The SEAPLEX cruise is going well. They are still in their intensive sampling phase, so everyone is tired, but other than that, they seem to be in good spirits. They are having great weather today, with no ill effects from Tropical Storm Felicia. They have seen a shark and some flying squid.
Hello everyone. I thought I’d fill you all in on some of the truly awesome events that have occurred while filtering seawater for phytoplankton analysis on the night shift these past few days. For starters, the 3 a.m. CTD cast on August 5th brought up some bioluminescent organisms from 70 meters (about 230 feet) deep. Bioluminescent organisms produce flashes of light through chemical reactions involving enzymes from the luciferase family. These flashes are often blue in color and can be used to deter predators, find mates, or attract prey. The bioluminescent organisms we’ve collected may have been small phytoplankton because they were very small (only retained on filters with pore sizes of 8µm (0.000 3 inches) or less), and were found at the chlorophyll maximum (the water column depth with the highest concentrations of chlorophyll, the compound used by most phytoplankton and terrestrial plants for photosynthesis). Furthermore, it is likely that the bioluminescent organisms we found only produce luminescent displays when triggered by mechanical stimulation like predation or wave motion. The reason I say this is because I had no idea that there were bioluminescent organisms in the water I’d filtered until I folded the filters and wrapped them in tinfoil for pigment analysis. The act of folding the filters is what stimulated the phytoplankton on them to bioluminescence. The resulting flashes of blue were startling, and incredibly beautiful.
Our night time seawater filtering has also resulted in other really interesting finds. Just this morning I filtered some seawater from 210 meters (689 feet) deep and found what appears to be a small (~0.5mm or 0.02 inch) piece of blue-green plastic. This was a really exciting and yet horribly depressing find because it suggests that plastic can be present at depth in the ocean. There are several possible ways for plastic particles to get to depth. First, and perhaps most simply, it could sink. It could also be mixed down into the ocean by wind or other physical processes. Organisms that migrate from the surface to depth could also potentially transport plastics. At this point, however, we really don’t know which, if any, of these processes are important for the transport of plastics to depth in the gyre as it is difficult to say anything substantive from one plastic particle. It will be really interesting to see if any more plastic comes up in the CTD or in the bongo and mid-water trawls at later gyre stations.
Cheers to you all from the night shift,
SEAPLEX researchers recover three plastic bottles covered with marine organisms, including large barnacles.