The oceans cover 71% of our planet, with over half with a depth greater than 3000 m.
Although our knowledge is still very limited, we know that the deep ocean contains a diversity of habitats and ecosystems, supports high biodiversity, and harbors important biological and mineral resources. Human activities are, however increasingly affecting deep-sea habitats, resulting in the potential for biodiversity loss and, with this, the loss of many goods and services provided by deep-sea ecosystems.
These conclusions come from an international study conducted during the Census of Marine Life project SYNDEEP (Towards a First Global Synthesis of Biodiversity, Biogeography, and Ecosystem Function in the Deep Sea). The authors, over 20 deep-sea experts, conducted a semi-quantitative analysis of the most important anthropogenic impacts that affect deep-sea habitats at the global scale in the past, present and future scenarios. The impacts were grouped in three major categories: waste and litter dumping, resource exploitation, and climate change. The authors identified which deep-sea habitats are at highest risk in the short and mid-term, as well as what will be the main anthropogenic impacts affecting these areas, in a paper published in PLoS ONE on Aug. 1, 2011.
During the Census of Marine Life program, a ten-year program that investigated diversity, distribution, and abundance of life in the global ocean and which ended inn 2010, researchers from its five deep-sea projects sampled and studied the different deep-sea habitats around the globe. The analysis of the current article is based on the results of the Census of Marine Life projects, synthesized during SYNDEEP, and also from data published previously in the scientific literature.
In the past, the main human impact affecting deep-sea ecosystems was the dumping or disposal of litter into the oceans. These activities were banned in 1972, but their consequences are still present today, together with the continuing illegal disposal of litter from ships and the arrival of litter and contaminants from coastal areas and river discharges. In particular, the accumulation of plastics on the deep seafloor, which degrade into microplastics, called mermaid tears, that can be ingested by the fauna, has consequences still unknown but predicted to be important. Moreover, there is increasing evidence of the accumulation of chemical pollutants of industrial origin, such as mercury, lead and persistent organic pollutants (e.g. dioxins, PCBs) in the sediment and fauna, including in species of commercial interest.
Currently, and because of the reduction of resources on land and in shallow waters, the largest direct impacts come from the exploitation of deep-sea resources and, in particular, from fisheries. In the future, however, the authors of this study predict that the most pervasive impacts may come from ocean acidification and climate change, which act at the global scale and can have important effects from surface waters to the abyssal seafloor. Some of these effects include an increase in water temperature that can cause important changes in stratification of the water column, accumulation of nutrients, and oceanic water circulation with corresponding alteration of hypoxia and faunal community structure.
Most importantly, the authors predict synergies amongst certain anthropogenic impacts and, in particular, between climate change and activities such as resource exploitation, wherein combined impacts may be particularly deleterious to deep-sea faunal communities.
- Climate Change to Have Biggest Impact on Deep Sea (livescience.com)
- Deep-Sea Exploration is the Next Big Thing For Billionaires | 80beats (blogs.discovermagazine.com)