Brenda Rashleigh

Predictive Habitat Models for the Occurrence of Stream Fishes in the Mid-Atlantic Highlands

Abstract In most wadeable streams of the mid-Atlantic Highlands region of the eastern USA, physical habitat alteration is the primary stressor for fish. Models that predict the occurrence of stream-fish species based on habitat measures can be useful in management, and predicted probability of occurrence can be a measure of habitat suitability with which to compare alternative habitat management scenarios and assess the effectiveness of stream restoration. We developed such models for each of 13 mid-Atlantic Highlands stream-fish species and species groups by using multiple logistic regression and six instream habitat measures: depth, temperature, substrate, percent riffles, cover, and riparian vegetation. The predictive ability of the models ranged from 61% to 79% in cross-validation and from 38% to 85% on an independent data set. The models predicted well for both the original and test data sets for black bass Micropterus spp., brook trout Salvelinus fontinalis, darters Etheostoma and Percina spp., shin...

Application of AQUATOX, a Process-Based Model for Ecological Assessment, to Contentnea Creek in North Carolina

ABSTRACT The aquatic ecosystem simulation model AQUATOX was parameterized and applied to Contentnea Creek in the coastal plain of North Carolina to determine the response of fish to moderate levels of physical and chemical habitat alterations. Biomass of four fish groups was most sensitive to changes in temperature and detritus, but showed little sensitivity to changes in nutrients, sediment, pH, or dissolved oxygen. The model appears useful for assessment of stream ecosystem response to certain types of stressors; its utility should be determined further by model applications in other study areas and ecoregions.

Progress and Challenges in Coupled Hydrodynamic-Ecological Estuarine Modeling

Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational power, and incorporation of uncertainty. Coupled hydrodynamic-ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, and evaluate remedial actions in response to eutrophication, habitat loss, and freshwater diversion. The need to couple hydrodynamic and ecological models to address research and management questions is clear because dynamic feedbacks between biotic and physical processes are critical interactions within ecosystems. In this review, we present historical and modern perspectives on estuarine hydrodynamic and ecological modeling, consider model limitations, and address aspects of model linkage, skill assessment, and complexity. We discuss the balance between spatial and temporal resolution and present examples using different spatiotemporal scales. Finally, we recommend future lines of inquiry, approaches to balance complexity and uncertainty, and model transparency and utility. It is idealistic to think we can pursue a “theory of everything” for estuarine models, but recent advances suggest that models for both scientific investigations and management applications will continue to improve in terms of realism, precision, and accuracy.

Formal Scenario Development for Environmental Impact Assessment Studies

Abstract Scenario analysis is a process of evaluating possible future events through the consideration of alternative plausible, though not equally likely, states (scenarios). The analysis is designed to enable improved decision making and assessment through a more rigorous evaluation of possible outcomes and their implications. For environmental impact and integrated assessment studies, the process of scenario development typically involves making explicit and/or implicit assumptions about potential future conditions, such as climate change, land cover and land use changes, population growth, economic development and technological changes. Realistic assessment of scenario impacts often requires complex integrated modelling frameworks that represent environmental and socioeconomic systems to the best of our knowledge, including assumptions about plausible future conditions. In addition, scenarios have to be developed in a context relevant to the stakeholders involved, and include estimation and communication of uncertainties, to establish transparency, credibility and relevance of scenario results among the stakeholders. This paper reviews the state of the art of scenario development and analysis, proposes a formal approach to scenario development in environmental studies and discusses existing issues. Major recommendations for future research in this area include proper consideration of uncertainty involved in scenario studies, construction of scenarios of a more variable nature, and sharing of information and resources among the scenario development research community.

Relation of fish and shellfish distributions to habitat and water quality in the Mobile Bay estuary, USA

The Mobile Bay estuary in the northern Gulf of Mexico provides a rich habitat for many fish and shellfish, including those identified as economically and ecologically important. The National Estuary Program in Mobile Bay has focused on restoration of degraded estuarine habitat on which these species depend. To support this effort, we used statistical techniques of ordination, cluster analysis, and discriminant analysis to relate distributions of individual fish and shellfish species and species assemblages to two dozen water quality and habitat variables in a geo-referenced database. Species appeared to respond to dominant gradients of low to high salinity and upland to offshore habitat area; many of the 15 communities identified via cluster analysis showed aggregated spatial distributions that could be related to habitat characteristics. Species in the Mobile River Delta were distinct from those in other areas of the estuary. This analysis supports habitat management in the Mobile Bay estuary; however, due to mobility of organisms among sampling locations and the dynamic environmental conditions in estuaries, we conclude that the analyses presented here are most appropriate for an evaluation of the estuary as a whole.

