A dolphin paradise lost?
With one of the highest population densities in the Mediterranean, the Amvrakikos Gulf, in north western Greece, could just a decade ago have been considered one of the last remaining strongholds of the bottlenose dolphin (Tursiops truncatus). Yet the dolphin population there is now significantly affected by anthropogenic impacts (derived from human activities) and is struggling for mere survival. With your help, we’re seeking to ensure the future of this vulnerable species in a region synonymous with one of the world’s most iconic marine mammals.
Research in the Gulf began in 2001 as the Tethys Research Institute, with Earthwatch support beginning in 2006, attempted to determine the seemingly healthy population density of the bottlenose dolphin - a factor largely owing to the abundance of prey in these waters.
Unfortunately however, high population density does not necessarily imply either a favorable conservation status or that dolphins are living in a healthy ecosystem. Eutrophication (where nutrient loading of the water has led to excessive algae growth), pollution and other anthropogenic impacts are on the increase, leading to a deterioration of water quality and therefore the natural habitat of bottlenose dolphins.
A semi-enclosed basin and one of the most productive coastal areas of Greece, the Amvrakikos Gulf was designated a Ramsar1 site in 1975 and was given National Park status in 2008. But dolphin populations in the area and other marine fauna are not subject to any measures of protection to improve their conservation status and ensure their long-term survival.
The particular features of the Gulf make it an ideal and unique area to monitor cetacean (whale and dolphin) population dynamics and assess the possible interactions between dolphins and local fisheries. The only link to the open Ionian Sea is a narrow and shallow strait called the Preveza channel. This restricts dolphin movements beyond the Gulf, therefore the immigration and emigration rates of dolphins are low.
Dolphins of Greece and the bottlenose dolphin
Despite the fact that bottlenose dolphins can be encountered almost all over the globe, the Mediterranean population of bottlenose dolphin is currently categorized as Vulnerable to Extinction after a recent review carried out by a team of IUCN specialists. The distribution of the bottlenose dolphin is increasingly scattered and fragmented into small units and declining trends have been reported as their habitats are degraded by pollution and overfishing.
The aim of today’s Earthwatch supported project is to identify the main threats affecting the animals, and offer scientific support to inform management actions that will successfully ensure a favorable status for the dolphins and their ecosystem. Public awareness and educational activities are also conducted within local communities, through collaboration with school teachers and fishermen.
Past, present and future perspectives
When research began in 2001, there were a large number of dolphins, sea turtles and sea birds present in the Amvrakikos Gulf. But in a very short time, fewer and fewer numbers were encountered and it became evident that the Gulf's biodiversity was being considerably affected by a number of anthropogenic impacts. When Earthwatch began supporting the project in 2006 it was to tackle these problems.
If things continue as they are, the reproductive isolation of the relatively small population, its reduced range and growing anthropogenic threats, could create a high risk of population extinction or, at the least, decline. But there is still hope. Habitat degradation within the Amvrakikos Gulf could be reduced by restoring water exchange with the open Ionian Sea, and curtailing eutrophication and pollution. To achieve this, dolphins could be important drivers of the conservation process by acting as the flagship species, raising awareness of the need for these measures, for the benefit of the entire Gulf ecosystem – and the small communities who’s livelihoods depend on a healthy Gulf.
The Earthwatch volunteer contribution
The Earthwatch project, Dolphins of Greece is led by field scientists Joan Gonzalvo and Dr Giovanni Bearzi. Joan has been working with the Tethys Research Institute since 1999, and having lived in the region close to the gulf for a number years has established good relationships with local fishermen. Giovanni, president of Tethys Research Institute, is based in Italy.
During Earthwatch expeditions, daily morning surveys are conducted along pre-defined routes to record dolphin encounter rates, as well as encounters with sea turtles, fish and the vulnerable Dalmatian pelican (Pelecanus crispus). Since 2001, 556 surveys have been carried out in the study area, with a total of 24,889km covered by boat, and 500 sightings of bottlenose dolphin and 408 of loggerhead turtle (Caretta caretta) have been recorded.
The participation of Earthwatch volunteers since 2006 has made it possible to increase the research effort significantly with volunteers actively contributing to all phases of the field work, from surveying at sea, to analyzing digital photos at the field station and engaging in sessions to further educate the local community about cetacean research and conservation strategies.
The research, based on photo-identification, has identified a total of 151 resident dolphins, showing a high level of site fidelity. Individual photo-identification is an important tool in cetacean research worldwide, enabling scientists to catalogue populations of bottlenose dolphin and other species. The method uses natural marks on dorsal fins of individual animals, which act like a "fingerprint." And the data collected provides information on dolphin abundance, population trends, movement patterns, fine-scale habitat use, social organization and reproductive success.
Report by Aina Pascual Cuadras.
Volunteer today and help secure the future of the Amvrakikos Gulf and the Dolphins of Greece.
Ramsar sites are wetlands of international importance designated under the Ramsar Convention.