On-board Diary: Documenting the sea beds of Gorringe
Author: Ana de la Torriente
Date: August 4, 2011
We set sail from Portimão 4 days ago and headed toward Gorringe with the support of the Foundation for the Third Millenium. It’s the second time this year that we’ve tried to study and document the sea beds of these seamounts because the weather and strong winds have prevented us from doing so up to now. The forecast looked good for 3 or 4 days, so we had to give it a try.
The crossing to the study area was long: roughly 24 hours of sailing with strong winds and waves. However, once we reached the seamount, the winds calmed down and the conditions were stable enough for us to work and dive both with the team and the ROV.
In total, we completed one dive with the team and nine with the ROV, documenting both the peaks and the beds at roughly 600 meters depth. We knew that the good wind and wave conditions could end abruptly, so we had to take advantage of the hours and explore as many areas as possible.
The divers dove on one of the seamount's peaks known as Gettysburg, at roughly 35 meters depth. The surface area located at this depth is so small –because the slope falls sharply and suddenly down to great depths- that locating the exact point was essential. Despite the strong currents in the area, we found the spot and the divers returned to the Ranger with some beautiful images of algae covering the rocky substrate, as well as amberjacks, grey triggerfish and seabass in the water column and numerous torpedoes that, if you didn’t look closely, looked like small “patches” of sand.
Apart from Gettysburg, there is another shallow peak on Gorringe located at roughly 45 meters called Ormonde. The fact that the light reaches the sea bed of these peaks means large, dense kelp forests form and generate high levels of productivity in the area. We completed one of the dives with the ROV between 35 and 130 meters in order to verify the depths the algae reaches. It was surprising to find that these forests covered the beds of the seamounts down to 80 meters, much deeper than we normally find them in the coastal areas we’ve studied before.
At increased depths, we documented oyster beds, fields of black corals and sponge fields comprised of a wide variety of species. We also documented a variety of fish species including conger eels, orange roughies, swallowtail seaperch and moray eels.
Today was the third day working on Gorringe. The waves were higher than other days and although we’ve been able to complete 2 dives on Ormonde, the forecast for tomorrow is not good and the conditions won’t allow us to continue working and documenting the sea beds. So we decided to return and set sail for the peninsula where we’ll search for an area where we'll be protected from the strong winds, from among the areas we've planned on working in this year.
We're all happy with the results. After all the dives, it’s obvious that Gorringe harbors many different habitats located a different depths and different slopes and that we've only just begun to explore the marine communities there. But just when we thought the weather conditions would not allow us to continue, we were able to sail to the area and obtain many hours of footage including new data from this mostly unexplored area.