Author’s little pond succumbs to ever-present algae problem
My little old pond – a 40-year-old quarter acre of water – looks sick this summer, and it makes me wonder whether it has joined the expanding ranks of waters affected by harmful algae blooms.
The pond is a uniform shade of pea green, and while not soupy “thick,” it is a shade I have not seen all these years. A moderate drought has dried out the land and dried up the flow in my local creeks, and as the pond has shrunk through evaporation and lack of rain replenishment, its flat “dead” murky-green appearance seems more pronounced. Disturbingly so.
A year ago I introduced a small triploid (sterile) white amur into the pond to eat down the usually heavy aquatic vegetation. This “grass carp” has grown like gangbusters in a year of constant eating, maybe tripling in size or better and virtually eating itself out of house and home. I have no vegetation problem – gone.
I don’t even know if my annual stocking of blue tilapia, done to assist in the vegetation-eating, has survived, let alone thrived. By now the pond should be crawling with schools of tiny tilapia, at least two generations’ worth. I have seen none. I have not even seen any of the stocker-size tilapia, nor any of the bluegills or largemouth bass I have stocked the last two summers. They seem to have evaporated – or disappeared into the gullets of great blue herons when I have not been around to chase away these voracious waterside predators.
I still have plenty of whirligig beetles spinning circles on the pond and plenty of dragonflies dive-bombing the surface and pond edges for insect dinners. Some bullfrogs remain, though their numbers, too, are down, likely because of the hunting by the pterodactyl-like herons and by the watersnake or two that hide in the cattails. A few painted turtles show up, but not as much as summers when the vegetation is thicker, and I have not seen the dinner platter-size snapping turtle in a month. I still have plenty of crayfish, but I am not seeing the muddy tracks of small mammals, such as raccoons, come to the water to drink.
It all makes me wonder, for this is not the summer norm for this pond.
Perhaps the amur has done its job too well in eliminating rooted vegetation. I see it rooting around in the shallows, bumping the bottom and stirring up black muck – in effect “feeding” the pond with resuspended, nutrient-rich sediment. Maybe that plus many quiet, 90-degree, sunny days in this drought have created the perfect storm for the murky pea-green condition of the water.
My pond is not alone. One of my favorite kayaking spots, the state’s Aldrich Pond along the Ohio Turnpike in northwest Sandusky County, is all but vegetation-free. Usually by this time of summer it is so choked my kayak usually rides the tops of the vegetation beds. Aldrich is a shallow “borrow pit” that was dredged to borrow soil to build Turnpike overpasses 70-plus years ago.
A check with a state fisheries biologist gave me no answers, just befuddlement about the currently nearly weed-free Aldrich. The state had not treated it with a herbicide, he said. Huh.
A recent article in The Blade newspaper in Toledo discussed the huge pea-soup algae bloom in Florida’s vast Lake Okeechobee this summer, comparing it to western Lake Erie’s recurring problems. El Nino-induced weather patterns, climate change, and a large influx of nutrients are among the factors to blame, though the sources are different.
In Florida, the big blame lies with cattle ranches where nutrients flow off land much as they do off corn fields in northwest Ohio, where a combination of synthetic fertilizers and soil soaked with animal manure gets into the Maumee River, the Sandusky River, and other area streams during heavy rains.
Both areas have problems from housing subdivisions, strip malls, and other forms of urban sprawl added to their soupy messes, including sewage overflows, street runoff, and releases from bad septic systems. Florida environmental groups also claim there’s a huge impact from the state’s powerful sugar industry near Lake Okeechobee.
Experts agree climate change and poor land-use practices are underlying reasons why harmful algae blooms have been on the rise throughout the world the past two decades, from thousands of small ponds across North America to massive Lake Taihu in China, Lake Victoria in Africa, and virtually any major freshwater body from the Arctic to South America.
Harmful algae blooms need freshwater, sunlight, nutrients, and stagnant air to bloom. Though there are no agricultural inlets into my pond, and its entire watershed lies on my own land, where no chemicals are sprayed, I still have the murky green this summer. Resuspended sediment by the rooting grass carp? Almost makes me wish for those thick mats of rooted vegetation that I have had to rake out twice a summer in years past. At least the water was clear then.
Maybe I need to pray for rain. And cooler temperatures and a little breeze.