ANKARA Pufferfish , a poisonous species long viewed as invasive, have become a permanent part of the Mediterranean’s natural population, an expert has warned. The species, which contain the potent neurotoxin tetrodotoxin and pose serious risks to human health, have risen sharply in number in recent years along the coast of the southern province of Antalya, according to Professor Mehmet Gökoğlu from Akdeniz University. With strong jaws and a diet that includes juvenile fish during spawning