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Cyst beds in ships and ports in Finland have previously been unstudied. Therefore, sediments from ships' ballast water tanks and four Finnish ports were sampled for dinoflagellate cysts and other phytoplankton. Untreated sediments were incubated at 10 degrees C and 20 degrees C in the local 6 psu salinity for 1, 4 and 7 days, and vegetative cells were examined with light and scanning electron microscope. Sediments were inhabited by various dinoflagellates, diatoms, chlorophytes, cyanophytes and small flagellates. Germinated dinoflagellates were found in 90% of ballast tanks and in all ports. Gymnodiniales spp. and Heterocapsa rotundata formed a major proportion of the proliferating dinoflagellate cells. One species, Peridinium quinquecorne, not previously reported from the Baltic Sea, was identified with SEM. The study emphasises that ships are potential transport vehicles for dinoflagellate cysts even in the low salinity Finnish waters, and small-sized dinoflagellates should be focused upon in ballast water studies.

Drawing reliable conclusions on changes in the trophic state of various subareas of the Baltic Sea is problematic, in large part because the monitoring of productivity parameters exhibiting high natural variability is based on sparse sampling. This emphasizes the importance of long-term data sets. Here we present a 30-year chlorophyll alpha data set from the western Gulf of Finland. The trophic state of the study area showed an increasing trend in the 1970s and 1980s manifested mainly as strengthened vernal blooms. This trend did not continue in the 1990s, and the seasonal phytoplankton biomass maxima since then has begun to show some bias toward the late summer. The changes in seasonal maxima of phytoplankton blooms probably reflect i) decreased availability of N suppressing the magnitude of the vernal bloom, which increases the P reserves for the summer, and ii) enhanced internal P loading, which further increases the summer P reserves.

Spectral absorption and fluorescence properties of living phytoplankton were measured across a salinity gradient in the northern Baltic Sea in August 2000. The discrete water samples (n=22) were size-fractionated (<2 μm and <20 μm) to study the origins of different optical signals. The concentration of chlorophyll-a (Chla) ranged from 1.6 mg m-3 to 6.0 mg m-3, from which picophytoplankton (<2 μm) contributed 18–54%. Phytoplankton community structure had a clear gradient; from the northern part, dominated by chlorophytes, to the southern part, dominated by cyanophytes (mainly Aphanizomenon sp.). The regional variability in the Chla-specific absorption coefficient was partly explained by variations in phytoplankton community size-structure, or species composition. Phycoerythrin absorption was notable, especially for picophytoplankton. Accordingly, phycoerythrin fluorescence arose mainly from picophytoplankton (average 74%, range 35–100%). Thus, pico-sized cyanophytes - predominated by phycoerythrin-rich cells - were the main source of the phycoerythrin signal. Large filamentous cyanobacteria, in turn, were responsible for the phycoerythrocyanin and phycocyanin signals. The observed spectral differences between size fractions contribute to the development of operational optical detection systems for cyanobacterial blooms and provide the background for other absorption and fluorescence-based algal detection systems and for remote sensing algorithm development. [ABSTRACT FROM AUTHOR]

Abstract: The distribution (fine resolution depth profiles) of major nutrients, chlorophyll-a, organic compounds, and phytoplankton (biomass and numbers) was examined in lead water in pack ice of the Weddell Sea. Samples were taken by pulling water into a syringe from a series of depths from 0.002 to 4m. While concentrations of compounds of interest remained constant in the water column, an enhanced depletion of nutrients (ammonium, nitrate, silicate, and inorganic carbon) occurred above the pycnocline at 0.1m. Coinciding with this depletion was an increase of organic matter and chlorophyll. The change in carbon isotopic composition showed that an enhanced primary production occurred at the sea surface. Cell counts and nutrient disappearance ratios suggest that primary production was dominated by diatoms. These results show that the sea surface can have different chemical characteristics than the deeper water column. [Copyright &y& Elsevier]