A System for Retrieval and Incubation of Benthic Sediment Cores at In Situ Ambient Pressure and under Controlled or Manipulated Environmental Conditions

Abstract

The investigation of benthic biodiversity and biogeochemical processes in the deep sea is complicated by the need to conduct experiments at in situ pressures. Recovery of sediment samples to the surface without maintaining full-depth ambient pressure may damage the organisms that are of interest or cause physiological changes that could influence the processes being studied. It is possible to carry out in situ experiments using remotely operated vehicles (ROVs) or lander systems. However, the costs and complexity of ROV operations are significant and, for both ROVs and landers, the complexity and repeatability of the experiments are subject to the limitations imposed by these platforms. A system is described—the Multi-Autoclave Corer Experiment (MAC-EXP)—that has been developed with the aim of offering a new experimental approach to investigators. The MAC-EXP system is designed to retrieve sediment cores from depths down to 3500 m and to seal them into pressure chambers before being recovered so that they are maintained at their normal ambient pressure. After recovery the core chambers can be connected to a laboratory incubation system that allows for experimentation on the sediment without loss of pressure and under controlled conditions of temperature and oxygen concentration. The system is relatively low cost when compared to ROV systems and can be deployed using methods and equipment similar to those used for routine deployments of small unpressurized multicorers. The results of sea trials are detailed.

Pressure and temperature effects on deep‐sea hydrocarbon‐degrading microbial communities in subarctic sediments

“…Whether obligate barophilic bacteria constituted a large fraction of the HDB community or significantly affected the rate of hydrocarbon degradation cannot be evaluated at this stage. No interruption of pressure conditions between sampling and experimentation would be preferable in this case, but, while this has been achieved successfully for water column samples (Tamburini et al, 2002), it remains challenging for sediments (Jackson et al, 2017). Council (grant reference HR09011) and contributing institutions.…”

“…The pouches were placed and incubated for six months at two Ps (0.1 and 30 MPa) and two Ts (5 and 20°C), in triplicate, in cylindrical pressure core‐shaped chambers (internal length = 500 mm, internal diameter = 90 mm, pressurized with a manual lever water pump to 30 MPa) and polyethylene boxes for samples at 30 and 0.1 MPa, respectively. Jackson, Witte, Chalmers, Anders, and Parkes () provide a detailed description of the pressure chamber design. At the end of the incubation, the entire content of each pouch was emptied into 125‐ml glass vials.…”

The influence of coring method on the preservation of sedimentary and biogeochemical features when sampling soft‐bottom, shallow coastal environments

“…Irrespective of those limits, diving time, and thus the number of cores per diving operation, may become reduced at greater depths because of increased decompression obligations for the divers and so the maximum depth for optimal sampling may be shallower than 30 m. That said, a number of studies (Dias et al 2008;Felden et al 2010;Van Gaever et al 2010;Jackson et al 2017), have used push cores mounted to remotely operated vehicles (ROVs) to sample sediments at depths in excess of a thousand meters.…”

“…The drawbacks of SCUBA are that most science‐based diving is limited to relatively shallow waters (< 50 m) either through national occupational diving regulations or because of the physiological challenges of working at greater depths. Irrespective of those limits, diving time, and thus the number of cores per diving operation, may become reduced at greater depths because of increased decompression obligations for the divers and so the maximum depth for optimal sampling may be shallower than 30 m. That said, a number of studies (Dias et al ; Felden et al ; Van Gaever et al ; Jackson et al ), have used push cores mounted to remotely operated vehicles (ROVs) to sample sediments at depths in excess of a thousand meters.…”

Measuring the biological impact of drilling waste on the deep seafloor: An experimental challenge

“…The more recently developed lander DOBS (Deep Ocean Benthic Sampler) is able to obtain core sediment samples from the deep ocean without microbial contamination and under in-situ pressure and temperature conditions until retrieval by the ship. Another system called the MAC-EXP system was designed by Jackson et al (2017) for the retrieval and incubation of benthic sediments under in-situ pressure and temperature conditions and in controlled or manipulated environmental conditions. This system is able to sample down to 3500 m and to incubate sediments on-board without decompression.…”