The Mar Piccolo of Taranto (Northern Ionian Sea), one of the most studied coastal areas in Italy, is a Long-Term Ecosystem Research site (LTER_EU_IT_095). Phytoplankton data, both as active stages in the water column and cysts in the sediments, have been collected since 1991 (with gaps). Notwithstanding a reduction of nutrients caused by a reduction of wastewater inputs during the early 2000s, phytoplankton biomass (in terms of chlorophyll a) did not show significant variations over the years. However, other relevant changes occurred such as a reduction of the community size, due to a shift of dominance from diatoms to nanoflagellates, an increased duration of secondary blooms (beside the spring one), and the appearance of a diversified dinoflagellate community, comprised mixotrophic and heterotrophic species. An increase of the pico-sized planktonic component has also been recently detected. Moreover, wastewater diversion did not preserve the Mar Piccolo from harmful algal blooms and about 25 harmful species were monitored throughout the years. These signals are in some ways mirrored in the sediments. In fact, the resting stages communities, during the last 20 years passed through many changes in their structure, even though calcareous dinocysts produced by Thoracosphaeraceae remained dominant. During the last 5 years, in particular, resting spores of some diatoms of the genus Chaetoceros were observed, together with the increase and new findings of some heterotrophic species, apparently a signal of the changes occurred in the Mar Piccolo. This change has been registered also with the disappearing of species, e.g. Protoperidinium pentagonum and P. divaricatum, whose cysts were regularly observed in surface sediments, even with low densities.
Dynamics of the phytoplankton communities in the Mar Piccolo of Taranto, an Italian Long-Term Ecosystem Research (LTER-Italy) site
Caroppo C;Rubino F
2017
Abstract
The Mar Piccolo of Taranto (Northern Ionian Sea), one of the most studied coastal areas in Italy, is a Long-Term Ecosystem Research site (LTER_EU_IT_095). Phytoplankton data, both as active stages in the water column and cysts in the sediments, have been collected since 1991 (with gaps). Notwithstanding a reduction of nutrients caused by a reduction of wastewater inputs during the early 2000s, phytoplankton biomass (in terms of chlorophyll a) did not show significant variations over the years. However, other relevant changes occurred such as a reduction of the community size, due to a shift of dominance from diatoms to nanoflagellates, an increased duration of secondary blooms (beside the spring one), and the appearance of a diversified dinoflagellate community, comprised mixotrophic and heterotrophic species. An increase of the pico-sized planktonic component has also been recently detected. Moreover, wastewater diversion did not preserve the Mar Piccolo from harmful algal blooms and about 25 harmful species were monitored throughout the years. These signals are in some ways mirrored in the sediments. In fact, the resting stages communities, during the last 20 years passed through many changes in their structure, even though calcareous dinocysts produced by Thoracosphaeraceae remained dominant. During the last 5 years, in particular, resting spores of some diatoms of the genus Chaetoceros were observed, together with the increase and new findings of some heterotrophic species, apparently a signal of the changes occurred in the Mar Piccolo. This change has been registered also with the disappearing of species, e.g. Protoperidinium pentagonum and P. divaricatum, whose cysts were regularly observed in surface sediments, even with low densities.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
