This report is an introduction to what I've slowly pieced together about the ecosystem found at Avon Point. I have no formal training in biological research and for the most part have had to stumble through the learning process on my own. The only two researchers to have reached out to be of assistance (and that assistance has now faded into many years ago) are Dr. Stansberry and Dr. Beeton, both who I am indebted to for their kindness.

The reef was formed by the collapse of the shore's shale cliffs into the Lake. Over these fallen cliffs have washed rocks left by the glacier that gave the Lake its birth. Winding through the heart of the reef is an old stream bed that has cut into the Lake's floor. Surrounding the reef area is almost perfectly flat plains of blue clay. The reef lies on a flat ridge that surrounds the lip of the Central Basin of the Lake. The Lake's bottom drops off quickly to a depth of 10 to 15 feet and holds this depth for more than a mile out. The reef has an eerie beauty. When diving I am able to view the reef as a bird in flight would view the land below it. Hovering over the tilted shale walls and cleaved blocks I see them not as small ridges and valleys, but rather they appear as vast western landscape seen from the view of a buzzard soaring over a land draped in a perpetual twilight of blue and green. Scattered amid these ridges and valley are shale blocks cleaved along straight lines that give the appearance of having been the works of masons. They are like ancient fallen temples surrounded by a sacred sleeping blue. 

There are two major forms of plant life living on the Lake's bottom; the laison and the long stalk algae Cladophora . The above photo is of the Cladophora growing on the rocks in summer. The laison is a complex ecosystem that grows on the rocks upper surfaces. The laison is formed by diatom alga that, after settling on rocks, secretes a gel that not only secures it to the rock's surface but also begins to act as a trap collecting sediment as the sediment filters down from the water. The laison varies in thickness from .25 mm to 2 mm. in thickness and becomes the home to numerous small crustaceans, annelids, nematodes, insects and rotifers.

Below is a photo of the laison completely covering a rock and all the life on it. Below the laison are zebra mussels that do not seem to be affected by being grown over. The cladophora algae are also grown over which is why it appears to look stick like. I can't tell whether the algae are able to live under this laison growth or not. The laison dies out over the winter. In the spring when I first begin diving the rocks are completely bare of all larger life forms except Zebra mussels. I have gotten so use to viewing the world under a microscope that I had better make clear that when I talk of a large life form I thinking of living things larger than 1 mm. Usually the cladophora is the first to dominate the rocks but as the spring comes to a close and summer begins the laison begins a relentless march covering everything on rocks that lie in suitable areas. 

The reef begins where Heider ditch runs into the Lake, almost directly in line with the boat launch pier. To the West is a vast expanse of blue clay, which has occasional large boulders resting on the flats, and a few small areas of rocks. To the east is the shale ridge. Actually there appears to be either two ridges or perhaps only one that is shaped like a horseshoe with the open end facing west. On leaving shore, once past the jetties, the bottom is of clay. Between fifty and one hundred yards out the reef begins. This reef was apparently formed by the collapse of the shale cliff. To the east, Avon Point extends out as a peninsula, but in the past the shore to the west of the Point probably lied as far out as the Point does today. The collapsed remnants of these cliffs are what make up the near shore reef.

Below, a view of Avon Point 

The picture below is of the boundary area between the reef and the clay flats. The rocks of the reef on the right side of the photo are here completely covered by Zebra mussels. This density thickness of mussels is highly variable but easily 50 to 75 percent of the reef area is free of mussels. Moving from the clay flats to the reef is analogous to moving from a desert ecosystem to a forest. What makes the reef so much richer in the number of animals and the number of species is both the numerous different types of habitats it provide and the stability of the reef itself. Avon Point is an unprotected shore that faces one of the longest fetches of the Lake. A fetch is the distance the wind blows over open water without meeting an obstruction and the Northeast fetch is about 80 miles long. The longer the fetch is the longer a waves length can be. And the longer the wave the greater the effect it has on the ecosystem. If a wavelength, that is the distance from the crest of one wave to the crest of the next one is 20 feet than the wave will start pulling on the bottom when the water's depth is ten feet. I have been on the reefs bottom several times when large waves were running overhead. The current was so strong that I had to grab on to large rocks to be kept from being swept away and all around me I could here the rocks banging against each other. Any animals on these smaller rocks would be extremely lucky not to be crushed by the rocks banging against each other. 

Over the years both ecosystems, the clay flats and the reef have been subject to constant change, first the coming of the Zebra mussels and most recently the arrival of the rounded gobies have vastly altered the ecosystems Anyone who has lived at Avon Point for a long time can remember finding large clams washed up on the shore after every storm. These clams, there were five species of them, have all disappeared, killed by the Zebra mussels. When I first started diving here it was not unusual to glide over thousands of snails of the species Pleurocera acuta. These snails are all gone now. They, as well as four other species of snails have been driven to all but extinction in this area. I really don't know what has caused their disappearance. Other changes are only visible on the Lake's bottom such as the increase in the number of sponges, the increase in bryozoans colonies, the disappearance of planarians and on and on. In the water itself the animals that make up the zooplankton have seen their numbers diminish year after year. As I said at the beginning of these notes I can't say why these things are happening, only that they are.

THE CLAY FLATS

The clay flats break up in many areas into what almost appears to be cut tiles with all of the life clinging to the areas formed by the gaps between these tiles. 

The area in the gaps between the clay are in above picture are thousands of Zebra mussels.