MAC-EXP: Development of a pressurised sampling, experimentation and cultivation system for deep-sea sediments

Most deep-sea organisms live under high pressure in the so-called piezosphere (the volume of the deep-sea at > 1000 m of water depth or > 10MPa pressure) and depend on organic particles sinking down from the surface waters for food. The most abundant organisms by far in marine sediments are prokaryotes (bacteria and archaea), and the biomass of the bacteria and archaea is so great that they are thought to be the main agents of the remineralisation of organic matter, a process which releases nutrients back into the water column and is thus very important for ocean productivity and, for example, fisheries. But our knowledge of deep-sea prokaryote diversity and ecosystem function is scarce. With fishing, mining, oil and gas exploration increasingly taking place in deeper waters, we urgently need to improve our understanding of the functioning of deep-sea ecosystems in order to assess appropriately the societal and economic implications of such activities and impacts and to ensure adequate management of deep-sea biodiversity and natural resources for future generations.
Unfortunately, this is not easy: the main reasons for our limited knowledge of deep-sea biodiversity and ecosystem functioning lies in the combination of its inaccessibility with the sensitivity to depressurization of deep-sea organisms and deep-sea biogeochemical processes. Pressure has significant effects on, for example, bacterial physiology or growth rates, as well as many biogeochemical processes that microorganisms are involved in. In consequence, meaningful experimentation has to be carried out under in situ pressure, which results in major financial and technical constraints. Remotely Operated Vehicles allow us to conduct experimental research at the deep-sea floor, but although now possible, this is still very risky and resource-intensive, requiring sophisticated deep-sea ROVs, operated by large crews from large vessels (e.g. 11 technical staff accompany a deployment of the French deep-sea ROV VICTOR 6000; and a large research ship is needed to accommodate and deploy it), and to-date very few such systems are available. In addition, samples in most cases suffer depressurization upon retrieval. As many deep-sea microorgansims may only be culturable without depressurization, this may explain why less than 1 % of deep-sea prokaryotes can currently be cultured.
Here we propose to develop a flexible, cost-effective alternative to in situ experimentation: a pressure-coring, experimentation and cultivation system that enables studies of deep-sea prokaryote biodiversity and ecosystem functioning, under ambient or manipulated pressure, temperature and oxygen conditions from any medium sized ocean going research ship with coring capability. In addition, the constant high pressure chain from sampling to culture overcomes limitations of in situ experiments related to depressurisation.
This Multiple-Autoclave-Coring and Experimentation system (MAC-EXP) will provide the possibility to systematically test the influence of environmental parameters, such as pressure, oxygen availability or pH on deep-sea organisms and their biochemistry, as well as on rates and pathways of biogeochemical and geomicrobial processes. The system will also allow pioneering work in the field of marine biodiscovery: secondary metabolites from marine microorganisms are a rich source of chemical diversity and several marine-microbe derived compounds are now in clinical trials. Recent evidence shows that pressure-adapted bacteria from deep-sea sediments produce biologically active and unusual secondary metabolites. But no pressure-adapted bacterial species have ever been investigated for their secondary metabolites and the proposed pressurised sampling system provides the possibility to conduct such studies.

A. The MAC-EXP project sets out to develop techniques to retrieve pressurised cores from the deep sea and maintain them at sea floor pressures whilst on the surface to enable manipulative experimentation and cultivation. The proposal draws on expertise from the TU Berlin, Oceanlab and UoCardiff to develop a facility that the UK currently does not have. This pressurized sample manipulation facility will provide a real alternative to cost adverse in-situ sampling & manipulation techniques such as ROVs, manned submersibles and sophisticated Landers, while at the same time avoiding depressurisation between sampling, experimentation and cultivation.
This proposal will concentrate pressurized coring and manipulation expertise and facilities in the UK. We propose offering this facility to other users from both science and industry. Oceanlab has a successful business unit where industry are able to utilise spare capacity in Oceanlabs current suite of environmental testing equipment. The pressurized coring and manipulation facility could be added to this suite of equipment to allow science and industry easy access. Equally, this facility could be added to the marine equipment pool as a facility available to all UK science.
B. Our science plan, and future science that will be possible with the MAC-EXP system, is closely aligned with NERC's Biodiversity and Climate System themes. In particular, the results of this project and opportunities created by MAC-EXP will be of great interest to
1. Biogeochemists and microbial ecologists working on Earth system science, sedimentary systems, C and nutrient cycling and biodiversity and ecosystem functioning, and the main method to disseminate information to these groups will be via conference presentations and scientific publications.
2. Marine biodiscovery. Biodiscovery is the discovery of compounds from natural sources with biological applications, particularly novel biomedicines. Marine organisms produce a diverse array of metabolites with novel chemical structures and potent biological activities as well as other desirable properties. MAC-EXP will allow investigation of metabolites from piezophile organisms.
C. Equally this information will also be of great interest to scientists and managers involved with the prediction and mitigation of global climate change. Changes to ocean circulation are a likely consequence of climatic alterations and increased land run-off of terrestrial carbon and the spreading of hypoxia and oxygen minimum zones are likely effects of climate change. MAC-EXP will enable research that is particularly applicable to the management of future oceans. The Deep-sea frontiers Initiative (Cochonet et al 2007) and a recent UNEP/HERMES study (UNEP 2007) showed the urgency and the magnitude of the task of developing socio-economic and governance research for the deep-sea in support of ocean governance. The European consortium HERMIONE has a focus on human impacts on the deep-sea environment and the translation of scientific information into policy. UW is a PI in this consortium and we will ensure dissemination of our results to stakeholders via the science-policy interface developed in this project.
D. The deep sea is often at the forefront of the wider public's imagination and topics related to the deep-sea have proven to be very attractive to children of all ages in many Oceanlab outreach programs. While 'Archaea' or 'carbon cycling' are less eye-catching than for example bizarre-looking deep-sea fish, and therefore receive much less attention, sophisticated deep-sea technologies are attractive and we will use this to help us create awareness of the importance of the 'hidden' biodiversity in marine sediments by a). developing targeted display materials for museums; b). via the www for which Ocean lab has a state-of-the art website. c). via outreach activities such as TechFest.