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What causes red algae in the Gulf of Mexico?

Asked by: Connor McCormack
School: St. James Middle School
Grade: 6
Teacher: Mrs. Walter
Hobbies/Interests: Skiing and baseball
Career Interest: N/A

Answer from Dale Madison

Professor of Biology

PhD school:
University of Maryland, College Park

Wife: Diane; four children: Ryan, Nathan, Lisa and Tracy

Ecology, fitness, landscaping, craftsmanship and welfare volunteering

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Good question, Connor, and I appreciate your interest in events outside our local community. I interpret from your question that you wonder why red algae at certain times becomes so abundant in the Gulf of Mexico, and why it is of such great concern to people living in that area and to scientists in general. Let's first discuss what red algae are, then what the problem is, and finally what we can do to reduce the problem. Red algae are typically small, plant-like organisms that live mainly in coastal areas around the world. They use their red pigment to capture energy from the sun, and then make their own food for growth and reproduction by using water, carbon dioxide gas and nutrients such as phosphorus and nitrogen - similar to grass in our lawns, except grass pigments are mainly green. Red algae under normal conditions seldom cause problems, and in fact certain kinds of red algae are major contributors to the growth of coral reefs. Red algae becomes a problem in coastal areas when several, one-celled versions of red algae reproduce out of control because of increased nutrients in the coastal waters - similar to excessive grass growth when your lawn is fertilized. The out-of-control red algae change the color of sea water into dense red patches (called blooms or red tides) from Maine to the Gulf of Mexico, and even along the California Coast. Some red algae produce neurotoxins, which in small amounts are not a problem, but when blooms occur, the toxins reach lethal levels in many marine organisms, such as fish, birds, and seals. People are warned when this happens, and entire fisheries along the coast of Maine may be shut down because of the danger to human health. At these times, marine mammals and birds may move around in confused ways before dying themselves, as experienced recently along the west coast of California. Increased atmospheric carbon dioxide and warmer coastal water can make the blooms even more extensive and destructive, which is one reason why scientists studying global warming are so concerned about red algal blooms. Other contributing factors to blooms include deep upwelling of nutrient rich water and drift of iron dust from northern Africa, and these factors are also associated with climate change. So what can be done about reducing the red tides and the harmful effects to coastal communities? Part of the answer begins in our own neighborhood in Binghamton. By simply using less fertilizer on our crops and lawns, we can reduce the concentrations of these chemicals flowing down the Susquehanna River into the Chesapeake Bay that fuel red tides along the northeast coast of the United States. People in the central U.S. can do the same to reduce fertilizers entering the Gulf of Mexico from the Mississippi River. We can also use less energy (fossil fuels: natural gas, coal, gasoline, oil, and electricity generated by coal-burning power plants) by car pooling and lowering our winter thermostat. Less energy consumption means a reduction in carbon dioxide that is an important fuel for rapid algal growth, and a reduction in carbon dioxide will also help reverse climate warming that also promotes algal blooms. Reducing fertilizer and energy use locally may not cure the problem of red tides, but we can reduce the problem, and your next vacation to the beach may become a little more enjoyable. Thanks, Connor, for your concern and curiosity; you show the early signs of being a leader in the movement to make the world a better place to live.

Last Updated: 3/1/17