Major U.S. GLOBEC Objectives
The U.S. Global Ocean Ecosystem Dynamics program (U.S. GLOBEC) is a
component of the U.S. Global Change Research Program. Its major
objectives have been stated in previously issued reports (e.g., GLOBEC
Report No. 1, Initial Science Plan, 1991) and are as follows:
U.S. GLOBEC's overriding goal is to "address the question of how changes
in global environment are expected to affect abundances, variations in
abundance, and production of animals in the sea" (GLOBEC Rept. 1, p. 5).
The approach chosen to accomplish this goal is to develop a fundamental
understanding of the mechanisms that determine the mean level and
variation in marine animal populations. Toward that end, U.S. GLOBEC is
planning investigations of (1) how changes in ocean physics interact
with biological processes to control the population dynamics of key
species, and (2) how such population-level responses to physical
processes affect the structure and stability of ocean ecosystems.
Increasing our understanding of the mechanisms and linkages between
physical processes, population dynamics and ecosystem structure will
lead to improved understanding of how population dynamics and ecosystems
will be impacted by climate change.
Goal of this Workshop
This workshop was intended to evaluate which optical technologies are
presently available, which could be modified and which could be
developed within the next several years to address some of the specific
U.S. GLOBEC objectives mentioned subsequently. The workshop
participants were asked to recommend technologies or instrumentation
that would be near optimal to accomplish those objectives.
The Significance of Technology
The importance of advanced technology, specifically for biological
oceanography, was emphasized in GLOBEC Report No. 1 (1991) and in the
Marine Zooplankton Colloquium 1(1989). Many of the difficulties
associated with studying plankton in the water column are obvious.
Proto- and metazooplankton live in three dimensions and can respond
instantaneously to external stimuli, feeding, swimming and darting about
in ways which cannot be observed easily by humans without aid of
instrumentation. To quantify and understand those organisms' behaviors,
we need to sample or observe continuously, or at frequent intervals, and
utilize approaches which do not alter natural behavior (non-invasive
approaches). These observations need to be made at space and time
scales relevant to the organisms' behaviors and appropriate for the
rates being studied.
To make the requisite observations-high frequency, high spatial
resolution, large dynamic range and non-intrusive-will require new
technology (Marine Zooplankton Colloquium 1, 1989, p.198). Currently
available instruments for quantifying the abundance, distribution, and
most physiological rates of planktonic animals are inadequate to address
the major goals of U.S. GLOBEC. At a U.S. GLOBEC Workshop on Acoustical
Technology in April 1991 it was emphasized that acoustical and optical
technologies were the "leading candidates from which the necessary tools
could be drawn to support the pursuit of GLOBEC's science goals" (GLOBEC
Report No. 4, 1991, p. 28).
Specific U.S. GLOBEC Objectives which could benefit from Optics Technology
To determine population dynamics of planktonic animals it is critical to
quantify not only the abundance and distribution of the respective taxa
over time, but also to quantify rates of birth, growth and mortality.
Feeding rate measurements are valuable because they strongly affect the
three above-mentioned variables. Neither acoustical nor optical
instruments alone can be used to quantify all of these variables.
Rather, these complementary technologies should be used together to
provide the needed data (GLOBEC Report No. 4, 1991). Bioacoustic
measurements of animals can perceive organisms larger than about 1 mm
rather well, and can make accurate, frequent and rapid measurements of
animal abundance and distribution. However, without ancillary
information on target identification-either by the use of plankton nets,
pumps, or optical sampling-current bioacoustical measurements are
unlikely to provide the species specific data desired by U.S. GLOBEC.
Nets and pumps are not adequate for target identification because in
general they do not sample the same parcels of water sampled
bioacoustically. Thus, optical instruments, which can provide target
identification from the same parcel, will significantly improve the
potential of acoustical methods to achieve the major goals of U.S.
GLOBEC. Thus, the promise of optics is four-fold: (1) rapid
identification of living organisms in situ, (2) quantification of
organisms smaller than 1 mm, (3) observation of behavior and rate
measurements directly and in situ, and (4) concurrent sampling of
organisms, their prey and potential predators at spatial and temporal
scales at which the physical environment can be sampled as well.
Organization of the U.S. GLOBEC Optics Technology Workshop
Workshop participants were provided a background document two weeks prior
to the meeting which outlined the goals of the workshop and provided
guidance for contributing. The workshop began with several
presentations on existing optical instruments which are used to measure
the abundance and distribution of zooplankton or to obtain rate
measurements. The intent was to inform workshop participants of the
status and capability of existing optical instruments to measure
zooplankton structure and dynamics in the ocean.
Presentations were made by the following participants who described
specific instruments and/or approaches.
Discussion following the overview presentations resulted in the
delineation of two major zooplankton issues to which the application of
optical technology could contribute significantly. These issues are:
- P. Donaghay/J. Katz
- Holographic Camera
- R. Strickler
- Holography and Schlieren Observations
- D. Davis
- Telemetry Developments
- U. Kils
- In situ technology, nested camera observations of predator and prey, video image processing
- V. Holliday
- Acoustical Estimation incl. MAPS and BITS; nesting of bioacoustical and optical technology; data reduction and analysis
- R. Zaneveld
- Coupling of physics and zooplankton food distributions
Workshop participants formed two working groups to examine in detail the
roles that current, planned and future optical based instruments could
play in addressing these two issues. The results are provided in the
working group reports which follow.
- the determination of zooplankton composition, biomass, and abundance, not only of target species, but also of their principal prey and potential predators, and
- the quantification of in situ zooplankton dynamics (i.e., rates), specifically studies of behavior, feeding, predation and conspecific interaction (e.g., mating).