NOAA Teacher at Sea: Nathan Pierantoni
University of Miami Ship R/V Walton Smith
South Florida Bimonthly Hydrographic Survey
Florida Keys, south of Key Largo
Friday, April 8 2011
Weather Data from the Bridge
1440 hrs Local Time
Barometric pressure = 1018 Millibars
Visibility = good
Wind E 12 knots
Science and Technology Log
In this log I want to talk about the two marine biology graduate students whom I have been working with this week, Chelsea Bennice and Lorin West. They are both 2nd year students at the University of South Florida, and they have been conducting biological sampling all week long. They have been a lot of fun to get to know, and in discussing their research I have really been struck by the similarities between graduate level scientific research and the science projects that many of my students have worked so hard on for this year’s science fair.
***This is cool– as I sit on the deck of the boat writing this, a pod of bottlenose dolphins has joined us! We are cruising at about 7 knots and they are leaping out of the water at the edge of our wake.
Both Chelsea and Lorin are working with a genus of macro algae known as Sargassum. There are two pelagic (floating) species of Sargassum: Sargassum fluitans and Sargassum natans. These species form clumps/patches on the surface of the ocean and serve as habitat for small organisms like crustaceans (and other invertebrates) and juvenile fishes. Throughout the Florida Keys and the Florida Bay, we have seen Sargassum nearly everywhere.
At different stations along the cruise, Chelsea and Lorin have conducted net tows, in which a 2 m^2 fine mesh, windsock-shaped net is pulled along side of the boat for 30 minutes. At the end of this tube is a selectively permeable collection bucket (cod end) that traps Sargassum and the organisms that it hosts, but it allows the water to pass through. These net tows have been pretty cool, because every time we bring one in, there are always interesting creatures waiting to be discovered. Crabs, shrimp, nudibranchs, eels, fishes (including puffers, filefish, frogfish, jacks, flying fish, juvenile billfish, pipefish), copepods, amphipods, cnidarians (“by the wind sailor”), and a sea horse are just a few of the organisms that live in the uppermost meter of the ocean and make the Sargassum their home. And here I thought we had been floating past little chunks of lifeless seaweed! In fact, each patch of Sargassum is its own little ecosystem. Here is where Chelsea and Lorin’s work begins.
Chelsea is conducting a study in which she intends to describe the habitat architecure of pelagic Sargassum species. I had her describe her work: She intends to answer the question of how habitat selection among fishes and shrimp in the pelagic Sargassum community are influenced by the habitat architecture (interstitial spaces and depth) of a Sargassum patch. She will be manipulating the patches by changing their interstitial spaces (spacing the pieces of Sargassum differently among the surface of the patch). Sargassum pieces that are spaced tightly together are thought to create “microhabitats or niches” in the Sargassum for the fishes or shrimp to hide in. She will also be varying depth of the patches of Sargassum. Patches of Sargassum can range from 2cm to 12 cm (sometimes deeper!) in the water column. Having a deep depth patch may make it easier for a fish or shrimp to find its “home” in the open blue water.
Lorin is also working with Sargassum, but her work focuses on the mechanisms (visual and chemical cues) by which organisms are attracted to Sargassum in the open ocean. Her master’s thesis is titled “The role of chemical and visual cues used by the the sargassum crab Portunus sayi in selecting and locating habitats.” Sargassum is highly variable and broken up by waves and even washes up on shore. So, she has created controlled experiments in her lab where she can test whether the sargassum crab can detect chemicals from sargassum when they are dripped into the aquarium. She will also test to see if the crabs can visually detect sargassum without chemical cues and if they can distinguish between the two species of sargassum
As I spoke with Chelsea and Lorin, I couldn’t help but hope that some of my students go to college and graduate school in order to study ocean science. These women love their work and it shows. They describe their studies with enthusiasm and excitement. Chelsea and Lorin both teach introductory biology labs (they were grading punnett squares after hours during the cruise!), attend classes, and take research field trips to the ocean. They are each about to finish a thesis, graduate, and head into a promising career in marine biology!
It is Friday now, and we have north back toward Miami. We had a few CTD stops along the way and couple of other samples to collect, but overall there is a general feeling on board the R/V Walton Smith that we are headed home! Everyone seems ready to head home to be with their family, including me. This ship will begin a 49 day cruise to ground zero of the Deepwater Horizon oil spill next week, and therefore everyone is anxious to get as much shore time as possible. This week went by very quickly, and I enjoyed all of the experiences I had on board, I wish I could stay longer, but I’m excited to get back to work at Heights!
Here is the net in action! Lorin keeps her hands on the cable so that it doesn’t come too far out of the water.
In this shot, Chelsea is gathering the sargasum she collected in a bucket.
Once all of the organisms had been rinsed off the seaweed, this is what she got! A ‘soup’ of fish and small organisms. These blue ones were unsuspected!
In the wet lab, everything gets rinsed again with sea water and filtered through a mesh.
Here are the fish they collected in a net tow. Sometimes fish use sargasum like a nursery to raise their juveniles. In this case, a small school of fish were found all at once.
Like all field science, they have plenty of work to do in the lab once their collection is done! Here they are writing their results. Nelson is also at his computer working on graphs from his experiments.
Here is a group shot we took at sunset off of Key West on Thursday night. From left to right, Josh, Lorin, Erik, Cheryl, Nate, Chelsea and Nelson.
A nice sunset cruise passes by off of Key West (in the background). As we worked a CTD offshore, about 10 of these ships came out of the harbor and did circles around us. It was a really nice sunset, too!