Exploring Farallon Basin
March 9, 2015
For today’s ROV dive we took a second look at Farallon Basin. Diving in the same location for two consecutive days gives us a chance to conduct night operations (such as trawling) and the opportunity to see how the water column changes day by day. From our dive video it would have been difficult to guess that we did not transit to another station because the water column today is very different from what we saw yesterday. The Gulf of California is a dynamic environment, characterized by tidal flows, dense layers and aggregations, and blooms of conspicuous species. Today we observed many more large siphonophores such as several species of Marrus, Apolemia, and Erenna and collected a lot of amphipods. We spotted few of the small white narcomedusae that were a dime a dozen yesterday.
The blue water SCUBA dives also confirmed the significant daily changes that can happen in the water column. Yesterday the upper water was full of at least four different species of heteropods (comical-looking swimming snails with an elephant-like trunk). There were also lots of little ctenophores (Ocyropsis) and siphonophores (Sulculeolaria), but today all of these were scarce. So, if you are hoping to study a specific target organism, you have to take advantage of every collection opportunity because you can never tell what tomorrow holds.
—Kyra Schlining and Steve Haddock