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Seasonal changes in the morphometric and physiological parameters of the cockle Cerastoderma glaucum (Bivalvia) from the Baltic Sea (GD), the North Sea (LV), and the Mediterranean Sea (BL) were investigated. The cockles from GD were much smaller than those from other populations due to osmotic stress. The female to male ratios did not differ significantly from 1 : 1. The northern populations (GD, LV) had a monocyclic reproductive pattern, whereas the southern population (BL) seemed to reproduce throughout the year. Seasonal changes in the contents of biochemical components appeared to be correlated with changes in trophic conditions and the reproductive cycle. Protein content was the highest in spring for all the populations. The highest lipid contents and lowest carbohydrate contents were noted in GD and BL in spring, while no marked differences were noted among seasons in LV (probably because the data from both sexes were pooled). Respiration rates in GD were the highest among the populations, which could have been due to osmotic stress. High metabolic rates expressed by high respiration rates in GD and LV in spring and autumn could have resulted from gamete development (in spring) and phytoplankton blooms (in spring and autumn).
This study discusses the occurrence of neoplasia in the Baltic clam Macoma balthica from the Gulf of Gdańsk in recent years and investigates potential relationships between toxic compounds in the environment and the presence of the cancer. The disease was identified at four sampling stations during 1999–2002. Comparison with previous results highlighted the substantial prevalence of the tumour between 1998 and 2002. The prevalence of the cancer was strongly dependent on the sampling location (p < 0.001): it was highest at sampling point H45 (the deepest part of the gulf) and lowest at station PB30 (central part of the gulf). Monthly studies showed a trend towards an increasing prevalence of neoplasia during the warm months. However, over several sampling months no strong statistical correlation between the prevalence of the disease and the sampling time was found. The results of the study suggest that several environmental factors may promote the progress of the cancer in M. balthica from the Gulf of Gdańsk: it is most probably an indirect effect of pollution, although causality cannot be proven at this stage. Seriously polluted and exhibiting a considerable asymmetry of contamination, the ecosystem of the gulf provides an ideal environment for testing potential cause-effect relationships between pollutants and their biological effects.
This paper summarises current knowledge of goods and services in the Polish Exclusive Economic Zone of the Baltic Sea ecosystem. It reviews specific properties of the Baltic that could be used for economic valuation. Goods and services range from the familiar resources of fish and minerals, which were valued with the Productivity Method, to less obvious services provided by the ecosystem such as biofiltration in coastal sands, valued with either the Replacement Cost or Damage Cost Avoided methods. Disservices to the marine ecosystem are also considered, e.g. erosion and coastal flooding, including the costs of planned mitigating measures. This paper emphasises the importance of using valuation methods to help make better-educated decisions for the sustainability of the Baltic Sea.
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