SEAPLEX

Our second post today is from Meg Rippy.

Meg writes:

Hello everyone, Meg Rippy here. I realized recently that I haven’t really described why I’m out here in the North Pacific subtropical gyre, other than a brief mention that I study marine bacteria. Let’s correct that, shall we? First, a bit about marine bacteria. Typically when we think about bacteria we conjure up images of infected wounds, colds, and other unpleasantness. Most bacteria, however, are beneficial. They can be thought of as the recyclers of the ocean because they play an important role in decomposing dead matter, which releases inorganic nutrients that other living organisms need to grow. Without bacteria nutrient concentrations in the ocean would decrease, the phytoplanktonthat form the base of ocean food webs (like plants do in terrestrial systems) would be less abundant, and zooplankton, fish, birds, and mammals would have less to eat. The ocean needs its bacteria folks, so leave the Lysol at home .

Besides playing an incredibly important role in marine food webs, the bacteria in our oceans are also extremely abundant and diverse. On average there are around one million bacteria living in every milliliter of seawater and no two bacterial species within that milliliter are exactly the same. Efficient recycling of dead matter requires an entire community of bacteria with complementary metabolisms that break down different compounds. Some of these bacteria specialize in the colonization of particulates and some are free living in the water column. A subset of the marine bacteria that specialize in particle colonization are called biofilm formers. They form thick coatings on solid objects. My work on the SEAPLEX cruise directly concerns these biofilming bacteria, which may opportunistically colonize plastic debris as well as organic matter. If these bacteria colonize plastic, then bacterial communities in high plastic areas could contain more biofilm formers than is typical for the open ocean. This could possibly perturb ocean nutrient cycling and/or food webs, but we don’t really know how. The role of bacteria as the ocean’s primary recyclers makes it important for us to find out.

It is also important to point out that some biofilm bacteria serve as cues for the settlement of invertebrates like polychaetes (marine worms) and mussels. In this light, plastic and associated bacterial biofilms could serve as a transport mechanism for coastal invertebrates, bringing non-native (invasive) species into the gyre and possibly to distant shores. Non-native organisms can be extremely problematic for local ecosystems because some invasives survive better than local species and can take over an area, drastically altering the local food webs that depend upon native species. The association between plastics, bacteria, and invertebrate fouling has been one of my focuses these past few weeks. So far we have collected large pieces of plastic from the small boat and smaller pieces via dip netting. The bacterial communities on these plastic pieces will be examined back on shore using genetic analyses that type bacterial groups using known DNA markers. Miriam Goldstein plans to examine the associated invertebrate fouling communities. So far we have already seen mussels, bryozoans, gooseneck barnacles, and an amazing number of small
crabs on our plastic samples. It will be really exciting to combine this information on invertebrate fouling with the bacterial data later this year.

The SEAPLEX team: (front row, left to right) Jesse Dubler, Andrew Titmus, Pete Davison, Doug Woodring, Karin Malmstrom, Miriam Goldstein, Darcy Taniguchi, Meg Rippy, and Chelsea Rochman. (back row, left to right) Timbo Stilliger, Jesse Powell, Mario Aguilera, Jim Leichter, Lara Dickens, Matt Durham, and Josh Jones.

All sampling on the SEAPLEX cruise has stopped.  They are experiencing some rougher weather (6 feet swells).  This means that the ship can’t travel quite as quickly, so they don’t have time to slow down even more to sample if they want to make it to Newport on time.  So now, they are packing and anxiously awaiting the time when they will be near enough to shore to have internet access again!

Our first post today is from Darcy Taniguchi.

Darcy writes:

Hello yet again outside world! This is Darcy Taniguchi, writing to you from the R/V New Horizon as our cruise winds down and we head closer to port. After all these blogs, I’m sure you have seen mentioned several times our various standard sampling instruments—the manta net, Matsuda-Oozeki-Hu trawl (aka Oozeki trawl), bongo net, and CTD. I am sure that you have read some of the other information about these pieces of equipment. However, I will use this blog
entry tell you what data we obtained from each one.

First, the manta net. Oh the manta net. This piece of equipment has become sort of the bread and butter for several people on this cruise.   It samples at the surface,  so it is used to catch particles and organisms which are floating at or very near the surface. In it, we have managed to capture such things as numerous types of crustaceans, gelatinous salps, glowing lantern fish, and, of course, multi-colored plastic pieces.

Next, the bongo net. This instrument is also used to collect zooplankton, just like the manta net. However, it is used to catch organisms deeper in the water. On this trip, the bongo net has been able to catch many little crustaceans, such as the often abundant copepods and krill, as well as glistening comb jellies and perhaps the occasional piece of plastic.

Now, the Oozeki trawl. This is another kind of net, but it is bigger than a bongo or a manta, with a frame about the size of a Smart Car. The target depths to which this equipment is deployed is between 150 and 800 meters (492 to 2625 feet). At these different depths, the net has come up with various types of interesting, sometimes rarely observed, fish, although, there are other (unlucky) organisms which have also been pulled on deck—pyrosomes that exhibit bioluminescence, jellies that you have to squint to see, and squid with googly eyes, to name a few.

Last, but most certainly not least, is the CTD, which stands for conductivity-temperature-depth. The CTD is a real workhorse in oceanography, being used in the realms of marine chemistry and geology, physical and biological oceanography to look at the structure of various properties of the water with depth. Besides the sensors for temperature and conductivity (used to determine salinity), the CTD can also be outfitted with equipment to measure oxygen, light from the surface, fluorescence (from things like phytoplankton), nitrate, and water clarity. These sensors are on a large, cylindrical frame that is also outfitted with special bottles called Niskin bottles. These bottles have caps on either end that are closed with a click of a button at whatever depth the scientists on board wish to snap them shut, thus collecting water from that chosen depth, which is later sampled. Thus, the CTD can provide immediateinformation about the different regions in the ocean described by these variables as well as for the collection of water within regions of interest.

With these different pieces of equipment, we are cooperatively trying to collect various types of organisms at different depths within the ocean, as well as put them in the context of the structure of the water column with depth. These instruments are by no means unique to our expedition but instead are tools which can be and have been used in a wide variety of studies. Nevertheless, we hope that they have done well on this particular cruise in collecting enough information to begin to help us determine what effects, if any, plastic may be having on organisms of the north Pacific gyre.

Captain Wes Hill on the bridge of the R/V New Horizon during the SEAPLEX research cruise.