474
Paul A. TYLER
well as outer space, is that such exploration costs
money and there is never a guarantee that there will
be a return, either intellectually, commercially, or in
publicity, for the investment of taxpayers’ money. It
is the very dramatic images from hydrothermal vents
that have kept these ecosystems in the public eye
and, indirectly, aided the public funding of research
in such environments. To maintain the momentum for
exploration and discovery in the deep sea it is necessary
for the deep-sea research community to emphasise the
importance of all aspects of their chosen ecosystem.
OBSERVATION
If there are ‘ages’ in science, the deep-sea biological
community is in the later stages of the age of observation. At hydrothermal vents the age of observation has
passed quickly. This may be a function of the relatively
low species diversity there; the dominant species were
described and aspects of their basic ecology were
studied within a few years of their discovery. Only the
more obscure taxa at vents still await identification,
although with a new phase of exploration new species
of even the dominant groups are sure to be found.
Observation of the ecology of vents has also proceeded
with the development of technology such as hightemperature probes, long-term temperature probes and
increasing sophistication of the chemical analysis of the
environment (Luther et al., 2001). These observations
have shown that the ecology of vent organisms is much
more refined than originally thought.
Studies of the non-vent deep marine environment
are still largely limited to observation. Most of the
major programmes over the last twenty years or so
have sampled the deep-sea with a specific aim in mind.
One of the main drives in deep-sea biology has been
to determine the level of biodiversity. Results from
the ‘heroic’ age suggested that species diversity in the
deep sea was low, but the pioneering work of Howard
Sanders and Bob Hessler (Hessler and Sanders, 1967)
with improved sampling apparatus demonstrated that
species diversity was made up mainly of small infaunal
species. As a result of a carefully designed sampling
programme, Grassle and Maciolek (1992) predicted
that there may be up to ten million species in the
deep sea. This conclusion led to much debate with
lower (May, 1992) or higher values (Lambshead, 1993)
being suggested. In addition, there are indications that
dysoxic environments at cold seeps, such as Beggiatoa
mats, harbour a novel diverse protistan and meiofaunal
community which may give insights into the origin of
eucaryotes in the sea (Bernhard et al., 2000).
The debate on species diversity is sure to continue
(see Levin et al., 2001 and Chapter 10). Sampling
of the remoter areas of the ocean is important. This
will enable the remarkable estimate of 10
7 [which
Grassle and Maciolek (1992, p. 333) based on the tacit
assumption of a linear increase in species number with
size of sample – an assumption clearly at variance with
all the small-scale evidence which they presented] to be
replaced with a more realistic figure.
Observational deep-sea ecology has led to detailed
understanding of seasonal processes in the deep-sea
bed and how energy from surface production fuels
the deep-sea ecosystem (Billett, 2001). This aspect of
deep-sea understanding is now moving into the phase
of experimentation.
EXPERIMENTATION
The testing of hypotheses and their falsification or
acceptance underpin modern science. Experimentation, especially manipulative experimentation, makes
it possible to obtain a real detailed insight into
the mechanisms that drive an ecosystem. Deep-sea
experimentation varies in scale, and there have been a
variety of approaches from observational experimentation at relatively large scales to detailed experimental
protocols on the sub-metre scale.
One of the earliest great experiments in the deep
sea was the HEBBLE (High Energy Benthic Boundary
Layer Experiment) programme in which the cause and
effects of the transmission of mesoscale eddies to the
seabed and the subsequent benthic storms on the fauna
in their path were studied. Hypotheses were tested, but
the data were essentially observational (see Chapter 2).
A more recent large-scale experiment has been the
DISCOL (Disturbance/Colonization Experiment) in the
deep southeast Pacific Ocean in which the seabed was
‘ploughed’ up (the disturbance) and observed over the
subsequent ten years to see how the perturbation was
overcome by the local fauna (the colonization). As
this volume is written the fauna has yet to reach predisturbance equilibrium (see Chapter 13).
