Environmental Engineering Reference
In-Depth Information
In conclusion we consider that even small quantities of harmful organisms present
in discharged ballast water may result in a successful transfer of a species which in
turn may have negative consequences. As a result the RA described here does not
consider the ballast water volume discharged in a recipient port and neither the dis-
charge frequency as a risk level indication.
D e fi nition of Potential Impacts
Studies have proven that organisms even after entering a new environment may not
survive, reproduce or cause harm. However, other species introductions resulted in
drastic negative impacts on various stakeholders (see chapter
“
The Transfer of
for examples). In many cases it was shown that the process of introduction and spe-
cies adaptation to the new environment, before they cause harm, may last for years.
If a newly arrived species is not being studied in depth case by case (i.e., for each
recipient environment) it is very diffi cult, if not almost impossible, to predict the
species behaviour in the new environment(s) with an acceptable reliability. Hence,
a prediction of these stochastic events seems impractical and almost impossible.
As a result, the precautionary approach for the RA decision process considers all
aquatic non-indigenous organisms as harmful, and assumes that all harmful species
present in the ballast water donor port, if discharged, will cause harm in the recipi-
ent environment. In conclusion this means that the discharge of ballast water from a
donor port that contains harmful species is already an undesirable event.
The Main Risk Assessment Model Premises
As outlined above, the RA model in the decision making process considers different
premises, which are based on best available scientifi c knowledge covering the
expertise from different fi elds (e.g., invasion biology, maritime transport, BWM,
RA, regulatory affairs, environment and human health protection, etc.). In sum-
mary, the premises on which this RA model (see Fig.
4
) is based are:
The input environmental (i.e., salinity) and biological data for the RA must be
reliable.
Biological data may be considered as reliable if a port baseline survey for HAOP
has been conducted, and a regular monitoring program for HAOP is in place.
If salinity based RA results in acceptable low risk, no biological data is needed.
If a species is present in the ballast water donor port it will be discharged alive
with ballast water in the recipient port.
The voyage length, quantity of ballast water discharged and the frequency of
discharges as RA factors are diffi cult to be defi ned to a reliable level to change
the RA result.
Search WWH ::
Custom Search