THE RELATIVE IMPORTANCE OF FOOD AND SEAWATER AS SOURCES OF COPPER ANDZINC TO TALITRID AMPHIPODS (CRUSTACEA, AMPHIPODA, TALITRIDAE)

1. Two species of talitrid amphipod Orchestia gammarellus (Pallas) and Orchestia mediterranea Costa were shown to accumulate copper and zinc from a range of copper- and zinc-enriched algal foods. Accumulation i ncreased with increasing dietary metal concentrations. 2. Laboratory r esults have been extrapolated to the field, in an attempt to compare t he relative importance of food and solution as sources of trace metals to the talitrids in relation to their respective position on the shor e. 3. It was concluded that, for O. gammarellus, accumulation of coppe r from food was a more important route than the accumulation of copper from solution. O. mediterranea, however, was unable to satisfy its co pper requirements from a food source, but was able to achieve all its copper requirements from solution. 4. Both species had equal rates of zinc accumulation from food. Dietary sources of zinc contributed more to final derived body zinc concentrations in both species than accumul ation of zinc directly from sea water. 5. Dietary zinc accumulation ra tes were enhanced for O. gammarellus from one zinc-polluted location, in contrast to copper accumulation rates which did not differ intraspe cifically between localities. This difference may be a consequence of adaptation or tolerance to the higher ambient zinc bioavailabilities a t the polluted locations.