Gametogenic cycle, gross biochemical composition, condition indices and soft tissue
caloric value of the brown mussel Perna perna were investigated in the
coastal waters of the Gulf of Aden over ten months, to delineate ecophysiological
performance of the bivalve. The timing of reproductive activity and seasonal variations of
physiological features appear to depend on interaction of environmental (exogenous) and
internal (endogenous) factors. Two major spawning events occurred during seasonal monsoons
i.e. in late summer (SW monsoon, August-September) and early spring (NW monsoon,
February-March), although these differed considerably in relative intensity and the extent
of the resulting changes in physiology and body weight. The summer breeding, which was
correlated with low water temperature and abundant food, exerted little effect on
biochemical constituents, indicating protracted and portioned spawning. Reserve stores
(lipids, carbohydrates and proteins) accumulated gradually in the cooler inter-monsoon
period of gametogenic quiescence, to provide energy for periods of natural nutritional
stress when water temperature increased and primary production diminished. The second
spawning in spring was accompanied by a substantial decrease in lipids, carbohydrates and
condition indices of the mussels probably due to the release of nutrient-rich gametes in
adaptive response to lower food availability in the environment. High reproductive effort
presumably induced increased mortality of females, which were strongly outnumbered by
males at a ratio of 1.8:1.0. Caloric value of this mussel falls within a range typical for
mussel species in other subtropical areas, highlighting the importance of Perna
perna as a local food resource and its potential suitability for
aquaculture.