Pemetic Tank Setup 4/3/14

We had a good day with Carol Null’s 7th grade class today learning about eelgrass and setting up an eelgrass tank. One thing I would like to clarify from my talk: When you are using the pH meter, you only need to calibrate it every day you plan to use it to measure pH. It doesn’t need to be calibrated on days you aren’t using it.

Here are some of the great questions that came up, and some pictures:

1. When looking at maps of eelgrass in Frenchman Bay in 1996 and 2008, a student asked why the patch of eelgrass in the middle of the upper bay, to the northwest of Hadley Point was still there in 2008 when so much of the eelgrass in the rest of the upper bay disappeared?

This is a question we are always working on. What is it that made the eelgrass disappear in some areas and not others? Some of the possible causes that have been suggested are: temperature, green crabs, dragging, pollution, genetic differences or salinity changes, to name a few. In the mapping done by the Department of Marine Resources of all the eelgrass in the state of Maine in 1996 and 2008, a pattern seems to be that between the two mapping periods, eelgrass was lost in upper bays and estuaries, and gained area in outer bays (closer to the open ocean) and around islands. Perhaps the same thing that caused that trend is the reason that bed survived. Another thing to consider is that the bed that survived is a very deep one.

2. How many organisms are in the tank? Does that depend on what organisms are in the tank?

Start counting organisms and recording what kind you see. Compare with other schools!

3. Does temperature affect eelgrass growth? How does our eelgrass growth compare with other schools’ eelgrass growth, if they have different temperature tanks?

If every school with a tank can measure temperature and leaf length over the duration of their tank project, and enter that information into the database, we can answer that question!

Another student was talking to me about how he was trying to decide if he wants to study marine biology or robotics in college. Anyone who’s wondering this kind of thing can try out some marine biology and see how you like it by participating in the Student Marine Science Symposium on June 5, 2014, the Young Environmental Leaders Program in the summer, and volunteering at our lab! Contact Anna about volunteer opportunities at afarrell (at)

-Jordan Bailey

Pictures (by Anna):











Conners Emerson Questions

Conners Emerson 7th and 8th grade science classes had their introduction to eelgrass and tank setup on Monday, Tuesday and Thursday this week. They came up with some great questions and ideas. We can’t wait to see their experiments!

7th Grade questions:

How large can eelgrass grow?

Does temperature affect the lifespan of individual eelgrass blades?

I mentioned that the eelgrass doesn’t usually spread vegetatively in the first year after it is transplanted. A student asked if it would if we made sure we transferred the entire rhizome.

Does eelgrass produce seeds once a year? Is there a trigger or conditions that can be maintained so it would produce more often?

How can we measure the amount of light reaching the plant? One student suggested installing a small waterproof solar panel in the tank. The amount of energy it stores would be able to tell us the amount of sunlight that has reached the plants.
(I forgot to mention that there are light meters that can be used to measure light intensity, but I am not sure if you can measure the cumulative light that reaches the plant over time with those.)

Does temperature affect growth?

Is there a limit to the number of organisms that can grow in the tank because of the amount of dissolved oxygen available?

Does eelgrass regulate the number of organisms?

Does eelgrass have any adaptations to defend itself against being eaten?

Does the slime layer help the eelgrass in any way?

Can eelgrass adapt to changing salinity?

8th Grade questions: 

Can eelgrass grow in fresh water? What is the range of salinity it can tolerate.

How many years can the eelgrass rhizome survive?

What would adding dye do to the plant?