Bacterioplankton and bacteriobenthos in surface layer waters and sediments between the Sakhalin Island and the Eastern Asia in June 2006

This work presents results of a study of plankton and benthic microbiocenoses of the Amur River estuary. It is shown that distribution of total abundance and indicator groups of bacteriobenthos are characterized by stronger heterogeneity compared with bacterioplankton and that it depends on the Amur River runoff and bottom type. The river runoff helps by increasing overall bacterioplankton abundance in the near-mouth part of the estuary. Microorganisms utilizing low concentrations of organic matter (OM) play major role in processes of OM utilization in water and bottom sediments. Saprophytic bacteria play a significant role in OM utilization only in water at certain sampling sites in the Tatarsky Strait and Sakhalin Bay and in bottom sediments sampled in the mouth part of the estuary. Some parts of the estuary subjected to organic contamination are found according to microbiological characteristics. It is shown that fluctuation of salinity leads to change of the role of bacteria with different food demands in the microbial community.

Acoustic multi-frequency indicator of four major groups on a spatial grid in the Bay of Biscay

The first data set contains the mean and cofficient of variation (standard deviation divided by mean) of a multi-frequency indicator I derived from ER60 acoustic information collected at five frequencies (18, 38, 70, 120, and 200 kHz) in the Bay of Biscay in May of the years 2006, 2008, 2009 and 2010 (Pelgas surveys). The multi-frequency indicator was first calculated per voxel (20 m long × 5 m deep sampling unit) and then averaged on a spatial grid (approx. 20 nm × 20 nm) for five 5-m depth layers in the surface waters (10-15m, 15-20m, 20-25m, 25-30m below sea surface); there are missing values in particular in the shallowest layer. The second data set provides for each grid cell and depth layer the proportion of voxels for which the multi-frequency indicator I was indicative of a certain group of organisms. For this the following interpretation was used: I < 0.39 swim bladder fish or large gas bubbles, I = 0.39-0.58 small resonant bubbles present in gas bearing organisms such as larval fish and phytoplankton, I = 0.7-0.8 fluidlike zooplankton such as copepods and euphausiids, and I > 0.8 mackerel. These proportions can be interpreted as a relative abundance index for each of the four organism groups.