The stark folly of poisoning a lakeshore (photos)

Next to my apartment complex is a large retention pond (henceforth, "the lake") which captures and processes runoff from the sprawling development around it. The major developments that border the lake are: Hertz Arena (where the ECHL champion Florida Everblades hockey team plays), Waterline Estero apartments (where I live), The Springs at Gulf Coast apartments, the Miromar Outlets mall, and the Interstate 75 highway.



According to satellite imagery on Google Earth, which I can rewind to 1985, there was some sort of waterbody there even the 1980s, though it was surrounded by woods then. My guess is that the lake began as a quarry, maybe related to construction of the interstate, before it was modified into a retention pond. Anyway, that's besides the point. The point is that nowadays it's an urban waterbody with the important jobs of:

1) Controlling flooding

2) Filtering pollution out of runoff water

3) Being something nice for people to look* at so they'll spend more money on rent, shopping, shows at the arena, etc.

*People used to do more than just look at the lake. In the early 2000s they did waterski shows in it, but that stopped before I arrived in SWFL in 2012. Probably for the best, but it's kind of sad they don't even allow fishing in the lake now.

4) Providing some vestige of habitat for plants and animals that are losing a lot of their other "real estate" as urban growth explodes in the area

Despite its burdens, the lake seems to be functioning well. I'm judging this by the fact that compared to other retention ponds in the area the water is surprisingly clear and full of submerged aquatic vegetation and fish. I know this from lots of looking at the lake, and a bit of snorkeling and deploying underwater cameras in it.

The lake's submerged aquatic vegetation, specifically Vallisneria americana, known as tapegrass or eelgrass, is its secret to clear water. The plants absorb excess nitrogen and phosphorus from the polluted runoff, so there's less in the water to fuel algae growth. This works really well, up to a point. If the loading of nutrient pollution becomes too extreme, or something knocks back the plant life, a lake can suddenly shift from plant-dominated with clear water to algae-dominated with murky water. This dynamic is called ASS - Alternative Stable States. For more info see Scheffer, M., Jeppesen, E. (1998). Alternative Stable States. In: Jeppesen, E., Søndergaard, M., Søndergaard, M., Christoffersen, K. (eds) The Structuring Role of Submerged Macrophytes in Lakes. Ecological Studies, vol 131. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-0695-8_31

I am nervous about this lake switching from its current, clear-water state into an algae-dominated ASS. The reason I'm nervous is that some parts of its shoreline are being managed very poorly. Specifically, the shoreline along Miromar Outlets and I-75 is being sprayed with herbicide to kill all the shoreline plants, leaving just bare mud and rocks. This video clip and the photos below it show the contrast between a well-managed part of the shoreline in front of The Springs apartments, and the terribly-managed part of the shoreline in front of Miromar Outlets.

Natural shoreline in front of The Springs apartments- Keep up the good work.

Semi-natural shoreline in front of Hertz Arena- They mow and do some "spot" spraying of plants, which I think is unnecessary, but it could be worse.

Herbicide-nuked shoreline in front of Miromar Outlet- Ugly, unsafe, and environmentally atrocious. Tsk tsk.

I assume Miromar is doing this as some misguided attempt to make it look "neat and tidy" because there's no legitimate ecological reason to do it. Here is why they should stop spraying herbicide on the shoreline:

1. It causes shoreline erosion.

2. It leads to more runoff pollution entering the lake. One reason ecologists recommend keeping a generous buffer of littoral and riparian vegetation around urban water bodies is because these plants are very effective at intercepting and removing pollution from runoff.

3. It reduces the abundance and diversity of native plant and animal life- bees, butterflies, birds, frogs, fish, etc.

4. While there might be a perception that nuking the shoreline down to a barren wasteland increases people's safety from alligators, it probably does the opposite, because it invites people to go closer to the water's edge where they're more likely to encounter an alligator. I think if the shoreline is reedy and brushy people are less likely to go down to the water's edge.

CONCLUSION: This lake is a local treasure, but it's in danger of losing its ecological integrity because of foolish management on the outlet mall side. I'll see if I can get in touch in with them and convince them of the error of their ways. If any of you readers know one of the higher-ups at the organization, please let me know.