MANGANESE NODULES
22
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).
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).
Megafaunal abundance
Normalized parameter value
r
2
= 0.94
y = 41.86x - 9.507
Macrofaunal biomass
r
2
= 0.96
y = 112.0x + 47.92
Macrofaunal abundance
Poc ux (g CM
-2
yr
-1
)
r
2
= 0.672
y = 250.552x + 1751.954
Microbial biomass
r
2
= 0.58
y = 9.024x + 11.11
0
0
0.5
1.0
1.5
0.5
1.0
1.5
2.0
2.5
Abyssal sea cucumber wresting – Psychropotes versus Adrian
Glover. Photo courtesy of C. Smith.
Tiny holothurians that live on the spines of sea urchins at abys-
sal depths in the CCZ. Photo courtesy of Adrian Glover.
