1. A short-term investigation of diel vertical migrations of the calycophoran Siphonophora in the open south Adriatic Sea (July 2003)Davor Lučić, Adam Benović, Mirna Batistić, Mira Morović, Ivona Onofri, Juan Carlos Molinero, Tjaša Kogovšek, Barbara Gangai, Marijana Miloslavić, 2011, original scientific article Abstract: Morning, midday, evening and night repetitive sampling was used to demonstrate calycophoran diel vertical migration (DVM) at a fixed station in the oligotrophic southern Adriatic Sea at 8 depth intervals. Of 20 calycophoran species collected, most of them inhabited layers of specific temperature and light intensity, and migrated during the night. The deep species Kephyes ovata is primarily non-migratory. Typical nocturnal movements to the surface were recorded for Lensia conoidea and sphaeronectes koellikeri. Lensia subtilis and eudoxoides spiralis migrated toward the surface in the evening but sank deeper at night. Lensia meteori and Lensia fowleri reached upper layers at midday. The DVM of sphaeronectes irregularis was irregular and independent of diel light patterns. Though low in numbers, some calycophorans were found above the thermocline at night. For mesopelagic species, however, higher summer surface temperatures proved an effective barrier to migration above 100 m. Thus, certain species could be represented as key species of planktonic cnidarian assemblages found within a certain depth range. Though not homogenous, and while some undertake nocturnal migrations in both directions, all are interrelated by preferences of bathymetric distribution and specific DVM behavior.
Keywords: sea, medusae, biological research, abundance, bathimetric distribution, siphonophora, calycophoran siphonophores, composition, Adriatic Sea
Published in DiRROS: 26.03.2025; Views: 1035; Downloads: 781
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2. The epiplankton community in the southern Adriatic: multiple trophic levels along the south - north and inshore-offshore gradientsValentina Turk, Davor Lučić, Jakica Njire, Senka Terzić, Tinkara Tinta, Adam Benović, Alenka Malej, 2012, original scientific article Abstract: The epiplankton community was investigated during Meduza cruises along south - north and offshore – inshore transects in the middle and southern Adriatic in spring 2002. The diel and vertical distribution of heterotrophic bacteria, phytoplankton pigment composition, micro- and mesozooplankton were assessed. At most stations we observed a thermocline at approximately 20 m and a prominent chlorophyll a peak at about 70 m depth. The integrated phytoplankton and bacterial biomass were lower at the station in the central part of the southern Adriatic, and increased gradually towards middle Adriatic and towards coastal stations. Vertical profiles of both bacterial abundance and production showed a distinct peak in the surface layer. Bacterial abundance was high also in the layer of the deep chlorophyll a maximum. Higher bacterial production was associated with elevated abundance of pico- and nanoplankton feeding zooplankton indicating that bacterial populations were generally controlled by predation.
Keywords: Meduza project, heterotrophic bacteria, Adriatic Sea, South Adriatic Sea, phytoplankton pigments, open sea, microzooplankton, mesozooplankton, research cruises
Published in DiRROS: 05.08.2024; Views: 2090; Downloads: 802
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