Arthington, Angela, H., 257 Balon. Eugene, K., 11, 225 Barlow, George, W., 331 Bence, James, R., 113 Boehlert, George, W., 59 Bowman, Ray, E., 171 Browman, Howard, I., 25 Bruton, Michael, N., 225 Cailliet. Gregor, M., 9 Cochran, Philip, A., 219, 325 Cowen, Robert, K., 193 Crowder, Larry, B., 147. 205 D’Avanzo, Charlene, 105 Ebeling, Alfred, W., 123 Gee, John, H.. 269 Govoni. John, J., 59 Holbrook, Sally, J., 135 Jastrzebski, Zbigniew, T., 256, 330 Jobling, Malcolm, 35 Kitchell, James, F., 205. 219, 309 Kraft, Clifford. E., 309 Lasta, Carlos, 105 Laur, David, R.. 123 Marcotte, Brian, M., 25 Masser, Michael, P., 321 McAllister. Don, E., 336 Menzel, Bruce, W.. 243 Miller, Marlyn, L., 243 Milton, David, A., 257 Mittelbach, Gary, 159 Mullen, Ashley, J., 183, 213 Neil], William. H.. 321 Noakes, David, L.G.. 95 Olson, Robert, J., 183 Pascual, Miguel, 105 Persson, Lennart, 51 Roberts. Tyson, R., 231 Schmidt, Kathleen, A., 294 Schmitt, Patricia, D., 79 Schmitt, Russell, J.. 135 Simenstad, Charles, A.. 9 Smith. John. D., 295 Stone, Dayton, Bryan, 267 Swales. Stephen, 279 Tarnchalanukit, Wit, 317 Valiela, Ivan, 105 Watanabe, Yoshirou. 59 White. David. S.. 105

Arthington, Angela, H., 257 Balon. Eugene, K., 11, 225 Barlow, George, W., 331 Bence, James, R., 113 Boehlert, George, W., 59 Bowman, Ray, E., 171 Browman, Howard, I., 25 Bruton, Michael, N., 225 Cailliet. Gregor, M., 9 Cochran, Philip, A., 219, 325 Cowen, Robert, K., 193 Crowder, Larry, B., 147. 205 D’Avanzo, Charlene, 105 Ebeling, Alfred, W., 123 Gee, John, H.. 269 Govoni. John, J., 59 Holbrook, Sally, J., 135 Jastrzebski, Zbigniew, T., 256, 330 Jobling, Malcolm, 35 Kitchell, James, F., 205. 219, 309 Kraft, Clifford. E., 309 Lasta, Carlos, 105 Laur, David, R.. 123 Marcotte, Brian, M., 25 Masser, Michael, P., 321 McAllister. Don, E., 336 Menzel, Bruce, W.. 243 Miller, Marlyn, L., 243 Milton, David, A., 257 Mittelbach, Gary, 159 Mullen, Ashley, J., 183, 213 Neil], William. H.. 321 Noakes, David, L.G.. 95 Olson, Robert, J., 183 Pascual, Miguel, 105 Persson, Lennart, 51 Roberts. Tyson, R., 231 Schmidt, Kathleen, A., 294 Schmitt, Patricia, D., 79 Schmitt, Russell, J.. 135 Simenstad, Charles, A.. 9 Smith. John. D., 295 Stone, Dayton, Bryan, 267 Swales. Stephen, 279 Tarnchalanukit, Wit, 317 Valiela, Ivan, 105 Watanabe, Yoshirou. 59 White. David. S.. 105

Baker, John, A., 121 Balon, Eugene, K., 173, 271 Barlow, George, W., 316 Beitinger, Thomas, L., 235 Block, Claire, J., 41 Bulkley, Ross, V., 29 Claussen, Dennis, L., 131 Cone, David, 79 Conover, David, O., 161 Cummings, Kevin, S., 160 De Silva, Sena, S., 205 FitzGerald, GCrald, .I., 301 Gibbons, J. Whitfield, 41 Giesy, John, P., 191 Hocutt, Charles, H., 85 Howard, James, H., 85 Hubert, Wayne, A., 309 Ihnat, Jean, M., 29 Ingersoll, Christopher, G., 131 Janssen, John, 191 Jastrzebski, Zbigniew, T., 15, 17, 19, 276, 300 Johansen, Kjell, 221 Jones, L. Michael, 107 Kroll, William, 21 Kynard, Boyd, E., 161 Lindquist, David, G., 83, 107 Lindsey, Casimir, C., 3 Love, Milton, 259 Magnan, Pierre, 301 Maitipe, Parakum, 205 Majkowski, Jacek, 63 Martin, F. Douglas, 113 McKeown, Paul, E., 85 McMichael, Robert, H., 121 Morgan II, Raymond, P., 85 Morris, Pamela, A., 259 Page, Lawrence, M., 83,139,160 Paine, Michael, D., 97, 173, 277 Perera, Mala, K., 205 Pettit, Michael, J., 235 Rantin, Francisco, Tadeu, 221 Ruple, David, L., 121 Ryan, Patrick, A., 229 Saint-Paul, Ulrich, 53 Sedberry, George, R., 241 Shute, John, R., 107 Shute, Peggy, W., 107 Spotila, James, R., 41 Sandora, Edward, A., 41 Stang, Douglas, L., 309 Stephens, Jr., John, S., 259 Swofford, David, L., 139 Van Dolah, Robert, F., 241 Waiwood, Kenneth, 63 Zerba, Kim, 259

