A second difficulty arises from the complex array of dif¬ 
ferent pollutants occurring in the marine environment, parti¬ 
cularly in estuarine ecosystems such as San Francisco Bay-Delta, 
which are most affected by man. 
Finally, sublethal effects of low pollutant concentrations 
on organisms are subtle and difficult to quantify on an indi¬ 
vidual or population level; their detection also may be obscured 
by inherent species variability such as age, sex, or genetic 
differences. 
A solution to this intricate problem requires a long-term, 
cooperative effort. The goal of the Physiological Ecology 
Investigation at Tiburon Laboratory has been to contribute to an 
understanding of the long-term ecological consequences of 
pollutant effect on aquatic resources. Specifically, we were 
concerned with developing knowledge of effects of chronic 
low-level pollutants on fisheries. Although the understanding 
of fate and effects of pollutants in the marine environment has 
increased in the past 20 years, this knowledge is still limited 
primarily to acute effects of single pollutants or pollutant 
classes. Little is known of chronic, interactive effects of pol¬ 
lutants within and between pollutant classes. Most effects 
studies are limited to the laboratory; little information exists 
on the quantitative effect of pollutants on a population level. 
Finally, few studies address the interactions of pollutants with 
inherent characteristics of the species or with other environ¬ 
mental factors. 
In order to to describe source of variability in pollutant 
effects on striped bass more completely, we used techniques of 
multivariate analysis similar to those used in epidemiology. We 
were then able to refine the data to determine the best methods 
for measuring pollutant effects in both the field and in labora¬ 
tory experiments. 
Our approach concentrated on "easy to measure" and/or "sensi¬ 
tive" characteristics of the organisms which appeared to cor¬ 
relate with pollutant burdens. Initially, the measurements were 
on several levels -- from the biochemical to the subsample (popu¬ 
lation) level. After preliminary studies, the most sensitive 
variables were delineated. Selected groups of variables 
(factors) were then designated as measures of body conditions, 
liver condition, and egg condition. Eventually, these factors 
coefficients were translated into an overall assessment of the 
health of the organism. The coefficients also can be used to 
estimate quantitative effects on a population level, such as 
reductions in growth, reproduction, and survival. Some of the 
measurements are also more sensitive and consequently more 
effective in giving us an early warning that individuals and/or 
the population are stressed. Ultimately, we hope to synthesize 
the results into a model of the impacts of long-term chronic 
pollution on "natural" mortality rates and resulting changes in 
the population of the affected fishery. 
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