Larus michahellis (IMAGE) University of Barcelona Caption Los expertos alertan de que es preciso conocer mejor el impacto ecológico de las especies oportunistas en los ecosistemas naturales. Credit Isabel Afán (EBD-CSIC) Usage Restrictions The image may only be used with appropriate caption or credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.