Book Chapter & Symposium Paper Citations and Abstracts

Attempts to obtain field data for risk ssessment of contaminants released into marine/estuarine systems can be complicated by a number of interrelated factors such as: complex circulation and mixing patterns, diverse stratification forces, dynamic short-term changes as well as seal movements of biota, and the ecosystem's physical scale. Tests conducted in simulated ecosystems are subject to constraints that restrict the effect of physical forces, limit physical scale of the test, and introduce biases from chemical partitioning and processing along the walls of the test system. These constraints restrict the broad application of test results as a model of dynamic marine systems. Through selected examples from literature and ongoing studies, we provide illustrations of how contaminant effects are studied at the individual population, and community level in the field and/or in simulated ecosystems, such as mesocosms. We discuss marine-environment field studies and simulated field studies that measure contaminant effects with respect to exposure-response relationships, food-web interactions, competition/colonization studies, and selected aspects of nutrient cycling. Based on results to date, we conclude that: (1) successful field studies must focus on selected endpoints fundamental to our understanding of contaminant effects, and (2) endpoints studied in simulated ecosystems must be representative of key structural and/or functional factors of the system of interest.

Middaugh, D.P, L.R. Goodman and M.J. Hemmer. 1993. Methods for Spawning, Culturing, and Conducting Toxicity Tests with Early Life-Stages of Estuarine and Marine Fishes. In: Handbook of Ecotoxicology, Volume One. EPA/600/A-94/034. Peter Calow, Editor. Blackwell Scientific Publishers, Ltd., Oxford, England. Pp. 167-192. (ERL,GB 749). (Avail. from NTIS, Springfield, VA: PB94-155389)

This chapter provides a detailed description of the life history, geographical distribution, and procedures for laboratory spawning, culturing and testing of five fishes,the sheepshead minnow, Cyprinodon variegatus, the inland silverside, Menidia beryllina, Atantic silverside, M. menidia, California grunion, Leuresthes tenuis, and topsmelt, Atherinops affinis. Procedures for conducting acute toxicity tests (static and flow-through) as well as early life-stage toxicity tests are presented. Methods required for culturing of food organisms, the alga, Isochrysis galbana, rotifers, Brachionus plicatilus, and brine shrimp, Artemia salina, are also described. Tabular and diagrammatic data summaries of pertinent information required for utilization of each species in evaluation of environmental toxicants is presented. Suggestions are also given on species indigenous to South America, Western Europe, the Adriatic, Caspian, Mediterranean and Red Seas, the Persian Gulf, Japan and the Western Pacific which may be useful in the assessment of environmental pollutants in the regions.

Kent, Michael L. and John W. Fournie. 1993. Importance of Marine Fish Diseases--An Overview. In: Pathobiology of Marine and Estuarine Organisms. EPA/600/A-93/130. John A. Couch and John W. Fournie, Editors. CRC Press, Boca Raton, FL. Pp. 1-24. (ERL,GB 751). (Avail. from NTIS, Springfield, VA: PB93-204113)

This chapter reviews the major diseases of marine and estuarine fishes in three categories: 1) those affecting wild fishes, 2) those affecting captive fishes (e.g., fishes reared in fish farms or aquaria), and 3) those used as models for biomedical research. The three categories reflect the two major research areas of fish pathology. Research on infectious diseases is performed primarily on captive fishes, whereas research on fish as sentinels of xenobiotic effects primarily utilizes wild fish but may use small aquarium species for biomedical models.

Clark, J.R. and C.R. Cripe. 1993. Marine and Estuarine Multi-Species Test Systems. In: Handbook of Ecotoxicology, Volume One. EPA/600/A-94/033. Peter Calow, Editor. Blackwell Scientific Publications, Oxford, England. Pp. 227-247. (ERL,GB 758). (Avail. from NTIS, Springfield, VA: PB94-155371)

