Tagging crustacean larvae: Assimilation and retention of trace elements

The uptake, assimilation, and retention of Se, Co, Ag, Ce, Eu, and Gd by crustacean larvae were measured to assess the suitability of these elements as tags for determining larval dispersal patterns and mortality rates. Gamma-emitting radioisotopes were used to determine the uptake and retention of each element by larvae of three crabs, Dyspanopeus sayi, Uca pugnax, and Sesarma reticulatum, and one barnacle, Semibalanus balanoides. Selenium was readily taken up by larvae from their food, was assimilated at efficiencies of 61-93%, was retained at concentrations detectable above background levels for weeks, and did not consistently affect larval survival or development in the laboratory. The other elements were not absorbed sufficiently from food or were not retained long enough to serve as appropriate tags for monitoring larval dispersal. Thus, only Se seemed to be transferred efficiently between trophic levels and is suitable as a larval tag.