Analisi delle comunità macrozoobenthonica e planctonica in un ambiente acquatico iperalino: le Saline di Tarquinia
Author(s)
Bramucci, Stefania
Date Issued
February 12, 2009
Type
Doctoral Thesis
Abstract
Tarquinia Salterns are a seminatural and hypersaline humid environment of about 190 ha, situated in central coast of Tyrrhenian Sea (north Lazio, Italy). They are separated from the sea by a thin line of dunes and connected to it through two channels: “Foce di Ponente”, marine water inlet channel and “Foce di Levante”, marine water output channel. Because of its naturalistic and ecological value, this area is protected by a State Reserve from 1980; then, was recognized as Site of Community Importance (SCI, Habitat Directive 92/43/CEE) and Special Protection Area (SPA,Bird Directive 79/409/CEE) with the aim of biodiversity conservation and protection.
Salt extraction ended in july 1997. Due to the ending of salt-mining activities and to a flood which overflowed all basins (December, 2004), hydrological infrastructures fall into ruin producing organic and inorganic matter sedimentation followed by eutrophication events. From 2003 to 2006 Tarquinia Salterns was interested by a three years project (Life Nature Project) aimed to environmental recovery of coastal lagoon habitat. Many measures were planned to recover hydrodinamism and to remove organic matter built-up (dredging) allowing a better water exchange.
Also a monitoring plan of the main habitats of the Reserve was carried out to assess the ecological conditions of this area relating to engineering restoration measures (Life project activities).So a physical-chemical and biological water monitoring was carried out with special interest on macrozoobenthic and planktonic communities, a good indicator of ecological water conditions.
After Life project activities (2006/2007), macrozoobenthic community was constituted by 26 taxa,mainly marine, opportunistic or typical brackish water species. The results, confirmed by statistical analysis, indicated that there are seasonal variations in community structure and biomass and that there are spatial variations among the sampling stations, along a confinement and salinity gradient:diversity, species richness and biomass are higher in basins with lower salinity values (North basins) than in hypersaline and more confinated basins (South basins).
Macrobenthic community monitoring conducted since 1997 has allowed to verify the effects of
man-induced and natural disturbance events on the humid seminatural environment. Multivariate
analysis indicates a significant difference between benthic community structure and composition from 1997 to 2007, with a clear decrease of diversity in relation to saltpan's ending activities and to the flood (1997-2005), while a recovery of benthos assemblages was observed in 2006-07 after restoration activities realized through Life Nature Project. The extraordinary maintenance activities
produced positive effects on the lagoon ecosystem with ecological recovery of North basins also
proved by the avifauna biodiversity increase observed in 2006 census. In the next years biological monitoring will continue to check if the benthic community changes are ephemerals or linked to a real improvement of environmental water conditions.
A study of phytoplanktonic and zooplanktonic communities biomass was conducted to estimate the
total biomass available as trophic resource, to improve Mediterranean hypersaline - seminatural
habitat knowledge and to collect data on biological resources useful to plan conservation and management activities.
The results show that phytoplankton biomass increase along a salinity and confinement gradient,with low values in the North area (lower salinity and confinement) and high values in the South area (higher salinity and confinement) while zooplankton biomass, as macrozoobenthic biomass,decrease from North to South area.
About seasonal variations of phytoplankton biomass, maximum values were observed in autumn
and winter, above all in South basins where monthly fluctuations were more evident. All the
sampling stations show minimum values in spring.
Zooplanktonic biomass doesn’t show evident seasonal fluctuations; in the North area the trend is similar to phytoplankton.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche
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