8/19/13 Arrival! My 5 days of great coastal science and freedom from the responsibilities of my household begin!
After meeting Jon Ramgren and his team of students from Waterville High School, we began with an orientation to the current situation in the bay. As it turns out, nearly all of the eelgrass, both naturally occurring and restored, failed to come up this spring. Dr. Disney is a bit despondent, as you might imagine, but our introduction to the ecological importance of eelgrass and those species who depend upon eelgrass led to a great discussion of the possible vector(s) of its demise this year. Dr. Disney and one of her summer interns, Lukas, narrowed the field to four possibilities so far: nutrient deficiency, global warming, green crabs, and _____.
Nutrients: This does not seem to be the source. Dr. Disney set up several experiments in the lab to see how well eelgrass will grow both in soil from the parts of the bay that are now eelgrass free and from areas where it is still growing. There was not any significant difference in the growth. Additionally, last year they completed a fertilizing experiment, but all of the eelgrass in that area died off as well.
Global warming: obviously this is a huge topic, but eelgrass exists in Chesapeake Bay where it is significantly warmer so probably this is not the cause of the loss of eelgrass.
Green crabs: Lobstermen and other fishermen are reporting much higher numbers of green crabs this year. The eelgrass rhizomes are still in the bay for now, though they are not producing plants and seem to be dead. Many of the plants washing up on shore are showing stem damage right at the base. Perhaps the crabs are disturbing the eelgrass for some reason, displaying a new behavior due to some kind of pressure. Dr. Disney has been working on crab surveys to try to establish how many crabs are present, their gender, and whether exclusion has any effect on eelgrass growth.
Wasting disease (labyrinthula zostera): this little pathogenic organism caused a massive eelgrass blight in the 1930s when 90% of the eelgrass died off. It recovered, though. Labyrinthula is recognizable by the black spots found on the surface of the eelgrass. When there are too many, the plant dies off. There are labyrinthula on the Frenchman Bay eelgrass but not enough to cause such a dieback.
We also spent a bit of time planning our week. We will be doing a variety of activities: monitoring water quality and plankton (specificially red tide), taking video of deep water areas to try to find deep water eelgrass, crab surveying, GIS mapping of current eelgrass extent.
In the afternoon, we went to the bar in Bar Harbor to map the eelgrass beds and collect samples of other organisms in the area that we will be looking at tomorrow.
And our sweet sunset hike up to Bubble Rock in the park. The water you see is Jordan Pond.
Water quality today: good turbidity, good dissolved oxygen content, terrible red tide news.
Todays plankton collection led to yet another Pseudonitzsche spp. red tide alert. Actually, the lab sent out three alerts for three different organisms all under the guise of red tide. Pseudonitzsche is a particularly nasty toxin that causes permanent short term memory loss. Levels were higher than 500cells in 0.2mL (around 5000 cells in 1mL of concentrate). Department of Maine Resources uses this information to begin more rigorous testing of the shellfish in the area to determine whether the concentration is high enough in mussels and other shellfish to necessitate banning their harvest. Apparently we interns and student interns will be eating mussels on Thursday with our lobsters…to partake or not to partake… Here is a photo from our collection today showing pseudonitzsche:
After lunch we spent time trying to use QGIS to map our eelgrass data from yesterday and compare it to older eelgrass data. Hopefully I will have a map to publish by the end of the week.
Our last task of the day was to look at some of the other stuff we brought back from the bar. In addition to surveying the existing eelgrass beds, we brought back samples of other organisms living in the same area just to see what kind of life is thriving around the eelgrass. Here are some examples:
This tunicate is a really interesting little organism. When mature it forms a rather gelatinous little colony on eelgrass or kelp, in this case, or on rocks. But in their earlier life stages they actually have a notochord and are therefore more related to us vertebrates than any other invertebrate. I found some of the tadpole stage as well with the notochord. If you’re interested in more information on these little guys, here is a pretty basic website.