IMPACTS ON THE BENTHIC ENVIRONMENT 
Mining will have both direct and indirect effects 
on the sea bottom and associated organisms. With 
the hydraulic system, assuming a unit production of 
5,000 metric tons of dry nodules per day, 1.9 square 
kilometers per day of the seafloor will be mined. A 
much larger area (25 percent larger) will be required, 
however, because of unminable topography and areas 
of low nodule concentration. The mechanical system 
(continuous line bucket) will directly affect the sea- 
floor along a narrow swath parallel to the ship’s 
track." 
Dredging 
e An obvious direct impact on marine organisms 
will be the destruction of a large percentage of 
those in the path of the nodule retrieval mecha- 
nism. The significance of this impact will be de- 
termined by the extent of the ocean floor that is 
mined. If a large enough area is affected, it is pos- 
sible that species with slow reproductive cycles 
could be lost (some are thought to require 200 
years to reach maturity) from the community in 
the mined area or even become extinct. This im- 
pact could be partially mitigated if mining is 
strictly regulated so that intermediary patches are 
left intact between dredge tracts.12-118 
The value of protection of these deep-sea orga- 
nisms is not measured in economic terms or even 
in terms of their importance in the food web. 
Their value lies in the fact that they represent a. 
unique assemblage of relict and seldom seen fauna 
important to the understanding of evolutionary 
biology. Negligent extinction of these faunal com- 
ponents through our mining efforts would be inex-. 
cusable, and careful preventive measures must be 
taken. 
Benthic Discharge Plume 
In addition to the effect of the actual dredging, 
the benthic fauna will be affected by the release of 
particulates in the near-bottom water column as a 
result of washing. The hydraulic system will create a 
specific benthic discharge in the form of a plume con- 
taining resuspended bottom sediments, nodule frag- 
ments, interstitial water, and benthic biota. Impacts 
are as follows: 
e The principal direct effects of this discharge will 
result from the resuspension of particulates in the 
™ U.S. Department of Commerce, NOAA. Progress Repori— 
Deep Ocean Mining Environmental Study—Phase I, NOAA Tech- 
nical Memorandum ERL MESA-15, August 1976, 178 pp. 
*? Richard Frank. Deep Sea Mining and the Environment. 
American Society of International Law, Studies in Transnational 
Legal Policy No. 10, 1976, 54 pp. 
“3 National Academy of Sciences. Mining in the Outer Con- 
tinental Shelf and in the Deep Sea, Panel on Occupational 
Safety in Marine Mining, Marine Board, National Research 
Council. Washington, D.C., 1975, 119 pp. 
lower water column and their subsequent settle- 
ment. Unfortunately, the physical processes con- 
trolling the redistribution are not well understood. 
At least a portion of the particulate matter will 
likely remain in the lower column and may settle 
out many kilometers from the disturbance site. 
The extent of this redistribution is unknown. 
Localized sedimentation rate will certainly be one 
to several orders of magnitude higher than normal. 
We may, therefore, assume that many additional 
benthic organisms will die as a result. Some will be 
suffocated as a result of clogging of the respira- 
tory system, others will starve as a result of in- 
crease in sediment cover and their inability to bur- 
row to the surface. Many of the smaller fragile 
forms will be destroyed by even a thin layer of 
sediment (1 to 2 mm);14 
e Resuspension and resettling of bottom sediments 
could increase trace metal content of the sediment 
surface and adjacent water column. Direct effects 
will probably be negligible. Indirect effects, how- 
ever, could be significant. There is evidence in the 
literature to indicate that heavy metals accumulate 
in organisms at the various trophic levels. The 
long biological half-life and the high concentration 
factors found in many marine species suggest that 
food web magnification can occur. If this is the 
case, toxic effects on consumers could then result 
from feeding on organisms further down in the 
food web. 
e An additional potential effect is the transportation 
of spores or other dormant life forms by means of 
sediment resuspension. There is initial information 
on the possible occurrence of dormant photosyn- 
thetic organisms in deep-sea sediments 11°1?° and 
some evidence for activation of these organisms 
with surface exposure.1!7 The implication of this 
impact is little understood, but it is likely to be 
relatively insignificant. The survival success of 
these previously dormant species will depend 
largely upon their ability to compete with the 
already well-established species. It has been specu- 
lated that they could indeed outcompete the local 
populations to the detriment of the community and 
even that they may possess some harmful char- 
acteristics. Again, this seems unlikely; however, 
data should be generated concerning the behavioral 
nature of these long dormant forms both to in- 
crease our understanding of food web stability and 
to ensure that we avoid speculations characteristic 
441).S. Department of Commerce, op. cit. note 111. 
15T. C. Malone, et al. “The Possible Occurrence of Photo 
Synthetic Microorganisms in Deep Sea Sediments of the North 
Atlantic,” Journal of Phycology 9: 482-483, 1973. 
16 Op. cit., NAS. note 113. 
™7U.S. Department of the Interior, Draft EIS—Proposed 
Involvement in Law of the Sea Negotiations Governing the 
Mining of Deep Seabed Hard Mineral Resources Seaward of the 
Limits of National Jurisdiction, 1974. 
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