hrvatski

Promjene sastava pigmenata u uzorcima sluzi tijekom pojave makroagregata u sjevernom Jadranu u ljeto 1997.

The occasional extensive appearance of mucous aggregates in the summer period is specific to the northern Adriatic. We followed this phenomenon from July to September 1997, focusing on temporal changes of phytoplankton in mucous aggregates as reflected by biomarker pigments. The qualitative and quantitative analyses of pigments (chlorophyll and carotenoid pigments as well as breakdown products of chlorophyll a) were determined using reversed-phase high-performance liquid chromatography (RP HPLC) equipped with serially-coupled spectrophotometric and spectrofluorimetric detectors. The phytoplankton biomass in mucilage samples, as expressed in chlorophyll a concentrations, was very high and ranged from 19.9ą7.2 to 141.5ą32.4 microg/g dry mucilage. The largest percentage of the autotrophic biomass in all samples was associated with fucoxanthin-containing phytoplankton i.e. diatoms (from 21.0ą3.9 to 148.6ą34.4 microg fucoxanthin/g dry mucilage) that contributed from 40.8ą2.1 to 74.7ą1.6 % of the total biomass, followed by peridinin (dinoflagellates), zeaxanthin (cyanobacteria), chlorophyll b (green algae), 19'-hexanoyloxyfucoxanthin (prymnesiophytes) and 19'-butanoyloxyfucoxanthin (silicoflagellates). Contribution of those individual biomarkers was generally less than 15 %, except for peridinin-containing species, which reached nearly 40 % in August. These results suggest that microplankton, especially diatoms, play a key role in the development and maintenance of mucilage. The total concentration of breakdown products of chlorophyll a was found in the range from 750ą160 to 19330ą109 ng/g dry mucilage. The most abundant breakdown product was chlorophyllide a, followed by phaeophorbide a_1, phaeophorbide a_2, phaeophytin a_1 and phaeophytin a_2.

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