suggested as the only meaningful approach to preserving coral reefs (Bohnsack and
Ault, 1996; Christensen et al., 1996).
1.1 OBJECTIVES
The goal of this chapter is to present a framework for the use of remote sensing
methods in investigations of the biogeochemical function of reef systems. The
objectives are to: 1) present a rationale for estimation of the community metabolism of
reef systems that is scaled in time and space by remote sensing; 2) provide a conceptual
model of reef system excess organic carbon production and calcification based on the
integration of multiple-source synoptic remote sensing with local metabolic functions
determined through in situ process measurements; and 3) provide an example of the use
of remote sensing in the spatial scaling of metabolic measurements.
2. Rationale
One of the aims of ecosystem studies is to understand apparently disjointed
individual observations by expanding the analytical scale, resulting in a capacity for
collective prediction (Levin, 1992). Typically, within ecosystem studies the physical
environment is regarded as the primary driver of variation in biogeochemical processes
and fluxes, and biological factors are regarded as secondary. A central aspect in this
approach is the reduction of complexity, achieved through abstraction, which shifts the
conceptualization of the ecosystem to higher levels of organization (Hatcher, 1997a).
This implies up-shift in time-space scales to estimate processes at higher levels in the
hierarchy, thereby eliminating detail and achieving an understanding of ecosystem-level
function (Hatcher, 1997a). Overall, most ecosystem studies seek to integrate seemingly
diverse observations, and reduce complexity, by quantifying key variables that emerge
as stable holistic properties at higher levels of system organization (Holling, 1992;
Hatcher, 1997a).
Model estimation of key rate variables that identify coral reef ecosystem state is a
means to evaluate net biogeochemical status (Arias-Gonzalez et al., 1997), determine
the limits of potential response to human exploitation (Grigg et al., 1984), and predict
the impacts of global change (Smith and Buddemeier, 1992; Hatcher, 1997a). Brown
(1988) noted that the assessment of community organic-carbon production and
calcification has potential for the indication of sub-lethal perturbation. Smith and
Buddemeier (1992) recognized that measures of community metabolism provide largescale functional status and indicate incipient change. The rates of such processes on
unperturbed reefs are remarkably consistent, and consequently, departures from the
norm are readily recognized (Kinsey, 1983).
Net primary production (P n ) is defined as the remainder after subtraction of
autotrophic respiration (R a ) from the gross primary production (P g ) of autotrophs
(Hatcher, 1988). The balance of total ecosystem respiration (R), inclusive of both R a
and respiration by heterotrophs (R h ), and P g , is called net community production (NCP).
Net community production is always significantly lower than net primary production
(Hatcher, 1997b). In this chapter, the organic-carbon-flux of interest is net community
production (NCP), to avoid the inference that the metabolism of a component zone can
be generalized to the entire ecosystem, whose domain may be a matter of perspective.
Ultimately, NCP integrated over diurnal, seasonal, or annual time periods is termed
excess production (E), a key variable because it represents the potential for biomass
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Ault, 1996; Christensen et al., 1996).
1.1 OBJECTIVES
The goal of this chapter is to present a framework for the use of remote sensing
methods in investigations of the biogeochemical function of reef systems. The
objectives are to: 1) present a rationale for estimation of the community metabolism of
reef systems that is scaled in time and space by remote sensing; 2) provide a conceptual
model of reef system excess organic carbon production and calcification based on the
integration of multiple-source synoptic remote sensing with local metabolic functions
determined through in situ process measurements; and 3) provide an example of the use
of remote sensing in the spatial scaling of metabolic measurements.
2. Rationale
One of the aims of ecosystem studies is to understand apparently disjointed
individual observations by expanding the analytical scale, resulting in a capacity for
collective prediction (Levin, 1992). Typically, within ecosystem studies the physical
environment is regarded as the primary driver of variation in biogeochemical processes
and fluxes, and biological factors are regarded as secondary. A central aspect in this
approach is the reduction of complexity, achieved through abstraction, which shifts the
conceptualization of the ecosystem to higher levels of organization (Hatcher, 1997a).
This implies up-shift in time-space scales to estimate processes at higher levels in the
hierarchy, thereby eliminating detail and achieving an understanding of ecosystem-level
function (Hatcher, 1997a). Overall, most ecosystem studies seek to integrate seemingly
diverse observations, and reduce complexity, by quantifying key variables that emerge
as stable holistic properties at higher levels of system organization (Holling, 1992;
Hatcher, 1997a).
Model estimation of key rate variables that identify coral reef ecosystem state is a
means to evaluate net biogeochemical status (Arias-Gonzalez et al., 1997), determine
the limits of potential response to human exploitation (Grigg et al., 1984), and predict
the impacts of global change (Smith and Buddemeier, 1992; Hatcher, 1997a). Brown
(1988) noted that the assessment of community organic-carbon production and
calcification has potential for the indication of sub-lethal perturbation. Smith and
Buddemeier (1992) recognized that measures of community metabolism provide largescale functional status and indicate incipient change. The rates of such processes on
unperturbed reefs are remarkably consistent, and consequently, departures from the
norm are readily recognized (Kinsey, 1983).
Net primary production (P n ) is defined as the remainder after subtraction of
autotrophic respiration (R a ) from the gross primary production (P g ) of autotrophs
(Hatcher, 1988). The balance of total ecosystem respiration (R), inclusive of both R a
and respiration by heterotrophs (R h ), and P g , is called net community production (NCP).
Net community production is always significantly lower than net primary production
(Hatcher, 1997b). In this chapter, the organic-carbon-flux of interest is net community
production (NCP), to avoid the inference that the metabolism of a component zone can
be generalized to the entire ecosystem, whose domain may be a matter of perspective.
Ultimately, NCP integrated over diurnal, seasonal, or annual time periods is termed
excess production (E), a key variable because it represents the potential for biomass
112
Brock, Yates and Halley