Just about one month ago, we put our tiny seed clams in the upweller tank. Because this was our first time rearing clams this small in the upweller tanks, there was a steep learning curve. A day after we spread the little clams evenly into six, one millimeter mesh-bottom buckets, we soon realized that these clams love to stick together. At their current size, clams like to attach themselves to other surfaces using thin byssal threads. Most of the clams end up attaching themselves to other clams or the sides of the bucket. The Downeast Institute (DEI) quickly informed us that our clams should be spread out evenly on the bottom of the mesh buckets every day as this allows all of our clams to have equal access to the nutrients in the water that flow up, through our mesh buckets. This meant swirling the clams around and breaking apart the clumps of clams that stuck themselves together. DEI also informed us that we needed to hose down the seed clams and their mesh-bottom buckets with saltwater daily. I didn’t understand why until I came into the lab the next morning and saw a whole lot of clam poop clogging up the holes in the mesh. If the mesh on the bottom of the buckets is clogged, then it prevents the clams from feeding.
Although we have to clean the clams and their buckets everyday, seeing lots of clam poop is a good sign. It means our clams are feeding and growing! We wanted to determine how fast this growth was occurring. However, these clams were very fragile and were only over one millimeter when we got them, so using a caliper to measure sample shell lengths of these clams would be too difficult. Instead we used the 1mm by 1mm mesh as a size reference to compare the clams over time. Below is a series of pictures taken about one week apart from each other of the small seed clams with the mesh background. Looking at the photos, we can observe that the clams are growing, but the growth is very small. It seems as if the clams grew less than a millimeter over the course of about a month. Right now, we have about 50,000 clams growing in each bucket. We recently combined two of the buckets so that one bucket now has 100,000 clams growing in it. We want to know if increasing the number of clams per bucket will increase the clam growth rate, have no effect, or decrease the clam growth rate. We will be keeping you updated on the growth of our tiny seed clams.