资源环境科技发展态势分析平台

We demonstrate that signal spikes in optical backscatter measurements provide information on the diel vertical migration patterns of oceanic zooplankton. During nighttime, we observed high frequency spikes in particulate optical backscatter coincident with increased acoustic backscatter from vertically migrating zooplankton. We used our measurements to examine the spatial patterns and daily timing of zooplankton migrations across the eastern Subarctic Pacific Ocean, demonstrating coherence of diel vertical migrations with regional hydrographic features. Vertical zooplankton migration was consistently observed in oligotrophic offshore waters but less apparent in higher productivity waters over the continental shelf, where bottom depth, hydrographic fronts, and plankton abundance influenced apparent zooplankton distributions. Our results suggest that spikes in optical backscatter data, which are normally removed during data processing, can be more fully exploited to examine marine zooplankton dynamics from autonomous measurement systems.

Plain Language Summary Measurements of light scattering at the ocean's surface provide information about the abundance and species composition of microscopic algae that constitute the base of the marine food web. Here we show that high-frequency spikes in surface backscatter data, which are normally removed during data processing, can also provide a signal of marine zooplankton, the small animals that consume algae. We observed day/night patterns in backscatter attributable to the daily vertical migration of zooplankton, providing a novel approach to observing this important behavior. Across our study area in the Subarctic Pacific, a clear signature of nighttime migrations was evident in open ocean waters, but not in coastal waters over the continental shelf, where spatial variability in seawater characteristics and phytoplankton abundance influenced apparent zooplankton vertical migrations. Water depth and water clarity were also strong predictors of vertical migration patterns. Building on our results, we propose an approach to facilitate improved analysis of zooplankton abundance from optical backscatter measurements and suggest that reexamination of previous data sets could reveal large-scale patterns of marine zooplankton vertical migrations.