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occurred on earth for at least a million years and per-
haps as much as 40 Myr (Pelejero et al. 2010 ; see
Chapter 2). In this chapter, the inl uence of this
important change in ocean chemistry on the biodi-
versity and function of marine ecosystems is consid-
ered, from basic physiological responses of individual
organisms and species, to the potential changes in
various ocean environments.
tems in a region), or functional diversity (the number
of functional roles performed by the species present)
(see Fig. 10.1 ; Petchey and Gaston 2006 ). Biodiversity
is a dynamic feature of natural systems, rel ecting
the continual evolutionary response of species in a
region to selection across a broad range of environ-
mental and ecological pressures. Biodiversity can
expand and contract as species diversity or other
elements of biological diversity are created, main-
tained, or lost to extinction.
The function of ecosystems is wholly dependent
on biodiversity that allows energy to l ow through
trophic webs and biological networks. Moreover,
the stability and resilience of ecosystem functions,
from nutrient cycling and energy l ow, to the
population dynamics of species, are thought to be
sensitive to the loss of biodiversity caused by per-
turbations of both human and non-human origin.
This concept has long been considered theoreti-
cally, with more diverse and trophically complex
systems expected to be more stable and resistant
to perturbations. Species complementarity (different
species have similar ecological roles) and species
redundancy (different species perform the same
function) are thought to provide 'insurance' for
ecosystem function in diverse systems by promot-
ing functional diversity and maintaining energy
l ow among trophic levels (i.e. ecosystem function)
10.2 Biodiversity and ecosystem
function
The term biodiversity is broadly dei ned, and used
to characterize aspects of the biological complexity
of natural systems. Often cast simply as the number
of species in a region (i.e. species richness ), biodiver-
sity has a far larger scope that spans the variation
within and among systems and organisms over
multiple scales and levels of genetic, organismal,
ecological, or ecosystem diversity. Measures of bio-
diversity attempt to estimate the richness and even-
ness of biological characteristics at different levels,
such as species richness and species diversity (the
number and evenness of species in a region), taxo-
nomic diversity (not just species richness, but diver-
sity at higher taxonomic levels), genetic diversity
(genetic variation in a population or species), habitat
or ecosystem diversity (range of habitats or ecosys-
Figure 10.1 Species diversity does not necessarily represent functional diversity. Note that both groups have equal species richness and diversity
(a single individual from each of eight molluscan species), but the group on the right has greater taxonomic distinctness and functional diversity.
Photo R. M. Warwick.
 
 
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