The bloom of Enteromorpha proliphera was probably caused by the
persistence of cold temperature and associated high nitrogen concentration
during early summer (Sanderson, 1997), considering that
temperature is the primary cause of the geographic boundaries of
species ofmacro-algae (Druehl, 1981; Schiel and Foster, 1986). In effect,
in June 2008 themonthlymean Sea Surface Temperature in the areawas
3 °C colder than in previous years [NASA Giovanni website, Goddard
Earth Sciences (GES) Data and Information Services Center (DISC)].
The event, which suddenly ceased in the first weeks of August with
the first intense sea warming, was captured from June onwards by
satellites in its full extent over an areamuch larger than the Qingdao Bay.
The huge extension of the agglomerates at the sea surface is clearly
visible in the MODIS (Moderate Resolution Imaging Spectro-radiometer)
image of June 28th, the only one informative (cloudless) in the
period. Although algal bloom is best visualized in RGB-composite
images (provided by the MODIS sensor with a spatial resolution of
500 m/pixel), algal agglomerates are clearly detected in band 2-only
images at a spatial resolution of 250 m