The Gulf of Maine Expedition 2002

Why Monitor Phytoplankton and Our Procedure for Doing So

Phytoplankton are microscopic algae that float in the surface zones of the ocean. It occurs by the millions where there is enough sunlight to drive photosynthesis.

In the Gulf of Maine, there are two dominant kinds: the diatoms and the dynoflagellates. Diatoms are abundant single-celled, or chained, phytoplankton that drift undirected. Dynoflagellates are solitary, rather than chained, and are equipped with two flagella, or hair-like structures, which help in propulsion through the water. On summer nights when any movement in the ocean seems to trigger an explosion of light, the dynoflagellates bioluminescent qualities are at work.

Phytoplankton is crucial to the functioning of the ocean as we know it today as it forms the basis of the food-chain. Small herbivores, such as zooplankton or copepods, sea squirts, sponges, barnacles, bryozoans, clams, and mussels, all eat phytoplankton by the millions. These species then become prey to someone else on the food chain. Copepods, for example, are small crustaceans that filter feed on phytoplankton. In turn, copepods are the primary food source for herring, mackerel, and other species of fish. Clams and mussels are eaten by starfish and humans.

In the spring, as daylight lengthens, phytoplankton increases its rate of photosynthesis enabling it to start dividing and multiplying. As the size of the phytoplankton population keeps growing, it is known as a phytoplankton bloom. Some blooms can become harmful to humans and other species high on the food chain. These harmful algal blooms, or HABs, are commonly known as "red tide".

As filter-feeding mussels and clams ingest the HAB species, the toxins accumulate in the tissue of the bivalves. Although not harmful to the mussels or clams, species higher on the food chain can be affected. In other words, when a human eats mussels which ate toxic phytoplankton, the human can get sick.

Volunteers throughout the Gulf of Maine are monitoring phytoplankton species to help sound the alarm when shellfish beds may be contaminated by HABs. The Gulf of Maine Expedition has joined this network of volunteers by monitoring phytoplankton along our entire journey. Our monitoring equipment and training was provided by the University of Maine Sea Grant Program and Cooperative Extension.

Procedure

Two times a week, the Gulf of Maine Expedition team takes a water sample and analyzes its content for phytoplankton. The procedure is simple and begins when we are still in our kayaks. At least two team members are necessary to take the sample.

While sitting in the kayak, one person takes the sample while the other stabilizes both kayaks and acts as a recorder. The phytoplankton net with the sample-collecting bottle at the net's tapered end is dropped in the water and towed for three minutes. Depth of sample, water temperature, current, wind speed and directions, and latitude and longitude are all recorded. The sample is then stowed for identification later back on land. Our tows are usually done in the afternoon before landing and the identification is usually carried out that same day before nightfall.

To identify the phytoplankton content in our sample, a small, handheld field microscope is used. A total of six fields of view split over two pipettes are examined under the field microscope. All species are identified (to the extent possible) and recorded, including abundance. In the event that we find HAB species (which we have not yet, as of June 19, 2002), these are reported to the Maine Department of Marine Resources, or its equivalent in other Gulf of Maine States and provinces.

At the end of the Gulf of Maine Expedition, all of our data will be incorporated into the data provided by all the other volunteer monitoring groups. For the purposes of this website, only the species observed and location are listed.