Fishing the Filament

Dolphins! A sure sign of a productive ocean

Cynthia, Laura, and Valerie run mddle-of-the-night zooplankton net processing during our first transect (Photo credit: Stephanie Matthews)

Last night we ramped up our sampling in earnest with a marathon cross-filament transect. A beautiful filament of cold, newly-upwelled water emerged off the coast of Morro Bay, California, a few days ago, giving us the perfect feature to begin our first sampling sequence.

A plankton sample from the middle of the filament – lots of green! (Photo credit: Stephanie Matthews)

We started the transect yesterday evening, just in time to catch a pod of whales and flocks of seabirds feeding off the stern – a sure sign that we were in high-productivity waters! Everyone worked through the night to deploy a rapid-fire 11 rounds of CTDs, trace metal water-sampling, and vertical Bongo net tows as we cut a straight line across the filament. We had several new people who had never done this work, but everyone rapidly got up to speed in the flurry of water sampling, filtering, and zooplankton processing. This transect will give us valuable information on the relative productivity within the filament compared to the surrounding waters. Time and data analysis will tell all, but at first glance we saw very green, high-chlorophyll waters (indicating high phytoplankton productivity) and lots of pyrosomes and jellyfish in the plankton samples.

Tonight we begin the second half of this sequence: a four-day cycle in which we deploy various instruments and follow them as they drift for several days in a parcel of ocean water. One piece of equipment is sediment traps, which capture sediments and organic particles as they sink through the water column. Another piece is an in situ incubator that holds phytoplankton as it floats through the ocean, allowing them to grow under real ocean temperature and light conditions. We will retrieve the arrays at the end of four days, but in the meantime, we will be deploying plankton nets and CTDs several times a day. All of this information will help us understand the evolution of the filament of upwelled water as it evolves over time.

Deploying the Moving Vessel Profiler ‘fish’ takes an all-star team! Laura, Kat, and Valerie lead the charge (Photo credit: Shailja Gangrade)


Posted by: Laura Lilly, SIO

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