G. corsicum samples were obtained either directly
from Alfacs Bay or from a pond when higher densities
were required. G. corsicum from Alfacs Bay was
collected by means of a pump. These samples of water
were used directly for fish challenge within 1–2 h,
when densities were higher than 2000 cells ml-1 (experiments
D and G). When G. corsicum densities were
lower than 2000 cells ml-1, a 300m3 concrete pond
was used to store water from Alfacs Bay. During the
day and with the absence of wind, G. corsicum aggregated
and formed visible patches that had significantly
higher densities than in Alfacs Bay water. Water was