OCEANOLOGIC STUDY OF AN OPEN COASTAL AREA IN THE IONIAN SEA WITH EMPHASIS ON ITS BENTHIC FAUNA AND SOME ZOOGEOGRAPHICAL REMARKS

The macrobenthic faunal composition, sedimentology and physical charac teristics were investigated in an open coastal area of the Greek Ionia n Sea. Hydrographic parameters were recorded at 26 stations using a CT D profiler during nine cruises performed between 1990 and 1991, while benthic samples were collected in November 1990 and April 1991 at 22 s tations with the aid of a Ponar grab. Macrobenthic variety indicated a n area of high scientific interest : 351 species in all, 18 of which a re new to the Creek fauna. Furthermore, 10 species are previously unre corded in the Eastern Mediterranean. Of the biological indices estimat ed, species richness was comparable to that of other open Greek areas, while population density seemed to be a function of a) depth and b) d egree of enclosure. Community diversity and evenness of distribution v aried within a great range. The minimal values which were noticed at t he stations situated in front of the Amvrakikos Gulf opening can be at tributed to the outflow of eutrophic waters from the Gulf of Amvrakiko s in combination with the area's hydrodynamism and bottom topography. The absence of Sine sediments at the shallow stations is indicative of a high energy regime as opposed to the high percentages of fines domi nating at the deeper stations. The area's water masses are mainly of A tlantic origin with some mixing of Levantine Intermediate Water at the deeper layers. Outflow of less saline water from Amvrakikos Gulf was observed during winter and spring. Classification analysis, based on t he faunal composition, produced four groups corresponding to different depth zones. However, due to the heterogeneity of sediment types with in each group, the biocoenotic approach showed a muddy biocoenosis onl y for the deeper group - associated with the biotope of the generally accepted Mediterranean muddy detritus (DE) biocoenosis and that of coa stal terrigenous muds (VTC) - while the other groups presented a more complex physiognomy.