A Crabby Couple of Days!

If you scroll down read my previous post ("Testing the Waters!"), you'll see that the youth staff here at Save the Harbor / Save the Bay is proudly taking part in a large effort of citizen scientists across the Harbor to holistically understand the water, and the species that inhabit it, better. In addition to testing salinity and clarity, we're also counting crabs! At many of our sites, especially the ones with shores to explore, we are taking random samples of the beach and counting what we find within a predetermined dimension. We're recording quantity, gender, and size (we measure the width of the carapace of the crab-- the main part of its body, which doesn't include its legs). Wednesday, our crab counts officially began!



I have to begin by telling you that South Boston is CRAWLING with green crabs and Asian Shore crabs. Put a trap down off the dock, and you'll have a green crab within a few minutes. Overturn any huge rock, down past the swimming beach, and you'll find several Asian Shore crabs frantically scuttling sideways for cover. Look at our friend Emily, elbow deep in a bucket of Asian Shore crabs! They're everywhere!

That being said, when we took our predetermined circle (a bike tire- how's that for citizen science?) and headed down to the intertidal zone in Pleasure Bay... can you guess how many crabs we found in our circle?

When we did the experiment on Wednesday afternoon, at first glance, the answer was zero. NO crabs, in SOUTH BOSTON? It's crab city over there! When we turned over a few of the bigger rocks in our sample area, we finally counted 5 tiny green crabs scurrying about. Each had carapaces under 1 cm in width and were so sneaky that they evaded their capture, so their genders are all still unknown. But what South Boston lacked in crabs during this experiment, it certainly made up for in periwinkles. In just our little sample circle, we found 32!

Today, Thursday, yielded similar results. The tide was slightly higher, which gave us even lower hopes for crabs along the shore-- it was much more likely we would find them in the lower intertidal zone, if we were going to find them at all. And, as expected, each time we threw down our circle, no crabs were found within. I am confident that low tide will expose many more crabs to our analytical fun, but the gray rocky shore at high tide seems less welcoming and far more exposed than what I would personally prefer if I were a crab. So I can't blame them for not coming out when we needed them, because that's science! And no experiment is a failure. Especially not when you're having fun.

Harbor Love,

Michelle

Testing the Waters!

Hello from Week 3! To a Senior Marine Educator such as myself, the third week means that I'm at completely new sites in our biweekly rotation around the Harbor. And I couldn't have asked for a better farewell to my sites last week, nor a better start to the new week!

I wrapped up a phenomenal week at Piers Park with a great group of truly enthusiastic and engaged Harbor Explorers. We caught our first fish, took a field trip to a local pier to see our harbor habitat from a different angle, and really bonded as a group of people excited about the water and what it has to offer. They'll be on my mind for the rest of the summer. Thank you everyone!

At both Piers Park and Courageous Charlestown, we were charged with two special projects during our second week. Dr. Judy Peterson, a great friend of Save the Harbor / Save the Bay, came to us asking us to join a large network of "citizen scientists" across the area in a large-scale effort to better understand the Harbor and how it is changing. Piers Park and Charlestown are specifically measuring the water for clarity - how clear or not clear the water is-- and salinity - the amount of salt in the water. The tests were great hands-on tools for the kids at both locations to consider the water in our Harbor a little differently, and to see how its composition isn't the exact same every single day, for various reasons.

We used a Secchi Disk-- a fairly simple tool, in fact-- to measure the water's clarity. The Secchi Disk consists of a black and white disk on the end of a nylon line, along which little beads are placed every meter. All our citizen scientists (like our very enthusiastic explorers at Piers Park) needed to do was hold on the line and slowly drop the disk deeper and deeper into the water until they cannot see the white part of the disk any longer. However deep the disk is when the white goes out of sight, according to the beads along the line, was our measurement. At both Piers Park and Courageous, our measurements were falling between 3 meters and 4 meters all week, with much higher measurements (more clarity) as the week went on, which also happened to correspond with the rain half way through the week.

To measure salinity, we were privileged to use a portable refractometer provided to us by Dr. Judy. If we place a little drop of water on the lens of the refractometer, it measures the deflection of light through the drop of water, which is affected by the amount salt (measured in parts per thousand, or PPT) in the water. When we did the test at Courageous last week we got readings of 26 PPT on Tuesday (7/13), 27 PPT on Wednesday (7/14), and 21 PPT on Thursday (7/15-- again, after the rain!). Both tests were a great activity for everyone to gather together and do at both sites, not to mention a great effort to be a part of across the Harbor!

Lots of Harbor Love,

Michelle