Characteristics of mesozooplankton sound-scattering layer in the Pacific Summer Water, Arctic Ocean

This study investigated the variations in the sound-scattering layer (SSL) that were reflected from the mesozooplankton communities around the Northwind Ridge in the western Arctic Ocean. A multi-frequency acoustic survey was conducted to reveal the SSL distribution dominated by Arctic copepods in the early summer of 2010. The SSL distribution was well correlated with the salinity, nutrients and chlorophyll a (chl-a) associated with the features of the Pacific Summer Water (PSW). The SSL was observed primarily in the uppermost 100 m of the PSW, which provided a desirable habitat for Arctic copepods due to high nutrients and phytoplankton biomass. The highest density SSL was observed in the eddy-like structure of the PSW, which is most likely because of the high nutrients and chl-a. High regional densities in the SSL indicated that Arctic copepods provide a large portion of the biomass and contribution to the food webs in the PSW, in the western Arctic Ocean.