Category Archives: Green crabs

Making Tuva Files Available to Students

Boothbay Harbor at low tide. Photo by Ryssby at the English language Wikipedia

In this post, we show you how to make a dataset that you uploaded to Tuva available to students for their own exploration and use. We will work with the Boothbay Harbor sea surface temperature (SST) dataset that we uploaded in an earlier “how to” post. We also illustrate a few of the many things you can do with Tuva, including “filtering” the data so that you only see a part of the data.  We will also show you how to change the range of the axes on a graph and how to save a particular graph for future use. As in our first post using Tuva, we will assume that you are using the basic, free version that Tuva makes available to teachers. Of course, what we show you here also works with the premium version. The premium version also provides with additional ways to make assignments available to students that you will probably want to use if you have access to that product.  Continue reading

The Green Crab Lifecycle

European Green Crab

European green crab (c) Can Stock Photo / mikemols

The European green crab (Carcinus maenas) arrived in the New York and New Jersey ports in the early 1800s, spread to Casco Bay by the 1890s, and continued to spread northward to Downeast Maine and the Bay of Fundy over the twentieth century (Fulton et al., 2013).  It is a voracious predator, but until recently the crab’s numbers in Maine were kept in check by cold winters. That was enough to make it possible for softshell clams to continue to thrive even though green crabs were eating them. All that has changed now that winters are warmer. Research by Dr. Brian Beal of the Downeast Institute, along with others (Beal, 2006; Tan & Beal, 2015), makes a strong case that the green crab has contributed substantially to declines in softshell clam populations in many parts of Maine.

Because CSI-Maine is designed to provide Maine communities with information they can use to protect clams from predators, knowledge about green crabs and their lifecycle is useful in interpreting the data we collect and in thinking about new approaches to increasing and sustaining the clam harvest. Continue reading