Weedlines: A Sargassum Research Blog

PS-18-05 Daily Log

June 5, 2018 (Day 7)*

*Note: these will be posted on a one-day delay, i.e., this report is for yesterday’s activities.

We’re back in the Loop Current, aka, ‘life in the fast lane’. Things float just a little bit faster down here (including our research vessel!). Here is a short synopsis of some of the day’s activities.

Point Sur

A view of the R/V Point Sur during the small boat operations. (Photo: Courtney Stachowiak)

Today we started our search for Sargassum early in the cobalt blue waters of the Loop Current. Our heading ran perpendicular to numerous thin weedlines, but today we were hoping  to sample larger features, with an emphasis on collecting reflectance and backscatter data, and other optical qualities of Sargassum and open ocean habitats.During our search we spotted a large group of birds feeding in the distance, which is always a good sign. We changed our course to investigate, and soon we were surrounded by a dozens of sooty terns, calling and feeding along the Loop Current edge.


The CTD roesette at the surface during deployment.

There was relatively little Sargassum in the immediate vicinity, but on this new heading we soon found ourselves approaching some of the most concentrated patches of Sargassum we’ve seen so far during this cruise.



Mengqiu Wang  and Caitlin Slife measuring reflectance during the small boat ops. (Photo: Josh Bierbaum)


The remainder of the morning was spent collecting optical data from a smaller inflatable boat, as well as water samples from the Sargassum habitat. In the afternoon, we collected additional water samples, a CTD profile, and two neuston net samples through Sargassum weedlines. Similar to our visit to the Loop Current region last week, each neuston tow yielded very few Sargassum shrimp, crabs and associated fishes. Again, this is in contrast to our sampling in the more northern Gulf along the blue-green convergence weedlines. While Sabiki fishing we collected several juvenile Blue Runners and Almaco Jacks, and observed several large Mahi Mahi cruising the Sargassum patches.



The neuston net during deployment as seen from the small boat

Tomorrow is our last day of sampling before we set sail for home. We will ride the Loop Current treadmill tonight to stay in relatively the same location as we sampled today. New satellite imagery suggests another wave of Sargassum biomass is moving up the Loop Current and heading our way.

We’ll be waiting !!


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