    Senitence I; What, event was\-blamied  on -the. introdiiction of, mneimiopsis:  into ‘The Black Sea? “> :  Sentehcd, 2: ‘The situation. ..was   aggravated ‘by other factors; such as  over-fishing. and, long-term:  environmental changes that: promoted  the; growth. -.of . the .-Mnemiopsis  popillation’