Man and the Last Great Wilderness: Human Impact on the Deep Sea

The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life – SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO2 and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO2 and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods

Oceanic biogeochemical controls on global dynamics of persistent organic pollutants.

Understanding and quantifying the global dynamics and sinks of persistent organic pollutants (POPs) is important to assess their environmental impact and fate. Air-surface exchange processes, where temperature plays a central role in controlling volatilization and deposition, are of key importance in controlling global POP dynamics. The present study is an assessment of the role of oceanic biogeochemical processes, notably phytoplankton uptake and vertical fluxes of particles, on the global dynamics of POPs. Field measurements of atmospheric polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and furans (PCDFs) are combined with remote sensing estimations of oceanic temperature, wind speed, and chlorophyll, to model the interactions between air−water exchange, phytoplankton uptake, and export of organic matter and POPs out of the mixed surface ocean layer. Deposition is enhanced in the mid-high latitudes and is driven by sinking marine particulate matter, rather than by a cold condensation effect. However, the relative contribution of the biological pump is a function of the physical-chemical properties of POPs. It is concluded that oceanic biogeochemical processes play a critical role in controlling the global dynamics and the ultimate sink of POPs

Polycyclic Aromatic Hydrocarbon Baselines in Gulf of Mexico Fishes

The lack of baseline data has hindered the assessment of impacts from large-scale oil spills throughout their history. Baseline data collected before an adverse event such as an oil spill are critical for quantifying impacts and understanding recovery rates to pre-spill levels. In the case of the two largest oil spills in the Gulf of Mexico (GoM), Deepwater Horizon and Ixtoc 1, the lack of comprehensive contaminant baselines limits our ability to project when the ecosystem will return to pre-spill conditions and assess the short- and long-term impacts of contamination on ecosystems. Beginning in 2011, we initiated comprehensive sampling in the GoM to develop broad-scale and Gulf-wide hydrocarbon contaminant baselines primarily targeting continental shelf fishes in the USA, Mexico, and Cuba. We also developed a time series of collections over 7 years from the region in which DWH occurred. In the event there is another oil spill in the GoM, the samples from these baselines will provide broad-scale but not installation-specific baseline information for the assessment of impact and recovery. This chapter provides a summary of historical sampling and current baseline data for pelagic, mesopelagic, and demersal fish in the GoM. Further, we outline the importance of ongoing and more specific collection of monitoring data for hydrocarbon pollution