Poster abstracts and manuscripts from the Third International ...

13
SESSION I POSTERS
Amounts, Types and Distribution of Marine Debris
Amos, Anthony F., Andrea Wickham, Charles Rowe, and Lynn Amos
An Evaluation of Volunteer Beach-Cleaning and Data-Recording
Methods
University of Texas Marine Sciences Institute, Port Aransas,
Texas, USA
The National Beach Cleanups, started in 1987 by the Center for
Marine Conservation (CMC), have generated much public interest,
and thousands of volunteers now participate in the twice-a-year
event. Volunteers both clean beaches and record their findings
on data sheets. The data are then compiled and published
annually by CMC. There is no claim by the organizers that the
results are statistically rigorous, but the number of "tons of
trash" collected is widely reported in the media. A considerable
database has now been amassed and, somewhat like the annual
Audubon Christmas Bird Count, has its detractors and supporters
as a means of assessing trends.
We have done several experiments in association with the Beach
Cleanups. These include counts of marine debris on beaches
immediately prior to, and then after, beach-cleaning by a group
of volunteers. In particular, we made a complete examination of
the contents of the bags of collected trash to compare our
findings with the data recorded on the data sheets. To avoid
bias, in each of the experiments the volunteers were not aware
while collecting and recording that the results would be checked.
One hundred twenty-seven (127) bags of trash were collected by 53
volunteers on San Jose Island, Texas. The beach is inaccessible,
by land and is not cleaned by any municipality. All bags were
returned to the mainland by boat and thence to our facility. It
took us a week to empty, classify, weigh and describe the 2,100
pounds of material collected (we worked in "English Units" to be
compatible with the units used by CMC). Sand accounted for 192
pounds of the overall weight. Mean weight of a bag was 13.5
pounds with a standard deviation of 17.2. In general, volunteers
under-counted by 50%. They were much closer on readily,
identifiable items even though some of the items were quite small
and numerous. For example, the counts were very close on onegallon
milk jugs, cigarette lighters, 6-pack yokes, straws,
Styrofoam cups, light bulbs, food cans and paper cups. Big
discrepancies were found in plastic bags, rope and, especially,
beverage cans. Few errors were found in checking the totalling
on the data sheets, but some important items were not entered
accurately (e.g., total number of bags). We discuss the