebrate communities were tested as candidate metrics for assessing biotic responses. The WCI we developed used six biological metrics to discriminate between disturbed and non-disturbed wetlands: 1) biomass of Culicidae larvae, 2) abundance of Chironomidae larvae, 3) macroinvertebrate diversity, 4) total number of plant species, 5) the proportion of exotic plant species, and 6) total number of sensitive diatom species. Disturbed wetlands had less taxa richness and species diversity and more exotic and nuisance (e.g., mosquitoes) species. Environmental differences between low and high impact wetlands included measures of total potassium, total phosphorus, total nitrogen, alkalinity, conductance, and sediment phosphorus concentration. Canonical analyses showed that WCI scores were weakly correlated (P = 0.057) with environmental variables in randomly selected wetlands. In addition, mean WCI score for random wetlands was higher than that for high impact wetlands, implying that floodplain wetlands were less impacted by the types of agricultural activities affecting high impact sites. Inter-year sampling of some wetlands revealed that WCI metrics were correlated in 2000 and 2001, implying that biological metrics provided useful indicators of disturbance in floodplain wetlands.

Evaluation of Injectable Fluorescent Tags for Marking Centrarchid Fishes: Retention Rate and Effects on Vulnerability to Predation

Abstract We evaluated the performance of injectable fluorescent tags for use in mass marking of centrarchid fishes. Using age-0 largemouth bass Micropterus salmoides and bluegills Lepomis macrochirus (50–100 mm total length), we compared (1) the retention rate of injectable photonic dyes (IPDs) applied to the fin rays of largemouth bass, (2) retention rates of IPDs versus visible implant elastomers (VIEs), and (3) the effect of colorless and brightly colored marks on prey selectivity by adult largemouth bass. Retention rate of IPDs declined appreciably in age-0 largemouth bass (50 mm) after 120 d with only 19% of fish retaining visible marks by that time. By the end of the experiment (day 310), no marks were visible in anal fin rays of largemouth bass. For larger age-0 largemouth bass (100 mm), retention rates of IPDs after 48 d were greatest for fish marked in the anal fin (40%), followed by caudal (20%) and dorsal fin (5%) markings. Visible implant elastomers were retained at a higher rate (84.4%) than ...

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.

Interactions between Walleyes and Smallmouth Bass in a Missouri River Reservoir with Consideration of the Influence of Temperature and Prey

Walleyes Sander vitreus are the most popular fish among South Dakota anglers, but smallmouth bass Micropterus dolomieu were introduced to provide new angling opportunities. Some walleye anglers have reported reductions in the quality of walleye fisheries since the introduction of smallmouth bass and attribute this to the consumption of young walleyes by smallmouth bass and competition for shared prey resources. We quantified the diets of walleyes and smallmouth bass in the lower reaches of Lake Sharpe (a Missouri River reservoir), calculated the diet overlap between the two predators, and determined whether they partitioned shared prey based on size. We also quantified walleye diets in the upper reach of the reservoir, which has a different prey base and allowed us to compare the growth rates of walleyes within Lake Sharpe. Age-0 gizzard shad Dorosoma cepedianum composed a substantial proportion of the diets of both predators, regardless of location, for most of the growing season; the patterns in shad vulnerability appeared to drive the observed patterns in diet overlap. Smallmouth bass appeared to consume a smaller size range of gizzard shad than did walleyes, which consumed a wide range. Smallmouth bass consumed Sander spp. in some months, but in very low quantities. Given that global climate change is expected to alter the population and community dynamics in Great Plains reservoirs, we also used a bioenergetics approach to predict the potential effects of limiting prey availability (specifically, the absence of gizzard shad and rainbow smelt Osmerus mordax) and increased water temperatures (as projected from global climate change models) on walleye and smallmouth bass growth. The models indicated that the absence of rainbow smelt from the diets of walleyes in upper Lake Sharpe would reduce growth but that the absence of gizzard shad would have a more marked negative effect on both predators at both locations. The models also indicated that higher water temperatures would have an even greater negative influence on walleye growth; however, smallmouth bass growth was predicted to increase with higher temperatures. Fisheries managers should consider strategies to enhance the prey base or mitigate the effects of increased water temperatures that may occur in the future as a result of global climate change. Such proactive actions may alleviate potential future competition between walleyes and smallmouth bass resulting from changes in the fish community.

Development and Evaluation of a Western Mosquitofish Bioenergetics Model

Abstract We developed a bioenergetics model for the western mosquitofish Gambusia affinis by combining data on temperature-dependent feeding rates with published information on respiration, temperature tolerance, and reproduction. To corroborate the model, we compared bioenergetics estimates with independent observations from laboratory feeding and growth trials. The model was then applied to a western mosquitofish population in Illinois to estimate feeding rates on natural prey taxa, including mosquito (Culicidae) larvae. Laboratory feeding experiments revealed that western mosquitofish have a high feeding capacity. Maximum consumption rates were 0.25–1.06 g·g−1·d−1 at water temperatures between 5°C and 40°C; the highest feeding rates were observed at 32°C. Bioenergetics estimates of food consumption agreed well with laboratory measurements across a wide range of water temperatures (10–35°C). However, for fish experiencing negligible growth, model estimates of food consumption were higher than actual val...

Growth and Food Consumption by Tiger Muskellunge: Effects of Temperature and Ration Level on Bioenergetic Model Predictions

Abstract We measured growth of age-0 tiger muskellunge as a function of ration size (25, 50, 75, and 100% Cmax) 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...

Spatiotemporal Patterns of Wetland Occurrence in the Prairie Pothole Region of Eastern South Dakota

We evaluated changes in wetland abundance, size, and classification between average (1979–1986) and above-average (1995–1999) precipitation periods for two physiographic regions in eastern South Dakota. Temporal shifts in wetland numbers, area, and class varied by topographic location. In high wetland density areas (> 8 wetlands/100 ha), our data suggests that larger, semipermanent wetlands expanded and absorbed nearby wetland basins into their margins, resulting in a net “loss” or disappearance of temporary and seasonal wetlands in above-average water condition years. “Losses” described here are not deemed permanent as in cases of draining or filling, and wetlands may re-form when water conditions return to normal. Nevertheless, temporary disappearance of smaller more isolated wetlands may have implications for breeding waterfowl and other fauna. Percent change of semipermanent basin numbers was positively correlated with wetland density, whereas the opposite was true for seasonal wetlands. Loss of temporary wetlands was correlated with wetland aggregation within the sample area. However, in low wetland density areas, the number and size of seasonal and temporary wetlands generally increased following above-average precipitation. We suggest that wetlands’ spatial arrangement be considered along with traditional wetland quantification techniques to better account for shifts in wetland habitat in dry versus wet years.

Invertebrate Composition and Abundance Associated with Didymosphenia geminata in a Montane Stream

ABSTRACT Didymosphenia geminata, a relatively new aquatic nuisance species that can form extensive, mucilaginous mats on stream substrates, was reported from Rapid Creek, South Dakota in 2002. To examine the association between D. geminata and the invertebrate community in Rapid Creek, macroinvertebrates were quantified using three gear types in the fall of 2006. D. geminata was present at two of four sites sampled (range = 5.53 to 809.68 g m−2 dry mass). At each site, invertebrates were collected using dip nets, Surber samplers, and drift nets. The combined percentage of Ephemeroptera, Plecoptera, and Trichoptera in areas with D. geminata was lower (41%) than in areas without D. geminata (76%). Diptera abundance was higher at sites with D. geminata than in sites where D. geminata was absent.