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July 21, 2006

Last day in Columbretes

BY: Ricardo Aguilar



Today is our third and last day in Columbretes. We will concentrate on the exterior west section of Isla Grossa. The wall is more prominent here and thanks to this, there are many communities of sponges and corals, such as scleractinian and stoloniferous corals. There is also more movement and currents in this area and, consequently, some species can be seen here which usually inhabit open waters, such as the greater amberjack (Seriola dumerili) or the European barracuda (Sphyraena sphyraena). Also, thanks to the many caves and rocks, it is a perfect place for other species such as groupers (Epinephelus marginatus), Mediterranean morays (Muraena helena), spiny lobsters (Palinurus elephas) and cardinal fish (Apogon imberbis).

By the way, we found one of these cardinal fish with an egg clutch in its mouth. This species keeps their eggs in their mouths in order to incubate them and protect them from predators.

In the Mediterranean, the scleractinian corals do not form those impressive reefs which are so characteristic of the tropical areas. Here, many of them are solitary or live in small colonies, but there are some species capable of covering extensive areas of the sea bottom and of these walls. For example, the Mediterranean madrepora (Cladocora caespitosa) or one of the cup corals such as the Polycyathus muellerae. This wall seems quite a good habitat for these communities and other colonial species related to coral family, like the encrusting anemone (Parazoanthus axinellae) and the jewel anemone (Corynactis viridis), which shows off impressive colours, from green to red and orange to pink. These dives in rocky and walled areas are a treat for the eyes thanks to the wonderful hues worn by the species that live here.

Here, the brown meagre (Sciaena umbra) seem more friendly. This species has suffered a strong decline and they are now included in the list of protected animals compiled at the Barcelona Convention on the Mediterranean Sea.

We concentrate most of the day on examining the details of the many species we find here. We would like to identify these species very carefully, and later, show them to everyone so they may become familiar with them and understand their significance. This is not an easy task, because sometimes the differences between species is minimal and not noticeable at first glance. And as far as sponges are concerned, these can only be correctly identified in a laboratory, with the exception of a few, very characteristic cases. Since we are in a natural reserve and we do not intend on collecting samples, we are satisfied by getting as close as we can to the taxonomic classification, but many times we can only say its “a sponge.” Luckily, we are able to identify one of them, the Acanthella acuta, which we believe has not yet been identified in these islands.

We take care to capture good images of the species we find here, because these images will later play a fundamental role when the time comes to explain their significance in the ecosystem and make the public aware of the importance of conservation. Many marine species do not have common names, only scientific ones, and this fact, together with the strange scientific language we use to describe them (bryozoa, sipunculids, rhodophyceae, etc.) tends to make the public shy away from the ocean. As land animals, the marine ecosystem is strange to us, and furthermore, the animals that inhabit that ecosystem behave in strange ways. Here, not everything anchored to the ground is vegetable nor everything that moves is animal. Here, the “grass” walks and the animals “sprout roots.”