Spatial and temporal variations in deep-sea meiofauna assemblages in the Marginal Ice Zone of the Arctic Ocean

In order to understand the response of the deep-sea meiobenthos to a highly varying, ice-edge-related input of phytodetritus, we investigated the abundance and composition of the meiobenthos at the arctic long-term deep-sea station HAUSGARTEN (79 degrees N, 4 degrees E) along a bathymetric transect (1200-5500 m water depth) over 5 consecutive years (from 2000 to 2004) in relation to changes in environmental conditions. Results showed high sediment-bound pigment concentrations (chlorophyll a and degradation products) ranging from 4.5 to 41.6 mu g/cm(3), and coinciding high meiobenthic densities ranging from 149 +/- 3 to 3409 +/- 525 ind/10cm(2). Nematodes dominated the metazoan meiofaunal communities at every depth and time (85-99% of total meiofauna abundance), followed by harpacticoid copepods (0-4.6% of total meiofauna abundance). The expected pattern of gradually decreasing meiobenthic densities with increasing water depth was not confirmed. Instead, the bathymetric transect could be subdivided into a shallow area with equally high nematode and copepod densities from 1000 to 2000 in water depth (means: 2259 +/- 157 Nematoda/10cm(2), and 50 +/- 4 Copepoda/10cm(2)), and a deeper area from 3000 to 5500 m water depth with similar low nematode and copepod densities (means: 595 +/- 52 Nematoda/10cm(2), and 11 +/- 2 Copepoda/10cm(2)). Depth-related investigations on the meiobenthos at the HAUSGARTEN site showed a significant correlation between meiobenthos densities, microbial exo-enzymatic activity (esterase turnover) and phytodetrital food availability (chlorophyll a and phaeophytines). In time-series investigations, our data showed inter-annual variations in meiofauna abundance. However, no consistent relationship between nematode and copepod densities, and measures for organic matter input were found. (c) 2006 Elsevier Ltd. All rights reserved.