of the andromeda syndrome. Assuming no harmful 
competition, a new phytoplankton bloom could 
contribute to reoxygenation of surface waters where 
oxygen will be used in oxidation of discharged 
sediment.1"® 
Benthic organisms may also be indirectly affected 
by events taking place within the midwater column 
and in the surface layers. Necessary nutrient accumu- 
lation in the deep-sea environment originates from 
the surface layers. 
In summary, there will be gross mortality of 
benthic fauna near the disturbance area. The signifi- 
cance of this impact will depend upon the extent and 
duration of the disturbance and the thickness and 
rate of resedimentation. Deep-sea faunal succession 
and recovery rates need further study to enable pre- 
dictions of long-term effects on the system as a whole. 
IMPACTS ON THE PELAGIC ENVIRONMENT 
When the sediment and near-bottom water is dis- 
charged, either at intermediate depths or at the sur- 
face, it will form a discharge plume. Characteristics 
of this plume have been cited as potential cause for 
concern. !19:120,121,122 
Productivity 
Surface plume models for assessing “worst case” 
situations have been developed by DOMES. The 
“worst case” evaluation includes situations where 
all discharged sediment remains in the surface mixed 
layer as well as those cases where particles settle 
through the layer. In this situation: 
Maximum initial direct effects on temperature and 
disolved solids would be so insignificant that they 
would be difficult to measure and any resulting 
biological impacts inconsequential. 
Increases in the concentration of plant nutrients 
(P04, S104, and N03) would be almost too slight 
to even measure, therefore, will likely be insig- 
nificant in the long term.*?"?4 
The increased particulate concentration may be of 
more concern. In the ‘‘worst case,” without sedi- 
ment sinking, light penetration will be greatly re- 
duced in the area of the discharge plume and this 
in turn will reduce productivity by as much as one- 
half in 24 hours. If one takes sediment settling into 
account, the above effect is diminished. In any 
case, there will likely be a decrease in standing 
stock, the extent of which is unknown, but is ex- 
pected to be a localized effect not extending 
8 Thid. 
2° National Academy of Sciences, op. 
32 U.S. Department of Commerce, op. 
321 Richard Frank, op. cit. note 112, p. 
122 
cit. note 113. 
cit. note 111. 
54, 
U.S. Department of the Interior, op. cit. note 117. 
23U.S. Department of Commerce, op. cit. note 111. 
4W. H. Thomas. “Phytoplankton Nutrient Enrichment Ex- 
periments Off Baja, California and in the Eastern Equatorial 
Pacific Ocean,” 
Journal of the Fisheries Resource Board of 
Canada 26:1133-1145, 1968. 
further than a few tens of kilometers from the drill 
ship. The significance of this impact will depend 
upon dispersion and settling rates, the extent of 
the mining operation, and its duration. Any large- 
scale reduction in productivity could obviously 
have ramifications throughout the ecosystem. 
Depending upon the above occurrences, there could 
be a reduction in zooplankton standing stock since 
changes in the phytoplankton community will have 
corresponding effects on higher trophic levels. The 
magnitude and significance of this effect are un- 
known at the present time. Baseline data in the 
DOMES area indicate a near steady condition for 
relatively long periods of time between phyto- 
plankton production and zooplankton feeding. Be- 
cause of this, it is possible that a reduction in 
productivity will result in a reduction in zoo- 
plankton numbers, possibly affecting higher trophic 
levels.1*° Bathypelagic and deeper living fish could 
also be affected since they probably depend, at 
least in part, upon the organic matter generated in 
the upper layers.**® 
Behavior and Toxicity 
Behavior of organisms in response to environ- 
mental signals is always of concern in areas where 
interference may occur as a result of man’s activities. 
It is a well-established fact that many marine species 
respond to changes in light intensity. For example, 
many adjust their position in the water column in 
response to ambient light changes. Little information 
exists regarding behavior in terms of deep-sea mining 
impacts. Current information indicates the following: 
Little zooplankton vertical migration occurs in the 
upper zone of the study area so that decreases in 
light as a result of surface discharge will not sig- 
nificantly affect migration patterns. Behavioral 
impacts are in need of further study.**’ 
Increased sediment concentration can affect respi- 
ration and feeding of zooplankton by increasing 
energy expended by filter feeders to capture and 
assimilate food, by increasing sinking rates of or- 
ganisms, and by increasing likelihood of trace 
metal accumulation. Quantitative evaluation of 
these impacts is not possible with available in- 
formation. 
Preliminary results from work done by Southwest 
Fisheries Center (NMFS) Honolulu Laboratory 
indicates tuna aversion to traversing areas of algal 
blooms, possibly to avoid turbidity which again 
raises the question of changes in behavior result- 
ing from alteration of the environment. Down- 
1% UY, §. Department of Commerce, op. cit. note 111. 
126M, Blackburn. Review of Existing Information of Fishes in 
the DOMES Area of the Tropical Pacific. Final Report NOAA 
Contract No. 
03-6-022-35125. Institute of Marine Resources. 
University of California, La Jolla, Calif., 1976. 
VI-31 
1271J.§. Department cf Commerce, op. cit. note 111. 
