current plumes could therefore interfere with 
migrating fish. The degree of impact will depend 
on the size of the plume and its duration. It should 
be noted that tuna are characteristic of clear 
water and are seldom found under turbid condi- 
tions.'**:'*°180° This could, therefore, indicate a 
possible effect on the efficiency of longline fishing, 
although the likely extent is not known at this time. 
e Highly mobile fish should, for the most part, be 
able to avoid high turbidity areas unless they are 
extremely widespread. The result would be indi- 
vidual deaths from respiratory clogging and inter- 
ference with feeding behavior. The significance of 
this impact is unknown, but the effects will likely 
be short term and localized. 
e There will also be possible effects from subsurface 
turbidity plumes, which may form in association 
with the pyncocline. The impacts in this instance 
would involve deeper epipelagic fish including the 
tuna taken by longlining down to 200 meters. 
Mobile epipelagic fish would move away from the 
layers with little mortality. Vertically migrating 
mesopelagic, fish will encounter these turbidity 
layers and may not pass through them in which 
case they would tend to move out of the area of 
their occurrence. The presence of these turbid 
layers will result in some mortality, but the overall 
effect on populations and community structure is 
unknown. 
e Both benthic and pelagic filter feeding organisms 
will ingest sediment particles and incorporate them 
into fecal pellets. It is not known to what extent 
this will be beneficial in clearing the water and in- 
creasing settling rates minimizing impacts on other 
organisms, nor is it known what effects, if any, this 
will have on the food web. It is, however, another 
avenue into the system for toxic substances. 
e Increased sediment will provide additional sub- 
strata for bacterial growth that could then use the 
dissolved organic matter in seawater. Studies 
are underway (DOMES) to investigate bacterial 
growth on the particles using dissolved organic 
matter. If bacterial growth resulted in greater use 
of the dissolved organic matter, this, in combina- 
tion with discharge of bottom water in the lower 
dissolved organic matter concentrations, could be- 
come limiting. Whether or not this is a potential 
problem is little understood, and opinion is divided. 
The studies should provide some insight. 
The above has been a description of the qualita- 
SH. Yabe, Y. Yabuta, and S. Ueganagi. “Comparative Dis- 
tribution of Eggs, Larva, and Adults in Relation to Biotic and 
Abiotic Environmental Factors, FAO Fish Report 6(3):979-1009, 
1963. 
9G. W. Bane. The Distribution of Abundance of Tunas and 
Tuna Bait Fishes in the Gulf of Guines. Thesis: Cornell Univer- 
sity, Ithaca, N.Y., 1961, 119 pp. 
%°G. I. Murphy. “Effect of Water Clarity on Albacore 
Catches,” Limnology and Oceanography 4:86-93, 1959. 
tive effects on benthic and pelgaic biota as a result 
of deep-sea mining. Our ability to assess impacts will 
improve as additional data from the DOMES effort 
become available. It should be emphasized that the 
value of biological information does not lie in the 
ability to say “some organisms will die as a result of 
these activities.” The value to the decision maker lies 
in the ability to provide an assessment of the signifi- 
cance of this destruction to the long-term health of 
the ecosystem. 
It is likely that the most significant unanswered 
questions center around the effects of the resus- 
pended sediment in the surface plumes at the pyc- 
nocline and in the benthic plume. 
IMPACTS OF PROCESSING 
Little or no information is available on the poten- 
tial environmental effects associated with transpor- 
tation and processing of manganese nodules. In view 
of this, and to complement the DOMES at-sea re- 
search, NOAA has contracted for studies to char- 
acterize possible onshore and offshore processing 
methods and likely transportation and waste disposal 
activities. These descriptive works were published 
in August 1977.'*! Followup phases of the NOAA 
program will use data from these reports to analyze 
potential environmental impacts. 
Impacts from land transportation will depend 
upon the method used. Potential modes include the 
haul system, conveyor, slurry pipeline, and trucking. 
Resulting impacts will likely be slight, barring acci- 
dents. The major environmental problems will cen- 
ter around waste treatment and disposal. The largest 
portion of mineral process wastes consist of finely 
ground rock slurried with liquid waste (tailings). Six 
alternative disposal methods have been described.**" 
Of these, three are felt to be the most likely for 
first-generation activities. These are disposal in a 
landfill, disposal in a conventional slurry tailings dis- 
posal system, and disposal by deep-ocean dumping. 
Careful impact evaluation will have to be done on all 
viable alternatives in order to ensure selection of an 
environmentally sound method and strict environ- 
mental and safety regulation. 
At-Sea Processing 
Though indications are that first-generation opera- 
tions will use onshore processing, the possibility 
still exists for these activities to take place at sea. 
There are three general options for processing at 
sea: 
® Physical benefication. 
e Partial processing to produce an intermediate 
product, and 
e Full at-sea treatment to finished products. 
1 U.S. Department of Commerce, op. cit. note 111. 
42 U.§. Department of Commerce, op. cit. note 111. 
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