Environmental Engineering Reference
In-Depth Information
Convention and the G7 Guidelines. It describes three different BWM RA methods,
“environmental matching”, “species' biogeographical” and “species-specifi c” RA.
The environmental matching RA between the areas of ballast water origin and
discharge considers non-biological parameters such as salinity and temperature as
surrogates for the species survival potential in the new environment. The species'
biogeographical RA seeks to identify species with overlapping distribution in the
donor and recipient ports and biogeographic regions. These overlaps are taken as
direct indications of the similarity of the environmental conditions and hence spe-
cies survival in the new environment. The species-specifi c RA is focused on infor-
mation on life history and physiological tolerances to identify a species' physiological
limits and estimates its potential to survive or complete its life cycle in the new
environment (IMO
2007
).
Environmental Matching Related Risk Identifi cation
The vector-related risk identifi cation can be based on two fundamental elements:
the likelihood of organism transfer (i.e., the quantity and origin of the discharged
ballast water and abundance of propagules therein),
the likelihood of organism survival in the recipient environment (match of
selected environmental parameters of donor and recipient regions).
Different marine regions are typically defi ned as biogeographic regions, but all
existing biogeographical schemes were developed for different purposes and not for
biological invasions RA, e.g., Briggs (
1974
) and Springer (
1982
), IUCN bioregion
system (Kelleher et al.
1995
), Ekman (
1953
), Longhurst (
1998
) provinces, Spalding
et al.
2007
and Briggs and Bowen (
2012
). IMO suggested to use the Large Marine
Ecosystems (LME) approach (see Fig.
2
) because at the time of drafting the G7
Guidelines this was considered the best available information, but local and regional
adaptations may be necessary.
In the G7 Guidelines environmental matching was determined to assess the like-
lihood that species found in the ballast water donor region are able to survive in the
recipient port. However, some uncertainty remains, namely the uncertainty to defi ne
the environmental conditions, which are predictive of the species to establish and
cause harm in a new location. Another key point is the determination whether the
risk of ballast water discharge is suffi ciently low to be exempted from BWM
requirements. Environmental matching RA is of limited use in cases where the dif-
ferences between a donor region and a recipient port are small. In these cases, such
as shipping within one biogeographic region, high similarity between donor and
recipient areas is likely and indicates a high likelihood of successful species
establishment. However, there are exemptions from this rule, e.g., areas with differ-
ent water salinities in the same bioregion, which may be caused due to, e.g., run-offs
of major rivers.
In addition to comparing the environmental conditions of biogeographic regions,
this comparison should further be undertaken between the donor and recipient ports,
i.e., in much smaller scale. Similarity of key environmental conditions between the
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