AA-EQS: Annual average environmental quality standard Abiotic factor: Physical, chemical, and other nonliving environmental factors Abundance: The total number of individuals or taxa in an area, sample, or volume A/C ratio: Ratio of acute (usually EC50 or LC50) to chronic (usually NOEC) effects AChE: Acetylcholinesterase Acute: Responses occurring within a short period in relation to the life span of the

organism. It can be used to dene either the exposure (acute test) or the response to an exposure (acute effect).