ISSN: 0001-5113 ACTA ADRIAT., UDC: 582.276(262.3.04) AADRAY 53(2): 181 - 188, 2012 (450.361 Trst) 581.522.6 Preliminary study on vertical migrations of dinoflagellates in a dynamic coastal sea (Gulf of Trieste, northern Adriatic) Janja fRANCÉ* and Patricija MOzETIČ National Institute of Biology, Marine Biology Station, Fornače 41, 6330 Piran, Slovenia *Corresponding author, e-mail:
[email protected] The purpose of this preliminary study was to define the vertical migration pattern in the dinoflagellate community in the shallow coastal sea. Migrations were followed in an area of mussel farming, through two 24-hour samplings, first during mixed and second during stratified water column conditions. Despite variable physical environment we were able to follow vertical migrations of some autotrophic dinoflagellate species in the period of stratified water column. The results also suggest that Heterocapsa sp. may preserve its vertical migration pattern also under mixed conditions. Migrations were observed also for Dinophysis sacculus that can cause DSP problems in the area. Key words: dinoflagellates, vertical migrations, dynamic environment, coastal sea, Adriatic INTRODUCTION of migratory behaviour. The majority of stud- ies of vertical migration have been conducted Vertical migration as one of advantageous under controlled conditions on isolated or cul- characteristics of dinoflagellates (SMAyDA, 1997) tured dinoflagellate species (hEANEy & EPP- permits these organisms to access the water layer LEy, 1981; kAMykOWSkI, 1981; MACINTyRE et with an adequate quantity of inorganic nutrients, al., 1997), whereas in situ studies are fewer since thereby improving their retrieval. Consequently, they offer less understanding of dinoflagellates’ the benefit of migration is especially evident physiological responses, but, on the other hand, present a true combination of environmental under stratified water column conditions where stresses.