Knowledge and implications of global change in the oceans for biology, ecology, and ecosystem services - Ocean Sustainability in the 21st Century - page 144

at this site revealed shifts in nematode abundance and community composition, reflecting
changes in food availability. For the larger organisms, a towed camera system revealed a
significant decrease in megafaunal abundance at 2500 m depth (Barange et al., 2011 ) .
Impacts induced by global change are occurring in all habitat types investigated so far,
although to different extents. The changes have been proven to be primarily the result of
long-term trends, either in temperature change, deoxygenation, or acidification. However,
some of the impacts related to climate change occur episodically. This is the case for dense
shelf water formation, with the creation of a cold cascade of sediment and cold water in
deeper ocean layers (Canals et al., 2006 ) , or temperature anomalies associated with the
deepening ofthethermocline, whichinducedmassmortalities incoastal shallowandmeso-
photic assemblages (Cerrano et al., 2000 ).