354
S. Sathyendranath and T. Platt
the basis of which the discriminations have to be made, will set limits on what is
possible in this new and emerging direction. But we have yet to reach those limits. Abundance-based methods rely on correlations, and it is essential to establish
whether such correlations hold for different regions of the world ocean, and whether
they hold over time in a given location.
Measuring phytoplankton physiological rate processes from space remains a
goal. It has long been suggested that the solar-induced fluorescence signal of chlorophyll can be used to infer some physiological rate processes of phytoplankton. New
methods have also emerged that relate environmental conditions revealed for example through sea-surface temperature, chlorophyll concentration and day length, to
infer photosynthetic rate parameters from satellites. One anticipates further development in these directions in the near future, but they would have to go hand in
hand with improved understanding of factors responsible for variations in algal
physiological processes in the natural environment.
20.4 Secondary Products and Novel Applications
The growth in the field may be judged not only from the new products that are
emerging, but also from the innovative ways in which the products are used to
generate new information. For example, ocean colour data are now being used
to characterise the phenology of phytoplankton dynamics in a systematic manner
at the global scale. Primary production (Platt et al., 2008) and new production
(Sathyendranath et al., 1991) were among the earliest and most valued secondary
products of ocean-colour remote sensing. But now the product range is being
expanded to include various phytoplankton loss terms, and to improve our understanding of the cycle of carbon in the ocean. These products are indictors of the
state of the marine ecosystem (Platt and Sathyendranath, 2008), extremely valuable
in ecosystem-based management of marine resources.
Ecological indicators are objective metrics, each quantifying some relevant characteristic of the pelagic ecosystem. They are intended for operational (routine)
application on serial data with a view to detecting ecosystem change in response
to perturbations such as global warming or over fishing. Remote sensing is particularly suitable for construction of ecological indicators, with superior attributes
such as rapidity of coverage, resolution, repeat frequency, cost-effectiveness and
ability to produce information on fundamental ecosystem properties quantified
in standard units (Table 20.1). At any instant, the state of the ecosystem can
be represented as a vector whose elements are selected from the list of possibilities, according to the question under consideration. Such a list of indicators
that can be produced using ocean colour and sea-surface temperature is given
in the Table 20.2 (adapted from Platt and Sathyendranath, 2008). The vector of ecosystem status is time-dependent, and the elements will evolve in an
informative way that can be revealed through analysis of time-series data. The
indicators, as well as being of intrinsic scientific interest, are useful in the
implementation of ecosystem-based management of marine resources, a principle
S. Sathyendranath and T. Platt
the basis of which the discriminations have to be made, will set limits on what is
possible in this new and emerging direction. But we have yet to reach those limits. Abundance-based methods rely on correlations, and it is essential to establish
whether such correlations hold for different regions of the world ocean, and whether
they hold over time in a given location.
Measuring phytoplankton physiological rate processes from space remains a
goal. It has long been suggested that the solar-induced fluorescence signal of chlorophyll can be used to infer some physiological rate processes of phytoplankton. New
methods have also emerged that relate environmental conditions revealed for example through sea-surface temperature, chlorophyll concentration and day length, to
infer photosynthetic rate parameters from satellites. One anticipates further development in these directions in the near future, but they would have to go hand in
hand with improved understanding of factors responsible for variations in algal
physiological processes in the natural environment.
20.4 Secondary Products and Novel Applications
The growth in the field may be judged not only from the new products that are
emerging, but also from the innovative ways in which the products are used to
generate new information. For example, ocean colour data are now being used
to characterise the phenology of phytoplankton dynamics in a systematic manner
at the global scale. Primary production (Platt et al., 2008) and new production
(Sathyendranath et al., 1991) were among the earliest and most valued secondary
products of ocean-colour remote sensing. But now the product range is being
expanded to include various phytoplankton loss terms, and to improve our understanding of the cycle of carbon in the ocean. These products are indictors of the
state of the marine ecosystem (Platt and Sathyendranath, 2008), extremely valuable
in ecosystem-based management of marine resources.
Ecological indicators are objective metrics, each quantifying some relevant characteristic of the pelagic ecosystem. They are intended for operational (routine)
application on serial data with a view to detecting ecosystem change in response
to perturbations such as global warming or over fishing. Remote sensing is particularly suitable for construction of ecological indicators, with superior attributes
such as rapidity of coverage, resolution, repeat frequency, cost-effectiveness and
ability to produce information on fundamental ecosystem properties quantified
in standard units (Table 20.1). At any instant, the state of the ecosystem can
be represented as a vector whose elements are selected from the list of possibilities, according to the question under consideration. Such a list of indicators
that can be produced using ocean colour and sea-surface temperature is given
in the Table 20.2 (adapted from Platt and Sathyendranath, 2008). The vector of ecosystem status is time-dependent, and the elements will evolve in an
informative way that can be revealed through analysis of time-series data. The
indicators, as well as being of intrinsic scientific interest, are useful in the
implementation of ecosystem-based management of marine resources, a principle