Marine and estuarine habitats have a great deal of temporal and spatial variability due to the highly complex physical and chemical components that interact with biological components to yield dynamic ecosystems. Salinity differences among component water masses represent one example of the many factors affecting the distribution of the biota within marine and estuarine systems. Salinity differences can range from a few parts per thousand to greater than fifty parts per thousand and commonly establish gradients within an estuary that change over time. This variability sometimes results from predictable and periodic short-term, tidal cycles and longer-term, seasonal changes in physical and chemical forces, such as freshwater inflow, temperature, and wind patterns operating within the ecosystem and at the system boundaries. Other, less predictable forces, such as daily winds, storm events, human intervention, etc., also contribute to temporal and spatial variability within marine systems over short-term and long-term durations and small and large areas. Understanding the effects of pollutants on these ecosystems requires tools that present defined ecosystem boundaries, control and manipulation of many environmental factors and minimal temporal and spatial variability or defined limits for change. These investigation and testing tools, commonly known as microcosms and mesocosms, offer a wide range of complexity in species and ecological make up and sophistication in materials and mechanical engineering for addressing ecotoxicological problems. In this chapter, we provide examples of various types of multispecies test systems that have been used in marine and estuarine studies and discuss their role in ecotoxicological assessments.

Coffin, Richard B. and Luis A. Cifuentes. 1993. Approaches for Measuring Stable Carbon and Nitrogen Isotopes in Bacteria. In: Handbook of Methods in Aquatic Microbial Ecology. EPA/600/A-93/221. P.F. Kemp, B.F. Sherr, E.B. Sherr and J.J. Cole, Editors. Lewis Publishers, Boca Raton, FL. Pp. 663-675. (ERL,GB 768). (Avail. from NTIS, Springfield, VA: PB93-234490)

Stable isotopes have been used successfully over the past three decades to trace through aquatic food chains. This technique, however, has only recently been used to examine aquatic microbial roles in elemental cycling. The major obstacle to measuring stable isotope compositions in bacteria has been the concentration of enough bacteria and separation of bacteria from other microorganisms and bacterial-sized particles. This paper describes direct and indirect approaches developed to measure stable carbon and nitrogen isotope compositions and sources of bacterial carbon and nitrogen.

Couch, John A. 1993. Observations on the State of Marine Disease Studies. In: Pathobiology of Marine and Estuarine Organisms. EPA/600/A-93/136. John A. Couch and John W. Fournie, Editors. CRC Press, Boca Raton, FL. Pp. 511-530. (ERL,GB 780). (Avail. from NTIS, Springfield, VA: PB93-204170)

State of marine disease studies is described. Perhaps the greatest area of success in the last 20 years has been in the identification and characterization of viruses, bacteria, fungi, protozoan and metazoan disease agents. Opening of new areas of investigation such as that of interactions between pollutants and infectious agents or non-infectious syndromes such as neoplasia have provided challenges to younger, better equipped investigators in recent efforts. These successes, though not complete in themselves, provide an impetus to understanding complex disease issues. Long standing enigmas, such as complete understanding of the complex life-cycles of devastating pathogens such as protozoans of shellfish, and roles of certain toxicants in fish diseases remain to be better understood.

Lloyd, J.R., L.R. Goodman and J.A. Couch. 1993. Chronic Exposure of Sheepshead Minnows to a 60HZ Electromagnetic Field. In: Electricity and Magnetism in Biology and Medicine. Martin Blank, Editor. San Francisco Press, San Francisco, CA. Pp. 842-844. (ERL,GB 793).

Sheepshead minnows (Cyprinodon variegatus) were reared in a reference aquarium and in an aquarium within a 60-Hz electromagnetic field (EMF) in a 156 day preliminary experiment. Modified Helmholtz coils surrounding the exposure aquarium generated a horizontal 1.0 to 1.25 mT rms magnetic field throughout the water volume. Two groups of fish and samples of their embryos were exposed in overlapping exposure periods. Fish in Group I grew from juveniles to reproducing adults during 54 days of exposure. Exposure of Group II began with artificially spawned embryos that hatched and grew to reproducing adults while exposed for 137-152 days. Naturally spawned progeny from both groups were incubated to hatching in the same saltwater aquaria as parents. Although some significant effects (a=0.05) on test endpoints were observed between treatments, they were not consistently significantly different across exposure groups, life stages, et cetera. No behavioral and histopathological effects related to the EMF were observed.

