Occurrence of species from the genus Pseudo-nitzschia in the Southwestern Atlantic and Southern Ocean

ALMANDOZ G., FERRARIO, M., FERREYRA G. & SCHLOSS I.

Copenhague, Dinamarca

Conferencia; 12th International Conference on Harmful Algae; 2006

The distribution of Pseudo-nitzschia species and its relationship with main environmental factors were studied in surface waters of the Argentine and Weddell Seas (38-55°S and 61-77°S, respectively). Both qualitative and quantitative samples, collected during summer and fall 2003, summer 2004 and spring 2005 were examined using light and scanning electron microscopy. Several Pseudo-nitzschia species were found in the Argentine Sea, including P. americana, P. australis, P. calliantha, P. fraudulenta, P. heimii, P. lineola, P. pungens, P. subcurvata, P. turgidula and P. turgiduloides. P. pungens and P. australis were the most common species recorded, especially in waters with elevated temperatures and salinities (around 15ºC, 33.8psu) and low nutrient concentrations. The rest of the species showed a more restricted distribution. P. calliantha and the epiphytic P. americana, both reported by the first time in Argentinean waters, were found only during spring. A lower number of species was found in cold (0.6 to -1.6ºC) and nutrient-rich waters of the Weddell Sea. Notably, P. lineola, P. prolongatoides, P. subcurvata and P. turgiduloides showed a widespread distribution, while P. heimii and P. turgidula were confined northward 62ºS. Morphometric data, abundances and ecological preferences are given and compared with previous studies.