Morphological Variability of Pseudo-nitzschia pungens Clade I (Bacillariophyceae) in the Northwestern Adriatic Sea

Pseudo-nitzschia pungens is a common component of the phytoplankton community of the northern Adriatic Sea. In this study, an in-depth morphological analysis of P. pungens was carried out in both cultured strains isolated in different periods and field samples, revealing a surprisingly wide variability in a number of details, with both the gross morphology and ultrastructural levels deviating from the nominal P. pungens. Colonies showed an overlap (from one-third to one-sixth) and a transapical axis (rarely reaching 3 µm), strongly differing from the original description of the species. Moreover, valves may be either symmetrical or slightly asymmetrical, with striae almost always biseriate but sometimes uniseriate or triseriate. Poroids’ morphology in cingular bands was characterized by a wide variability (square, circular, or rectangular poroids without or with up to two hymen sectors), with several combination of them, even within the same cingular band. Phylogenetic analyses based on ITS rDNA showed that the P. pungens of the northern Adriatic Sea belonged to clade I. Domoic acid was not detected.

NUTRIEN PEMBATAS DI EAST RIVER, KOREA

This study presents information on physico-chemical and nutrients that limit the water of East River, Korea. Collected water samples from 16 main streams and 7 branches in MayNovember 2008 were measured for their heavy metal and nutrients concentration. Nutrient enrichment bioassay tests with the use of Nitzschia pungens was also conducted. This threeseason study indicated that the phosphorus was the limiting factor for algal growth.