Deep oceans massively under-explored

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A recent study conducted has concluded that the deep ocean - the largest biome by volume on earth - is poorly understood and vastly under-explored.

The study opens rather poignantly with the following: "The tragedy of studying biodiversity during an extinction crisis is that we are losing our subject matter faster than we are able to describe it.

"This is especially true in the marine environment where the need to value and conserve taxa and habitats that we know little about has been termed a paradox of marine conservation."

Despite substantial advances made by the likes of the Census for Marine Life in recording marine species, the pelagic ocean remains grossly under sampled. 

The research team, led by Dr Tom Webb, used data from the world’s largest holder of marine species distribution data, Ocean Biogeographic Information System (OBIS), to plot the locations of around 7 million recorded marine species occurrences to reach their conclusion.

Interestingly, the majority of occurrences were recorded from either the seabed, or from surface water and shallow areas of the ocean (sea bed less than 200 metres in depth). 

Abysall Plain

The study goes on to show that greater than 50% of the OBIS records are from the continental shelf, an area that only makes up 10% of the ocean. 

Conversely, only 10% of records are from the Abyssal Plain (4000m-6000m) that makes up about 50% of the ocean.

The report offers two possible reasons for the dearth of information from the deep ocean:  either that the area actually is low in biomass, or that it has been especially under-sampled – perhaps even a combination of the two. 

Belts

There is a long-held belief that life in the deep is concentrated to one of two “belts”, one belt near the seabed and the other near the surface. 

Such belief was first brought about by Charles Wyville Thomson, who led the Challenger Expedition in the 1870’s that effectively launched the discipline of deep-sea biology. 

It was Thomson’s belief that the area between the two belts, the deep pelagic, was “nearly or entirely absent” of larger marine animals.  However, recent evidence suggests that under sampling and net avoidance is more likely than an absence of animals.

For further information see the paper: Webb TJ, Vanden Berghe E, O'Dor R (2010) Biodiversity's Big Wet Secret: The Global Distribution of Marine Biological Records Reveals Chronic Under-Exploration of the Deep Pelagic Ocean. PLoS ONE 5(8): e10223. doi:10.1371/journal.pone.0010223