In this paper, we report new records of rare diatoms that have recently been found in Southern Poland. Planothidium nanum was found only in the upper reaches of the Centuria River, which is not exposed to human influence, while Navicula flandriae was found in two rivers (the Bolina and the Mleczna) affected by salt mine water from hard coal mines. The impact of anthropogenic salinity on diatom communities is as yet poorly documented. Therefore, we conducted a survey on this phenomenon. We surveyed seven sampling sites for diatom assemblages and habitat characteristics, including three sampling sites impacted by mine water. Navicula flandriae was recorded at both sampling sites affected by salt mine water and in two other rivers (the Centuria and the Mitręga), indicating its wide preference for salinity. We confirmed the occurrence of P. nanum at the same site where this species was found and described in our previous paper. In addition, we recorded the occurrence of this species at two other sites in habitats with similar characteristics (lower reaches of the Centuria and Wiercica rivers). Our results indicate a more common occurrence of N. flandriae and P. nanum, which means that further monitoring of diatoms is necessary.
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Recent results of field studies on the exposed coast of Lithuania were used to model the area occupied by the red alga Furcellaria lumbricalis using the Natural Neighbor interpolation technique, while linear regression was applied to estimate the species' standing stock. The area covered by F. lumbricalis extended for 26 km along the coast between depths of 1 and 15 m. The maximum species cover in the study area ranged between 4 and 10 m depth, which is one of the widest in the Baltic Sea. The modelled area of F. lumbricalis covered 35 š 11 km2 with a total biomass of 7554 š 3813 t.
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A biomonitoring program was developed to assess the ecological status of streams based on the phytobenthic algal community structure. The study presented here focuses on siliceous sites of streams in the central highlands of Germany. Phytobenthic algae belonging to eight classes and 74 taxa were grouped into four categories according to their ecological distribution pattern. A formula was designed to calculate an index ranging from +100 to –100 to assess stream health. Based on these values, the sampling sites were assigned to one of the five ecological quality classes required by the Water Framework Directive (WFD) of the European Union.
Results of investigations carried out in June 1995 at the same stations as in June 1992 are presented. Only small differences in species composition, biomass and the range of phytobenthos occurrence were observed. Obtained results confirmed that the trends of phytobenthos changes in the Gulf of Gdańsk are similar to those in inner Puck Bay, i.e. the existing predomination of brown algae of the Ecto-carpus and Pilayella genera and a decrease of the area of underwater meadows. However, in spite of these changes there still exist natural phytobenthos stands in the Gulf. Therefore, active protection measures will create potential possibilities of reviving the phytocenoses of the Gulf of Gdańsk.
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