Diapositiva 1

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Macroscopical appearance of a water sample with
aggregates of Trichodesmium
Fotografías Dr. L. O Shanahan
The Trichodesmium bloom was also observed at
several locations along the coast of Gran
Canaria and Tenerife (Canary islands). In the
picture, a view of an algal patch reaching the
shoreline, very close to a bathing beach (La
Laja, Gran Canaria) (black arrow).
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Fotografía Dra. Alicia Ojeda
Microscopical identification. Samples were
observed under a light Microscope Olympus (600
X). Identification was done in the Laboratory of
Phytoplankton of the Canary Is. Institute of
Marine Sciences (ICCM) (Dr. A. Ojeda). Samples
showed massive occurrence of Trichodesmium
erythraeum Ehrenberg (1000 filaments/ml).
Colonies were formed by chains of cells.
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Management Measures were adopted according
Articles 7 and 8 of Directive 2006/7/EC. Article
7 Management measures in exceptional
circumstances Member States shall ensure that
timely and adequate management measures are taken
when they are aware of unexpected situations that
have, or could reasonably be expected to have, an
adverse impact on bathing water quality and on
bathers' health. Article 8 Cyanobacterial
risks 1. When the bathing waters profile
indicates a potential for cyanobacterial
proliferations, appropriate monitoring shall be
carried out to enable timely identification of
health risk. 2. When cyanobacterial
proliferations occurs and a health risk has been
identified or presumed, adequate management
measures shall be taken immediately to prevent
exposure including information to the public.

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A Trichodesmium 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
(1) and/or to the massive dust storms from the
Sahara Desert observed in the NE Atlantic in
August 2004 (2) (Texts and pictures in this slide
by Ramos et al., 2005).
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Ramos et al., 2005. Bloom of the marine
diazotrophic cyanobacterium Trichodesmium
erythraeum Ehrenberg in the Northwest African
Upwelling. Marine Ecology Progress Series, vol.
301303-305, 2005.