Mayer, F.L., T.W. Duke and W.W. Walker, Editors. 1993. Estuarine Assessment and Contaminant Problem Identification. NOAA Technical Memorandum NMFS-SEFSC-330. 63 p. (ERL,GB 794).

This document summarizes a workshop on Estuarine Assessment and Contaminant Problem Identification held in Biloxi, Mississippi, April 23-25, 1991. The workshop concept evolved through the U.S. EPA's Gulf of Mexico Program (Toxic Substances & Pesticides Subcommittee) and involved scientists and managers from throughout the Gulf of Mexico area.

Mueller, J.G., S.E. Lantz, R.L. Thomas, D.P. Middaugh and P.H. Pritchard. 1993. Remediation of Ground Water Contaminated with Organic Wood Preservatives Using Physical and Biological Treatment Technologies. In: International Symposium on Environmental Contamination in Central and Eastern Europe: Budapest '92, October 12-16, 1992, Budapest, Hungary: Symposium Proceedings. Florida State University, Tallahassee, FL. Pp. 819-821. (ERL,GB 800).

Pilot-scale field studies at the American Creosote Works Superfund Site, Pensacola, Florida, evaluated two technologies for their ability to treat ground water contaminated with creosote and pentachlorophenol (PCP): 1)Hyperfiltration (volume reduction), and 2) Bioremediation using specially-selected microorganisms (terminal destruction). The hyperfiltration unit was operated in a cross-flow mode yielding "concentrate" (containing excluded chemicals) and "permeate" (clean, aqueous material passing through the membrane). Operating over a 6-day period on site, a total of 6,300 gallons of creosote- and PCP-contaminated ground water (average total semi-volatile concentration was 88.5 mg/L) was processed there by reducing the volume of contaminated material less than 80% while removing less than 95% of the PAHs. Simultaneously, the concentration of chlorinated dioxins and furans were reduced from 22.5 ppb in the feed to 0.047 ppb (cumulative) in the permeate. Based on chemical analyses and biological toxicity and teratogenicity assays, the permeate stream was acceptable for direct discharge. A two-stage, continuous-flow, sequential inoculation bioreactor strategy for the bioremediation of ground water contaminated with creosote and pentachlorophenol (PCP) was also evaluated. Performance of continually stirred tank reactors using specially-selected microorganisms was assessed according to chemical analyses of system influent, effluent and bioreactor residues, a chemical mass balance evaluation, and comparative biological activity and teratogenicity measurements. When specially-selected bacteria capable of utilizing high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs) as primary growth substrates were used in pilot-scale bioreactors (454 L), the concentration of creosote constituents was reduced from ca. 1,000 ppm in the ground water feed (flow rate = 114 L/day) to less than 9 ppm in the system effluent (removal efficiency of less than 99%). Notably, the cumulative concentration of 8 HMW PAHs (containing 4 or more fused rings) was reduced from 368 ppm in the ground water feed to 5.2 ppm in the system effluent. Moreover, the toxicity and teratogenicity of the bioreactor effluent was significantly reduced. Biodegradation of PCP was limited (ca. 24%) due in large part to poor inoculation and a high degree of abiotic loss (bioaccumulation and adsorption).

Devereux, Richard and David Stahl. 1993. Phylogeny of Sulfate-Reducing Bacteria and a Perspective for Analyzing Their Natural Communities. In: Sulfate-Reducing Bacteria: Contemporary Perspectives. J.M. Odom and Rivers Singleton, Jr., Editors. Springer-Verlag, New York, NY. Pp. 131-160. (ERL,GB 807).

Authors summarize recent phylogenetic studies of sulfate-reducing bacteria and the application of 16S rRNA sequence information to environmental studies of these bacteria. A brief overview is provided on the use of 16S rRNA sequences to infer phylogenetic relationships. Where possible, some of the nutritional and biochemical characteristics of sulfate-reducing bacteria have been placed in an evolutionary context.

Mueller, J.G., J.-E. Lin, S.E. Lantz and P.H. Pritchard. 1993. Innovative Methods for Implementing Bioremediation Technologies. In: Proceedings of the Sixth Annual Environmental Management and Technology Conference/Central: 93 HazMat Central. Advanstar Expositions, Glen Ellyn, IL. Pp. 352-364. (ERL,GB 824).

