green water

WaterLine photo by Capt. Josh Olive

Clear green water and stormclouds are two things that can’t coexist for long in Southwest Florida.

A lot of folks who move to this area from the northern half of the U.S. do so to escape the ravages of cold, snowy winters. Then they complain because “Florida has no seasons.” Well, first off, y’all are silly. And second, you’re dead wrong. Florida may not have the same four season that you were used to “back home,” but there are definitely seasons. And we find ourselves right at the beginning of one now.

I’ve had the same conversation about Charlotte Harbor with many people after their first year of living in Florida full-time. It always starts out with them wishing the water was always clear and green all year like it is in late winter and spring, then progresses to complaints about how nasty the Harbor looks in summer. But I always tell them that if we didn’t have that ugly dark water, this estuary would lose a huge amount of its productivity.

Fresh water flowing in from the rivers that reach up into Florida’s heartland is a magic ingredient. That water brings with it land-based nutrients that spark the growth of phytoplankton, which feeds millions of small fish and crustaceans, which in turn feed bigger fish. Take that fresh water away, and Charlotte Harbor is no longer a place that can produce such a massive amount of life. The water will be pretty, but it will be dead.

The start of our rainy season more or less coincides with hurricane season, and for the same general reason: Heat, and plenty of it. High temperatures lead to storms — mostly the afternoon thunderboomer type, but also tropical systems like Cristobal which gave us several inches of rain last week.

When the storms start, most of the water gets soaked into the parched ground, but since we usually go from no rain at all to a whole bunch, it doesn’t take long until the top layers can’t absorb any more and it starts collecting in sloughs, marshes and swamps, then running off into small creeks and then rivers.

These waterbodies have been sitting still all dry season, fermenting dead vegetation in much the same way you might steep a cup of tea (or a gallon, if you’re southern). Just like when making tea, the water leaches out astringent brown chemicals called tannins. And as the water builds up and starts to flow toward the sea, it carries those tannins along.

Now that we’ve had significant rainfall (and plenty more in the forecast), we’re going to see those tannins showing up in the Harbor. Our season of pretty green water is coming to a halt. As I write this, the Peace River at Arcadia is flowing along at 1,400 cubic feet per second — triple what it was doing just a few days ago. That black water’s on the way.

The impending changes are more than just color. Rainwater is fresh. The upper end of the Harbor is going to get a lot less salty, and that will chase out a lot of the gamefish. They go not because they can’t take low salinity, but because a lot of the smaller forage fish prefer high salt content. If you want to be well-fed in the wild, it pays to follow your food source.

Dark water also moves fish for another reason: It absorbs more heat energy from the sun. On hot days, inshore water temperatures can push up into the mid 90s. That’s a problem itself, but then it’s compounded by the fact that hotter water hold less dissolved oxygen. If you find yourself someplace that’s way too warm and where you have trouble breathing, you’re probably going to be looking for a way out — fast. Fish too.

Tannins make it harder to see fish in the water, so sight-casting becomes a much trickier task. On the flip side, it’s also harder for the fish to see you. That means you can get closer to mangrove shorelines or docks without scaring the fish.

The reduction in water clarity can cause real problems for boaters. Sandbars that are obviously visible when the water is clear will have no problem hiding under the dark-tinted tannic waters. If you haven’t taken the time to get acquainted with bottom contours in the shallows, that can easily trip you up and leave you aground. More caution and vigilance are in order.

These changes don’t usually occur overnight, but they are already happening on the Harbor. We’ll have decent-looking water near the passes for a bit yet, especially on the incoming tides. But as we get more rain, even that will darken. The water’s not getting dirty. It’s not pollution. It’s not red tide (not yet, anyway). It’s just the natural course of the seasons for our local waters. And you’d better get used to it, because that clear green water isn’t coming back for about 8 months.

Contact Capt. Josh Olive at 941-276-9657 or Publisher@WaterLineWeekly.com.

Contact Capt. Josh Olive at 941-276-9657 or Publisher@
WaterLineWeekly.com.

0
0
0
0
0

Load comments