Summer project: Ridding little pond of vegetative mess
It took most of the summer, but I finally can declare victory in a battle against rampant aquatic vegetation that threatened to choke my pond and kill my fish.
Indeed, rooted pondweed known as chara, and an assorted of floating algae killed some of my fish before I even had realized it. Chara also is called musk grass or skunkweed and has a musky, garlicky odor; over the years it virtually sometimes has choked my pond almost to death. (The pond was designed too shallow, but that’s another story.)
Exploding vegetation literally sucks the oxygen out of the water, suffocating fish. I lost some largemouth bass, bluegills, and even last year’s triploid (sterile) white amur, or grass carp, a hardy species which had done yeoman’s work in chewing down a lot of chara, though not all.
I am not a fan of using chemicals on my property, including in my little quarter-acre pond. Too many farm families around me over the last 45 years have seen various cancers kill family members, and while I know that anecdotal observations are not scientific proof of links, I remain sufficiently wary of modern agriculture’s profligate, willy-nilly use of chemicals on the land. So, I resort to natural means to fight the growing green menace that threatened to turn my pond into little more than a mucky marsh.
It all started last winter, a very mild one with little ice or freezing. An unusual winter-grade algae arose and thickened on the pond over the colder months. It was a strain I had not seen before. Don Schooner, my pond-management guru, understood and said he had received many such reports. But winter algae will dissipate once the warm (eventually, finally) warmed, he advised.
But hidden underneath the winter algae, about a third of the pond was choked with chara, which my now-dead amur had not yet chomped. Sadly, a spring survey showed that at some point oxygen levels must have gotten so low even the amur succumbed, along with a small basketful of largemouth bass, some sporting size, and smallish bluegills.
What to do? Schooner recommended planting a couple new amurs to control the chara. But before they arrived, I took a Minnesota lake-rake to the pond. This is a long, heavy aluminum bar with long, widely spaced, heavy, long teeth of tough plastic or nylon. It is designed to drag heavy vegetation. I made about eight large piles of chara…which brought out the dead fish tangled in its twisted green masses. But I wanted to give the incoming young amurs a head start. You never get it all, raking.
Even as I stocked the amurs and the winter-algae subsided, a summer-grade of slimy, thick-matting filamentous algae started to form. What now, pray tell? Guru Schooner suggested stocking some blue tilapia (and related “pink” forms). They do not eat chara but they gulp algae. Unfortunately, by the time I stocked five or six tilapia, the summer algae had such a head start that they could not keep up.
As summer progressed weekly, I watched the algae mats grow thicker and thicker. Finally I took the problem into my own hands. I wagered that if I took a fanlike leaf-rake – to which I had duct-taped an old broomhandle extension for a 15-foot reach – I could lightly and deftly skim off the mats. It took several weeks and patience, but it worked, a little at a time. I would flock off whatever the rake brought in…and wait for the remaining mats to reform. Every few days I would rake and the mats slowly were reduced in size, till my final afternoon of raking, where I could see that I had it done. From here on, the tilapia were in charge. It had not been a strenuous job, like hauling out the chara mats earlier with the Minnesota rake. But it was tedious.
Now, between the amur and tilapia at work 24/7, I have a vegetation-free pond, without the use of chemicals. I enjoy now watching these fish, and other young bass and bluegills, painted turtles and more, all free-swimming in open water. Actually, the amurs have taken out so much rooted vegetation that they are rooting around for plant roots in the pond bottom, churning up and muddying the water.
I am OK with that. It all will settle out this fall. I will fish out and eat the tilapia, which do not survive in water colder than 45 degrees Fahrenheit. And the amurs will settle down for winter. The pond will be clear, and I can store the rakes…maybe for good?