Deep Sea Minerals - Vol 2 - Manganese Nodules
Global geographic context 2.2
Nodule regions sustaining different levels of particulate organic carbon flux appear to have different levels of species diversi- ty and substantially different faunal communities, both in the soft sediments and on the nodules themselves. (Figure 16; Mul- lineaux 1987; Veillette et al . 2007a; UNESCO 2009; Ebbe et al . 2010). The CCZ, the area of most intense interest for manganese nodule mining in the Pacific, experiences substantial east-west and south-north gradients in overlying primary production and the flux of food to the abyssal sea-floor (UNESCO et al . 2009; Watling et al . submitted). Based on these gradients, as well as on patterns of faunal turnover, the CCZ is expected to harbour distinct faunas and levels of biodiversity in different subre- gions. The CCZ is also thought to straddle a major biogeograph- ic provincial boundary in the abyssal Pacific (UNESCO 2009; Watling et al . in press).
Normalized parameter value
1.5
Abyssal sea cucumber wresting – Psychropotes versus Adrian Glover. Photo courtesy of C. Smith.
Megafaunal abundance
r 2 = 0.94 y = 41.86x - 9.507
1.0
Macrofaunal biomass r 2 = 0.96 y = 112.0x + 47.92
Microbial biomass r 2 = 0.58 y = 9.024x + 11.11
0.5
Macrofaunal abundance
r 2 = 0.672 y = 250.552x + 1751.954
0
0
0.5
1.0
1.5
2.0
2.5
Poc ux (g CM -2 yr -1 )
Figure 16 Links between abyssal benthic ecosystems and particulate organic matter. Regression relationships demon- strating the strong dependence of abyssal benthic ecosystem structure and function on the level of particulate organic matter (expressed as carbon) flux to the sea-floor. All relationships are statistically significant (p < 0.05). Bioturbation intensity is based on 210Pb Db SCOC = sediment community oxygen consumption Modified from Smith et al. (2008a).
Tiny holothurians that live on the spines of sea urchins at abys- sal depths in the CCZ. Photo courtesy of Adrian Glover.
MANGANESE NODULES 22
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