ABSTRACT
A substantial body of data for the concentration in marine organisms of the naturally-occurring alpha-radioactive element 210Po is available. Concentrations of 210Po show an extremely large variation between different categories of marine organism, e.g. 210Po concentrations in penaeid shrimp from the genera Gennadas and Bentheogennema are generally more than two orders of magnitude higher than those in euphausiids. We show that the 210Po data for euphausiids, carid shrimp and penaeid shrimp can be fitted to allometric relationships: the slopes for the three categories of organism are similar even though the concentrations vary widely. It is well-established that the dominant source of 210Po in a marine organism is the food eaten by the organism; it should thus be possible to use the 210Po concentrations in marine organisms as natural tracers to obtain information about organism diets. The "unstructured" marine food-web model proposed by Isaacs (1) generated equations which can in principle be used to predict the steady-state concentrations of chemical substances in organisms from various feeding categories. We apply this model to the available 210Po data with modest success. We suggest that the same approach could be used fruitfully with other trace elements: an Isaacstype model, combined with trace element concentration data, could be an important tool for (a) predicting trace element concentrations in marine organisms and (b) identifying the nature of the food consumed by the organisms.
