THE EFFECT OF GEOGRAPHICAL LOCATION ON THE CELLULAR COMPOSITION OF THE MANTLE TISSUE OF THE MUSSEL, MYTILUS-EDULIS

The cellular composition of the mantle tissue of Mytilus edulis L. was determined, using quantitative microscopy (stereology) techniques, in three populations of mussels from differing environments, and the dat a compared. The results indicated that mussels from an estuarine or sh eltered coastal environment had a greater proportion of adipogranular tissue than animals from an exposed, open coastal environment. The dif ference in cellular composition was attributed to differences in nutri ent availability in the water column between the various sites. A 15-m onth transplantation of mussels from an open coast to estuarine condit ions resulted in a decrease in the proportion of vesicular connective tissue in the mantle and an increase in gamete production. This sugges ts that Mytilus edulis can exhibit a high degree of phenotypic plastic ity by using not only the more conservative strategy of nutrient stora ge during, periods of high food availability, but also the more opport unistic approach of maximizing gamete production when conditions are f avourable.