Organophosphorus insecticides (OPs) are widely used to control crop pests, and can enter aquatic systems draining agriculturalwatersheds. Because OPs are highly toxic to aquatic organisms,monitoring is important, yet difficult due to the low persistenceof many OPs. Cholinesterase (ChE) inhibition can be used to monitor organisms' exposure to OPs and carbamates; however, highvariability in ChE activity may interfere with the ability of theassay to detect OP exposure. Several potential sources of variation in ChE activity, including water temperature, storage of samples, euthanasia method, and fish sex and size, were investigated in bluegill (Lepomis macrochirus). ChE activity did not vary significantly with water temperature in the range 20–31 °C, or following short-term storage ofeuthanized bluegill up to 8 h at 4 and 19 °C or long-term storage of brain homogenates up to 389 d at –198 °C. There was no difference in ChE activity by euthanasia method (spinal cord severing or anesthesia with Finquel®), nor by sex of fish. Mean ChE activity variedinversely with fish total length. Of the variables investigated in this study, only size needs to be restricted in fish collectedfor monitoring of OPs.

We examined head capsule cholinesterase (ChE) and foraging behavior in nymphs of the dragonfly, Anax junius, exposed for 24 h to 0.2, 0.6 and 1.0 μg l−1 of the organophosphorus (OP) insecticide, chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate]. The invertebrate community is an important component of the structure and function of wetland ecosystems, yet the potential effects of insecticides on wetland ecosystems are largely unknown. Our objectives were to determine if exposure to environmentally realistic concentrations of chlorpyrifos affected foraging behavior and ChE activity in head capsules of dragonfly nymphs. Nymphs were exposed to different concentrations of chlorpyrifos and different prey densities in a factorial design. ChE activities and foraging behaviors of treated nymphs were not statistically different (p ≥ 0.05) from control groups. Prey density effects exerted a greater effect on dragonfly foraging than toxicant exposures. Nymphs offered higher prey densities exhibited more foraging behaviors but also missed their prey more often. High variability in ChE activities within the control group and across treated groups precluded determination of relationships between ChE and foraging behaviors. It appears that A. junius is relatively tolerant of chlorpyrifos, although the concentrations we tested have been shown in other work to adversely affect the prey base; therefore the introduction of this insecticide may have indirect adverse affects on top invertebrate predators such as Odonata.

Cholinesterase (ChE) inhibition has been demonstrated to be useful as a biomarker for exposure to organophosphorus (OP) and carbamate insecticides in many environments; however, there are questions about whether ChE activity may be affected by common environmental conditions such as low oxygen concentrations or by concurrent exposure to multiple chemicals. This article describes experiments in which larvae of Chironomus riparius were exposed to hypoxia (dissolved oxygen concentrations of 0.1 mg L-1; <1% saturation) in wetland mesocosms and in the laboratory (1.90 mg l-1; 19% saturation), and in which C. riparius larvae were exposed to mixtures of the OP, chlorpyrifos and the herbicides, atrazine and metolachlor, in hypoxic wetland mesocosms and in normoxic conditions in the laboratory. Larvae exposed to hypoxia for up to 35 h had no change in ChE activity, nor did atrazine or metolachlor cause ChE inhibition. There was no significant difference in ChE inhibition between larvae exposed to a mixture of chlorpyrifos (0.5 μg l-1), atrazine and metolachlor and larvae exposed to chlorpyrifos (0.5 μg l-1) alone. Larval chironomids are good candidates for monitoring of ChE inhibitors in shallow aquatic systems. Chironomid larvae are easy to handle and can be caged in areas where pesticide inflow is a concern. Chironomids can be placed in hypoxic aquatic systems as they are able to tolerate hypoxia for several hours up to a few days. Finally, in this study, larval ChE activities were significantly depressed following a range of exposures to chlorpyrifos, indicating that chironomid ChE activities are a sensitive indicator of exposure to OPs.

Exposure of aquatic organisms to suspended sediments can impair growth and survival and increase bioaccumulation of sediment-associated contaminants. However, evaluation of the effects of suspended sediments and their associated contaminants on aquatic organisms has been hampered by the lack of a practical and inexpensive exposure system for conducting bioassays. We present a cost-effective system for assessing the effects of suspended sediments and associated contaminants on small aquatic organisms. A 7-day suspension test was conducted with nominal sediment concentrations ranging from 0.0 to 5.0 g 1−1. The system maintained relatively constant suspended sediment concentrations, as measured by turbidity, and caused minimal mortality to test organisms.

