Scientists from ODU and WHOI are at the Florida State University Coastal Marine Laboratory this summer to study the role of seagrasses in sequestering carbon in the shallow waters of the Gulf of Mexico.  The team led by Drs. Zimmerman and Burdige of ODU, and Dr. Matt Long from Woods Hole Oceanographic Institution, are utilizing cutting-edge methods for measuring photosynthetic oxygen and carbon exchange (Eulerian and eddy covariance techniques) combined with sediment geochemistry measurements to build and test numerical models that can be scaled up to quantify the dynamics of carbon flux in seagrass meadows.

 

Photos.  Upper Left:  Sediment traps collect samples for analysis of carbon deposition rates in seagrass meadows.  Upper Right:  Our 28’ research vessel on station in St. George Sound, Fl.  Lower Left:  A dense meadow of seagrass Syringodium filiforme at one of our stations.  Lower right:  Graduate student Brian Collister preparing to collect seagrass and sediment samples using SCUBA.

 

Follow this link to see an video of all of the under ice photographs from our Arctic buoys for this season. At first the water looks blue, due to there being very little material absorbing light. In July the water turns the color of peak soup, this is from the presence of a phytoplankton bloom. This was very interesting as the presence of blooms under the ice has only recently been documented. After the bloom the water is again blue in color as the absorbing materials sink out to deeper waters.

Barneo, the North Pole ice camp. Our latitude is 89N and 20E, outside temperature -27oC, you could be fooled into thinking that you are on land, but in fact under the 2 m of ice there is 2,000 m of water. Barneo is a public camp, run by Russians and populated by polar explorers and thrill seekers, plus scientists. To get here you fly through the Norwegian Spitzbergen islands, and it is here that I met up with the group from the University of Washington that operates the North Pole Environmental Observatory. A couple of days to sort through all the equipment that was shipped here over the last year, and we are ready to head to camp. It is a 2.5 hour plane ride to Barneo and we arrive at lunchtime. As I only have 3 days here I was eager to find a location for the buoy and get it deployed. We spent our first day searching the surrounding flows for a good spot. The ideal location is a flat ice pan surrounded by ridges, the fracturing of the floe will most likely occur at these ridges, meaning that as summer progresses and our floe drifts south, our buoys will hopefully stay intact in the middle of the floe. There is plenty of tea, coffee, hot chocolate and cookies available in the mess tent, and we retire there every few hours to warm up and refuel. With my satellite phone I am able to stay in contact with Pacific Gyre and keep them updated on my progress, it also enables me to call home and let everyone know that we are ok. While we are looking for our perfect buoy location, I turn on the WARM buoy GPS, so my colleagues can at least see that our camp is drifting south several miles a day. Each day the plane arrives with more adventurers and several dog teams cycle through the camp. It is always funny, as the dogs are so excited to be on the ice, they start howling when individual dogs are harnessed up, it’s as if they are worried that they will be left out of all the fun!

Sunday comes around and we spend the morning, collecting ice core samples, and measuring light profiles, we are just waiting for a snow mobile team to drag the buoy over to our location. This finally happens at about 4pm local time. We have 24 hours of sunlight so we can work at any time of the day or night. It only takes 30 minutes to unpack all the sensors and feed them down the 10 inch ice hole. After this I call Pacific Gyre to make sure that all the sensors are uploading. Back in California they can even see the crack in the ice from the below ice camera at 20 m. With the news that the buoy is working I can breathe a sigh of relief, and just like that my Arctic field season is over for this year.

Number 2 deployed. Done for this year

Number 2 deployed. Done for this year

Barneo tent camp

Barneo tent camp

While I make my way back home, the rest of the team here have several more buoys to deploy both at camp and at various locations around the pole. I am hoping that I can come back next year, now I have seen the camp, I have some ideas for experiments to conduct while I’m here.

It’s T-1 day until I head to the Arctic toa Russian ice camp near the north pole. I will be deploying an ice teathered buoy with a string of temperature and light sensors. I will be posting video blogs to the wesbite, just look under field blogs Arctic on the top banner.

In the meantime here are a few pictures of the buoy i will be deploying.

GPS and satellite uplink inside the buoy float

GPS and satellite uplink inside the buoy float

Checking that the sensors will fit through a 10 inch hole.

Sensor string laid out in the Pacific Gyre warehouse

Sensor string laid out in the Pacific Gyre warehouse

 

 

Becky Walawender from the Department of Biology here at ODU has been monitoring the soft shell clams that were recruited into our tank this spring. Here she describes the results so far.

Soft-shell clams (Mya arenia) have fragile, thin shells made of calcium carbonate and are susceptible to breaking under the acidic conditions associated with excessive carbon dioxide. To test this, we placed 110 soft-shell clams into sediment and monitored their survival in five different pH levels (6.0, 6.5, 7.0, 7.5, 8.0). After two months, we noticed a decrease in survivorship of the clams in pH 6.0. Of the remaining 90 clams in the pH 6 tank (20 were removed for genetic analysis), 55 were confirmed dead, mortality in the other treatments was approximately 6-11 clams. The shells of the dead clams from pH 6.O became brittle and eroded through at the middle, below the umbo.

