A belt transect setting strategy for mark-recapture experiments to evaluate the 1D diffusion coefficient of beached litter in the cross-shore direction

摘要

We propose a belt transect setting strategy for mark-recapture experiments (MREs) to evaluate the time-independent 1D diffusion coefficient (< D-p0 >) of marine litter in the cross-shore direction that determines the backwashing flux of the litter, based on two-year MREs for plastic floats (PFs) on Wadahama Beach, Nii-jima Island, Japan. When the alongshore width of the belt transect (L-t) was of the order of, or longer than, the length scale of wave-induced nearshore current circulation (L-c), the PFs were rarely transported alongshore across the selected transects prior to being backwashed offshore. Thus, the transect residence time became longer and showed a much weaker dependence on the transect position, in contrast to when L-t was even shorter than L-c. We therefore obtained the diffusion coefficients close to the value of (< D-p0 >) when we set L-t to the order of, or longer than, L-c. (C) 2016 Elsevier Ltd. All rights reserved.