Geoscience Reference
In-Depth Information
century, but also the unprecedented change in sea water temperatures recorded over the
past 10-15 years, can affect the metabolic rates of marine organisms, population and com-
munity dynamics, and community structure and function. It is expected that change in the
temperature of the global ocean will have consequences for the distribution of marine biod-
iversity throughout the globe.
The production of organic carbon in the surface ocean is also being affected, which
has a consequence for food supply to deep-sea ecosystems. Change in the upper ocean tem-
perature can affect the availability of nutrients for phytoplankton production and the sub-
sequent flux of exported carbon to the deep-sea sediments. It appears that ocean warming
has already caused a 6% decline in global ocean primary production. This tendency will
continue through this century and will affect, in particular, the tropical ocean.
Long-term changes in plankton communities are likely to have an impact on com-
mercial fish stocks, which in turn will have social and economic consequences. Changes
in faunal abundance and composition, correlated to change in the productivity of the sur-
face ocean, have been observed in the Pacific and the North Atlantic at greater than 4000
m depth. These changes, also expected in the equatorial abyss, result in dramatic effects
on the functioning of deep-sea ecosystems due to the observed exponential relationship
between biodiversity and ecosystem functioning in these ecosystems.
The combined effects of multiple stressors (environmental change - in particular, hab-
itat destruction - associated with climatic change) on large ecological processes determ-
ine changes in larval dispersal and recruitment success, shifts in community structure and
range extensions, and the establishment and spread of invasive species. The disruption
of the connectedness among species may lead to a reformulation of species communities
and to numerous extirpations and possibly the extinction of some species, and the loss of
some species may have negative effects on ecosystem function. The role of alien species
therefore should be assessed in a more integrated and dynamic context of shifting species'
ranges and changing compositions and structures of communities.
Global change has an effect on multiple marine habitats. The response of marine sys-
tems to climate change will also depend on interactions with other human-induced changes
