Zooplankton community dynamics Ballast water transport as a
taxonomic and numeric 'filter' Zooplankton data collected from
ballast tanks at the beginning and end of 25 voyages showed an
overall decline in total zooplankton abundance during a voyage.
Mortality within tanks could be caused by a number of factors,
including: - Lack of settlement substrate - Exposure to toxic
substances - Physiological stress caused by changes in physical
conditions In addition, the duration of a voyage or the age of
the ballast water is also an important factor, as mortality
within tanks appears to increase with time. For example, our
data indicated that: • On short voyages (<10 days) survival of
zooplankton is unpredictable, but typically high (both increases
and decreases in abundance were recorded) . • On long voyages
(16-22 days) there were large declines in survivorship (>95%
decrease in abundance in all cases. This an important finding
because in order to survive, establish, and thus achieve a
successful ballast-mediated i