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Seafloor Ecology Expedition 2019 – Log 3

ROV Pilot Ben Erwin looks over the moon pool as the ROV Doc Ricketts is deployed into the beautiful blue waters above Davidson Seamount.

Seafloor Ecology Expedition 2019 – Log 3

Octopus Garden

When MBARI and MBNMS researchers were onboard the E/V Nautilus last year they had the opportunity to check out a spot near Davidson Seamount.  They found something so surprising and intriguing that we revisited the same site on this expedition. On the seafloor, in cracks and crevices on the edge of this underwater mountain made of ancient lava, they saw octopuses—not hundreds, but thousands of octopuses—sitting on their eggs! When an animal protects its eggs, we call it brooding. This was the first time scientists have ever seen such a large aggregation of brooding octopuses anywhere in the world.

On last year’s dive, the scientists were able to get a first look. Just last month, MBNMS researchers joined Woods Hole Oceanographic Institution (WHOI) on the R/V Atlantis and visited the site again and were even able to collect some eggs and measure the water temperature. Now, with ROV Doc Ricketts, we had the opportunity for a short dive on the site as we headed to Sur Ridge from Station M (off Southern California).

What is creating this oasis in the deep sea? On the Atlantis expedition, the team measured the water temperature in the crevices where the octopuses lived and found that it is nine degrees Celsius (48 degrees Fahrenheit) warmer. It seems that the warm water is what brings the octopuses to the area, but why? Do the eggs develop more quickly at higher temperatures? Why is warm water seeping out of the seafloor here? These are all questions we are hoping to answer with continued research at the site. MBNMS Research Coordinator Andrew DeVogelaere, says they plan to return with E/V Nautilus again in October and hope to continue to answer some of these questions.

Below is a video showing the octopus garden on NOAA’s E/V Nautilus.