Amphipod (or amphipoda) An order of malacostracan crustaceans. General characteristics include no carapace, laterally compressed body, different forms of appendages, size range from 1 to 340 mm in length (most are less than 10 mm), and most are aquatic detritivores (scavengers). Areas of concern Areas in the (Laurentian) Great Lakes that were identified in the 1970s by the International Joint Commission as having a severely degraded aquatic environment (Grapentine 2009). Bioavailable The portion of a chemical that is available for uptake by an aquatic organism and reaches the site(s) of toxic action, where it exerts a toxic effect; tissue concentrations of a chemical are generally used as a surrogate measure of bioavailable chemical, as it is not usually feasible to measure the concentration of the chemical at the actual site of toxic action. Bioaccumulation The process by which chemicals are taken up by aquatic organisms directly from water as well as through exposure through other routes, such as consumption of food and sediment containing the chemicals (Rand 1995). Critical body concentrations Body concentrations of a contaminant (or contaminants) measured in test organisms that are associated with observed toxicity. Direct toxicity Toxicity that results from the toxic agent(s) acting directly at the site(s) of toxic action in and/or on the exposed organisms that are exhibiting the adverse biological response in question (Rand 1995). Dissolved oxygen The amount of oxygen (O 2 ) dissolved in water, commonly measured as milligrams of O 2 per liter (mg/L), millimoles of O 2 per liter (mmol/L), or percent saturation. Ecology A branch of biology dealing with the relations between organisms and their environment (Random House College dictionary). Ecosystem A biological community and its chemical/physical environment. Ecotoxicology The study of the impact of toxic chemicals on biological organisms (populations, communities, and ecosystems). Flow-through An exposure system for aquatic toxicity tests in which the test material solutions and control water flow into and out of test chambers on a oncethrough basis either intermittently or continuously (Rand 1995). In situ (exposures) Exposure of a defined population of test organisms in confined chambers in the field, under natural or near-natural conditions, followed by measurement of typical toxicity or bioaccumulation test end points. In situ exposures possess more realism than laboratory tests but more control than field studies (Chappie and Burton 2000). In vivo (tests) Tests using whole, living organisms (as opposed to in vitro tests), which are conducted on organs, tissues, cells, etc. Indirect toxicity Adverse effects or toxicity that results from the toxic agent(s) acting on and producing changes in the chemical, physical, and/or biological M 672 Macroinvertebrate Ecotoxicity Testing (MET) Abbreviations AOCs Areas of concern ASTM American Society for Testing and Materials CCME Canadian Council of Ministers of the Environment EC Environment Canada EEM Environmenta...