Another parameter of a pond's health is the clarity of the water. Very turbid water indicates either an overabundance of silt and/or of phytoplankton. Abundance of the latter (mostly algae) is a function of the nutrient level in the pond -- the more nutrients, the better it grows until it has consumed all the oxygen and the pond becomes eutrophic. Well, this summer, the pond was exceptionally clear. It was a great pleasure to swim in the soft, clear and warm water. And unlike last year, the plant growth was much less. In the summer of 2000, one swam through a quagmire of plants that grew from the bottom of the pond to the surface, whereas this summer, most of the pond surface was free from those weeds.
Why the increased clarity and decreased growth of weeds? Well, at this point we don't really know. There may be more than one explanation. For one, the pond went down about 6 inches or more. That drop represents a significant fraction of the total volume and means that a lot of nutrient-rich water was drained into Vineyard Sound. What remained may have gotten diluted by the rain and ground-water inflow and become a less nutritious environment for phytoplankton and pond weeds. Or perhaps the higher salinity is not so conducive to weed growth or the type of phytoplankton now dominant in the previously fresher water. An answer will have to await the results of analysis of samples for nutrient levels and a comparison with previous years. Hopefully, the Falmouth Pond Watchers program will be able to furnish these data.
Do Water Fowl Foul the Water?Back to water fowl. As long as the fowl make their living from the Pond, that is, are not supported by feeding from humans, there is a balance: there will only be as many birds as the pond can support. And our current fowl population does not produce enough fecal coliform to be of concern. As to their poops' contribution of nutrients: unlike humans, who, with their septic systems and fertilizers, only create input into the pond, birds remove biomass, i.e., potential sources of nutrients, with their feeding. Swans and geese consume plant life. Fishing ducks remove fish. They don't produce more than they consume! |
Swans float by Treetops on Oyster Pond. Photo by B. Rose
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