James A. Rice - Research Program Summary
In the broadest terms, my research interests fall in the
realms of behavioral and aquatic ecology. I am interested in how
species interactions, especially predator-prey relationships,
influence the structure and dynamics of aquatic communities and
systems. My past work has been mostly, but not exclusively, with
fishes in both freshwater and marine systems. Generally I tend to focus on particular questions rather
than particular species or systems, working wherever I can
effectively address the question. In my experience, computer simulation models can be helpful tools in ecological research when
used in concert with experiments or field observations. I try to
use a blend of these approaches in my work, and encourage my
students to as well.
Yellow Perch Recruitment
A major focus of my present research program concerns the mechanisms governing larval and juvenile survival and recruitment in fishes. I am especially interested in the importance of body size, growth rate variability, and size-dependent mortality in determining survival of young fish. Since the early 1980s I have been addressing many of these
issues in the Lake Michigan ecosystem with support from the University of Wisconsin Sea Grant program, in collaboration with Larry Crowder (Duke Marine Lab), Fred Binkowski (University of Wisconsin-Milwaukee WATER Institute), Tom Miller (Chesapeake Biological Lab) and our students. We have used a combination of field work and lab experiments to explore the mechanisms governing recruitment and population dynamics of Lake Michigan fishes, and changing interactions in the offshore food web. In the laboratory we used experiments with alewives,
bloaters, and yellow perch (which hatch at very different sizes) to test the relative importance of
body size vs. species differences for larval fish survival, and to develop a general size-dependent, individual-based simulation model of all the key
processes affecting survival of larval and juvenile fish. Currently Fred Binkowski, Tom Miller and I (along with graduate students Richard Fulford and Chris Heyer) are using these approaches to explore the causes of persistent recruitment failure of yellow perch in Southern Lake Michigan over the last eight years.
Fish Responses to Hypoxia
With support from the UNC Sea Grant program, graduate students Regan McNatt, Trevor Yip-Hoi and I are examining behavioral and growth responses of estuarine organisms to hypoxia. North Carolina's coastal rivers are experiencing increasing problems with noxious and toxic algal blooms, hypoxia, and fish kills, due to excessive nutrient loading. Extensive efforts are underway to model changes in water quality in response to nutrient loading, but the information necessary to extend these models to predict responses of fish and invertebrate populations to these changes is not available. We are conducting a series of lab experiments with a suite of representative estuarine fish and shrimp species to determine their ability to detect and avoid hypoxia, identify their hypoxia avoidance thresholds, characterize how their probability of mortality changes as a function of the degree and duration of hypoxia exposure, and evaluate how feeding and growth rates are affected by low and varying oxygen concentrations. Results from these experiments will help us develop a model of fish and shrimp behavioral and population-level responses to oxygen dynamics in coastal rivers that can be coupled with models of water quality dynamics.
Many of the effects of hypoxia may be indirect; if estuarine organisms move to avoid areas of low oxygen, density-dependent processes and changes in food web interactions may exert the most important effects. Our results from recent experiments in ponds and field enclosures demonstrate density-dependent effects on survival and growth of estuarine fish (spot) and on their prey base. We will continue to explore the consequences of such indirect effects.
Striped Bass Bioenergetics
I have just begun two new projects in collaboration with NC Wildlife Resources Commission fisheries biologists and several colleagues in the N.C. State Zoology Department. The first (with coPIs Pete Rand, Randy Jackson, Joe Hightower and Rich Noble) concerns patterns of growth and condition (mostly poor) in striped bass populations in North Carolina Reservoirs. Most NC reservoirs provide marginal stiper habitat in the summer, with fish squeezed between warm surface waters and hypoxic deeper waters. These conditions, as well as the forage base, vary substantially among reservoirs, and likely interact to produce the observed growth and condition patterns. We will be using a combination of field sampling, hydroacoustics and bioenergetics modeling to determine striped bass growth rates, condition, age and size structure, diet composition and abundance, as well as the size distribution and biomass of forage fish. These data, coupled with information on temperature and oxygen distributions and fish caloric densities, will be combined in a bioenergetic analysis to determine the relative contributions of the factors causing the observed patterns.
Community Impacts of Flathead Catfish
The second project (with coPIs Tom Kwak, Randy Jackson, Joe Hightower and Rich Noble) concerns the impacts of introduced flathead catfish on native fish communities in coastal rivers. The flathead catfish is a large, piscivorous predator that is rapidly spreading beyond its native range, throughout the southeast, and has become established in most of North Carolina's main coastal streams and rivers. Here and elsewhere flathead catfish typically deplete or extirpate bullheads and other native catfishes, and then cause substantial changes in redbreast sunfish and other native fish populations as well. Our study will focus on three different stream reaches with different levels of flathead population establishment in the NC coastal plain. We will use field sampling, mark-recapture and telemetry to determine flathead catfish abundance, growth rates, age and size structure, diet composition, microhabitat use and movement rates, as well as the abundance, age and size composition of the rest of the fish community. We hope to gain a better understanding of how flathead catfish affect NC fish communities, whether their impacts are likely to vary depending on characteristics of the habitat, and if their are potential control methods that might be effective in reducing their impacts.
