Effects of water column processes on the use of sediment traps to measure zooplankton non-predatory mortality: a mathematical and empirical assessment

Zooplankton populations can suffer mass mortality due to non-predatory mortality (NPM) factors, and the resulting carcasses can be captured by sediment traps, or be removed by ingestion, turbulent mixing and microbial degradation in the water column. We presented mathematical formulations to calculate NPM from sediment trap data by accounting for carcass removal by processes in addition to sinking, and demonstrated their application in Lake Shira, Russia. The estimated NPM values were comparable to physiological death rates. Estimated ingestion by the amphipod Gammarus lacustris could account for the disappearance of carcasses above the traps. Wind-driven turbulence could extend the carcass exposure time to microbial degradation. Collectively, these water column processes facilitate the remineralization of carcasses in the water column, and diminish the carcass carbon flux to the benthos