Our understanding of the biodegradation of potentially hazardous organic chemicals in the environment continues to expand at a rapid rate. For example, unique microorganisms possessing novel biodegradative abilities continue to be discovered, our knowledge of physicochemical factors limiting biological activity in the field (eg., bioavailability has increased, and innovative methods for assessing and monitoring field performance have been developed. Concomitantly, innovative strategies for integrating microbiological advances with new implementation tools have provided bioremediation technologies with significant application potential. This paper summarizes existing biotreatment approaches, presents some of the inherent benefits and disadvantages associated with each technology, and describes some of the more recent advances in the bioremediation industry made by SBP Technologies, Inc. (SBP) and our collaborators IEG Technologies, Inc., Charlotte, NC, GfS-Germany, The U.S.Environmental Protection Agency, The University of Waterloo-Canada, and The University of West Florida. We also summarize laboratory and field studies designed to demonstrate the ability of these strategies to provide cost-efficient, effective tools for full-scale remediation of soil and water impacted by compounds notoriously difficult to treat biologically.

Devereux, R., J. Kurtz and G. Mundfrom. 1993. Molecular Phylogenetic Explorations of Natural Microbial Community Composition and Diversity. In: Trends in Microbial Ecology. EPA/600/A-94/115. R. Guerrero and C. Pedros-Alio, Editors. Spanish Society for Microbiology, Barcelona, Spain. Pp. 387-390. (ERL,GB 886). (Avail. from NTIS, Springfield, VA: PB94-190832)

Comparative sequence analysis of ribosomal RNA molecules has led to a phylogenetic-based approach to characterize natural microbial communities. The approach has been applied to study natural communities of sulfate-reducing bacteria. Hybridization probes were used to measure relative amounts of specific sulfate reducer rRNAs in an estuarine sediment. Selective amplification, cloning, and comparative sequence analysis of 16S ribosomal RNA gene sequences have revealed new diversity among sulfate-reducing bacteria.

Genthner, Barbara R. Sharak. 1993. Anaerobic Biodegradation of 5-Chlorovanillate as a Model Substrate for the Bioremediation of Paper-Milling Waste. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 131-136. (ERL,GB X762).

The anaerobic biodegradation of 5-chlorovanillate (5CV; 5-chloro-4-hydroxy-3-methoxybenzoic acid) was investigated. 5CV was selected as a model compound for studying the biodegradation of paper-milling effluents because it contains the methoxy-, chloro- and carboxyl side groups representative of those present on aromatic chlorinated compounds released in paper-milling effluent. Using sediment from a river receiving discharge from a paper milling plant, an anaerobic enrichment culture was developed which degraded 5CV. The major pathway of 5CV degradation in this enrichment culture was concluded to be stepwise demethoxylation to 5-chloroprotocatechuate (5CP; 5-chloro-3,4-dihydroxybenzoic acid), decarboxylation to 3-chlorocaechol (3CC; 3-chloro-1,2-dihydroxybenzene), and dechlorination to catechol which was completely degraded. Dechlorination of 3CC was the rate-limiting step of degradation.

Lin, Jian-Er, James G. Mueller and P. Hap Pritchard. 1993. Factors Determining the Effectiveness of Microbial Inoculation in Soils and Sediments: Effectiveness of Encapsulation. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 86-89. (ERL,GB X763).

Effectiveness of microbial inoculation in soils and sediments for bioremediation and pollution control may be determined by the following factors: 1) concentration of active inoculants, 2) interaction between added microorganisms and indigenous populations, 3) nutrient (including electron acceptor) supplies to the target microorganism,, 4) availability of target compounds to the added microorganism, and 5) effects of heterogenous matrices on the biodegradation process. Manipulation of these factors has become a critical issue in an inoculation practice. In this study, use of cell encapsulation technologies was proposed to overcome some of the existing difficulties associated with inoculation for bioremediation. To understand the effect of encapsulated microbial inoculants on a biodegradation process, several encapsulation technologies were established or evaluated. Use of these technologies for biodegradation of HMW PAHs and pesticides in soil-associated systems was explored. The outline of this work follows.

