(By Robert Howell) We’re having some beautiful days here on Estero Island. And maybe you’ve noticed, our Gulf side water has been especially beautiful! Our Bay side also has been quite pretty. The color and clarity of the water is affected by many factors.
First and foremost the rain. The less rain we get the bluer and greener our water gets on the gulf side, the less wind the clearer the water becomes. However during our rainy summer season more rain hits not only the water stirring up the bottom, but also the land bringing all sorts of runoff into our watershed.
The color of the water is also affected by one of our most important attributes and species here: Mangrove trees. These mangrove trees have a unique ability to filter fresh water from salt water but to do so they must sacrifice some of their leaves (the yellow ones).
When this happens eventually the leaves fall off, more so during storms and rainy season. All these leaves along with all the other biomass filtering down into the water stains the water just like tea leaves or coffee beans. The brown stain comes from the tannic acid or tannins found in the biomass.
As the “winter” season descends, the heavy rains of the previous months diminish and the water is able to process these acids and stains taking them further out to sea.
The temperature of the water is changing as well. For humans some of these changes might be welcome such as the warm temperatures both in the air and in the water. Even manatees are enjoying the warmer conditions. So much so that they are not migrating as long as they used to.
I’ve seen a drop in manatee activity up the Caloosahatchee river during the winter. Just a few years ago manatees by the hundreds took advantage of the Fort Myers power plant for their warmth. (Manatee cannot live in water under 70 degrees for very long; it puts them into a state called cold stress and can effectively shut down their bodies). Manatee all over our region will normally seek out warmer water, whether it be from natural sources such as springs or unnatural sources like a power plant.
Manatee were typically seen from late December to early March if not longer. Now, however, “manatee season” up river is late January until mid-February. One might think the population is decreasing, but we’re finding that’s not the case. Because water in the Gulf, and in our estuaries, is staying so warm, they’re down river, in our busy waterways for longer periods of time.
Hopefully this article raises some questions or sparks interest in the ecology of our beautiful area. Please contact me Robert Howell via Instagram @RangerRobFMB or Beach Talk Radio so we can answer some in future articles.