C. Caroppo et al., Seasonal variations of nutrients and phytoplankton in the coastal SW Adriatic Sea (1995-1997), BOTAN MARIN, 42(4), 1999, pp. 389-400
Monitoring cruises were carried out on four coastal transects of the southe
rn Adriatic Sea over two years to investigate the effects of the hydrodynam
ic regime on environmental factors and phytoplankton species composition an
d succession. The concentration of nutrient salts is usually low except for
the winter months. Biomass levels tin terms of chlorophyll a) proved to be
very low, with values ranging between 0.05 and 1.25 mu g Chl a L-1. Phytop
lankton densities showed specific oligotrophic water values and varied in a
wide range from 9 x 10(3) to 2.9 x 10(6) cells L-1; the maximum values wer
e reached in January-February mainly because of a bloom of the diatom Skele
tonema costatum. Diatoms were present throughout the year and represented t
he majority of the population (44.3%) together with phytoflagellates (39.6%
), while dinoflagellates and coccolithophorids reached, respectively, 10.3
% and 5.8 %. During the year, diatoms were dominant with high cell densitie
s in winter time, while phytoflagellates had a larger distribution over tim
e and reached the highest Values in spring and summer. Species diversity va
lues were typical of temperate coastal areas (H-' = 2.79 +/- 0.73).
The type of circulation determined the distribution of thermohaline charact
eristics, abundance and biomass, as well as species composition and success
ion of phytoplankton in time. However, no great spatial variations were obs
erved.