PrefaceBy R. P. Harris |
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ContentsQuestions |
PrefaceZooplankton
are the diverse, delicate and often beautiful, assemblage of animals that
drift the waters of the world’s oceans. These microscopic organisms play a
key role in the pelagic food web by controlling phytoplankton production and
shaping pelagic ecosystems. In addition, because of their critical role as
food source for larval and juvenile fish, the dynamics of zooplankton
population, their reproductive cycles, growth, reproduction and survival
rates are all important factors influencing recruitment to fish stocks. It is
this latter role which has made zooplankton ecology of particular interest to
ICES. The
International Council for the Exploration of the Seas, ICES, is the oldest
intergovernmental organization in the world concerned with marine and
fisheries science. Since it’s establishment in Copenhagen in 1902, ICES has
been leading scientific forum for exchange of information and ideas on the
sea and its living resources, and for the promotion and coordination of
marine research by scientists within its member countries. Each year, ICES
holds more than 100 meetings of its various working groups, study groups,
workshops and committees. Membership
has increased from the original eight countries in 1902 to the present 19
countries which come from both sides of the Atlantic and include all European
coastal states except the Mediterranean countries eastward of, and including,
Italy. ICES established a Study Group on Zooplankton Production in 1992
chaired by Hein Rune Skjoldal, of the Institute of Marine Research, Bergen,
Norway. The Study Group were given as terns of reference to: a)
review existing methods for measuring biomass and production
processes; b)
make proposals for improvement and standardization of methods, and
prepare a methodological manual; c)
consider the need for laboratory and seagoing workshops to
intercalibrate experimental methods and evaluate new technology. The
Study Group has met eight times, in March 1992 in Bergen; in March 1993 in
Las Palmas; in March 1994 in Plymouth; in June 1995 in Woods Hole, in March
1996 in Bergen, in March 1997 in Kiel, May 1998 in Santander, and May 1999 in
Reykjavik. In 1997 Roger Harris of the Plymouth Marine Laboratory, United
Kingdom, assumed the chairmanship. The
Study Group decided at the first meeting to produce a Zooplankton Methodology
Manual recognizing the need for improvements and standardization in methods
for studying this important and challenging group of organisms. To assist in
the review of methods and to provide input to the issue of standardization an
improvement of methods, three special workshops were convened. The first was
a seagoing workshop onboard RV Johan Hjort and RV A.V. Humboldt on
zooplankton sampling methods (June 1993). The two others were laboratory workshops at the University of Bergen,
on production methods using the copepod Acartia
tonsa (October 1993) and Calanus
finmarchicus (April 1994). A fourth workshop was arranged by US GLOBEC in Hawaii using
marine copepods (April 1994). Results from these workshops have been
incorporated by the Study Group in producing this Manual. ICES
changed the status of the Study Group to a Working Group on Zooplankton
Ecology (WGZE) in 1994. The working group has taken over the task of
completing work with the Manual. The
scope of the Zooplankton Methodology Manual is to provide an updated review
of the basic methodology used in studies of zooplankton including
recommendations on improvements, harmonization and standardization of
methods. The chapters aim to maintain a balance between being introductory
and comprehensive. They provide an overview of methods that are useful, for
example to graduate students who are starting in a new field. They emphasize
the sources of error and the strengths and weaknesses of methods for various
purposes and tasks. It has not been possible, however, to go into great
detail for all methods, and reference to recent reviews and detailed
description of methods is used where possible and appropriate. Each
chapter begins with a review of methods which in most cases is accompanied by
recommendations regarding choice and conduct of methods. These reviews
consider the background and history of the
methodology, the basic principles, sources of variability, equipment
and procedures, comparative evaluation of alternative methods, general
recommendations, and extensive literature references. Where possible detailed
descriptions of standard protocols are included. The aim is to give practical
instructions on how to carry out particular measurements and procedures.
Equipment, procedures, data analysis and interpretation are described, where
possible. These protocols either define standard methods, or give examples of
little-known methods. If many methods are used, or many instruments, guidance
is given on the most highly recommended, or the most often used, or likely to
be used. In some cases it proves difficult to propose an agreed standard
protocol. It is however, possible to provide guidelines that reduce the
variability in methods and contribute towards harmonization and
standardization. The
various chapters of the Manual have been reviewed by the ICES WGZE, and in
addition, peer reviewers from outside this group have evaluated each chapter
independently. Grateful thanks are due to these reviewers for their
invaluable contribution to the overall project. Each
chapter is authored by an expert, or group of experts, selected from both
members of the WGZE and other international specialists. The writing has been
organized and co-ordinated by the main author assisted by the co-authors.
Chapter 1 provides an introduction to zooplankton. Chapters 2, 3, 4 and 5
consider sampling and experimental design, collecting zooplankton, techniques
for assessing biomass and abundance, and the specialized methodology required
for protozooplankton enumeration and biomass estimation. Chapters 6 and 7
describe new and emerging optical and acoustic techniques for estimating
zooplankton biomass and abundance. In chapters 8, 9 and 10, methods for
measuring zooplankton rate processes are described; feeding, growth and
reproduction, and metabolism. Chapter 11 gives a modern account of methods
for population genetic analysis of zooplankton, and Chapter 12 a
comprehensive treatment of modelling zooplankton dynamics. While
striving to be a comprehensive treatment of modern methods in zooplankton
ecology, it is inevitable that some topics have not been covered. In
particular it was the original intention to include chapters on methods for
investigating zooplankton behavior, and for studying population dynamics. The
former chapter was never commissioned, while the latter, although originally
written as a part of the ICES Manual project, was ultimately published as a
separate scientific article; Aksnes et al. 1997. Estimation techniques used
in studies of copepod population dynamics – a review of underlying
assumptions. Sarsia, 82: 279 – 298. This may still be referred to as being
complementary to the work. The original concept of the Zooplankton
Methodology Manual included a related CD-ROM to include data, graphics and
video images, particularly relating to sampling methods, and deriving from
the seagoing workshop. This is not included with the Manual, however the WGZE
are still considering the preparation and distribution of such a CD-ROM. The
ICES WGZE has been encouraging and co-ordinating zooplankton monitoring
activities in the ICES area, and this manual should contribute to these
activities. Similarly, the development of major international initiatives
with a particular focus on zooplankton, particularly the IGBP / SCOR
/ IOC co-sponsored Global Ocean Ecosystem Dynamics (GLOBEC) project, and the Living Marine Resources
module of the Global Ocean
Observing System (GOOS-LMR)
make the publication of this Manual particularly timely. While not formally
adopted by either programme, the ICES Zooplankton Methodology Manual will
contribute significantly to the standardization of methodology that both
GLOBEC and GOOS-LMR strongly endorse. The
preparation of the Zooplankton Methodology Manual has by definition been a
team effort. The members of the WGZE and the Editors have lead in this, over
the years of development. It is a great pleasure to acknowledge the
enthusiasm, dedication and patience of all the authors and co-authors during
this process. I am particularly grateful to Dr. Sarah Stafford, Clare
Nehammer and Teresa Netzler of Academic Press who have all worked with me
during the editing and production of the Manual. Plymouth December
1999 Questions |