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1.2. Potential phytoplankton impacts
Transport of nutrient-rich deep water into the euphotic zone could
significantly enhance productivity and alter community composition from
nitrogen fixers and species associated with low nutrient to those with higher
nutrient preferences.
Trace metal release into the euphotic zone could have a positive or
negative impact on productivity, by either providing necessary
micronutrients (e.g. iron) or poisoning sensitive species, thereby altering
community composition.
Release of particulates into the euphotic zone may reduce water
clarity, decreasing euphotic zone depth. This would be expected to
particularly impact phytoplankton in the deep chlorophyll maximum.
1.3. Potential zooplankton impacts
Release of particulates may reduce feeding efficiency of suspension
feeders. This will particularly impact species in the zone of sediment and
mine-tailings discharge, and zooplankton in the near-bottom layer most
impacted by mining activity. Little is known about the productivity of
deepwater zooplankton but they are presumably food limited; reduced
feeding efficiency may significantly impact growth and reproductive
efficiency.
Enhanced (decreased) productivity at lower trophic levels will
enhance (decrease) secondary productivity and potentially alter community
composition and food web pathways. Changes to the microbial loop and
phytoplankton community structure may have fundamental implications for
the size structure of the zooplankton community.
Enhanced trace metal concentrations within the sediment plume or
sediment discharge, and mobilization of trace metals in the oxygen
minimum, could all have potentially toxic effects on zooplankton groups.
1.4. Potential micronekton impacts
Potentially there are both direct and indirect impacts of mining on
the micronekton. The discharge may directly impact the micronekton in the
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