The SABRE Study
We recently completed the South Atlantic Bight Recruitment Experiment (SABRE), a long-term, joint effort by NOAA and Academic scientists to identify the key processes and life stages governing recruitment of off-shore spawning estuarine-dependent fishes, such as Atlantic menhaden. As part of this effort, we examined patterns of abundance, age, and spawning date distributions of Atlantic menhaden Brevoortia tyrannus larvae immigrating over two seasons through three North Carolina inlets, Oregon, Ocracoke, and Beaufort, to elucidate their spawning and transport dynamics. These patterns, derived from analysis of daily otolith growth increments, were examined in conjunction with corresponding predictions from a three-dimensional, wind- and tide-driven hydrodynamic model. Larvae immigrating through different inlets showed both consistent similarities and marked differences in temporal patterns of abundance, spawning dates, and transport times. Intraseasonal patterns in abundance and spawning date distributions among inlets suggested that in both study years spatio-temporal dynamics of menhaden immigration were driven by large-scale patterns along the Atlantic coast, rather than by localized variation in spawning activity. Interannual differences in the temporal patterns of spawning dates and larval immigration indicated interannual differences in transport dynamics and/or the spatial-temporal distribution of spawning. When spawning locations predicted by the hydrodynamic model were interpreted in conjunction with AVHRR sea surface temperature information, the results were consistent with the limited historical information available on spatio-temporal distribution of Atlantic menhaden eggs and larvae. The transport model also predicted distributions of arrival times for immigrating larvae that were comparable in range and variability with observed patterns. Our use of data from immigrating larvae coupled with a hydrodynamic transport model and sea surface temperatures allowed us to uncover relationships between spatio-temporal patterns of Atlantic menhaden spawning and transport dynamics that could not have been identified by either approach alone. The results of this work are currently in press (Rice et al. 1999, Fisheries Oceanography).
Flounder-Spot Size-Dependent Predation
For many years Larry Crowder and I and our students have been working in estuarine systems (supported by NC Sea Grant) to examine how size-dependent predator-prey interactions affect the survival and size structure of juvenile fishes. Our experiments with southern flounder preying on young-of-year spot showed that changes in the relative sizes and growth rates of predators and prey can dramatically alter prey survival and size structure. We have found that an individual-based simulation model of this size-dependent interaction, built from independent lab observations, can successfully predict population-level results in pond-scale field experiments. Recently we used our model to examine the extent to which these size-based interactions may contribute to interannual variations in prey survival and size structure in the field. When predation intensity is high, year to year differences in predator or prey sizes or growth rates can cause major variations in prey survival, independent of predator density. MS student Brian Burke developed a a bioenergetics model for southern flounder and linked it with the foraging model, so that the combined model can now predict growth and size structure effects for flounder as well as for their prey.
Several years ago we elaborated on our flounder-spot experiments to examine the role of direct and indirect trophic linkages in the estuarine food web. In a pond experiment we tested the hypothesis that predation by southern flounder (which tend to forage in deeper water) and predation by fish-eating birds (which forage in shallow water) would have a non-additive impact on young-of-year spot survival. We did find a significant non-additive effect, but not in the direction we anticipated! We expected that birds and flounder together would result in higher spot mortality than the summed effects of the two predators seperately. However, the combined effect was less than the sum of the two predators' individual impacts. Our observations suggest that changes in spot behavior in the presence of birds also reduce their vulnerability to flounders (see Crowder et al. 1997, Ecology 78:1796-1804).
Colorado Squawfish Recruitment
Recently I worked in collaboration with Kevin Bestgen and Dan Beyers (Colorado State University Larval Fish Lab) and Bruce Haines (U.S. Fish & Wildlife Service), to address a problem concerning recruitment of the endangered Colorado squawfish in large western rivers. Red shiners, an exotic minnow, occur at high densities in the shallow backwater habitats where squawfish larvae spend their first summer, and recent evidence suggests that red shiners eat larval fish. We adapted the individual-based size-dependent predation model I developed for Lake Michigan larvae and the flounder-spot interaction, and used it in conjunction with lab and mesocosm experiments to evaluate the potential effects of predation by red shiners on squawfish larvae. Our results indicate that red shiner predation may be having major impacts on Colorado squawfish recruitment, and suggest possible management actions that may help reduce this impact.
Bioenergetic Costs of Stress
Dan Beyers (Colorado State University) and I recently completed a study bringing two disparate approaches to bear on the problem of evaluating chronic, sublethal effects of toxicants on fish populations. Traditional toxicology studies measure acute effects (e.g., time to 50% mortality) of stress on fishes. Bioenergetics models are powerful tools for predicting fish growth, but they have traditionally only been applied to "healthy" fish. We integrated both approaches by measuring the dose-dependent metabolic costs of sublethal toxicant exposure (dieldrin), and then incorporating these relationships into a bioenergetics model to predict long-term effects on fish (largemouth bass) growth. The combined model works, and allows us to sort out the relative effects of toxicant exposure vs. those of temperature and food availability. Results of this work were recently published (Beyers et al. 1999, CJFAS 56(5):814-822, and Beyers et al. 1999, CJFAS 56(5):823-829).
In addition to the projects summarized above, other research topics pursued by me and/or my students in the past include; community dynamics, recruitment and food web interactions in freshwater reservoirs; shrimp trawl bycatch issues; winter habitat use by coastal cutthroat trout in Oregon;
hydroacoustic analysis of the spatial and temporal patchiness of
pelagic forage fishes; effects of turbidity and structural
complexity on foraging success of marine piscivores; size-
dependence of predation by juvenile southern flounder and
bluefish, and; community effects and growth responses of hybrid
striped bass stocked in freshwater ponds.
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J.A. Rice Research Summary (modified October 1997) / Jim
Rice / email@example.com