CASE STUDY: DIELDRIN ATTACK IN DALYAN LAGOON

During the first two weeks of December of 2005, NATO sponsored an Advanced Study Institute (ASI) In Istanbul, Turkey. Part of this ASI involved a case study of a terrorist attack, where a chemical was assumed to be dumped into Sulunger Lake in Turkey. This chapter documents the response developed by the ASI participants to this scenario, in terms of hydrodynamic transport, ecosystem effects, and decision making.

Fish Assemblage Groups in the Upper Tennessee River Basin

Abstract A hierarchical clustering technique was used to classify sites in the upper Tennessee River basin based on relative abundance of fish species. Five site groups were identified. These groups differed mainly by the occurrence of minnow and darter species. Drainage area and ecoregion were the primary factors explaining the differences among groups; elevation and human influence were of secondary importance. The Blue Ridge site group had the most distinct fish assemblage, large-river sites supported the highest species richness, and the upper Ridge and Valley sites contained the highest percentages of environmentally sensitive species. These results can provide a regional framework for management and conservation activities.

Forecasting fish biomasses, densities, productions, and bioaccumulation potentials of Mid-Atlantic wadeable streams

Regional fishery conditions of Mid-Atlantic wadeable streams in the eastern United States are estimated using the Bioaccumulation and Aquatic System Simulator (BASS) bioaccumulation and fish community model and data collected by the US Environmental Protection Agencys Environmental Monitoring and Assessment Program (EMAP). Average annual biomasses and population densities and annual productions are estimated for 352 randomly selected streams. Realized bioaccumulation factors (BAF) and biomagnification factors (BMF), which are dependent on these forecasted biomasses, population densities, and productions, are also estimated by assuming constant water exposures to methylmercury and tetra-, penta-, hexa-, and hepta-chlorinated biphenyls. Using observed biomasses, observed densities, and estimated annual productions of total fish from 3 regions assumed to support healthy fisheries as benchmarks (eastern Tennessee and Catskill Mountain trout streams and Ozark Mountains smallmouth bass streams), 58% of the regions wadeable streams are estimated to be in marginal or poor condition (i.e., not healthy). Using simulated BAFs and EMAP Hg fish concentrations, we also estimate that approximately 24% of the game fish and subsistence fishing species that are found in streams having detectable Hg concentrations would exceed an acceptable human consumption criterion of 0.185 μg/g wet wt. Importantly, such streams have been estimated to represent 78.2% to 84.4% of the Mid-Atlantics wadeable stream lengths. Our results demonstrate how a dynamic simulation model can support regional assessment and trends analysis for fisheries.

Watershed Management in the United States

A watershed approach provides an effective framework for dealing with water resources challenges. Watersheds provide drinking water, recreation, and ecological habitat, as well as a place for waste disposal, a source of industrial cooling water, and navigable inland water transport. Consequently, much depends on the health of watersheds. Watersheds are threatened by wastewater and nonpoint source runoff that load surface waters with excess organic matter, nutrients, pathogens, solids, and toxic substances. Physical alterations, such as paving and stream channelization, change both the hydrologic regime and habitat. Estuaries are of particular importance, since they have great economic, ecological, recreational, and aesthetic value. An approach to the protection, management, and restoration of these water resources in the United States, and the respective roles of federal, state, and local governments, as well as the private sector and volunteer groups, is discussed. Protecting and sustaining watersheds requires that water resource goals be prioritized within a coordinating framework.

Ecosystem Services of Rivers: The Don River (Russian Federation) and the Roanoke River (USA)

The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. River systems provide many services to people, including freshwater provisioning, carbon storage, fisheries, recreation, transportation, and biodiversity. Here, we review the services provided by rivers and describe a conceptual model relating services to drivers, pressures, ecosystem state, and management responses. This approach allowed us to highlight how policies and decisions can lead to trade-offs among services, which must be considered for sustainable watershed management. We have used this conceptual framework to compare two rivers, the Don River in the Russian Federation and the Roanoke River in Virginia/North Carolina, USA, to demonstrate the usefulness of the ecosystem services approach. Future science needs for ecosystem services in rivers are to identify service indicators and map services, link drivers/pressures to services with models, and relate natural systems to social and economic systems.