Researchers monitor 10 sites in Old Tampa Bay for the presence of, or conditions favorable to, harmful algal blooms.
At nearly 400-square miles, Tampa Bay is Florida’s largest open-water estuary. But one of its smallest inhabitants plays an important role in the bay’s ecology. Microscopic phytoplankton (single-celled algae) provide a valuable food source for many bay organisms, such as fish and oysters. But several species of phytoplankton in Tampa Bay are capable of producing toxins. Under certain conditions, toxic phytoplankton can grow to high concentrations and form a harmful algal bloom (HAB). These toxic blooms can have adverse effects on fish, shellfish, birds, humans and other mammals.
Scientists do not have the ability to predict algal blooms, but the Fish and Wildlife Research Institute’s (FWRI) HAB group is investigating the possibility by learning as much as they can about the conditions that facilitate blooms. They monitor 10 sites in Old Tampa Bay by boat twice each month during spring, summer and early fall, when harmful algal blooms are most likely. During each trip, HAB scientists collect water samples at each site and analyze phytoplankton biomass (amount present) and community composition (types present); toxins; nutrients; and other environmental components that may help them understand and predict toxic blooms.
Yellow balloons mark HAB monitoring sites in Old Tampa Bay.
Scientists use a microscope to visually identify phytoplankton species present in water samples. The different species and total amount of phytoplankton present at each site can indicate when blooms might occur. FWRI HAB researchers pay close attention to the presence of three harmful algal species in Tampa Bay.
Pyrodinium bahamense blooms are the most common threat to environmental health in Tampa Bay because this organism produces a very potent toxin called saxitoxin, which can accumulate in shellfish and pufferfish. People who consume contaminated shellfish or pufferfish can suffer from Paralytic Shellfish Poisoning (PSP) or Saxitoxin Puffer Fish Poisoning (SPFP). Blooms of P. bahamense in Tampa Bay have not been associated with the acute toxic effects of SPFP that have occurred in the Indian River Lagoon, but scientists preemptively monitor for its presence in the bay. Blooms of P. bahamense discolor the water a rusty brown. This phytoplankton species is also bioluminescent, and a blue light can be seen at night when water with high concentrations of the cells is disturbed. Other potentially toxic phytoplankton in Tampa Bay include the diatom Pseudo-nitzschia and dinoflagellate Karlodinium.
Pyrodinium bahamense Pseudo-nitzschia pungens Karlodinium veneficum
Scientists use a flow-through sampler to continually pump water onto the boat during monitoring trips. As water pumps through, a data-sonde records information – such as latitude and longitude, temperature, salinity, turbidity (cloudiness) and chlorophyll – every five seconds. Staff uses these data to create maps of blooms in Tampa Bay.
Nutrient and Biotoxins Monitoring
In the FWRI labs, researchers analyze water samples for nutrient and toxin content. HAB staff measures nutrient content using color-changing chemical reactions in an autoanalyzer; the darker the color, the higher the nutrient concentration. Scientists can use these data to determine if phytoplankton have the necessary resources to form a bloom and how long a bloom could last. Additionally, HAB scientists in the Biotoxins Laboratory use a variety of methods to measure the toxin content of the water samples.
All of these methods help scientists study the ecology of Tampa Bay and identify potential harmful algal blooms that could have toxic effects on humans and other animals. View images and learn more about HABs in the Blooms of Harmful Algae and Other Plankton Flickr set.