Rafal Lasota

Estuaries - a biological point of view

Estuaries — a biological point of view Estuaries are considered adverse environments for many living organisms because of their unstable environmental conditions. Variability in salinity, temperature and oxygen concentration of the water, diverse substrata and geomorphological structures are major contributors to increased ecological stress in estuaries. These variations contribute to the characteristic estuarine spatial and temporal changes of physico-chemical properties, which operate even at small scales. In terms of biology estuaries represent fascinating environments — transition zones between freshwater and marine biomes. Freshwater entering an estuary has a major influence on the ecology of the system, its productivity, diversity and the distribution of organisms, with a high variability of niches favouring an increase of biodiversity and biomass. Many estuarine species/organisms show broad and efficient physiological adaptations (ecotypes) in response to these environmental factors. Under locally specific conditions, even different genetic clades (groups) can be formed. Estuaries serve as vital nursery systems for many fish and unique feeding grounds for migratory birds. On the other hand, estuaries are often seriously degraded habitats, hence providing an ideal environment for combining studies on ecology, nature conservation and human impact.

Genetic Evidence for the Existence of Two Species of the “Bipolar” Pelagic Mollusk Clione limacina

Abstract: Clione limacina (Phipps, 1774) was attained from a broad bipolar distribution in latitudes of 40°N and 40°S. So far southern populations have been described as a subspecies and even a separate species based on morphological and physiological characters. In this study we found a 23.17% (± 0.59%) difference in cytochrome c oxidase subunit I (COI) gene sequences between C. limacina collected from the Arctic and Antarctic oceans. Our work indicates that Clione limacina from the Southern and Northern Hemisphere are not genetically similar enough to represent a single bipolar species and confirms their separate taxonomic status on molecular level.

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

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.

Fast and easy method for total DNA extraction and gene amplification from larvae, spat and adult mussels Mytilus trossulus from the Baltic Sea

Three nuclear DNA markers that diagnostically differentiate mussels within the Mytilus edulis complex (M. edulis, M. trossulus and M. galloprovincialis) are commonly used in taxonomic investigations: Glu5’, ITS and EFbis. As a rule, DNA extraction is performed before amplification. It is a time consuming process in the case of traditional methods based on chloroform and phenol extraction or relatively expensive using kits with ready spin columns. Moreover, DNA isolation from larvae is problematic, because of the small amount of tissue available. In this report we describe a simple, fast and inexpensive method of DNA extraction and gene amplification from larvae, spat and adults of the Baltic mussel Mytilus trossulus. The extraction method is adapted from that of Wang et al. (2006) and is based on digestion of tissue or whole animals in STE solution and direct gene amplification. On the basis of the results of routine analyses of mussels carried out in our laboratory we have concluded that the method we propose gives results that are consistent with standard methods, without requiring expensive reagents/equipment and is time saving.

Abnormalities in bivalve larvae from the Puck Bay (Gulf of Gdansk, southern Baltic Sea) as an indicator of environmental pollution

This study described the occurrence of abnormalities in bivalve larvae from the Puck Bay. Analyses of plankton samples collected in 2012-2013 showed that larval Mytilus trossulus, Mya arenaria, and Cerastoderma glaucum exhibited abnormalities that could indicate adverse environmental impacts. The deformities were mainly in shells, but missing soft tissue fragments and protruding vela were also noted. In addition to larval studies, we analyzed benthic postlarvae of Mytilus trossulus. Interestingly, grooves and notches at different locations of the prodissoconch, dissoconch, and shell margin were observed. Some of these deformations were reminiscent of the indentations found on the shell edge of larvae. Comparing the proportion of abnormal postlarvae to larvae with shell abnormalities suggested that the survival of larvae with shell abnormalities was low. Overall, our results suggested that the ratio of abnormal bivalve larvae could be used as an indicator of the biological effects of hazardous substances in the pelagic environment.