Poster abstracts and manuscripts from the Third International ...

22
first two time points for each region. Power was calculated for
the different sampling frequencies and number of survey units and
tabulated.
Ribic, Christine, Heidi Lovett and Ginnie Gottshall
A Pilot Project for Detecting Trends in Marine Debris Along the
East Coast of the United States
Department of-the Interior, National Biological Survey,
Madison, Wisconsin, USA
The USEPA Office of Water has decided to implement pilotstudies
to detect changes in trends of litter in the aquatic environment
due to the implementation of legislation. The ideal question to
answer is, "Has the legislation reduced the amount of floating
litter in U.S. waters?" This question is probably not answerable
directly due to the problems of sampling in the aquatic,
environment. Therefore, the question was reformulated as, "What
is the trend in aquatic floating litter as reflected by the trend
in the amount of litter that is on the nation's lands adjacent to
waters of interest?,,
The approach used, here is to use indicator survey units, defined
as land areas adjacent to surface waters of interest that have
large amounts of litter on them, and sample these units over.
time.' For water quality trend surveys, one general approach is
to establish a few survey units and intensively sample the units
uniformly over time. The actual number of survey units is
usually dictated by economic considerations.
In this program, the suggested survey periodicity was once a
month for five years. Sites in New Jersey and Maryland were
considered. The Center for Marine Conservation (CMC) picked one
survey unit in New Jersey and one in Maryland and conducted
surveys approximately every 28 days (range 27-30 days for New
Jersey). The New Jersey survey site successfully completed a
year and a half of surveys. The Maryland site, during the first
survey year, was impacted by severe winter storms that washed the
beach away. The site was also used by nesting seabirds. This
resulted in noncomparability of data (due to the major changes in
beach structure) and missing data (due to the nesting birds).
The analysis presented here is an example of the types of
analyses that can be done with the data.
The data were rewritten into CMC general categories. We
considered total debris and total debris by source (ocean, land,
unknown). Ocean-source waste was divided into galley, operations
and commercial wastes categories. Land-source waste was divided
into sewage and medical wastes. Each survey was assigned to a
season (spring, summer, autumn or winter) using the usual