Chapter 1
Toward an Ecological
Geography of the Sea
I
deally, marine biogeography should have three components. First, it should describe
how, and suggest why, individual species from bacterioplankton to whales are distributed in all oceans and seas. Second, it should tell us how those species form
characteristic ecosystems, sustaining optimum biomass under characteristic regional conditions of turbulence, temperature, irradiance, and nutrients. Third, and most important
for some purposes, it should document the areas within which each characteristic ecosystem may be expected to occur: such a partition of the ocean is the principal focus of
this work.
Unfortunately, marine biogeographers have almost exclusively occupied themselves
with the first of these tasks, the distribution of individual species and genera, and even
in this they have made only limited progress in describing the complexity that evidently
exists. Meanwhile, biological oceanographers or marine ecologists, occupied with the
analysis of marine ecosystem structure and function, have—on the whole—not been very
interested in how ecosystems are constrained spatially.
This, then, has become the objective of ecological geographers, who are interested
in the regional distribution of characteristic types of ecosystem. Their studies go a little
beyond what has come to be termed macroecology (Brown, 1995a), which is the analysis
of pattern in the characteristics and relative abundance of biota in complex ecosystems,
often using statistical techniques. Macroecology can have a spatial element and may seek
geographic patterns in ecosystem structure and function, but it is largely constrained to
the identification of statistical pattern in large data sets, over large scales of space and
time, in which local details are subsumed. In ecological geography, all relevant data and
indicators are used to interpret ecosystem characteristics and spatial distribution: all is
grist that comes to its mill.
To be useful at the global scale, ecological geography requires that sufficient information be available from all oceans and seas, a requirement that has been met only in
the last few years. All that could be done even 20 years ago (e.g., Longhurst, 1981) was
the analysis of functions within some kinds of ecosystem: coastal upwelling, low-latitude
gyres, subarctic gyres, abyssal depths, and so on. It was not possible at that time to map
the characteristics of these ecosystems globally or even regionally, because we lacked the
tools with which to gather the required information.
But, since then, there has been a steep increase in our ability both to acquire and
manage knowledge about oceanic ecosystems, and so the task has now become feasible.
The tools have come to hand not only to describe how marine ecosystems differ from one
region to another, and to set bounds to each, but also to understand how the biological
functions within them are forced by physical processes in ocean and atmosphere. Finally,
we can go beyond merely descriptive geography toward its functional explanation.
1
Toward an Ecological
Geography of the Sea
I
deally, marine biogeography should have three components. First, it should describe
how, and suggest why, individual species from bacterioplankton to whales are distributed in all oceans and seas. Second, it should tell us how those species form
characteristic ecosystems, sustaining optimum biomass under characteristic regional conditions of turbulence, temperature, irradiance, and nutrients. Third, and most important
for some purposes, it should document the areas within which each characteristic ecosystem may be expected to occur: such a partition of the ocean is the principal focus of
this work.
Unfortunately, marine biogeographers have almost exclusively occupied themselves
with the first of these tasks, the distribution of individual species and genera, and even
in this they have made only limited progress in describing the complexity that evidently
exists. Meanwhile, biological oceanographers or marine ecologists, occupied with the
analysis of marine ecosystem structure and function, have—on the whole—not been very
interested in how ecosystems are constrained spatially.
This, then, has become the objective of ecological geographers, who are interested
in the regional distribution of characteristic types of ecosystem. Their studies go a little
beyond what has come to be termed macroecology (Brown, 1995a), which is the analysis
of pattern in the characteristics and relative abundance of biota in complex ecosystems,
often using statistical techniques. Macroecology can have a spatial element and may seek
geographic patterns in ecosystem structure and function, but it is largely constrained to
the identification of statistical pattern in large data sets, over large scales of space and
time, in which local details are subsumed. In ecological geography, all relevant data and
indicators are used to interpret ecosystem characteristics and spatial distribution: all is
grist that comes to its mill.
To be useful at the global scale, ecological geography requires that sufficient information be available from all oceans and seas, a requirement that has been met only in
the last few years. All that could be done even 20 years ago (e.g., Longhurst, 1981) was
the analysis of functions within some kinds of ecosystem: coastal upwelling, low-latitude
gyres, subarctic gyres, abyssal depths, and so on. It was not possible at that time to map
the characteristics of these ecosystems globally or even regionally, because we lacked the
tools with which to gather the required information.
But, since then, there has been a steep increase in our ability both to acquire and
manage knowledge about oceanic ecosystems, and so the task has now become feasible.
The tools have come to hand not only to describe how marine ecosystems differ from one
region to another, and to set bounds to each, but also to understand how the biological
functions within them are forced by physical processes in ocean and atmosphere. Finally,
we can go beyond merely descriptive geography toward its functional explanation.
1