The benthic boundary layer is a region often perceived to be high in faunal abundance and biomass. In this study, we investigated the distribution of near seafloor bioluminescent zooplankton (BL), macrozooplankton (>1. cm) and macroparticles (>430. μm) at the Northern Mid-Atlantic Ridge at ca. 2500. m depth.At sites south of 52°N, the Charlie Gibbs Fracture Zone, BL density increased weakly towards the seafloor. This trend was driven by small bioluminescent crustaceans, comprising ca. 90% of the total BL density. Macroparticle density was coherent with BL density, exhibiting a small increase towards the seafloor. Appendicularians (animals as well as occupied and discarded houses) were the most abundant macrozooplankton, and the only group to show a significant increase in density towards the seafloor. The absence of pronounced increases in BL and macroparticle density, and no increase in macrozooplankton (except appendicularians), towards the seafloor do not support the conventional view of high concentrations of particulate organic matter and zooplankton biomass in the benthic boundary layer relative to overlying waters.
|Number of pages
|Deep Sea Research Part I: Oceanographic Research Papers
|Published - 1 Apr 2015
We thank the captain, crew and company of the RRS James Cook, cruises JC011 and JC048 and the ISIS ROV team at the National Oceanography Centre, Southampton, UK. This work was supported by the NERC Consortium Grant ECOMAR (Ecosystem of the Mid-Atlantic Ridge at the SubPolar Front and Charlie Gibbs Fracture Zone (Grant no. NE/C512961/1). J. Craig was funded by UK NERC studentship (NE/F012020/1).
- Benthic boundary layer
- Mid-Atlantic ridge