BACKGROUND

      Seagrass beds exist in coastal waters worldwide and are important habitats for juvenile fish and many other marine organisms. The seagrass meadows in Florida Bay were known for their species richness and large expanse. Animals that depend on these grassbeds off Florida are pink shrimp, spiny lobsters, bald eagles, manatees, crocodiles, and sea turtles. Thalassia testudinum, turtle grass, is a common seagrass here.

      In 1987 sport-fishing guides began to notice large patches of brown, floading Thalssia in western Florida Bay. The water was also different; normally the water column in the Bay was clear and you could see the bottom in many places, but that year the water was murky and turbid. More seagrass beds deteriorated and fishermen suggested that rotting grass was depleting the water of oxygen and killing more seagrass. In fact, the causal agent of the Thalssia die-off remains controversial. Some blame very high salinity (<70 ppt), a result of freshwater diversion from the Everglades and also droughts.

      Brian LaPointe, a scientist from the Harbor Branch Oceanographic Institution in Fort Pierce, Florida, is a well known for his research in Florida Bay. LaPointe does not support the salinity theory and points to high nutrient concentrations in Florida Bay water as the cause. He supports his hypothesis with his own research (see Data Set #5) and the fact that nutrient loading to coastal waters is resulting in seagrass die-offs worldwide. In Florida the main nutrient sources are agriculture and sewage.

      The main focus in this activity is application. Students often don't appreciate that scientists must use data from other locations or organisms and assess the validity of applying these findings to their own situation. This is certainly true for environmental scientists and planners who must make decisions with limited information. In this case, students are asked to apply data from a bay off western Florida and another off Cape Cod to the Florida Keys.