Teratological forms of diatoms (Bacillariophyceae) as indicators of water pollution in the western part of Puck Bay (southern Baltic Sea)

Studies of benthic diatom communities in the surface sediments of the Swarzewo area of Puck Bay were carried out during 1998 and 1999 in order to assess water quality, and in particular the organic load. Among the 192 taxa identified, teratological forms of diatoms were recorded in 17 diatom species, primarily in the species Opephora mutabilis, Planothidium delicatulum and Fragilaria fasciculata. The number of teratological forms was significantly higher in sediments rich in organic matter, which had concurrent high concentrations of phosphorus and nitrite nitrogen compounds. The highest teratological diatom abundances were recorded in α- mesosaprobic conditions, especially during spring and summer. It is postulated that teratological diatom valves are indicative of poor water quality.