S. Marshall Adams

A Quantitative Health Assessment Index for Rapid Evaluation of Fish Condition in the Field

Abstract The health assessment index (HAI) is an extension and refinement of a previously published field necropsy system. The HAI is a quantitative index that allows statistical comparisons offish health among data sets. Index variables are assigned numerical values based on the degree of severity or damage incurred by an organ or tissue from environmental stressors. This approach has been used to evaluate the general health status offish populations in a wide range of reservoir types in the Tennessee River basin (North Carolina, Tennessee, Alabama, Kentucky), in Hartwell Reservoir (Georgia, South Carolina) that is contaminated by polychlorinated biphenyls, and in the Pigeon River (Tennessee, North Carolina) that receives effluents from a bleached kraft mill. The ability of the HAI to accurately characterize the health offish in these systems was evaluated by comparing this index to other types of fish health measures (contaminant, bioindicator, and reproductive analysis) made at the same time as the HAI...

Energy Partitioning in Largemouth Bass under Conditions of Seasonally Fluctuating Prey Availability

Abstract Allocation of consumed energy by largemouth bass Micropterus salmoides into their major physiological processes was determined to investigate mechanisms by which these predators maintain condition (overall health) in a system with a seasonally fluctuating prey base. Consumed energy is partitioned into growth, energy storage, and gonads according to temporal prey availability, metabolic demands, and reproductive needs. Throughout minimum-feeding periods in the winter and early spring, largemouth bass utilize energy from visceral fat and body protein for standard metabolic demands and gonad development. Catabolism of energy from body tissue during the winter was less than 33% of standard metabolic demands, indicating that some consumption had to occur during the winter. The calculated activity metabolism of largemouth bass ranged from 18 to 144% of standard metabolism depending on time of year and sex. Parallel trends of activity metabolism and consumption over the year suggest that foraging costs ...

Induction of heat shock proteins, changes in liver ultrastructure, and alterations of fish behavior: are these biomarkers related and are they useful to reflect the state of pollution in the field?

Heat shock protein (hsp70) expression, changes inliver ultrastructure, and alterations of swimmingbehavior were simultaneously investigated in browntrout (Salmo trutta f. fario) exposed towater from test streams in southern Germany undersemi-field conditions during 1995 and 1996. Chemicalanalyses revealed different levels of contamination ofthe two streams by pesticides, PAHs, PCBs, and heavymetals, whereas stream pollution was only partlyreflected by body burdens of contaminants in fish.Biomarker responses were compared after differenttimes of exposure and with respect to differenttemperature conditions. Differences in pollutionstates of the streams were reflected by differentbiomarker responses of the trout. In the highlycontaminated stream, the biomarker responses were morecoincident with one another than in the moderatelypolluted stream in which the biomarkers showed littlerelation to one another. This is primarily due to thedifferential capacities of the biomarkers to integratestress responses over time. Understanding the dynamicsof the stress response curves and the effects oftemperature on biomarker responses is essential forevaluating the effects of environmental stressors suchas contaminants on the health of organisms.

Establishing Causality between Environmental Stressors and Effects on Aquatic Ecosystems

Establishing causal relationships between environmental stressors and observed effects in natural systems is difficult due to the many intrinsic environmental factors that can hinder this process and because there are no widely accepted and proven approaches for determining such relationships. Several types of approaches or combinations of approaches, each with their own sets of advantages and limitations, have been applied in a variety of ecological systems to investigate possible causal relationships between stressors and effects. These include controlled laboratory studies (including acute and chronic bioassays), experimental field manipulations, field studies based on synoptic field surveys, mathematical simulation modeling, statistical associations, various combinations of laboratory, experimental, and field studies, and the ecoepidemiological (weight or evidence) approach. The use of ecoepidemiological (“forensic toxicology”) principles is becoming increasingly attractive as a method to help establish causality because it does not involve the same limitations of other approaches and it can also be used to integrate disparate information within a logical framework so that scientifically and defensible regulatory decisions can be made. The objective of this Commentary series of papers on the issue on causality is to demonstrate the application of the ecoepidemiology approach, using a variety of case history studies, for establishing causal relationships between specific stressors and biological effects. For each case history provided in the following series of papers, the authors describe their study situation, summarize the results supporting a causal relationship, and then compare their study results against seven standard causal criteria.

