Out With the Old, In With the New

As of August 31, 2010, our very first outdoor eelgrass trough will be closed for business as the Back Bay Science Center will be replacing the dock system, including the pumps that move water from the bay through the eelgrass trough:(

Over the past year, we have harvested over 200 shoots, and have observed significant increases in species diversity and abundance within the trough (which seems to be directly related to eelgrass abundance and health) as well as declines.


The majority of the challenges we have experienced this year mainly stem from light limitations due to sedimentation and algal growth on the eelgrass blades, and the shallow depth and small size of the trough, which most likely contributed to warmer temperatures, little flow, and algal blooms.

However, in the last month we have finally seen new growth (for the first time).

Although many of the plants did not survive in initial plantings (November and March), individuals from the last harvests (April and July) have survived much longer and remain relatively healthy, but have still lost both above- and below-ground biomass. This Spring, we have seen the largest increase in invertebrate diversity and abundance yet, including Speckled scallops, topsmelt, Gould's bubble snails, nudibranchs (Navanax sp.), Nassa mud snails, and a single nudibranch (Phyllaplysia taylori) specific to eelgrass.

It is sad to see the trough go and we will have to return our mud organisms to the bay, however, over the next couple of months, while the Back Bay Science Center is installing the new amazing dock, we will be experimenting with growing plants from the trough in an indoor tank, in which we can control most all environmental conditions. Currently, we have moved half of the plants and a few invertebrates from the trough and transplanted them into the tank, using gravel and water directly from the bay to provide natural nutrients and food for many of the invertebrates.



In October, we will be installing two (5.5ft diameter, 2.5ft deep) round tanks capable of supporting larger eelgrass populations and hopefully, with the help of many experts and outside resources, and modeling cultivation systems similar to that of the Battelle Marine Sciences Lab in Sequim, Washington, we will be able to establish a healthy, sustainable eelgrass population, minimizing those stressors encountered during the first "Year of the Trough." And no, we absolutely will not use the word trough ever again.

Eelgrass habitat photos

These photos were taken of a small sample size from the eelgrass trough habitat.

Possible leads to eelgrass blues

The eelgrass in our trough has been periodically replaced as die off occurs. The good news is that the bio diversity in the tank is very high currently. Snails, pipe fish, crabs, limpets, scallops, mussels, small fish, slugs, and a few more species have been spotted. The bad news is the eelgrass, the habitat that has allowed for all this great bio diversity still hasn't stabilized. Black blotches that start out small but can grow larger over time till entire leaves are covered might be our best clue at the moment. It's too soon to tell but these legions are tell tale signs of eelgrass wasting disease caused by a species called Labyrinthula zosterae, a marine unicellular protist.

If this happens to be the case it indicates that the eelgrass in the trough is stressed and becoming susceptible to disease. This has the potential to be beneficial to our cause if we can identify the symptoms as wasting disease. Eelgrass is a great indicator of water quality and if clarity, toxicity, or nutrient levels fluctuate eelgrass is usually one of the first species to show signs. One of which is the increased susceptibility to wasting disease. From there we can test to find what stress factors are causing the eelgrass to be more susceptible to disease and hopefully keep it healthy in the near future.

Update

Went down to Back Bay yesterday. The eelgrass in the trough isn't thriving, but it's still alive. Amanda and sometimes interns will head down to Back Bay daily to clean algae off of the eelgrass. Cleaning the algae off of the eelgrass is a monotonous job, but has to be done in order for the eelgrass to survive.

The trough (seen in the picture) has a pretty wide range of aquatic life living among the eelgrass including sponges, scallops, crabs, anemones, and more.

Although the inside tanks are still being monitored, all of the eelgrass is pretty much dead. We're looking into a problem with the amount of light being used, and will try again once that problem is fixed.