Poster abstracts and manuscripts from the Third International ...

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of the Mackinac Straits in northern Lake Michigan. It is about
9.6 kilometers west of the Mackinac Bridge, 3.2 kilometers off
the coast of Michigan's upper peninsula, and approximately 0.8
kilometer north of the Lake Michigan-Lake Huron shipping lanes.
The island has been essentially uninhabited since the early
1920's. The shallow water and limestone reefs that surround most
of the island, together with unpredictable and sometimes severe
weather and lake conditions have, in general, limited access to
the island.
The clean-up of the beach on this inland was considered of
interest since: (1) this clean-up is believed to be the first on
this privately owned island,‘ and (2) the close proximity of the
island to the Lake Michigan-Lake Huron shipping lanes. It was
theorized that the items found on the beach would reflect waterborne
debris deposited, over many decades from both remote shore
dumping and ship litter.
For the collection, the beach zone was divided into 100 meter
sections and three-person crews collected, sorted and recorded
the nature of the debris. A data sheet supplied by the Inland
Seas Educational Association of Suttons Bay, Michigan was used to
count and classify the items. Only items roughly the size of a
soft-drink can or larger were classified. Approximately 350
items/kilometer were collected from the beach zone; Some items
that had been on the beach for many years had disintegrated into
small pieces or did so when handled. It is estimated that if
these items were included in the clean-up that approximately 750
- 1,000 items/kilometer would have been collected. The
distribution of collected items was 46% plastic, 16% glass, 13%
metal, 11% Styrofoam, 8% paper, 3% wood, 2% rubber, and 1% cloth.
Borne by the prevailing current of Lake Michigan into Lake Huron,
the variety of items collected included: syringes and test tubes,
most likely from a recorded illegal dumping of medical waste in
Lake Michigan near Holland, Michigan, in 1989; a Michigan
Department of Natural Resources sign from either Wagauschance
Point or North Manitou Island warning visitors not to enter a
Piping Plover nesting area; the top of a telephone pole;
balloons; plastic containers; Styrofoam; and, a freon recharging
container. Many of the metal cans and drums were heavily rusted
and disintegrated from exposure including one bucket with a 15
centimeter tree growing through the middle of it.
Evidence of ship littering included: fish net remnants; floats;
numerous unbroken light bulbs; a large cabled industrial tire
that probably served as a fender on a barge or freighter; and,
soft-drink cans printed in Dutch and Japanese. Two items gave
indication that some of the debris was deposited from a counter
current in the Straits. One was a bottle containing a note dated
October, 4, 1974, and the second was a wooden traffic control