4
1. Introduction
professional or activist- the chances are good that you have already noticed the need to put together the many pieces of information on those systems, and to anticipate the be havior of those systems in time and space. If
you have then tried to communicate your conclusions, and the assumptions
on which they are based, to a diverse community of stakeholders' in science , policy, industry or the public, you will have noticed how difficult
such a task can be. This book is dedicated to all of you who share those experiences, and who have asked yourselves: Wouldn't it be nice to have a
tool available to make the use of information and assumptions transparent ,
to then explore the likely consequences of alternative assumptions, and to
effectively communicate with others so that we can advance our knowledge for the conservation of marine systems?
For many pe ople-some of the best scientists included- the mere notion
of formal modeling evo kes images of unfamiliar variables that are related to
each othe r in impenetrable equ ations, and that are related to the "real
world " in mysterious ways. People's perceptions of models, and especially
of computer-based modeling, has perhaps been tainted by the predominance of archaic computer code, which uses an un intuitive syntax and
could be deciph ered only by the few familiar with the particular programming language. This book will show you that computer modeling of dynamic systems can readily be made accessible to a wide audience at relatively low cost, and that the resulting computer models can empower that
audience to take computer-based pro blem solving into their own hand s.
Although we may think of modeling as an esoteric activity, we all have
learned to develop models in our minds of the apparently simple processes
that we face throughout our lives. We actually solve an amazing class of dynamic problems, such as crossing a busy street, every day. Through trial and
error , we acquire the skills necessary to put the various compo nents of a dynamic system together mentally, to draw the necessary conclusions and to
react accordingly. When crossing a busy street, we make calculations about
the spee d and direction of oncoming traffic and make subtle adjustments in
our trajectory and spee d such that we arrive at the other side of the street
unscathed. Some of us do this surprisingly well, without any explicit knowledge of the advan ced physics that one could bring to the same problem.
Like walking across a busy street, many dynamic problems can be
quickly and satisfactorily solved with common sense, experience, rules of
thumb, or similar everyday methods. In contrast, systems with a large number of interacting compo nents, subtle interactions among these compo -
nents, and long spatial and temp oral lags between an action and systems
response, make it very difficult for us to anticipate the results. Examples of
such systems include marine systems with many interacting trophic layers.
Changes in one trophic level may directly and almost immediately influ1 Phrases and words in bold face are explained in the Glossary at the end of the
book.
1. Introduction
professional or activist- the chances are good that you have already noticed the need to put together the many pieces of information on those systems, and to anticipate the be havior of those systems in time and space. If
you have then tried to communicate your conclusions, and the assumptions
on which they are based, to a diverse community of stakeholders' in science , policy, industry or the public, you will have noticed how difficult
such a task can be. This book is dedicated to all of you who share those experiences, and who have asked yourselves: Wouldn't it be nice to have a
tool available to make the use of information and assumptions transparent ,
to then explore the likely consequences of alternative assumptions, and to
effectively communicate with others so that we can advance our knowledge for the conservation of marine systems?
For many pe ople-some of the best scientists included- the mere notion
of formal modeling evo kes images of unfamiliar variables that are related to
each othe r in impenetrable equ ations, and that are related to the "real
world " in mysterious ways. People's perceptions of models, and especially
of computer-based modeling, has perhaps been tainted by the predominance of archaic computer code, which uses an un intuitive syntax and
could be deciph ered only by the few familiar with the particular programming language. This book will show you that computer modeling of dynamic systems can readily be made accessible to a wide audience at relatively low cost, and that the resulting computer models can empower that
audience to take computer-based pro blem solving into their own hand s.
Although we may think of modeling as an esoteric activity, we all have
learned to develop models in our minds of the apparently simple processes
that we face throughout our lives. We actually solve an amazing class of dynamic problems, such as crossing a busy street, every day. Through trial and
error , we acquire the skills necessary to put the various compo nents of a dynamic system together mentally, to draw the necessary conclusions and to
react accordingly. When crossing a busy street, we make calculations about
the spee d and direction of oncoming traffic and make subtle adjustments in
our trajectory and spee d such that we arrive at the other side of the street
unscathed. Some of us do this surprisingly well, without any explicit knowledge of the advan ced physics that one could bring to the same problem.
Like walking across a busy street, many dynamic problems can be
quickly and satisfactorily solved with common sense, experience, rules of
thumb, or similar everyday methods. In contrast, systems with a large number of interacting compo nents, subtle interactions among these compo -
nents, and long spatial and temp oral lags between an action and systems
response, make it very difficult for us to anticipate the results. Examples of
such systems include marine systems with many interacting trophic layers.
Changes in one trophic level may directly and almost immediately influ1 Phrases and words in bold face are explained in the Glossary at the end of the
book.