Peter G. Ryan, Annerie Lamprecht, Debbie Swanepoel, Coleen L. Moloney,
The effect of fine-scale sampling frequency on estimates of beach litter
accumulation, Marine Pollution Bulletin, Available online 16 September
2014, ISSN 0025-326X, http://dx.doi.org/10.1016/j.marpolbul.2014.08.036.
(http://www.sciencedirect.com/science/article/pii/S0025326X14005888)
Abstract: The effect of sampling frequency on estimates of the rate of
litter accumulation was determined for two South African sandy beaches.
After initial cleaning, all manufactured items >10 mm diameter were
collected in alternating bouts of daily or weekly cleanups. Daily
sampling collected 2.5 (range 2.1?3.4) times more litter items than
weekly samples and 1.7 (1.3?2.3) times more litter by mass. Low density
items such as foamed polystyrene showed a greater differential (4?5
times more items from daily sampling), presumably due to faster turnover
of lightweight litter items. Variation in weekly samples was not
consistently less than daily estimates, suggesting that less frequent
samples only partly integrate short-term fluctuations in litter
dynamics. Researchers using beach accumulation data to infer trends in
nearshore marine litter, or to assess the efficacy of litter mitigation
measures, need to ensure consistency in sampling frequency.
Keywords: Stranded debris; Plastics; Sample rate; Accumulation;
Meta-analyses; South Africa