How we count counts: Examining influences on detection during shoreline surveys of marine debris.

Shoreline surveys are a common approach for documenting loads of marine macrodebris (≥ 2.5 cm). When surveys are conducted repeatedly over time and space, patterns in source, abundance, geographic distribution, and composition can be detected. Yet to realize their full potential, monitoring programs that rely on surveys must grapple with high variability in debris abundance, and appropriately manage uncertainty when reporting estimates of debris quantity. A potentially important source of bias in estimating debris loads from shoreline monitoring datasets is variability in debris detection rates. With this in mind, we conducted field experiments using common strip-transect marine debris survey protocols, designed to test detection of macrodebris. We quantified how protocol, shoreline, and debris characteristics influence the detectability of marine macrodebris. Detection rates varied according to debris distance from observer (0-5 m), number of observers, debris characteristics (size, color), and shoreline substrate. Our results highlight considerations for monitoring program design. Comparisons across datasets should be approached cautiously given differences in survey protocols and sources of bias that may affect debris density estimates should be quantified and addressed. We hope these results will inform marine debris monitoring efforts that are optimized for intended data use and impact.

Walking the talk: The responsibility of the scientific community for mitigating conference-generated waste.

An estimated 19-23 million metric tons of global plastic waste reportedly entered aquatic environments in 2016 with mounting evidence that plastic marine debris causes ecological effects across all levels of biological organization in aquatic systems. Scientific conferences generate opportunities for waste through food and beverage services, giveaways, marketing and registration materials, poster and trade exhibits, attendee travel, lodging services, and local transportation. Zero waste measures instituted at the Sixth International Marine Debris Conference resulted in the avoidance of 76,300 single-use items. Zero waste is a process defined by a spectrum of actions ranging from no reduction whatsoever to generation of absolutely no waste. Achieving 100% zero waste is very difficult. Deciding where on the spectrum you wish to land and being comfortable with that target is paramount for event planning. Planning for reduced waste takes time, funding, and determination, but environmentally-themed organizations have a responsibility to lead by example.