Algae

In freshwater lakes in Florida algae can make the water green and slimy. However, they are essential to the ecosystem, providing food for all types of animals including fish, insects, mollusks, zooplankton (microscopic animals), and humans. Algae occur naturally in all types of systems and are indicators of an ecosystem’s condition, including the amount and type of nutrients that run through the system.

Are algae plants? The classification of algae has long been debated by plant taxonomists. Algae are able to photosynthesize, a key characteristic of plants, but lack true roots, stems, or leaves so are not considered plants. The two main groups of algae are prokaryotes (no nucleus) including the blue-green algae; and eukaryotes (contain a nucleus). There are microscopic algae, like phytoplankton; and macroalgae that can be seen by the naked eye.

Types of algae

Cyanophyta - These are the blue-green algae which can exist in low nutrient to very high nutrient environments. Some species of blue-green algae have a competitive advantage over other algae by having the ability to fix nitrogen. This characteristic allows these species to exist in areas where low nitrogen availability inhibits growth. Some groups produce potentially harmful toxins:

Lyngbya - Grows in dense mats at the bottoms of nutrient enriched lakes. When they rise to the surface, winds pile the algal mats against shorelines or in navigation channels. The blooms can cover so much of the pre-existing vegetation that it can cause serious damage and wipe out other species including eelgrass, a favorite of manatees. Some species in this genus have been linked to the production of a skin irritant leading to "swimmers' itch".

Microcystis – Some strains of Microcystis have the ability to produce a toxin known as microsystin which is potentially harmful to animals when in abundance.

Chlorophyta - Green algae

Bacillariophyta Diatoms - Considered the most beautiful group due to their silica shell (glass)

Xanthophyta - Yellow-green algae

Charophyta - Stoneworts, often mistaken for true plants due to the whorls of filaments that occur at nodes along the shoot