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8 O.E. TUREYEN

Table 3. Number of Invaded Seas Score
4 (Very High)
Invaded Seas
3 (High)
All four seas of Turkey (Marmara, Black, Mediterranean and 2 (Medium )
Aegean)
1 (Low)
Established in three seas of Turkey
Established in two seas of Turkey

Only established in one sea

Table 4 shows the management difficulty of invasive species which means the effort required to
reverse the threat or remove the species completely.

Table 4. Management Difficulty Levels of Invasive Species

Management Difficulty Score

Irreversible and cannot be contained or controlled 4 (Very High)
3 (High)
Reversible with difficulty and/or can be controlled with
significant ongoing management 2 (Medium )
1 (Low)
Reversible with some difficulty and/or can be controlled with
periodic management

Easily reversible with no ongoing management necessary
(eradication)

2.4 Frequency Factor

Risk is a measure of the likelihood that an undesirable event will occur together with a measure
of the resulting consequence within a specified time i.e. the combination of the frequency and
the severity of the consequence.

Therefore, for determination of risk classes or risk ranking of invasive species there is a need to
know the likelihood of the discharging the ballast water carrying those invasive species. To
measure this likelihood, native environment of every single invasive species must be known and
the total amount of ballast water carried from those environment needs to be recorded or
calculated.

GiDB|DERGi Sayı 5, 2016