The use of biomarkers in ecological risk assessment: recommendations from the Christchurch conference on Biomarkers in Ecotoxicology

S. MARSHALL ADAMS1, JOHN P. GIESY 2, LOUIS A. TREMBLAY3 and CHARLES T. EASON3* 1 Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 USA 2 Aquatic Toxicology Laboratory, Department of Zoology, Institute of Environmental Toxicology, National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI 48824 USA 3 CENTOX (Centre for Environmental Toxicology), Landcare Research, PO Box 69, Lincoln, New Zealand.

Evaluating Effects of Contaminants on Fish Health at Multiple Levels of Biological Organization: Extrapolating from Lower to Higher Levels

Effects of environmental stressors such as contaminants on the health of aquatic ecosystems usually involve a series of biological responses ranging from the biomolecular/biochemical to the population and community levels. To establish relationships and to determine the feasibility of extrapolating between higher and lower levels of biological organization, spatial patterns in fish responses to contaminant loading were investigated in a stream receiving point-source discharges of various contaminants near its headwaters. Relationships among fish responses at four major levels of biological organization (biochemical/physiological, individual, population, and community levels) were evaluated relative to patterns in contaminant loading along the spatial gradient of the stream. Both individual and integrated response analysis demonstrated that bioindicators at several levels of biological organization displayed similar downstream patterns in their response to contaminant loading within the stream. Some of the bioindicator responses at lower levels of organization appear to be useful for the ecological risk assessment process because of their sensitivity and apparent relationships to higher levels. By identifying and establishing relationships between levels of biological organization we should be better able to understand the mechanisms of stress responses in ecological systems that could ultimately result in improved predictive capability of ecological risk assessment and also allow for more informed decisions regarding remedial actions.

Relationship between genotoxicity, mutagenicity, and fish community structure in a contaminated stream

Genotoxic responses (chromosomal damage, DNA strandbreakage) of redbreast sunfish (Lepomis auritis)populations exposed to industrial effluent andmutagenicity of the associated sediments weredetermined in order to compare them to changes incommunity structure. Data were collected from areference stream and East Fork Poplar Creek (EFPC), afirst-order stream which originates on the grounds ofthe Department of Energy Y-12 Plant at Oak Ridge, TN. This stream is contaminated with mercury, PCBs, andnumerous other compounds. Previous studies have shownthat sediment contaminant concentrations, as well asphysiological biomarker responses of the local fishpopulations, are highest at the headwaters of EFPC anddecrease with increasing distance from the DOEfacility as contaminant loading decreases. Chromosomal damage was measured by flow cytometry – asreflected by variation in cellular DNA content – andstrand breakage was determined by agarose gelelectrophoresis using blood as the source of DNA. Mutagenicity was determined by theSalmonella/microsome assay using organic solventextracts of sediment surface samples. Community levelresponses included community diversity and percentpollution-tolerant species. Biomarker responses andmutagenicity were found to be highest at theheadwaters of EFPC, and tended to decrease withincreasing distance from the effluent. In general,biomarker responses appeared to be correlated withmutagenicity of the sediment, and both of theserelated to fish community disturbance and level ofstream contamination. Because responses at severallevels of biological organization show similarpatterns of downstream effects, this suggests thatthere may be a causal relationship betweencontamination and biological effects.

