The brackish water ostracod Cyprideis torosa (Jones) in marine deposits: the case of the Adriatic sea.

Cyprideis corosa (Jones), which is one of the most common brackish writer species, has been "Wend in the thanatocoenoses sampled at the offibore bottoms of the Adriatic Sea. C. torosa is characterized by the presence of both well-preserved adults and juveniles valves. This evidence should exclude transport processes and, in consequence, should ensure its autochthony. Findings of autochthonous specimens of C. cornea occur in some marine settings of the Saline Gulf (NE Sardinia). There, this species was found in nearshore settings, which are characterized by the presence ofifivsle water submarine springs, and that may have created favourable conditions such as microhabi rats of brackish water. In the Adriatic Sea the situation is quite different. In fact; C. rorosa has been found in several offihore sampling stations that are far away flow any firsh water influence and are located in correspondence to deposits with a high content of sand related to late Quaternary littoral settings (e.g., nearshore, lagoon) that characterized the central-northern Adriatic region. During the Holocene transgression, these deposits were subsequently preserved and eventually eroded. Moreover the location of the offlhore sampling stations containing C. cornea seems to have a pattern following that of the Holocene shorelines in the northern Adriatic area. Then, C. torosa found within these deposits has to be considered part af an autochthorrous late Quaternary brackish water ostracod fauna, that also contains other very shallow marine species tolerating strong fresh water influence, together with rare non-marine ones. Subsequently, some modern deeper water' ostracods may have contaminated this fauna as it results flan the presence of an apparently mixed brackish/marine ostracod assemblage.