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Midwater Ecology Expedition Fall 2019 – Log 2

When this bait tray was first placed on the seafloor, it was full of squid—but the deep sea is a busy and active place with some hungry foragers.

Midwater Ecology Expedition Fall 2019 – Log 2

Updates from researchers on the R/V Western Flyer:

Sunday, November 17, 2019
Astrid Leitner

This polychaete worm generally considered a seafloor resident was found swimming in the midwater.

We started out at our deep dive location just outside Monterey Bay on Saturday. We dove all the way to the bottom to about 3,000 meters (9,800 feet) where we deployed Henk-Jan and Stella’s bait package and filled up the Midwater Respirometry System for a 48-hour deep experiment. For this experiment, we managed to collect a very interesting polychaete worm which was swimming in the midwater, although it is generally considered a seafloor resident.

The weather got a bit rougher, and Saturday evening we were glad to head back into the more protected waters of Monterey Bay to our southern canyon wall site. We spent our full dive day on Sunday at this site, taking advantage of the late sunrises of the season to catch the daily downward dawn migration of midwater animals on video with the ROV. Because the ROV launches at 6:30 a.m. every day, and dawn was at 6:20 a.m. today, our timing was just right.

When this bait tray was first placed on the seafloor, it was full of squid—but the deep sea is a busy and active place with some hungry foragers.

I am interested in looking at how migrating midwater animals are affected by the abrupt canyon topography in Monterey Bay. I am especially interested in what happens to those animals which cannot complete their normal morning descent into deep waters because they ended up over the shallow canyon rim during the night while they were busy feeding near the surface. We completed both a set of morning transects down the wall and a complementary set of evening transects back up the wall. This will allow me to compare the distributions of animals relative to the canyon topography at different stages in the daily migration cycle. These transects involve difficult maneuvers in very challenging, steep terrain. Thanks to our team of talented ROV pilots we were able to collect two full sets of transects at the beginning and at the end of the day. Tonight we will be heading back out to the deep station to pick up the Midwater Respirometry System. Hopefully we will have calm seas for our dive out there tomorrow.

About Midwater Ecology Expedition Fall 2019

November 15-21, 2019 – The Midwater Ecology Group is studying and collecting midwater animals in conjunction with collaborators from GEOMAR Helmholtz Centre for Ocean Research and Auckland University.