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Comparative study of ecophysiological and biochemical variation between the Baltic and North Sea populations of the invasive soft shell clam Mya arenaria (L. 1758)

Lasota R., Pierścieniak K., Miąc J., Wołowicz M.

Oceanological and Hydrobiological Studies

2014

Vol. 43, No. 3

303--311

Seasonal variations of environmental factors, such as temperature and salinity, require metabolic acclimatization in sedentary benthic fauna distributed over a wide geographical range. The soft-shell clam Mya arenaria inhabits the coastal waters of the North Atlantic including North America and Europe. In Europe, M. arenaria populations are distributed from Iceland to the Mediterranean Sea, including the North Sea, the Baltic Sea and the Black Sea. Seasonal changes in physiological parameters (gonad index, condition index, biochemical composition and respiration rate) of M. arenaria from the Baltic Sea (the Gulf of Gdańsk, Poland), and the North Sea (Versee Meer, the Netherlands) were studied. The sex ratio of both populations did not differ from 1:1 and the seasonal gonad index was higher in the Baltic population. The average condition index changed seasonally at both studied sites, and was also higher in the Baltic population (except the autumn) compared to the North Sea. In both studied populations, the content of proteins, lipids and carbohydrates in the soft tissue followed the seasonal variations, and it was higher in the Baltic population. The respiration rate was lower in the Baltic population, and seasonal changes in the respiration rate seem to be correlated with changes in the water temperature. Based on the results obtained in the present study, we suggest that Mya arenaria is characterized by a large phenotypic plasticity and differences in the observed physiological traits are due to acclimatization to ambient environmental conditions.

Differences in reproduction and condition of Macoma balthica and Mytilus trossulus in the Gulf of Gdańsk (Southern Baltic Sea) under anthropogenic influences

Pierścieniak K., Grzymała J., Wołowicz M.

Oceanological and Hydrobiological Studies

2010

Vol. 39, No.4

17-32

Seasonal changes in gametogenesis, spawning behaviour and morphometric parameters of Macoma balthica and Mytilus trossulus from two depth zones in the Gulf of Gdańsk (Southern Baltic Sea) were investigated. The studies allowed the authors to make observations of the ecophysiological features of both species and revealed major differences in the weight index between deep and shallow water subpopulations. Both condition and gametogenesis probably depend mainly on the availability of nutrients and on temperature changes. The data showed that Mytilus trossulus spawned earlier at the shallow water station than at the deeper one. No differences were observed between the run of the Baltic clam’s reproductive cycle at 10 m and at 75 m depths.