Thin soup

A business acquaintance once asked if I would join him for an evening meal. When I accepted, he said, “Good. Then I’ll call mama [his wife] and have her put a little more water in the soup.” Not exactly cooking the fatted calf (fortunately he was kidding).

Thin soup may not be very nourishing to us humans, but in reality your lake is a thin soup that has plenty to eat for creatures that live in it. The meat and vegetables in your lake’s broth are plankton, of two basic kinds: plant (phytoplankton) and animal (zooplankton).

Books could be (indeed have been) written about plankton – it is an incredibly rich and important source of food in a lake’s ecosystem. It is also incredibly interesting to observe under a microscope. The little zooplankton creatures are fascinating, and the phytoplankton (mainly algae) are amazing in their variety, symmetry and, yes, beauty.

There is much more to write on this very large topic. For now, suffice it to say your lake’s water is loaded with plankton. Just how loaded depends on where your lake falls on the nutrient scale – from oligotrophic (nutrient poor) to eutrophic (nutrient rich). But then, that’s a whole other subject.

If you were to take a long net with an extremely fine mesh and drag it behind your boat for perhaps 1,000 yards, you would collect a sample of your lake’s plankton. In fact, by knowing the size of the net’s frame and the distance you traveled, you would be able to calculate the density of plankton in the water. Of course that calculation involves a little lab work, too. You would have to dilute the captured plankton in a known volume of water, take a sample of that, and under a microscope, count the numbers of phyto and zoo pieces, and crunch some numbers. It’s a process, but the math isn’t all that complicated.

The point for now is that when you look down into your lake, you are looking not just at water but through a liquid full of life-giving food. Plankton form the base of any lake’s food chain – or perhaps more correctly, the anchor points for the lake’s food web. It’s plankton that tiny fish fry eat when they are too small for anything else. Bigger fish then eat the fry, they get eaten by still bigger fish, and so on all the way up to the mighty muskellunge. So, in the end, no plankton, no musky.

If big oaks from tiny acorns grow, then in a somewhat different sense, trophy fish grow from tiny plankton. It’s a neat concept to dwell on.