Shields, Malcolm S., Michael Reagin, Robert Gerger, Rhonda Schaubhut, Robert Campbell, Charles Somerville and P. Hap Pritchard. 1993. Field Demonstration of a Constitutive TCE Degrading Bacterium for the Bioremediation of TCE. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 73-79. (ERL,GB X764).

The degree to which trichloroethylene (TCE) has been recognized as a significant environmental pollutant is reflected by the amount of research into methods for its remediation. Despite the demonstrated environmental hazards, its industrial use continues apace because few alternatives exist. TCE owes its environmental behavior partly to its physical properties (i.e. high density and water solubility and low chemical reactivity), and partly to its biological recalcitrance. Both contribute to its notoriety as a persistent point source pollutant, despite numerous reports of both anaerobic and aerobic bacterial transformation capabilities. Aerobic bacteria are more rapid TCE metabolizers, but do so only in a cooxidative fashion. TCE serves as a cooxidative substrate for various bacterial oxygenases, but not as an inducer of them. These bacteria require co-inducers that include, toluene, phenol, methane, ammonia, isoprene, 2,4-dichlorophenoxyacetic acid (2,4-D), and propane. Our research has centered on the microbiology of P. cepacia G4, which expresses a unique toluene ortho- monooxygenase (Tom) in response to various aromatic inducers. Tom carries out the cooxidative metabolism of TCE by this strain. We have developed a non-recombinant derivative of G4, called G4 PR1, that constitutively expresses Tom, and consequently degrades TCE without the need for co-inducer. This communication deals with out characterization, alteration and application of this constitutive derivative.

Shields, M.S., R. Snyder, M. Reagin, R. Gerger, R. Campbell, C. Somerville and P.H. Pritchard. 1993. Bioremediation of TCE: Monitoring the Fate and Effects of a Microorganism Used in a Field Bioaugmentation Study. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 80-85. (ERL,GB X765).

The development of a constitutive trichloroethylene (TCE)-degrading Pseudomonas cepacia provides us with a unique opportunity to study several microbiological aspects of bioremediation that many believe to be altogether overlooked. Methods for the utilization of such organisms range from contained above ground bioreactors, to more passive in situ designs. Implicit to our understanding of the overall effectiveness of this organism in its biodegradation of a target pollutant like TCE, is an exploration of the microbial behavior of such a laboratory construct under anticipated operational conditions. At the onset, these questions are more readily addressed in a contained bioreactor than in an environmental application. Problems associated with the use of laboratory bacteria in field releases include both optimizing the activity of the organism under environmental conditions and defining the risk associated with the introduction of a non-native or genetically altered microorganism. The use of a co-oxidative bacterial pathway does not permit direct selection for the organism because the pollutant cannot be utilized as a carbon and energy source. Therefore, nutrients must be added to the contaminated aquifer in order to feed the TCE degrader. As a result, a significant shift in the downstream aquifer microbial community is anticipated. The primary purpose of this research is to address not only the fate of the introduced altered bacterium and the specific genetic elements involved, but also the extent to which this treatment technology may affect the native microbial populations during an in situ bioremediation experiment. The anticipated application of this organism in situ will involve the addition of TCE, and nutrients to an aquifer engineered to contain a bacterial treatment system.

Mueller, James G., Suzanne E. Lantz, Jian-Er Lin and P. Hap Pritchard. 1993. Innovative Bioremediation Strategies for Creosote: Characterization and Use of Inocula. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 47-50. (ERL,GB X766).

We are currently using encapsulation technologies to improve the solid-phase bioremediation of soils contaminated with organic wood preservatives (i.e., creosote and PCP). The importance of the encapsulated cells for these applications is to: 1) ensure the consistent presence of catabolically relevant, active biomass, 2) provide for slow-release of essential nutrients and electron acceptor, and 3) offer an ecological niche conducive to microbial growth, proliferation and catabolism. Results to date have identified effective encapsulation and immobilization technologies for various PAH- and pesticide-degrading bacteria. Depending on the desired end points, this strategy may offer a viable remedial approach for creosote- and similarly contaminated soils. Similarly, immobilized cells in liquid bioreactor systems (above ground or in situ bioreactors) are being tested for their ability to treat ground water impacted by related compounds. In addition, research is being conducted to determine the effectiveness of co-encapsulating microorganisms (e.g., HMW PAH-degraders) with nutrients, electron acceptors and/or electron donors.

