Thread by @DrCraigMc

The Vast Majority of the Deep-Sea Remains Completely Unexplored: A Thread 1/n

Although the earliest interest and sampling in the deep sea occurred in the late 1800’s, a majority of deep-sea exploration did not occur until after the 1960’s. 2/n

The current amount of sampling and exploration of this great environment is without precedent. Despite this, new species and new habitats are constantly being found 3/n

Take the Yeti Crab. Only discovered in 2005. mbari.org/discovery-of-y… 4/n

Hydrothermal vents were not discovered until 1976. 5/n

So how much of the deep sea has actually been explored or sampled? This is indeed a tough question to answer. 6/n

To derive an exact answer we would have to know of every single sample of every deep-sea expedition taken plus all the submersible and ROV dives and how much area they have covered. Of course this is extremely unreasonable… 7/n

but let’s go for an exercise in estimation…. 8/n

All estimates here will be estimates and approximations…so I don’t want to hear in any nit picking. 9/n

Let’t begin with ROVs and Sumbersible assume

Total Number of ROVS and Submersibles 20
Total Number of Operational Years 30
Total Number of Dives Per Day 1
Total Number of Lifetime Dives 153600

Yeilds Total Area Covered by ROV and Submersibles (km2) 1536 11/n

Trawls and Sledges
Average Trawl Distance (km) 1
Average Trawl Opening (m) 5
Total Area Sampled Per Trawl (km2) 0.005
Number of Total Trawls 20000
Total Area Covered by Trawls and Sledges 100 km2 12/n

Push Cores
Core Size (m2) 1
Total Number of Cores 20000
Total Area Covered by Cores (km2) 0.02

Benthic Landers
Total Number of Benthic Landers 20
Total Visual Field (km2) 1
Total Area Covered by Landers (km2) 20. 14/n

So for the final estimate this would give us

Total Area of Deep Sea Sampled (km2) 1656.02
Earths Surface Area (km2) 150,000,000
Percentage of Surface Covered by Deep Sea 70.8%
Area of Deep Sea (km2) 106,200,000
Percentage of Deep Sea Area Covered 0.0016%

The above estimate is likely to be unreasonably high for several reasons. 16/n

The assumption that all the ROV’s/submersibles dive every day is unreasonable and does not take into account downtime for travel to sampling sites or maintenance. 17/n

Likewise, although the total number of ROV’s/submersibles is near the current total estimate not all of these have been in operation since 1975, although the Alvin was commissioned in 1964. 18/n

I also feel that the total distance covered per dive is high, especially when dives visit specific features such as hydrothermal vents or methane seeps. 19/n

Perhaps more importantly, the assumption that each of the above samples/dives were taken in a unique location is unlikely has ROV’s/submersibles dives frequently return to specific sites. 20/n

I can adjust these parameters (reduce the operational years to 20, dives occur every other day, and limit travel distance to 0.75km) the estimate falls to 504.03 km2 or 0.0005% of the deep-sea floor. 21/n

In addition, the trawl distance, average trawl opening, total number of trawls and cores, and field of few for the benthic landers are likely to be high as well. 22/n

Of course this depends on what we mean by “explored”, more specifically at what level of detail. As a kind of straw man example – how much of the deep sea has been sounded for depth at a 100 square meter level. 23/n

Alsot how much of an area can we characterize with a single sample? The observation window if you will. If for example, a box core can adequately characterizes the organisms in 100m2 then this estimate goes up. 24/n

Also if we think of the 1x1 km mapping of the seafloor then exploration takes another meaning 25/n

So Tl;dr only about 0.0016% of the #deepsea floor has been truly explored for life