By: Michael Morando
I am a sixth year graduate student residing within the Capone lab, where we focus on the cycling of nitrogen and carbon, primarily in the marine environment. Therefore, it is fitting that I am a student within USC’s Marine Environmental Biology program.
My interests lie in biogeochemistry and microbial ecology. Biogeochemistry. Sounds intense, right? That’s almost all of the major science words crammed into one. It’s less intimidating than it looks; it means that I examine how microbial communities affect the cycling of different N substrates (sources). My most basic questions are: who is doing what in the environment and how does this change with space and time?
I examine several different nitrogen substrates, i.e. ammonium, nitrate, urea, and N2, and identify which organisms are actively assimilating them and to roughly what extent. This can provide information on the metabolic diversity within the community and how it may respond to a changing environment. We have formulated ideas about the activity and community structure of the ocean, but recently many canonical views of have come into question as new evidence has been obtained. I hope to uncover more data that will further help to piece the picture together.
My work has taken me to many cool and interesting places over the years. I work primarily at the USC monthly time series, the San Pedro Ocean Time-series (SPOT), based in the San Pedro Channel. But, when given the opportunity, I like to compare what we see there with other environments. I have been way out in the Pacific Ocean, to the river plume of the Amazon River and, most recently, off the coast of Saudi Arabia on the Red Sea. Saudi is not very open to the outside world, so not many people get to travel to there. Because this makes it hard to do research in the Red Sea, we know relatively little about it. I feel very fortunate to have had the opportunity to explore both this interesting and under-researched body of water, as well as Saudi Arabian culture.
We spent twelve days out on the Red Sea, which is relatively short compared to the other cruises I have been on, but we were still able to get a lot done. The word “cruise” can make it sound like we were lounging on the deck playing pinochle, but in reality I worked about 14.5 hours a day. This workday would start by collecting samples around dawn and then catching a little breakfast. After breakfast, it’s time to set up that day’s incubations. After that, filtration of the previous day’s incubations needs to start. After a lunch break, the filtration of SIP samples starts. This brings you through dinner and up to bed. If you are lucky and get done a little early, you can sit in the lounge and watch a movie with the other people on board. The cinematic theme of this particular cruise was action movies…and I’m not bragging or anything but, over the course of the 12 days, we did watch all four Rambo movies. That guy is a machine.
This brings me to the boat, which itself was quite interesting. It was a retrofitted fishing boat. Let’s just say not ideal for ocean sampling, but we got it done. It was also made of aluminum so it is very light; when the seas kick up it can get pretty rough. We came across some very turbulent seas, the roughest I had ever been in, and without going into too much graphic detail…not many people made it to dinner that night. We were puking. There, I said it.
We had an eclectic group of people on the boat. Some were crew members, and some were other scientists. There were people from all over the world. The captain and many of the deck crew were from the Philippines, the first mate was from Ukraine, the chef was from Sri Lanka, and both of the boat’s research technicians were from Ireland. The scientists were a mixed group as well, with a couple Germans, Singaporean, a Frenchman, an Indian, and a few of us Americans, including a former faculty member of USC, Burt Jones. Having such a mixture of cultures made mealtime conversations quite interesting. And diversity is always important in great collaborations, as it combines many different areas of expertise and ways of thinking.
The big story toward the end of the cruise was a bloom of Trichodesmium (we tend to call it Tricho for short) that we happened upon during the last station. This cyanobacterium is able to fix (incorporate into biomass) an inert form of nitrogenous gas (N2) from the atmosphere into a useable form that helps fuel its metabolism and facilitate its growth. Most organisms, including people, must acquire their N needs through their diet or absorb it from their environment. Only certain prokaryotes, bacteria and archaea, have the ability to fix N themselves. Without this process, the world would eventually run out of new bioavailable forms of N and populations’ stocks would decrease. This makes diazotrophs (organisms that can fix N), crucial in maintaining global homeostasis. It also gives them an advantage in ecosystems that are low in N, e.g. the open ocean.
Tricho form large filamentous colonies, so they are bacteria that can actually be seen with the naked eye!!! This bloom of Tricho was so large that the first mate driving the boat at night thought that we were driving through another boat’s dumped sewage. Which would’ve been nowhere near as exciting, to say the least.
Tricho is often referred to as the ‘saw dust of the sea’ because the masses of floating colonies can resemble fragments of wood and many people mistake them for this. You may be able to see why from the picture above. These large slicks of Tricho could be seen all around the boat in every direction and it was believed that the bloom stretched over 10s of kilometers, if not more. It was very fortuitous for us to come across this mass of Tricho. It presented a unique opportunity to examine what may have caused this bloom to form and how it affects the ecology and biogeochemistry of the area, and ultimately the rest of the Red Sea. Looking forward to processing those samples!