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6 O.E. TUREYEN

 Growth and reproduction rate of invaders
 Management difficulty of invasive species

Fig 1. Flowchart of the ERA process
Many different kinds of indicators can be used including both living and nonliving assets giving
qualitative and quantitative informantions. Indicators used in this study are;

 Single species distribution change
 Population of native species
 Migration of native species
 Invasion rate of invaders
 Growth and reproduction rate of invaders
 Management difficulty of invasive species

2.3 Ecological Impact Factor
The number of invasive species introduced an ecosystem does not reflect the hazard caused by
invasive species. Some marine invaders can adopt the new environment only with few
disruptions while others can damage whole ecosystem and may cause extinction of some native
species. An ecological impact factor was determined for each marine invasive species in this

GiDB|DERGi Sayı 5, 2016