| Abstract: | Hyalella azteca are presently used in toxicity tests designed to evaluate adverse biological effects associated with exposure to contaminated sediments. Biological endpoints examined in a sediment test include changes in survival, as well as sublethal effects such as changes in growth, and reproduction. Length and weight, two methods used routinely to measure growth, were compared using H. azteca recovered from a 10-day sediment toxicity test. Length of individual organisms was measured using an image analyzer and dry weight of organisms was determined using an electronic microbalance. Statistical analysis was conducted using one-way analysis of variance to compare treatment sites. Length measures were shown to have greater power, a small minimum detectable difference, and smaller amount of underlying variability. The results indicate that length, measured using an image analyzer, was a more sensitive means to detect significant changes in growth and can be conducted with a greater degree of statistical confidence than use of weight measures. © 1998 John Wiley & Sons, Inc. Environ Toxicol Water Qual 13: 243–248, 1998 |
