This is the first day I am able to observe the minnow mandala without overcast skies. The sky is cloudless, with a brisk north wind that whips through the trees and around the building’s corners. The breeze makes ripples across the bulk of the pond that makes observation of the bottom nearly impossible. It’s calm however at my usual observation point and the sun is streaming into the area making the minnows much more active. They are much more numerous as well. I count 30+. They still prefer the calm behind and around the rock island but many more are venturing into the slow deep whirlpool that is generated by the waterfall on the other side of the rock.
Looking closer I see my first dead minnow, a larger one, slowly being pushed around the edges of the whirlpool. Then another smaller one appears, and then another. A few minutes later another struggling minnow gets caught in the flow. It does slow rolls as it tries to keep motion through its gills. It will be dead soon as well. Four dead minnows; other minnows swim up occasionally to watch them. At first I think they’re eating they’re own dead but it turns out they’re just curious.
Life expectancy for these fathead minnows is two to three years, the longevity of which surprises me. I guess these examples had reached their limiting factor. Some were not full grown. Maybe they had spent valuable energy trying to brave the rapids. Old age or lack of food caused by too large of population could be a cause. The onset of some disease perhaps that may affect the rest of the minnow community could be a cause.
Both limiting and enabling factors influence the fish. The pond is limited by its human-made area, which in turn limits minnow size and population. There are no bugs to fill the diet due to winter, also a limit. The lack of bugs as a food source is made up for by plenty of algae. The pond’s configuration limits natural predators which in turn is an enabling factor for minnows. During a heavy rain the water will change chemical composition as there is no runoff in this contained area. This may affect the fish in some way. The fish also depend on human intervention if the water becomes depleted. So the pond has its share of limiting and enabling factors that will influence the minnow’s lives.
The death of the four minnows is an enabler of recycled life in the pond. They will eventually provide the pond with nutrients from their decay, which in turn will enable bug larvae and plants to feed once the season transitions out of winter. These will provide more food for the minnows. Their deaths have also enabled more room in the environment and less competition. If the larger minnow’s size had proved a threat to the smaller fish, then that threat too has been removed. But so has the protection larger size may have provided. Another large minnow will fill the void. The death of the four may have unseen consequences. One of them may have been carrying the last gene mutation that would have prevented a future disease. Conversely, one may have taken to its death the last of a detrimental gene. For now however their bodies are all just riding an endless circle around the whirlpool along with bits of algae and dead leaves.
I got to look a little closer at surrounding ground cover today as well. At first glance I thought I spied dollar weed. But closer inspection showed a carpet of some type of small-leafed green fern with a few strands of dollar weed trying to compete for space. Dollar weed won’t win that battle this season. Nothing flying today either. I fear the yellow-jacket from week #1 was lulled into a premature Sacre du Printemps.
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