Publication Date:
2014-07-23
Description:
The concept of phytoplankton functional types has emerged as a useful approach to
classifying phytoplankton. It finds many applications in addressing some serious
contemporary issues facing science and society. Its use is not without challenges,
however. As noted earlier, there is no universally-accepted set of functional types,
and the types used have to be carefully selected to suit the particular problem being
addressed. It is important that the sum total of all functional types matches all
phytoplankton under consideration. For example, if in a biogeochemical study,
we classify phytoplankton as silicifiers, calcifiers, DMS-producers and nitrogen fix-
ers, then there is danger that the study may neglect phytoplankton that do not
contribute in any significant way to those functions, but may nevertheless be a
significant contributor to, say primary production. Such considerations often lead
to the adoption of a category of “other phytoplankton” in models, with no clear
defining traits assigned them, but that are nevertheless necessary to close budgets
on phytoplankton processes. Since this group is a collection of all phytoplankton
that defy classification according to a set of traits, it is difficult to model their physi-
ological processes. Our understanding of the diverse functions of phytoplankton is
still growing, and as we recognize more functions, there will be a need to balance the
desire to incorporate the increasing number of functional types in models against
observational challenges of identifying and mapping them adequately. Modelling
approaches to dealing with increasing functional diversity have been proposed,
for example, using the complex adaptive systems theory and system of infinite
diversity, as in the work of Bruggemann and Kooijman (2007). But it is unlikely that
remote-sensing approaches might be able to deal with anything but a few prominent
functional types. As long as these challenges are explicitly addressed, the functional-
type concept should continue to fill a real need to capture, in an economic fashion,
the diversity in phytoplankton, and remote sensing should continue to be a useful
tool to map them.
Remote sensing of phytoplankton functional types is an emerging field, whose
potential is not fully realised, nor its limitations clearly established. In this report,
we provide an overview of progress to date, examine the advantages and limitations
of various methods, and outline suggestions for further development. The overview
provided in this chapter is intended to set the stage for detailed considerations of
remote-sensing applications in later chapters.
In the next chapter, we examine various in situ methods that exist for observing
phytoplankton functional types, and how they relate to remote-sensing techniques.
In the subsequent chapters, we review the theoretical and empirical bases for the
existing and emerging remote-sensing approaches; assess knowledge about the
limitations, assumptions, and likely accuracy or predictive skill of the approaches;
provide some preliminary comparative analyses; and look towards future prospects
with respect to algorithm development, validation studies, and new satellite mis-
sions.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Inbook
,
peerRev
Format:
application/pdf
Permalink
