On-board Diary: Placer de la Barra Alta

Author: Ricardo Aguilar
Date: July 22, 2006



“Placer de la Barra Alta” is the strange name given to a small hillock measuring 60-70 meters in height located a few miles west-southwest of the Columbretes Islands. It rises from a flat sea floor at 80 meters and some of its peaks rise up to just 9 meters below the surface. It is not an extensive area, although the sea bed is quite interesting. Since this area is not protected like Columbretes, the sea bed is more deteriorated: we found fishing line and nets caught on the rocks and no sign of any large sessile animals (attached to the substrate). Even the spectacular bush-like sponges (Axinella polypoides) are small in size.

We do not expect to find large groupers nor other species common within the reserve due to the presence of professional and sporting fishermen and scuba divers here. Even the only forkbeard (Phycis phycis) we have seen quickly swam away from us when it felt our presence, nothing like the forkbeards within the reserve posing for our photographs.

It is also interesting to find the classic rhodolites or "balls" of calcareous algae of the Lithothamnion and Phymatolithon types which generate important maerl beds (or forests of coralline algae), in small sandy spots between the rocks. Part of the sea floor in this area is made up of pieces of dead animals, such as mollusc shells, the "skeletons" of bryozoans, corals, etc. and also calcareous algae.

Even so, the place is worth a visit. The sea floor is dressed in red, green and brown algae, although the dominating algae covering extensive areas is the brown Dictyopteris membranacea, as in many other areas of the Columbretes. Among the brown algae, we also find various types of kelps here, as well as some species resembling sponges such as the Colpomenia sinuosa. We also find some Mesophyllum alternans, the calcareous red algae that forms large colonies which protect various species, and some very interesting green algae, Halimeda tuna, with its calcareous interior resembling coral, or Codium bursa that resembles a green ball.

Actually, the day has been quite interesting: various gobies, including a Gobius xanthocephalus, ornate wrasse (Thalassoma pavo), damselfish (Chromis chromis), colonies of alcyoniidae (Maasella edwardsii), hermit crabs (Dardanus calidus) with their shells covered in calcareous algae of the Lithothamnion type resembling a ball of maerl, groups of marine snails called banded-dye murex (Hexaplex trunculus) laying eggs together and forming a large ball… So much information to process.

Unfortunately, we have not had the luck of spotting any sharks in the area. We knew it would be difficult, but we had not lost hope; the thintail thresher shark (Alopias vulpinus) has been spotted in this area, showing off its impressive tailfin, almost as long as half its body. Maybe some other time. The problem is the Mediterranean sharks, which were so common long ago, have suffered such severe declines that today they are quite difficult to find. Just another sign of the terrible ways we manage our oceans and seas.