A comparison of health assessment approaches for evaluating the effects of contaminant-related stress on fish populations

Various methods are available for investigating the effects of environmental conditions or stress on fish ranging from assessments at the individual level to the population and community level. Each method, however, has limitations and advantages, and the type of method used influences the interpretation of stressor effects on fish health. We compared and evaluated three methods for investigating the effects of contaminants on fish health for populations in a stream receiving a variety of industrial effluents including PCBs, heavy metals (primarily mercury), and chlorine. These methods are: (1) individual bioindicator variables including measurements of biochemical, physiological, histopathological, and organismal-level responses, (2) statistically based integrative indices based on multivariate responses, and (3) integrative ecologically relevant measurements such as population and community-level responses. Many of the individual-level measurements reflect biochemical and physiological conditions and are therefore short-term response indicators of stress. Use of several individual variables in multivariate discriminant analysis allows a more integrative approach for evaluating response of fish to stressors. Community- and population-level measurements integrate the responses to a variety of environmental conditions and therefore may be less reflective of contaminant-induced stress. The three methods used together provide the best strategy for evaluating fish health in order that environmentally sound decisions can be made regarding the implications of contaminant-related stress on aquatic ecosystems.

Biomarker/bioindicator response profiles of organisms can help differentiate between sources of anthropogenic stressors in aquatic ecosystems.

Aquatic ecosystems can be chronically stressed by multiple environmental factors which originate from a variety of point and non-point sources. In addition, these stressors may vary both spatially and temporally, and, combined with synergestic and cumulative interactions of these stressors, complicate the interpretation and evaluation of stress responses in organisms. To help identify and differentiate between sources of anthropogenic stressors in aquatic systems, a diagnostic approach based on exposure-response profiles in sentinel organisms was developed from the known effects of various anthropogenic activities on biological systems. To generate these exposure-effects profiles, biomarkers of exposure were plotted against bioindicators of corresponding effects for several major anthropogenic activities including petrochemical, pulp and paper, domestic sewage, mining operations, land-development, and agricultural activities. Biomarkers of exposure to environmental stressors varied widely depending on the type of anthropogenic activity involved. Bioindicator effects, however, including histopathological lesions, bioenergetic status, growth, reproductive impairment, and community-level endpoints were similar among several of the major anthropogenic activities because responses at these higher levels are less specific to stressors than are biomarkers. This approach appears useful for helping to identify and diagnose sources of stress in environments impacted by multiple stressors. By identifying the types and sources of environmental stressors impacting key components of biological systems, aquatic ecosystems can be more effectively protected, regulated, and managed to help improve and maintain environmental quality and ecosystem fitness.

Application of multiple sublethal stress indicators to assess the health of fish in Pamlico Sound following extensive flooding

Multiple indicators of sublethal stress (bioindicators) were used to assess the health and condition of two important estuarine fish species in the Pamlico Sound estuary following extensive flooding from three sequential hurricanes that occurred during early fall 1999. Bioindicators ranging from the biochemical to the reproductive and organism-level were used to assess the health of southern flounder and spot in Pamlico Sound compared to the health of these same species sampled from a relatively unaffected references site in lower Core Sound. Many of the physiological, reproductive, immunological, histopathological, and general condition indices suggested that both species, and particularly spot, in Pamlico Sound were sublethally stressed and in poorer condition than fish sampled from Core Sound. The major environmental stressors causing these sublethal stress responses in Pamlico Sound fish appears to be those related to episodic hypoxic exposure or a combination of effects associated with hypoxic conditions such as alterations in preferred habitat and food availability. Although fish populations in Pamlico Sound do not appear to be severely damaged or impaired at this time, organisms that are sublethally stressed can incur increased vulnerability to additional or future stressors such as modified physicochemical regimes, changes in food and habitat availability, and increases in infectious pathogens. Because of the low flushing rate (∼1 yr) of Pamlico Sound, recovery rate may be exceptionally slow, prolonging any adverse effects of altered nutrient regimes (such as hypoxia) on the health and fitness of resident fish populations. Flooding from the 1999 hurricanes may have contributed to the short-term health and condition of finfish species in Pamlico Sound and also influenced longer-term recovery and ecological status of this system. Longer-term manifestation of effects from flooding may be of particular concern as the frequency of hurricanes is expected to increase over the next few years and the accelerated uses of the coastal zone places further stress on estuarine resources.