Behavioral toxicity tests, if properly designed, can be used in conjunction with standard acute lethality tests, chronic full or partial life cycle tests, and early life stage toxicity tests to add ecological realism to toxicant assessments and the regulations made as an outgrowth of these assessments. Changes in certain fish behaviors, especially cough rate and avoidance reactions, are very sensitive indicators of sublethal exposure to metals. Other tests involving predator avoidance, feeding behavior, learning, social interactions, and a variety of locomotor behaviors show promise but have been insufficiently studied to judge their sensitivity or utility. No behavioral tests have been standardized and few have been verified in the field. We discuss the behavioral tests that have been used with metals, examine their sensitivity compared with standard laboratory toxicity tests, and assess the potential ecological significance of the behavioral changes observed.

Abstract : A review of pertinent research, suggests that dikes and revetments have short-term and long-term effects on major riverine ecosystems. Short-term effects may be beneficial and include increases in aquatic habitat diversity physical stability which, in turn, results in high densities and diversities of fish and macroinvertebrates within the main stem of the river. Dike fields are intermediate physically, chemically, and biologically to the main channel and backwaters of rivers. Dike fields often support the most diverse fish and macroinvertebrate community of any habitat within the river. But community composition is less stable than backwaters and is dependent upon river stage and water velocity. Moderate and slow-water areas within dike fields provide important spawning and nursery areas for many lotic species of fish within the modified river. Revetments of broken rock stabilize banks and provide additional hard substrate for colonization by dense populations of invertebrates. Interstitial spaces between rocks may provide areas of moderate flow for juvenile and forage fish. Long-term effects of river training structures may be detrimental to the biotic integrity of the river.

The three-ridge clamAmblema perplicata was used to monitor two streams for the presence of zinc (Zn) and cadmium (Cd) derived from an industrial source. Clams were collected from a relatively uncontaminated area in one river and transported to four study sites in the two contaminated streams. The clams were placed into polyethylene cages and left in these streams for one week. Control clams were treated in a similar manner and left in the uncontaminated river.

Levels of cadmium and zinc in various components of Williamson Ditch (an industrially contaminated stream flowing into Palestine Lake), Trimble Creek (a stream draining Palestine Lake) and the Tippecance River (a river receiving Trimble Creek) were determined. Water, sediment, plant, fish and clam samples were analyzed for cadmium and zinc content by atomic absorption spectrophotometry. Unweighted mean metal concentrations in Trimble Creek were the following: water, 51 µg Zn/1 and 4.2 µg Cd/1; sediment, 592 µg Zn/g and 48.8,µg Cd/g; plants, 375 µm Zn/g and 7.91 µg Cd/g; fish, 145 µg Zn/g and 6.02 µg Cd/g. These concentrations were generally lower than those found in Williamson Ditch and higher than those found in the Tippecanoe River or background levels previously reported for other aquatic ecosystems.

Effects of metal contamination on microbial biomass in sediment samples from three areas in Palestine Lake (one area highly polluted with chromium, cadmium and zinc) were determined. Adenosine triphosphate (ATP) concentrations, determined by the luciferin-luciferase bioluminescent technique, and microbial colony numbers on pour plates were used as biomass indicators. Plate counts showed a significant (P < 0.01) site effect with the highly contaminated area having an order of magnitude lower microbial population than the control area. ATP concentrations also indicated lower microbial biomass in contaminated sediments. The metal concentrations of the most contaminated area averaged 17,840 µg Zn/g, 4380 µg Cr/g and 585 µg Cd/g based on dry weight of sediments. A suppression of organic decomposition was evident in the impacted area; high metal levels and resultant low microbial biomass may have been causative.

The development of rapid, yet sensitive toxicity testing methods is needed for the establishment of water quality standards to protect aquatic life. A technique using changes in the behavior of bluegill (Lepomis macrochirus) was utilized to evaluate the impact of five sublethal levels of a cadmium (Cd) and zinc (Zn) mixture. The technique proved very sensitive and various changes in behavior occurred at the lowest metal levels used; 21 ug Cd per liter and 99 ug Zn per liter. Coughs, yawns, partial jerks and jerk swimming were especially sensitive indicators of elevated metal levels. The frequency, but not the form, of eight of the nine behaviors quantified changed significantly with increasing metal levels.

Relationships between sublethal concentrations of cadmium and zinc in natural water and metal uptake by and growth of fish were investigated. RNA-DNA ratios and weight gain were used to assess seasonal growth differences between yellow perch populations from contaminated and control sites. Whole-body concentrations of cadmium and zinc in young-of-the-year perch (Perca flavescens) were significantly different between sites. Measurable growth differences did occur and were significantly correlated with cadmium levels. Growth differences that were prominent during mid-summer were reduced by late summer. RNA-DNA ratios were sensitive indicators of fish growth.