Posted by: Vicki Burns | March 19, 2013

Blue-Green Algae, Diminishing Coral Reefs and Dying Manatees – What’s the Connection?

Maui Shoreline

Maui Shoreline

Over the past year I’ve had the good fortune to travel to both Florida and Maui for warm, sunny holidays. Its quite a privilege to be doing that in a year where our Manitoba winter has been very cold and long. However on both trips my vacation was marred by worry about what I was observing in both those locations. It was a reminder that the ecological damage caused by human development is becoming evident in many areas around the world. Improving our sewage treatment systems along with adopting best management practices in agriculture and implementing various ways of holding water on the land, are of utmost importance everywhere if we want to protect our precious lakes, oceans and all the aquatic life they support.
Just weeks ago in Maui, we were disappointed to find far fewer fish on our snorkelling adventures than what we had seen just 4 years ago. When I searched for information about whether it was just one isolated experience I was dismayed to find this report from the Hawaii Division of Aquatic Resources. It documented the decline in coral reef cover at several Maui sites, and stated that:
“Concentrations of nutrients (Nitrogen and Phosphorus) are highly elevated in nearshore areas where algal blooms are found.
Stable isotope ratios (ä15N ‰) in algal tissue are indicative of animal waste (presumably sewage) being their primary source.”
At the same time I received a copy of an article about the death of 174 manatee in southwest Florida as a result of a red tide bloom that has stayed for much longer than usual. A few months ago, I found information about the incidence of red tide increasing dramatically since the 1990s. Red tides are fed by increased nutrients of phosphorus and nitrogen, similar to blue-green algae blooms in freshwater lakes. Although both red tides and blue-green algae have occurred historically, the frequency and size of the blooms is growing related to the increased nutrients running into our waterways from human sewage, animal waste, fertilizers and natural run-off.
We do know now some of the ways that we can decrease the excess nutrients getting into our water. What we seem to be lacking is the will to get started on processes that will cost us more $$ but will protect our precious waters and all the fish, birds and animals that they support.


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