Giving DMR a Hand in John Small Cove

Schoodic Institute uses the word “authentic” to describe student scientific investigations that addresses real community problems and questions. It is also authentic because students learn by working with professional scientists and, along the way, learn that science goes on outside as well as inside, requires hard work, and sometimes involves getting dirty and, as this picture shows, can require some agility.

Collecting Spat

Over the summer of 2017 the Maine Department of Marine Resources (DMR) conducted a number of experiments to learn whether clam fishermen might improve settlement of juvenile clams (called clam “spat”). One of the experimental sites was at John Small Cove, west of Schieffelin Point in Gouldsboro.

Below is a photo of Department of Marine Resources (DMR) scientist Heidi Leighton as she took a sample from the mud on the site. Later, she used a sieve to wash away the mud in the can and will count the number of clams that were in the sample. The black plastic boxes in front of her were part of the experiment. The conjecture was that the disturbance in seawater flow that the boxes created as tides moved in and out would increase the rate of settlement of spat, which might then increase the number of clams that would eventually grow to legal size.

DMR field biologist Heidi Leighton collecting a sample from the mud at the experimental site.

The piece of “scientific equipment” that Heidi used to collect the sample from the mud qas a number 10 can with a hole drilled in the bottom and a cork to seal the hole. She removed the cork, pressed the can down into the mud, replaced the cork, and lifted up the sample. Then, as illustrated in the picture below, she placed the entire can into a plastic bag, which was held by a student in this picture. When she removed the cork, the mud, clams, and whatever else was in the sample dropped into the bag.

Placing the sample into a bag for later analysis.

Each plastic bag with a core sample was labelled according to its plot in the experiment. Below is a diagram of the different plots and treatments. Each plot was 12 feet square. Half were covered with a net to protect small clams from crab predation, half were left uncovered. Half contained the plastic boxes intended to improve clam settlement, half did not. Half were higher up along the tidal gradient, half were lower. Plots 1-2 and 2-3, which had neither a net nor boxes, served as control plots, representing the “no treatment” condition.

The layout of the plots (the rectangles) on the site. Each plot contained 10 or 20 of the plastic boxes or no boxes at all. Half the plots were protected with nets, half were not.

The plastic bags containing core samples were carried via “jet sled” from the site up to the DMR pickup truck — a distance of about a sixth of a mile. We also carried up two of the boxes from each plot that had boxes, together with mud, clams, and whatever else was in there. The picture below shows the jet sled and the student power that made it work. As Heidi said, “Wow. I sure wish I could haul a sled with two full boxes through this mud.”

Transporting samples from the site back up to shore for transport back to the DMR lab.

Just a quick look at the plastic boxes was enough to indicate that wild clams actually had settled in the top layer of mud and had started to grow. Although some of the boxes were carried back to DMR for sieving, some were “flipped” so that the juvenile clams that had settled into the boxes would be placed back on the flats where they might continue to grow. Once the boxes were flipped, the students needed to dig through the resulting “mud pie” so that the newly settled clams, which are still only a few millimeters across, could still extend their tiny siphons up to the surface.

Students “flipping” boxes and then working through the mud to bring the juvenile clams closer to the surface.

Once all the boxes were empty, they had to be washed and stacked. The same was true for the nets that had been used to cover half the plots. The photos below show what that work looked like.

Cleaning the mud from the boxes. We chose a day with a small tide so that the water would be close by.
Cleaning the nets used to cover the plots.

The students who were involved in this project got the opportunity to find out that the life of a working scientist can be much different from the kind of activity that students typically encounter in high school science class. Just as important, the students were an essential part of making this study possible and knew that. They were working very close to the edge of tide on a day when the low tide was about two feet above mean low tide. We chose a day with a small tide in order to make washing the nets and boxes easier than it would have been if there had been a couple hundred feet of mud between the study site and the water line. But working right around the tide meant that we did not have a lot of time to do the work. These students had already assisted the Downeast Institute in another project and so knew how to watch out for and avoid walking through control plots that are not netted, help collect samples, wash nets, and, in general, look out for what needs to be done.

The week after the students helped collect the samples, they sat down with the washed-off samples and used  digital calipers under Heidi’s direction to measure and record the size of each clam in each sample. This follow-on post describes the task of turning samples into data.

Leave a Reply