One of the most difficult aspects of the deep sea
for experimentation is temporal phenomena. Because
of the necessity to collect data over a period of time,
‘landers’ have been developed which can be freefloated to the seabed, left for the duration of the
experiment and released to the surface on command
Paul A. TYLER
well as outer space, is that such exploration costs
money and there is never a guarantee that there will
be a return, either intellectually, commercially, or in
publicity, for the investment of taxpayers’ money. It
is the very dramatic images from hydrothermal vents
that have kept these ecosystems in the public eye
and, indirectly, aided the public funding of research
in such environments. To maintain the momentum for
exploration and discovery in the deep sea it is necessary
for the deep-sea research community to emphasise the
importance of all aspects of their chosen ecosystem.
OBSERVATION
If there are ‘ages’ in science, the deep-sea biological
community is in the later stages of the age of observation. At hydrothermal vents the age of observation has
passed quickly. This may be a function of the relatively
low species diversity there; the dominant species were
described and aspects of their basic ecology were
studied within a few years of their discovery. Only the
more obscure taxa at vents still await identification,
although with a new phase of exploration new species
of even the dominant groups are sure to be found.
Observation of the ecology of vents has also proceeded
with the development of technology such as hightemperature probes, long-term temperature probes and
increasing sophistication of the chemical analysis of the
environment (Luther et al., 2001). These observations
have shown that the ecology of vent organisms is much
more refined than originally thought.
Studies of the non-vent deep marine environment
are still largely limited to observation. Most of the
major programmes over the last twenty years or so
have sampled the deep-sea with a specific aim in mind.
One of the main drives in deep-sea biology has been
to determine the level of biodiversity. Results from
the ‘heroic’ age suggested that species diversity in the
deep sea was low, but the pioneering work of Howard
Sanders and Bob Hessler (Hessler and Sanders, 1967)
with improved sampling apparatus demonstrated that
species diversity was made up mainly of small infaunal
species. As a result of a carefully designed sampling
programme, Grassle and Maciolek (1992) predicted
that there may be up to ten million species in the
deep sea. This conclusion led to much debate with
lower (May, 1992) or higher values (Lambshead, 1993)
being suggested. In addition, there are indications that
dysoxic environments at cold seeps, such as Beggiatoa
mats, harbour a novel diverse protistan and meiofaunal
community which may give insights into the origin of
eucaryotes in the sea (Bernhard et al., 2000).
The debate on species diversity is sure to continue
(see Levin et al., 2001 and Chapter 10). Sampling
of the remoter areas of the ocean is important. This
will enable the remarkable estimate of 10
7 [which
Grassle and Maciolek (1992, p. 333) based on the tacit
assumption of a linear increase in species number with
size of sample – an assumption clearly at variance with
all the small-scale evidence which they presented] to be
replaced with a more realistic figure.
Observational deep-sea ecology has led to detailed
understanding of seasonal processes in the deep-sea
bed and how energy from surface production fuels
the deep-sea ecosystem (Billett, 2001). This aspect of
deep-sea understanding is now moving into the phase
of experimentation.
EXPERIMENTATION
The testing of hypotheses and their falsification or
acceptance underpin modern science. Experimentation, especially manipulative experimentation, makes
it possible to obtain a real detailed insight into
the mechanisms that drive an ecosystem. Deep-sea
experimentation varies in scale, and there have been a
variety of approaches from observational experimentation at relatively large scales to detailed experimental
protocols on the sub-metre scale.
One of the earliest great experiments in the deep
sea was the HEBBLE (High Energy Benthic Boundary
Layer Experiment) programme in which the cause and
effects of the transmission of mesoscale eddies to the
seabed and the subsequent benthic storms on the fauna
in their path were studied. Hypotheses were tested, but
the data were essentially observational (see Chapter 2).
A more recent large-scale experiment has been the
DISCOL (Disturbance/Colonization Experiment) in the
deep southeast Pacific Ocean in which the seabed was
‘ploughed’ up (the disturbance) and observed over the
subsequent ten years to see how the perturbation was
overcome by the local fauna (the colonization). As
this volume is written the fauna has yet to reach predisturbance equilibrium (see Chapter 13).
One of the most difficult aspects of the deep sea
for experimentation is temporal phenomena. Because
of the necessity to collect data over a period of time,
‘landers’ have been developed which can be freefloated to the seabed, left for the duration of the
experiment and released to the surface on command