Phytoplankton

Phytoplankton are a diverse and abundant group of microscopic plants that float freely in the lighted surface waters, and are the foundation of the marine food chain and vital to all life on earth. When present in high enough numbers, the water may appear colored due to the presence of chlorophyll and other chemicals within their cells. As the base of the food chain, phytoplankton turn the energy from the sun, combined with nutrients in the water, into carbohydrates. Through photosynthesis, phytoplankton are responsible for producing as much as 90% of the oxygen present in the Earth's atmosphere and are an important absorber of carbon dioxide.

GBCW Volunteers

Phytoplankton Monitoring by volunteers has become a mainstream effort in many coastal areas around the United States. When GBCW began its volunteer monitoring program in June of 1999 (from April through October) only two other states used volunteers to monitor for the presence of potentially toxic phytoplankton in their coastal waters. Today eight states have implemented programs and others are preparing to follow.

The first program was developed in 1991 by the California Department of Health and Safety in response to a seabird, cormorant, and brown pelican mortality event which was traced to a bloom of the toxic diatom Pseudonitzchia spp.. Subsequently, in 1995 the University of Maine Cooperative Extension in cooperation with the Maine Department of Marine Resources (DMR) established a similar program. The Maine program quickly showed its potential when in 1996 volunteers identified the toxic dinoflagellate Alexandrium spp. two weeks before DMR detected the saxatoxin produced by the cells in local shellfish meats.

In 1999, Great Bay Coast Watch became the third state to implement a volunteer phytoplankton-monitoring program. Today, South Carolina, Georgia, North Carolina, Texas, Alabama all have established formal programs that use volunteer collected observations as an early warning system for red tides. For more information on phytoplankton monitoring, please contact Candace Dolan at candace.dolan@unh.edu.

Goals

To act as an early warning system for harmful algal blooms (commonly known as red tides).
They do this by collecting samples of phytoplankton and then examining those samples using field microscopes identifying the presence of potentially toxic phytoplankton species. Shellfish such as clams and mussels are filter feeders and, when ingesting toxic phytoplankton, will concentrate the toxins in their bodies. When these now toxic shellfish are consumed by humans, illness or even death may result.
To identify any toxins.
Since toxins are specific to certain species of cells, the information collected by GBCW volunteers can give shellfish managers early warning that toxic cells are in the area, which species, and which toxin may be present.

Decisions regarding the opening or closing of shellfish beds are made by New Hampshire Department of Environmental Services Shellfish Program personnel after testing harvested shellfish meats for accumulated toxins. When toxin levels measure above 80 ug/100g shellfish tissue, shellfish harvesting activities are suspended to protect public health.

Health Risk

Although volunteers record the presence of all phytoplankton species identified in their collected samples and note certain other cells of interest, their primary target is a cell called Alexandrium spp. This single-cell dinoflagellate produces a naturally occurring poison called saxitoxin, reported to be one of the most toxic non-protein substances known. When people consume shellfish which has accumulated this toxin by feeding on Alexandrium spp., they very quickly succumb to the effects, a syndrome known as paralytic shellfish poisoning (PSP). Death can usually occur within 2–12 hours in untreated cases, and there is no cure. Timely medical assistance, in the form of mechanical artificial respiration, is essential, with the result that most human intoxications are non-lethal.

An additional reason to monitor phytoplankton populations:

Research has shown that populations of phytoplankton are fairly resilient. Marine sediment cores that have been examined contain diatoms, those single-celled organisms with a coating or shell of calcium carbonate as fossils. Eventually, when diatoms die their calcium carbonate shells fall to the ocean floor and become part of the oceans sediment layers.

Photosynthesizing organisms use carbon dioxide to create energy and so remove carbon dioxide from the atmosphere. Some of the carbon that phytoplankton take out of the air as carbon dioxide is used to make their calcium carbonate coatings. Because these coatings eventually make it into the sediment, they do not immediately return to the atmosphere. It is not until chalk or limestone beds are exposed to the elements that weathering returns the carbon to the atmosphere.

The factors that were altered in the upper marine environment during previous abrupt climate change events included increases in temperature (11 degrees over 1000 years) and changes in thermal structure, changes in salinity and alkalinity, and changes in nutrient patterns and trace elements. It is important to recognize that many of the species we see today are highly specialized, and exist in a very narrow ecological niche, as soon as some group disappears; another species comes in to occupy that niche.

Today, we are sort of in the middle of a mass experiment, with the oceans warming, we do not really know what the end result will be, but we can look to the fossil record to see how they were affected in the past and collect data to document changes in the present.

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