Algal Blooms

This summer some of you might have heard about the algal bloom in Lake Okeechobee or the red tide along the shores of Southwest Florida near Tampa.  Algal blooms (algae blooms) are a natural phenomenon, but have increased in abundance due to anthropogenic activities.  An increase in human population have increased the addition of nitrates and phosphates entering our waterways. 

Algae are unique.  They have plant characteristics, but are not really plants.  Some people classify them as protists.  Either way, algae are very important because they play an important role in food chains and in the production of Earth’s oxygen supply.  But too many algae in a body of water can bring about devastating effects.  Algal blooms are a rapid increase in the population of algae in either freshwater or marine environments.  The population of the algae is so great that light penetration is minimized, and the water can be the color and texture of pea soup. 

Dead algae sink to the bottom of the lake or ocean where it becomes food for the bacteria that decomposes it.  As the dead organic matter increases so does the bacteria.  The bacteria can become so numerous they used up the dissolved oxygen in the water.  The decrease in dissolved oxygen can result in the death of fish and other aquatic organisms.

The rapid growth of blue-green algae (cyanobacteria) can release cyanotoxins resulting in what is known as a harmful algal bloom (HAB).  HABs can harm fish, other wildlife, livestock and pets, and threaten public health.  Red tides are HABs and this past summer have raised a lot of concerns for the citizens of Southwest Florida who live along the coast. 

Algal blooms are more prevalent during the summer months because of the longer days and higher temperatures.  Like plants, algae need sunlight, water, and nutrients to grow.  It is the overabundance of nutrients in our waterways causing algal blooms.  The excess nutrients come from fertilizer runoff, animal waste, chemical discharge and waste from industrial plants, urban sewage runoff.  Fertilizer runoff can come from agricultural fields and from residential neighborhoods.  The excess nutrients travel through the watershed eventually leading to a lake or an ocean.

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Phytoplankton are one type of algae and are the base of the aquatic food chain (the producers).  Primary consumers will feed upon the phytoplankton and secondary consumers feed upon the primary consumers.  Phytoplankton are essential to the health and productivity of our aquatic systems.  We need to do our part to help mitigate the sources of excess nutrients and prevent algal blooms.

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