First harmful algal bloom record of tycoplanktonic dinolfagellate Prorocentrum lima (Ehrenberg) F. Stein, 1878 in the Dardanelles (Turkish Straits System, Turkey)

摘要

This study focused on daily variations and harmful algal bloom features of toxic dinoflagellate Prorocentrum lima (Ehrenberg) F. Stein (P. lima), 1878 in middle summer period (9th July–6th August 2013) in the Dardanelles. Harmful algal bloom of P. lima was recorded for the first time in the Turkish Straits System. Density of P. lima reached to 2.40 × 106 cells/L and exhibited four excessive blooms over 1.0 × 106 cells/L during the study. The contribution of P. lima to both Prorocentrum spp. and dinoflagellates reached to 100%, particularly at the moment of the harmful algal bloom attested by regresion (R≥0.70) and correlation findings (R≥0.80). Nutrient concentrations were lower than previous levels due to excessive blooms. Concentrations of NO-2+NO-3, PO-34 and SiO4 varied between 0.20 and 0.78 µmol/L [(0.44 ± 0.17) µmol/L], 0.08 and 0.18 µmol/L [(0.12 ± 0.03) µmol/L] and 0.25 and 0.65 µmol/L [(0.41 ± 0.09) µmol/L] respectively. During the bloom, nutrient ratios were more different than redfield ratios due to eutrophication (NO-2+NO-3/PO-34=4.04 ± 1.74;SiO4/PO-34=3.79 ± 1.24;SiO4/NO-2+NO-3=1.04 ± 0.36). Chlorophyll a concentration reached to 8.52 µg/L (average:4.82 ± 2.29 mg/L) in the bloom period. Temperature [(24.70 ± 0.44) °C], salinity [(22.9 ± 0.49) ppt], pH (8.23 ± 0.15) and dissolved oxygen levels (7.35 ± 0.60 mg/L) were approximately constant. The compact bloom of P. lima, similar to excessive blooms of other dinoflagellates and diatoms, was associated not only with eutrophication, but also with ocean warming interactions. Results revealed that it will be possible to reach to millions of cell number of P. lima (2.40 × 106 cells/L) in eutrophied waters characterized by high chlorophyll a biomass (8.52 µg/L).