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My dictionary defines limnology as "the scientific study of the life and phenomena of fresh water, especially lakes and ponds." My mentor on a visit to Conesus and Honeoye lakes last week, professor Kenton Stewart, adds that limnology is the freshwater equivalent of oceanography.

I have known Ken for many years, but this was my first opportunity to join him on one of his regular scientific excursions to the Finger Lakes. He has studied these lakes since the 1960s, taking a wide range of readings many times each year, and he plans to continue to do so even though he recently retired from the University at Buffalo biology department.

Rarely have I enjoyed a day more. I knew Ken to be a committed and deeply informed scientist, but on this day I learned that he is also a congenial mentor. And he could not have delivered better weather. The early morning fog cleared, and by noon the sky was almost entirely blue. The days before and after our trip brought rain and high winds, but on our excursion the breeze barely rippled the water. And the bright sun enhanced the already rich palette of colors on the nearby hillsides.

To repeat Marv Levy's cliche, I could think of nowhere I would rather have been. And I learned a great deal. Most important, Ken led me to realize how restricted was my thinking about lakes. Like most of us, I considered them almost entirely in only two dimensions. What lay below the surface, except for a few feet near the shore, fit that old saw, "Out of sight, out of mind." We simply don't think about the characteristics of deep water.

Professor Stewart does think about and study those underwater qualities. At each lake, we loaded his boat and rowed out to where he knew the maximum depth was to be found. Then he used various instruments to measure, at one meter intervals, water temperature and light penetration and to sample for later evaluation plants and animals and chemicals.

These two lakes that appear so similar are in fact very different. The water of Conesus Lake appeared brownish and cloudy; Honeoye Lake was greenish from its many larger and slowly drifting particles. But this was in at least one way quite misleading.

One of our tests was to lower a dinner plate-sized Secchi disk down until it disappeared from view. I was surprised to find that we could see it almost twice as deep in Honeoye as in Conesus. Those large particles did not have the effect I expected. Another measure demonstrated that less than one-five thousandths of the light reached 33 feet below the surface of Conesus Lake. It is indeed dark down there.

Ken assigned to me the simplest task -- lowering a net with a small collecting vial attached and slowly raising it to collect plankton -- tiny animals and plants that serve as food for fish and other larger organisms. When we held the vial up to the light, I could at first see only little green specks, aquatic plants or algae, but Ken had me look closer. To my amazement, the bottom of the vial churned with activity. These were minute animals, daphnia and other even smaller species.

Our delightful day represented just one point in Ken's extensive data collection: His long-term measurements provide evidence on which theories like global warming are built and tested.

I salute Ken Stewart for his contributions to science and thank him -- as only the most recent of his hundreds of students -- for his generous spirit.


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