Mueller, James G., Suzanne E. Lantz, Richard Devereux, Deborah L. Santavy and P. Hap Pritchard. 1993. Innovative Bioremediation Strategies for Creosote: Geographic Diversity of PAH Degradation Capabilities at Wood-Treating Sites. In: Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations. EPA/600/R-93/054. U.S. Environmental Protection Agency, Office of Research and Development, Biosystems Technology Development Program, Washington, DC. Pp. 208-213. (ERL,GB X767).

The use of specially selected microorganisms to enhance bioremediation efforts has proved effective in a number of applications, especially when combined with bioreactor systems. In our studies, the successful use of such isolates for the remediation of soil and water contaminated with organic wood preservatives (e.g., creosote and pentachlorophenol [PCP]) has resulted in the opportunity to employ these technologies at similarly contaminated sites throughout the world. However, prior to world-wide dissemination of bioremediation strategies, concerns regarding the introduction of foreign biota needed to be addressed. Therefore, we embarked on a research program to ascertain: 1) whether microorganisms similar to those used in our bioremediation strategies could be found in other soils, and, 2) if so, whether the introduction of these isolates offers any advantages to the bioremediation system.

Pritchard, P.H. 1993. Effectiveness and Regulatory Issues in Oil Spill Bioremediation: Experiences with the Exxon Valdez Oil Spill in Alaska. In: Biotreatment of Industrial and Hazardous Waste. EPA/600/A-94/205. Morris A. Levin and Michael A. Gealt, Editors. McGraw-Hill, New York, NY. Pp. 269-307. (ERL,GB X794). (Avail. from NTIS, Springfield, VA: PB95-122933)

The use of bioremediation as a supplemental cleanup technology in the Exxon Valdez oil spill, in Prince William Sound, Alaska, has proven to be a good example of the problems and successes associated with the practical application of this technology. Field studies conducted by scientists from the U.S. Environmental Protection Agency have demonstrated that oil degradation by indigenous microflora on the beaches of Prince William Sound could be significantly accelerated by adding fertilizer directly to the surfaces of oil-contaminated beaches. Our results from the application of an oleophilic fertilizer are presented as exemplary field and laboratory information. The fertilizer enhanced biodegradation of the oil, as measured by changes in oil composition and bulk oil weight per unit of beach material, by approximately twofold relative to untreated controls. These studies supported bioremediation as a useful cleanup alternative that was subsequently used by Exxon on a large scale. They have also generated a number of insightful lessons that have significant relevance to future oil bioremediation efforts. This chapter discusses these lessons and examines complications and difficulties in asssessing the effectiveness of bioremediation in the field.

Gealt, Michael A., Morris A. Levin and Malcolm Shields. 1993. Use of Altered Microorganisms for Field Biodegradation of Hazardous Materials. In: Biotreatment of Industrial and Hazardous Waste. EPA/600/A-94/203. Morris A Levin and Michael A. Gealt, Editors. McGraw-Hill, New York, NY. Pp. 197-208. (ERL,GB X797). (Avail. from NTIS, Springfield, VA: PB95-122958)

The large amount of hazardous waste generated and disposed of has given rise to environmental conditions requiring remedial treatment. The use of landfills has traditionally been a cost-effective means to dispose of waste. However, increased costs of transportation and decreasing numbers of landfill sites now necessitate the examination of treatment processes that can be carried out on site (land farming, composting), and, preferably, in situ. Thus, economics dictate the exploration of bioremediation techniques as potentially environmentally sound cost reduction methods. Although the use of genetically engineered microorganisms has been considered, to date most bioremediation has been accomplished by enhancing the growth of indigenous microorganisms, or by augmenting the microbial population with exogenous organisms isolated from the site in question or from similar sites (Fox, 1992). Bioaugmentation, as currently practiced, uses naturally occurring organisms. The added organisms either furnish an associative consortium or, perhaps most importantly, significantly increase the titer of degraders. The delay in utilization of laboratory-bred microorganisms results in part from unclear regulatory procedures promulgated by federal, state, and local agencies as to which organisms are sufficiently modified to warrant regulation as novel (i.e., engineered) organisms. In an advertising circular for The Bioremediation Report (published by COGNIS, Inc., Santa Rosa, CA 95407) the author noted that'...bioremediation is very much an enigma. Albeit, a well studied enigma.' It is anticipated that the enigma will be clarified within the next few years. This chapter will examine the advantages and disadvantages of using natural and modified organisms from scientific and regulatory perspectives.

