On-board Diary: Seco de los Olivos

Author: Ricardo Aguilar
Date: August 8, 2006

Yesterday, the ROV technicians arrived in order to prepare the equipment and begin our investigations in the waters of the Chella Massif (Macizo de Chella), also known as Seco de los Olivos.

The ROV is a submarine Robot that allows us to film sea floors at depths which are impossible for divers to reach. Our idea is to work from the surface of this small marine mountain, which is at 70-80 meters, down to 240 meters depth.

Seco de Los Olivos is a group of small peaks measuring about 200 meters high, containing a larger peak formation on the inside, with a flat top measuring less than one square mile. From there, a platform falls to between 125 and 200 meters depth, and from here the whole cluster falls to over 600 meters depth.

The area is well known and important for species such as the bottlenosed dolphin (Tursiops truncatus) or the long-finned pilot whale (Globicephala melas) which can be found here.

At 08:00 in the morning, everything is prepared and we are ready to go. We will reach our destination in a couple of hours, but we will dedicate quite some time to outlining the profile of this location with the probe. During the trip, we spot many different species such as salp (Salpidae), a bank of sardines, small horse mackerel caught in the tentacles of a fried egg jellyfish (Cotylorhiza tuberculata), a multitude of fish larvae, a loggerhead turtle (Caretta caretta) dozing on the surface, low-flying Cory's shearwaters(Calonectris diomedea), and of course, a group of about 12 pilot whales.

At 11:30 we begin working with the ROV. During the first dive, we will sample the superficial areas in order to verify that everything works properly and that we are coordinating the work correctly.

For almost three hours, we cover close to one mile of this area observing the fauna that lives here. We are surprised by the abundance of maerl and the large quantities of corals and gorgonias, but especially by the diversity of the species: Paramuricea clavata, Eunicella verrucosa, Ellisella paraplexauroides, Dendrophylla ramea, Dendrophylla cornigera and black corals that we think belong to the Antipathes genus. We spot many fish, such as the swallowtail seaperch (Anthias anthias), the comber (Serranus cabrilla), the small-spotted catshark (Scyliorhinus canícula)…as well as long-spined sea urchins (Echinus acutus), the basket starfish (Astropartus mediterraneus), the strange Bonellia viridis and a few sponges, such as the elephant ear sponge (Spongia agaricina) with its characteristic cup shape.

In the afternoon, we will increase the depth. Starting at 240 meters, we will follow the hill up to 100 meters. This is a sandy bottom full of detritus. Thanks to the radar, we instantly spot the multitude of marks left by bottom trawlers. This area is heavily punished by these fishing methods, although we can still find some interesting species here, even if they are somewhat dispersed. We spot sea pens (Pennatula rubra or the Virgularia mirabilis) in certain areas, although many of them are dead or drooping, not far from a strange gorgonia (Eunicella filiformis) which is easily confused with a thin cable, many cuttlefish (possibly Rossia macrosoma), streaked gurnards (Trigloporus lastoviza), finless snake eels (Apterichthys caecus), mud and rock forkbeards (Phycis spp.), boarfish (Capros aper), tube anemones (Cerianthus sp.), king's sea cucumbers (Stichopus regalis)…

We have collected a wealth of information that we will have to carefully analyse. Now we must return to port; unfortunately, we are having problems with the port-side engine which is not running. Hopefully, it will be easy to repair.