Investigation of the mass appearance of toxic dinoflagellates from the genus Ostreopsis on a public beach north of Rovinj

Abstract

Cilj ovog istraživanja bilo je dokazati prisutnost dinoflagelata roda Ostreopsis uz Istarsku obalu Jadranskog mora te ispitati njihovu toksičnost. Istraživanje smo proveli na javnoj plaži Borik sjeverno od Rovinja u razdoblju od 22. rujna 2010. do 27. listopada 2010., za vrijeme maksimalne zabilježene brojnosti roda Ostreopsis. Alge roda Ostreopsis su epifitske, one za svoje stanište zahtijevaju stabilnu podlogu jer prilikom nepovoljnih vremenskih uvjeta dolazi do odvajanja stanica sa supstrata. Svakodnevno smo pratili raspone temperature, saliniteta, vremenske uvjete te brojnost na makroalgi Cystoseira crinita, koja predstavlja odličan supstrat za prihvat biofilma algi roda Ostreopsis. Ovim istraživanjem bolje smo upoznali ekologiju roda Ostreopsis. Praćenje dinamike cvjetanja ukazalo je na važnost okolišnih čimbenika na razvoj i završetak cvjetanja, posebno hidrodinamičkih uvjeta poput vjetra, valova i struja. Zabilježeni su toksini palitoksin i ovatoksin, te smo njihovom analizom pokazali su da je proizvodnja tijekom prirodnog cvjetanja bila iznimno visoka.The aim of this study was to prove the presence of the dinoflagellate genus Ostreopsis along the Istrian coast of the Adriatic Sea and investigate its toxicity. The research was conducted at a public beach north of Rovinj, in the period from the 22nd September 2010. until the 27th October 2010., during the maximal recorded abundance of the genus Ostreopsis. Algae of the genus Ostreopsis are epiphytic. They require a stable habitat and settlement base because adverse weather conditions might cause a separation of cells from the substrate. We followed temperature, salinity, weather conditions and abundance of Ostreopsis sp. on the macroalgae Cystoseira crinita, which is a perfect substrate for the biofilm produced by the genus Ostreopsis. This research allowede us better insights into the ecology of this genus. Monitoring the dynamics of this bloom showed the importance of environmental factors for the development and completion of a bloom event, especially the hydrodynamic conditions such as wind, waves and currents. We recorded the toxins palytoxin and ovatoxin. Our analysis showed that their production was extremely high during this natural bloom