Clams from pH6

 

 

After a year and a half of planning, construction and wiring we have finally reached the start point of our long-term seagrass ocean acidification experiment. Last week Dick and I spent two days diving in the seagrass meadow in South Bay on the Eastern shore collecting over 1 thousand seagrass shoots to fill our experimental tanks. The rest of the BORG team spent their days cleaning the tanks and awaiting our seagrass booty.

As the plants need to survive and thrive in our tanks we had to collect not just the shoots, but the rhizomes and roots as well. In the muddy sediment of South Bay this required lots of rooting around, so much so that it looked like I had been eating mudpies when I came to the surface!

 

It took three days to plant all of the collection, each tray now has approximately 40 shoots and each tank has between 3 and 5 trays of South Bay grass, some tanks have grasses from Washington State for a side experiment on their tolerance to our warm summers. Now we have wait for a couple of weeks to make sure that the growth rates in all the tanks are the same before we can turn on the CO2 and start the different treatments. We have managed to recruit some folks from both Biology and OEAS to run experiments in our tanks, Becky, a graduate student is going to study the clams that were recruited into the tanks during the spring and Dr Dobbs is going to look at bacterial films.

I will post more details on those experiments once they get started. In the meantime we will all be working on our tans this summer as we spend several days each week tending to our seagrass crop.

Victoria

Meredith came to us as an undergraduate student, she wanted to gain some experience working in our lab, and brought with her an infectious enthusiasm. During her time with us she has traveled with us to California, Florida and closer to home in the Chesapeake Bay. She already has one publication to her name and is as we speak busy turning her thesis into a manuscript. Her master’s work was focused on the environmental and physiological influences on productivity of eelgrass through δ13C. You can read her defense abstract at the end of this entry. We are all sorry to see Meredith leave us, but she is moving on the new pastures or should we say meadows. One thing that I realized while going through all the pictures of Meredith that I have taken over the past few years is that even when cold, tired and hungry she was always smiling. Now I just have to find a reason to go to a meeting in San Fransico so we can catch up. Victoria

Meredith measuring the reflectance of exposed seagrass PIC_020820110624__Sea Grass_photog Carly Rose_0020Image9Image25Image8

A reflection of lessons learned (post-thesis defense):

Sometimes these types of things are so much more anti-climactic than you hoped they would be.

I didn’t have a great weight lifted off my shoulders, and I always expected to pass (although I had doubts at one point during the defense!). Don’t get me wrong, I’m ecstatic and feel like I’m on top of the world (at least for now), but in my mind, there were no fireworks shooting off in the distance or dancing in excitement around the room after the results came in from my committee. Of course, there are edits to be made to the thesis, but who doesn’t have those? Right? Oh, and that manuscript I still have to submit…

I would have never gotten to the place I am without so many people around me. Leaving for California in three weeks has left with conflicted emotions. There’s a constant cloud of sadness over my head in the anticipation of leaving my real family, and my school family. All of whom I will miss terribly. However, life is giving me new opportunities for adventure and success, so, I must take them. And what better place than beautiful Northern California, where the hills are so steep that I can’t even ride my bike up them and kelp forests call me to the chilly sea?

I’d like to leave you with 3 lessons I’ve learned over the course of 6 years with the BORG,

  1. Never be scared to ask for help or admit that you were wrong. You can learn a lot from people when you open up to them.
  2. Stay at the lab until 2 am to finish those last minute experiments before that meeting that you secretly regret signing up to give an oral presentation at.
  3. Travel those 5,500 miles to present at a meeting that you’re not even sure if people care about your research because every little bit helps. No matter how expensive it is.

 

So, goodbye BORG and ODU. It’s been real. And wonderful!

 

 

Abstract

Seagrasses’ relatively low capacity to exploit HCO3 as a source of dissolved inorganic carbon (DIC) for photosynthesis forces them to rely extensively on CO2(aq), which is typically present at low concentrations in seawater. As a result, seagrass photosynthesis is generally carbon limited. This study investigated the influence of CO2(aq) transport to RUBISCO, controlled by environmental and physiological mechanisms, on photosynthesis, and the impact on seagrasses stable carbon isotope (δ 13 C) composition. Light saturated photosynthesis (PE) was measured at a variety of flow and DIC regimes to understand carbon uptake at the leaf level, boundary layer conditions, and permeability of the unstirred layer. PE was saturated with respect to increases in flow above ~2.3 cm s-1. The non-linear response of PE to [CO2(aq)] was used to predict the maximum physiological photosynthetic rate (Pm). Stable carbon isotope signature for light-saturated conditions was modeled from the theoretical relationship between PE/Pm and physiological responses to [CO2(aq)] and flow that drive changes in fractionation. Predicted δ13C for flow saturated, ambient [DIC] was ~7‰, well within the range of reported values for seagrasses. Measured δ13C values from the Goodwin Islands were lower than predicted light saturated δ13C. However, when historical epiphyte loading was taken into account, δ13C signatures agreed with published values from similar light-limited environments. The ability to accurately model productivity and δ13C of seagrasses suggests a comprehensive understanding of the influence of light, carbon acquisition, and environmental conditions on photosynthesis.