Hermaphrodite little tunny, Euthynnus alletteratus. (Photo Credit: IEO)
Hermaphrodite little tunnies warn of environmental pollutants in the Mediterranean
Friday, January 31, 2014, 04:50 (GMT + 9)
Scientists at the Spanish Institute of Oceanography (IEO) have found intersex (hermaphrodite) little tunny specimens (Euthynnus alletteratus) for the first time in the Mediterranean. They attribute this condition to hormonal disorders possibly caused by environmental pollutants.
Hermaphroditism or intersex, the way this condition is more accurately called, is the same individual having characteristics of both sexes in its gonads or sex organs, which can naturally and temporarily appear in those species that change sex throughout their life cycles.
However, most of the cases described in the literature of intersex individuals in vertebrates are related to hormonal disorders, whether caused by problems during development or environmental pollutants.
Since the 90s, it is known that artificial compounds similar to human hormones, called estrogen-mimics, can cause intersex in different taxonomic groups. Therefore, there are some substances like dicofol or DDT pesticides, widely used in the past and currently prohibited by recommendation of the World Health Organization, which may act as estrogen mimics.
Recently, as a result of the monitoring of little tunny populations in the Mediterranean, within the National Plan of Basic Fishery Data (funded by the European Union and managed by the IEO), two intersex individuals of this species have been detected. This finding was recently published in the journal Marine Biodiversity Records.
The article, written by the Tuna and related species in the Mediterranean team of Malaga Oceanographic Centre under the IEO, shows a low prevalence of intersex in the species. However, the detected specimens were captured in two consecutive recent years of the series (2011 and 2012) whereas similar cases in the area had never been described before.
"This could indicate an anthropogenic origin of the problem," explain the authors. However, further studies analyzing contaminant levels in these populations and specifically in intersex specimens are needed, which will provide the information needed to clarify the causes of the appearance of these anomalies.