MEPS 301:303-305 (2005)  -  doi:10.3354/meps301303

Bloom of the marine diazotrophic cyanobacterium Trichodesmium erythraeum in the Northwest African Upwelling

Antonio G. Ramos1,*, Antera Martel2, Geoffrey A. Codd3, Emilio Soler2, Josep Coca1, Alex Redondo1, Louise F. Morrison3, James S. Metcalf3, Alicia Ojeda4, Sonia Suárez2, Michel Petit5

1SEASnet Canarias, Dpto. de Biología, University of Las Palmas de Gran Canaria, Campus de Tafira, 35017 Las Palmas de Gran Canaria, Canary Islands, Spain
2National Bank of Algae, Centro de Biotecnología Marina, Muelle de Taliarte s/n 35214-Telde (Gran Canaria), Canary Islands, Spain
3Division of Applied and Environmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 4HN, UK
4Instituto Canario de Ciencias Marinas (ICCM), Carretera de Taliarte s/n, PB 56. 35200 Telde (Gran Canaria), Canary Islands, Spain
5SEASnet Montpellier, Institut de Recherche pour le Développement (IRD), Maison de la Télédétection, 500 Rue JF Breton, 34093 Montpellier Cedex 05, France

ABSTRACT: A bloom of the non-heterocystous diazotrophic cyanobacterium Trichodesmium erythraeum Ehrenberg is reported in the Canary Islands Archipelago during August of 2004, the warmest period of a meteorological series recorded by the National Institute of Meteorology (Spain) since 1912. Samples showed massive occurrences of T. erythraeum (1000 filaments ml–1) in different sectors of northern and southern waters off the central Canary Islands. Water analyses also showed a relatively low presence of dinoflagellates and diatoms. Quasi-true colour satellite images of dust storms, elevated sea surface temperature (the warmest satellite-derived record), chlorophyll a and geostrophic current fields showed satellite-derived optical positives of Trichodesmium in an African upwelling advective, jet-drifting westward current off the south Canary Islands. Analyses for cyanotoxins using HPLC found microcystins, which was confirmed by immunoassay, at concentrations from 0.1 to 1.0 µg microcystin-LR equivalents (g–1 dry weight of bloom material). A T. erythraeum bloom such as that observed in August 2004 in the NW African Upwelling does not appear to have been recorded for the area previously. The bloom may have developed due to the exceptionally warm weather and/or to the massive dust storms from the Sahara Desert observed in the NE Atlantic in August 2004.


KEY WORDS: Cyanobacteria · Trichodesmium erythraeum · Remote sensing · NW African Upwelling · Advective jet · Toxicity


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