22
G.R. Carvalho et al.
our current models are based. For example, the scale of disturbances in oceanic
environments that can happen on a daily basis means that climax communities like
those that can develop on land rarely develop in the ocean. DeLong and Karl (2005)
are applying genomic technologies to search for the genomes of as-yet unidentified
microbes in samples from the environment. Given the central role that microbes
play in functioning ecosystems, ecogenomics has enormous implications for understanding of diversity in the oceanic microbial community (Eisen 2007), and can also
shed significant insight into the health of ecosystems if the assemblage of microbes
and their functions are eventually understood and mapped onto their geographic
locations (Hoffman and Gaines 2008).
1.3.3 Environmental Change and Microbial Diversity
The world’s oceans are facing many rapidly increasing threats from human disturbance. Ecosystems around the globe are currently undergoing dramatic changes
in species composition because of the influence of human activity. The manner
in which natural communities utilise resources affects the physical environment
and interacts with other species suggests that biodiversity (that is, the composition, structure and function of an community) is essential for the functioning
and/or sustainability of an ecosystem. These changes have usually led to a reduction in species diversity. Changes in species composition, species richness, and/or
functional type affect the efficiency with which resources are utilised within an
ecosystem, and suggest that biogeochemical functioning of an ecosystem will be
impaired by biodiversity loss. Much remains unknown about how species richness or functional groups affects ecosytem level responses. Experiments to test the
relationship between species richness and ecosystem function have been largely
confined to terrestrial systems, but more recently marine systems have also been
utilised, though with some conflicts between simulations and real observations. In
recent years, many models have attempted to describe how changes in species richness may affect ecosystem function. A specific ecosystem function is thus seen as
a function of (i) biodiversity and the functional traits of the organisms involved, (ii)
associated biogeochemical processes, and (iii) the abiotic environment. The concept of resilience, as applied to an ecosystem, is loosely defined as the ability of the
system to maintain its function when faced with novel disturbance. The concept is
related to stability, but with its focus on maintenance of function and novel disturbance, resilience uniquely encompasses aspects of society’s reliance on ecosystem
services and increasing anthropogenic change (Webb 2007). Thus, ecologists can
study resilience from a complex adaptive systems (CAS) approach or a social–
ecological systems (SES) approach, which places equal weight on the human and
ecological dimensions of ecosystem function and maintenance (Webb 2007).
Although documented global extinctions are rare in the marine environment,
local extinctions and dramatic changes in abundance are widespread. The causes
of this loss and its consequences for the functioning and stability of ecosystems
G.R. Carvalho et al.
our current models are based. For example, the scale of disturbances in oceanic
environments that can happen on a daily basis means that climax communities like
those that can develop on land rarely develop in the ocean. DeLong and Karl (2005)
are applying genomic technologies to search for the genomes of as-yet unidentified
microbes in samples from the environment. Given the central role that microbes
play in functioning ecosystems, ecogenomics has enormous implications for understanding of diversity in the oceanic microbial community (Eisen 2007), and can also
shed significant insight into the health of ecosystems if the assemblage of microbes
and their functions are eventually understood and mapped onto their geographic
locations (Hoffman and Gaines 2008).
1.3.3 Environmental Change and Microbial Diversity
The world’s oceans are facing many rapidly increasing threats from human disturbance. Ecosystems around the globe are currently undergoing dramatic changes
in species composition because of the influence of human activity. The manner
in which natural communities utilise resources affects the physical environment
and interacts with other species suggests that biodiversity (that is, the composition, structure and function of an community) is essential for the functioning
and/or sustainability of an ecosystem. These changes have usually led to a reduction in species diversity. Changes in species composition, species richness, and/or
functional type affect the efficiency with which resources are utilised within an
ecosystem, and suggest that biogeochemical functioning of an ecosystem will be
impaired by biodiversity loss. Much remains unknown about how species richness or functional groups affects ecosytem level responses. Experiments to test the
relationship between species richness and ecosystem function have been largely
confined to terrestrial systems, but more recently marine systems have also been
utilised, though with some conflicts between simulations and real observations. In
recent years, many models have attempted to describe how changes in species richness may affect ecosystem function. A specific ecosystem function is thus seen as
a function of (i) biodiversity and the functional traits of the organisms involved, (ii)
associated biogeochemical processes, and (iii) the abiotic environment. The concept of resilience, as applied to an ecosystem, is loosely defined as the ability of the
system to maintain its function when faced with novel disturbance. The concept is
related to stability, but with its focus on maintenance of function and novel disturbance, resilience uniquely encompasses aspects of society’s reliance on ecosystem
services and increasing anthropogenic change (Webb 2007). Thus, ecologists can
study resilience from a complex adaptive systems (CAS) approach or a social–
ecological systems (SES) approach, which places equal weight on the human and
ecological dimensions of ecosystem function and maintenance (Webb 2007).
Although documented global extinctions are rare in the marine environment,
local extinctions and dramatic changes in abundance are widespread. The causes
of this loss and its consequences for the functioning and stability of ecosystems