In Naples, when people think about algae, they usually conjure up images of red tide and blue green algal blooms with discolored water and dead fish in the mix. These events, however, tend to be on the edge of the spectrum for algal behavior. There are tens of thousands of species of algae. Blue green algae (cyanobacteria) are among the earliest known life forms according to the fossil
record, extending back billions of years.
In fact, blue green algae may be the reason why there is oxygen in our atmosphere. We wouldn’t be here if it weren’t for algae. Algae are the base of aquatic food webs. Fish, birds, and people ultimately depend on algae for our food resources (particularly seafood). In fact, there is a direct
relationship between the concentration of nutrients in ocean waters (nitrogen) and fish harvest. The nutrients feed the algae which feed the fish. We have learned, however, that not all algae
have such good, positive impacts on our environment. Many are harmful and some are increasing in bloom intensity and frequency. What causes one species of algae to bloom over another? Why
do some species bloom, and others “behave”? There are no easy answers to these questions, which form the basis of much research.
Algae need light and nutrients to grow. Sometimes the water is too cloudy or the algae sink too deep to get adequate light. Oftentimes, nutrient levels are too low to support luxuriant algal growth. But when light and nutrient conditions are optimal, you can get an algal bloom. Historically, scientists documented these blooms during the springtime in temperate waters (up
north where it snows). A combination of snowmelt and rainfall causes run-off to bring nutrients into receiving water bodies from the surrounding landscape. Here in Florida, we experience
a similar phenomenon at the end of dry season. The afternoon thunderstorms can bring in nutrients that have been sitting on the landscape for weeks or months during dry conditions. Couple this nutrient pulse with higher light intensity (longer days in the summer) and conditions can be ripe for a bloom (April showers bring May flowers).
If you take a drop of water and look at it under the microscope, you will see hundreds of algal cells, of various sizes, shapes and colors, representing numerous species. When a bloom occurs, you
will see many more cells, typically all the same species. How did that single species come to dominate the waters? What happened to the other species? Will anything eat the bloom? Is the bloom harmful?
When will the bloom go away? These are questions that scientists and concerned citizens equally ask. As wet season and summer approaches, will blue green algae again bloom in our waterways? Will red tide continue to lurk in our coastal waters or will it go away until the Fall? Only by better understanding how the algae respond to water conditions and interact with their fellow algae can we truly manage and mitigate algal blooms