Blue Diatoms: Global Phenomenon of ˝Greening˝ in Shellfish and Record of Planktonic Haslea Species in the South Adriatic Sea

Diatoms are unicellular, photoautotrophic eukaryotic microorganisms, often forming colonies and can be found in most aquatic and moist terrestrial habitats. All known diatoms today have specific golden-brown pigment fucoxanthin that masks chlorophylls in diatom plastid, but one genus represents an exception, having the additional specific pigment marennine due to whom the cells appear blue. Blue diatoms from genus Haslea cause a global phenomenon of ˝greening˝ in shellfish (mostly oysters) affecting them in both positive and negative ways. In this study, historical and recent review regarding blue diatoms and physiological and behavioural effect of marennine as well as challenges in shellfish farming from diatom perspective is addressed. This study is also a first record of blue Haslea diatom in the South Adriatic Sea during BIOTA (Bio-tracing Adriatic Water Masses) cruise in March 2016. Investigated blue diatom was cultured in laboratory and morphologically analysed with light microscopy. Diatom investigations are very important for better understanding of the ecology of specific marine area, but also for the economy, aquaculture and tourism. The emergence of green coloured flesh of shellfish in the Adriatic Sea has not been recorded yet, but this finding of the blue diatom from genus Haslea does not rule out this possibility in the future

Dinamika populacije kalanoidnog kopepoda Acartia italica Steurer u malom slanom jezeru

The calanoid copepod Acartia italica is the only metazoan plankton species surviving and reaching high abundance in the middle Adriatic saline coastal Lake Rogoznica. Seasonal variations in the abundance of nauplii, copepodites, adults and their faecal pellets were assessed in the period January 2000 to December 2004. Development and behaviour of A. italica were regulated by thermohaline conditions, biology (phytoplankton, bacteria, ciliates), and chemistry (organic matter, dissolved oxygen, reduced sulphur species) of the lake. The diatom Chaetoceros curvisetus could provide important food for A. italica adult specimens; however, great diatom abundances could reduce copepod reproductive ability. This study show that top-down control which characterized the lake ecosystem before the disastrous anoxia event in 1997 were re-established again.Kalanoidni kopepod Acatia italica je jedini predstavnik mezozooplanktona koji se uspješno razvija u slanom jezeru Rogoznica u obalnom dijelu srednjeg Jadrana. Sezonalnost nauplija, juvenilnih i odraslih jedinki kopepoda A. italica, kao i njihovih fekalnih peleta reguliraju termohalini odnosi, biološki parametri (fitoplankton, bakterije, cilijati) i kemijski parametri (organska tvar, otopljeni kisik, reducirani sumporni spojevi) u jezeru. Dijatomeja Chaetoceros curvisetus važna je za ishranu odraslih jedinki A. italica, međutim njene velike abundancije mogu negativno utjecati na reprodukciju vrste. „Top down“ kontrolu u jezeru narušili su anoksični događaji iz 1997. godine