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12 O.E. TUREYEN

4. Conclusion and Risk Reduction Strategies

Species can be carried by multiple ways from their native range to other regions where they are
identified as invaders. Although there are several vectors for transportation of marine invaders
such as aquaculture and fisheries, drilling platforms, canals, aquarium industry and even dive
practices, ships are the most important and common vectors for transportation of marine
invasive species by ballast water exchange processes and hull fouling.

The spread of marine invasive species is taken more seriously with their noticeable and
unneglectable harmful consequences for countries by huge economic and environmental
impacts. That is why more environmental friendly regulations and implementations are required
for prevention of invasive species. Even though global awareness of the situation and the
number of studies dealing with alien species are increasing, there is a need for studies focusing
invasive species problem on national scale with national resources and information because the
ship traffic, total ballast water amount carried from other regions, native species and natural
conditions are unique for every country and every ecosystem. According to those national level
studies, specific and targeted national regulations should be prepared concerning all the needs of
the environment and species.

It is clear that governments don’t have unlimited sources and funds for prevention or
management of invasive species. Regulations are not enough for dealing with the invasive
species problem alone also effective and sufficient supervision on ships is required. Therefore
prioritization of ships, routes and species according to the risk level is very significant which
provides better allocation of limited sources. For example, in this study Mnemiopsis leidyi was
found the most dangerous invader for coasts of Turkey and the native seas of this invader is
well-known. Ships carrying ballast water from those native areas should be prioritized for
investigations and supervisions. Besides the studies should focus on characterizations, control
and eradication methods of Mnemiopsis leidyi. National level regulations, effective allocation of
resources and the better control on ships will prevent to face the same problem caused by
uncontrolled ballast water discharge with Mnemiopsis leidyi in early 1990s. [3]

General risk reduction approaches such as reducing uptake of invasive species on board while
taking ballast water to ballast tanks, prevention and removal of ballast sediment, treatment of
ballast water and discharging ballast water to reception facilities, are also required to be
improved.

The effectivity of studies focusing on invasive species is related with the chosen range of the
ecosystems. More localized studies provide a better resolution of the ecoregion and better
understanding the dynamics of the ecosystem. National level studies lead well-detailed, well-
designed and well-organized national regulations including all the actions like operational
standards for ships and ports, prevention and control mechanism, management and eradication
processes and clear responsibilities and roles of authorities. Negative impacts of marine invasive
species can be taken under control with clarifying priorities, allocating limited sources and
effective national regulations which are coherent with global regulations.

GiDB|DERGi Sayı 5, 2016