BIOI/DGICAL INDICATIONS OF POLLUTION IN PUGET SOUND 
Edward R. Long 
Ocean Assessments Division, NOAA 
Seattle, Washington 
Introduction 
Recent studies of pollution in Puget Sound have largely focused upon the 
identification of the kinds and amounts of certain chemicals. Many of the 
chemicals that have been found in water, sediments, or marine life are 
known to be toxic in laboratory studies. However, the toxicity of these 
chemicals in a marine environment is not always predictable. Many highly 
complex (and poorly understood) factors influence the toxicity of many 
chemicals. Therefore, the presence of a chemical or a group of chemicals, 
or even a relatively high concentration of a single chemical, does not 
necessarily ensure that the resident marine life are suffering adversity. 
Some direct evidence of biological impact is needed to answer the 
biological "So what?" question. 
In our attempts to provide answers to this question, marine scientists 
have developed a wide variety of tests to determine adverse effects. 
There is no universally accepted single test or methods, so a variety have 
been used to develop a broad base of evidence for effects. Some involve 
examining the toxicity of a sample of water or sediment from the Sound to 
marine organisms. The test is conducted in a laboratory under controlled 
conditions and is called a bioassay. Some methods involve examining 
animals living in the study area to determine if the health of individuals 
or the abundance and composition of communities of organisms is impaired 
relative to that of residents of non-contaminated areas. The results from 
both the bioassay tests and the studies of resident biota can be compared 
with the complementary chemical data and also can be compared between 
samples from contaminated areas and non-contaminated areas. 
Since it is widely known that many toxic chemicals readily attach to 
suspended particles and eventually sink, the bottom sediments become the 
final repository for much of the contamination entering the Sound. The 
animals living in or upon the sediments, then, may become exposed to 
concentrations of chemicals in the mud far in excess of those in the 
overlying water. Therefore many of the biological studies have emphasized 
testing of sediments and examination of bottom-dwelling organisms. 
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