engleski

High prevalence of congenital umbilical hernia in bottlenose dolphins (Tursiops truncatus) from the Adriatic Sea

As part of a long-term project to investigate marine mammal strandings, 131 bottlenose dolphin {;Tursiops truncatus) carcasses found in the Croatian part of the Adriatic Sea were examined from 1990 to April 2009. In 13 cases (five of them were either fetuses found in uteruses of dead mothers or aborted fetuses ; while eight were born alive and lived for various periods of time) we observed congenital umbilical hernia, a malformation of the ventral abdominal wall. This malformation is well known in animals and humans and causes death in-utero or soon after birth in terrestrial animals. In humans, the congenital umbilical hernia appears in 3.5 out of 10, 000 births. The bottlenose dolphin is the only resident marine mammal species in the Adriatic Sea, with an estimated number of around 200 adult individuals and around 20 cubs living in the Croatian area. It is estimated that between 15 and 20 bottlenose dolphin births occur there annually, so the estimated total number of births since 1990 is between 270 and 360. This means that congenital umbilical hernia appears in between 361 and 482 out of 10, 000 births of bottlenose dolphins in the Croatian Adriatic Sea. Our findings indicate that the incidence of congenital umbilical hernia in the Adriatic bottlenose dolphins is more than 100 times higher than that recorded in humans. The cause of such high incidence in the bottlenose dolphin remains unknown. Our future research will focus on determining a degree of relatedness among affected animals using molecular markers, in which we would test the hypothesis of the genetic basis of this malformation in the bottlenose dolphin. Furthermore, we do not know whether such high incidence of congenital umbilical hernia is found only in the Adriatic bottlenose dolphin population, or is it inherent to the bottlenose dolphin species.

dolphin; hernia

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