Earth from Space: Bloom-filled Baltic This Envisat image
captures blue-green algae blooms filling the Baltic Sea, which
is roughly 1600 km long, 190 km wide and has a surface area of
about 377 000 sq km. 'Algae bloom' is the term used to describe
the rapid multiplying of phytoplankton, microscopic marine
plants that drift on or near the surface of the sea. Floating
freely in the water, phytoplankton are sensitive to sunlight and
local environmental variations such as nutrient levels,
temperature, currents and winds. The blooms seen here are due to
favourable conditions – lots of sunshine, little wind and an
increase of nutrients from run-off following the ice season – in
the area over the past weeks. Although algae blooms are a normal
and essential phenomenon, they can be harmful to humans and
animals when they produce toxic substances, occur too often or
last too long, depleting the concentration of oxygen in the
water. Due to the toxicity of some phytoplankton and marine
algae species, it is important to mo