The Tide Pool

On Tuesday I ventured out to the South end of the Island with Drew, who was checking on his settlement plates in the large tide pool that is a favorite spot for swimming as well as for scientific research. The pool is near the tip of the Island, where the currents and the tides converge and create huge waves that come crashing against the rocks. While every field project is affected by the weather, Drew’s is especially at the mercy of the elements because he is attempting to study the effects of currents on “fouling communities,” organisms that settle on hard surfaces in the intertidal zone. Drew has lost two racks of settlement plates to normal wave action, and lost three more in the storm that reached Kent Island during Hurricane Arthur, which brought 60 mph winds and turbulent seas. Drew has to check on the plates he has placed in high current areas frequently to do maintenance work, and has no idea what condition his plates will be in, or whether they will be there at all.

Getting to the tide pool is an adventure in itself, because it involves crossing deep into gull territory, and then clambering over the forest of slippery rockweed that is exposed on the bedrock at low tide. Drew managed the journey with all of his equipment in tow, while I, struggling to keep up, followed behind him almost all the way to the edge of the sea. In the early morning, these rocks are a prime spot for watching migrating Minky Whales and harbor porpoise when there is less glare off of the water. I have also seen puffins and razorbills in the distance, birds that are in the same auk family as the Black Guillemots that Ben studies, and share the Guillemots’ black and white coloring and red feet.

The fauna in the tide pool are less obvious, but equally fascinating. The water is dark turquoise with a cobbled bottom, and the walls are wreathed in Laminaria digitata kelp around the edges. Digitata are so named because their brown, palm-shaped fronds look like fingers, which, like rockweed, provides habitat for a variety of organisms, including the fouling communities that Drew is studying. In the shallows of the pool I saw pink and yellow sponges, delicate anemones, large and small periwinkles, a swirling neudobronch, and a tiny sea star. Deeper in the pool, benthic fish swim silently, grazing the ocean floor.

Drew’s settlement plates float in the center of the pool, and the device is anchored to submerged aquaculture cage on one end and the huge iron wreck of a salmon weir that is moored on the rocks. He created a clothesline system that allows him to pull on the rope to check the plates for growth and to photograph them without having to enter the pool every time. One of the ropes had snapped in the storm, so Drew donned his snorkeling mask and wetsuit, complete with a hood, booties, flippers, and a knife strapped to his calf. He is an experienced scuba diver, and expertly entered the water and dove down into the dark center of the pool. He asked me to stand by the edge and watch the tide, which was outgoing, but the powerful surf crashed against the nearby rocks. Hannah Baggs, another Bowdoin student, filmed the process for an educational video about Kent Island ecosystems that she is making for Maine biology classrooms.

Drew diving to fix his plates in the tide pool

Drew diving to fix his plates in the tide pool

“Wow, it’s a mess,” was the first thing that Drew said when he surfaced. His plates were thankfully still in the pool, but the snapped line had tangled on itself in the turbulent water. For half an hour he unsnarled the lines with his knife, and Hannah and I helped him to retie the clothesline system while he was in the water. While the tide pool may look like a swimming pool, its temperature is in the high 40s. On a day off I had jumped off the rocks into the water in my bathing suit, and was completely numb after a few minutes. When I asked Drew whether he was cold, he said “It’s pretty comfortable with my wetsuit, and I can probably swim for an hour or so without getting cold.” A wetsuit is another item of clothing that I wish I had packed, because it would be great to explore the intertidal ecosystem more thoroughly.

drew_scuba

After re-attaching and photographing his plates, which were vacant of fouling communities, Drew conducted some plot surveys of the smaller tide pools in the area. He used Christine’s quadrant, a square wooden frame, and surveyed the organisms floating underneath it and those attached to rocks and algae. Unlike Christine, who counts all of the organisms that she is looking for, Drew’s quick and dirty method records the presence or absence of the fouling community organisms that he is studying. The plot surveys will give him an idea of the biodiversity of fouling communities that are present on the Island, and will serve as a point of comparison for those that may grow on his plates. If nothing grows on his plates by some function of his experimental design, the surveys can serve as a backup plan that will give him positive results. He hasn’t given up hope yet that fouling communities will grow on his plates, however, and is lucky enough to be able to return to Kent Island in September to check for bryozoans, sea squirts, tunicates, and other organisms on his list.

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