Lewis, M.A. 1993. Freshwater Primary Producers. In: Handbook of Ecotoxicology, Volume One. Peter Calow, Editor. Blackwell Scientific Publications, Oxford, England. Pp. 28-50. (ERL,GB X837).

Freshwater algae and vascular plants (macrophytes) have been used by aquatic ecologists for many years to monitor basic limnological characteristics and to determine the impact of pollution on ponds, lakes and rivers. Reviews of the various methodologies used in floristic surveys have been published by, among others, Shubert (1984) and Stevenson & Lowe (1986). In contrast to their use as bioindicator species, the use of aquatic plants as test species in laboratory toxicity tests has been less common than animal species such as daphnids and fish. For example, only 3% of the premanufacturer notices (PMN) required by the U.S. Toxic Substances Control Act(TSCA) have contained phytotoxicity data (Benenati, 1990). This is changing, however, due to increasing environmental regulations for chemicals in the USA (Holst & Ellwanger, 1982; US EPA, 1985a) and in the EC (OECD, 1984; EEC, 1987; ISO, 1987; Freemark et al., 1990). Phytotoxicity data are also considered for the development of water quality criteria (Stephen et al., 1985) and to evaluate the toxicities of dredge and fill material (US Army COE, 1989), food and drug additives (Eirkson et al, 1987) and industrial and municipal effluents (Laake, 1982; Weber et al, 1989). Overall, the ecological importance of freshwater plants and current regulatory expectations make them desirable test species in toxicity studies. This chapter reviews the current test methodologies and discusses the use of the results. The information presents an overview only; additional details are included in the references and are essential if the toxicity tests described are to be successfully conducted.

Benson, W.H., J.M. O'Neal, J.C. Allgood, M.A. ElSohly and J.K. Summers. 1993. Evaluation of Tissue Residues for the Environmental Monitoring and Assessment Program Near Coastal - Louisianian Demonstration. In: Proceedings, Twenty-Third Mississippi Water Resources Conference, 6-7 April 1993, Jackson, Mississippi. B. Jean Daniel, Editor. Water Resources Research Institute, Mississippi States, MS. Pp. 77-85. (ERL,GB X915).

The Environmental Monitoring and Assessment Program (EMAP) is a national program developed by the U.S. Environmental Protection Agency in response to the need for information about the degree to which existing pollution control programs and policies protect the nation's ecological resources. EMAP-Estuaries represents one portion of EMAP's efforts in near coastal environments. These efforts are designed to provide a quantitative assessment of the regional extent of coastal environmental problems by measuring status and change in selected condition indicators. The Louisianian Province Demonstration Project, which focuses on the Gulf of Mexico, provides a mechanism by which cooperators can collect and assemble environmental data relevant to the Gulf. Currently, one-sixth of the U.S. population lives in states bordering the Gulf of Mexico. Many of these citizens either directly or indirectly depend on the Gulf of Mexico for their livelihood (DOC 1990a; 1990b). Two-thirds of the contiguous U.S. drains into the Gulf of Mexico (Buff and Turner 1987). Ports along the Gulf handle 45% of U.S. import-export shipping tonnage. Approximately one-third of the marine recreational fishing activities in the continental U.S. occur in the Gulf. Forty percent of the U.S. commercial fish and shellfish yield, approximately 2.5 billion pounds each year, come from the Gulf. The Gulf provides critical habitat for 75% of the nation's migrating waterfowl, some 500 species, and is home to numerous endangered species (EPA 1992). Nevertheless, to date, relatively little attention has been focused on environmental concerns in the Gulf as compared to its counterparts in the northwest and northeast. This study represents the first year of data available for analytical chemistry evaluations which will encompass species (fish and shellfish) collected from the EMAP - Louisianian Province Demonstration Project for 1991.