Research Product

The effect of substances on development of estuarine communities was assessed by comparing the numbers, species, and phyla of benthic animals that grew from planktonic larvae in an uncontaminated apparatus and three identical apparatuses continuously contaminated (each with a different concentration) for two to four months. Each apparatus was separated into 10 sand-filled compartments (40 total) and received a continuous flow of seawater containing natural plankton. We conducted six experiments, using Aroclor 1254, toxaphene, pentachlorophenol, Dowicide G-ST, barite, and a lignosulfonate drilling mud. The communities that developed during each test were diverse, averaging more than 4000 individuals, 50 species, and seven phyla. Comparison of the results of these tests with results of acute and chronic exposures of single species demonstrates that: (a) the test can be as sensitive or more sensitive than chronic exposures of single species because the often more sensitive early developmental stages are exposed; and (b) species typically impacted are representatives of phyla also sensitive in single species tests. Also, the test may identify sensitive species not normally tested, thereby helping us to select species for additional toxicity tests. The test can also assess impacts of substances that affect community structure by physically altering the substrate.