Hydromedusae are diverse zooplankton that sometimes have great impacts on aquatic ecosystems. We investigated the seasonal occurrences and assemblage structure of hydromedusae in the offshore area of Sagami Bay, central Japan. Throughout the study, 33 holoplanktonic and 9 meroplanktonic hydromedusae species were collected. Unlike the nearshore hydromedusan assemblage, low species richness of meroplanktonic hydromedusae was a c...

We studied seasonal variations of the mesozooplankton swimmer community collected by a sediment trap moored at 873 m in the Kuroshio–Oyashio Transition region off the east coast of Japan from 5 August 2011 to 23 June 2013, with sampling bottles rotating at 26-day intervals. The total flux of mesozooplankton swimmers varied between 0 and 11.1 individuals m –2 d –1 , with a mean of 3.1 individuals m –2 d –1 during the sampling p...

The heterotrophic prokaryotic carbon demand (PCD) in the ocean's interior often substantially exceeds (by up to two orders of magnitude) the amount of organic carbon supplied by sinking particulate organic carbon (POC). A hypothesis to explain this carbon imbalance proposes that some non‐steady‐state processes have not been considered in previous studies based on snapshot data. To test this hypothesis, we collected time‐series...

The dry mass of zooplankton and backscatter from an acoustic Doppler current profiler (ADCP) used in Sagami Bay, Japan, from 9 to 13 April 2005 were well correlated (correlation coefficient = 0.72, root mean square dry weight = 2.5 mg m −3 ). The horizontal current field and zooplankton distribution were estimated from shipboard ADCP data. Although sea surface temperature and chlorophyll a concentration observed by satellite w...