John P. Manderson1 and
Josh T. Kohut2
The co-authors
contributed equally to the development of this white paper submitted for 2012 National Workshops for Habitat Assessment (09/05/12) & Integrated Ocean Observation Systems (11/13/12)
1NOAA/NMFS/NEFSC
James J. Howard Laboratory, Highlands, NJ 07732
2Rutgers,
The State University of New Jersey, New Brunswick, NJ 08901
“..comparison
of marine and terrestrial dynamics has more than theoretical interest. As we
utilize marine and terrestrial environments, the consequences, deliberate or
accidental, depend on [ecosystem] responses to physical and chemical change.
The imposition of terrestrial standards for marine problems may produce too
strict or too lax criteria--or most likely quite inappropriate ones” (John Steele, 1991. Can ecological theory cross the land-sea boundary?)
1.
Introduction
Ecosystem
assessment and management in the sea is holistic, based upon interdisciplinary
science that considers physical, chemical and biological processes, including
feedbacks with human ecological systems, that structure and regulate marine
ecosystems. Space and time based tools for the
management of human activities in the sea need to be informed by a regional
scale habitat ecology that reflects the dynamic realities of the ocean. Current spatial management strategies
including marine spatial planning (MSP) and ocean zoning are based upon the
patch-mosaic paradigm of terrestrial landscape ecology modified to consider
principles of dispersal ecology, primarily for pelagic early life history
stages of algae, fish and invertebrates. This modification is not enough
because fundamental differences in the role fluid properties and processes play
in controlling ecological processes on land and in the sea makes blanket
application of paradigms developed on land to the problems of ocean management
fundamentally flawed.
The rapid evolution of the Integrated Ocean
Observation System (IOOS) made possible through interdisciplinary partnerships
and networked data sharing provides descriptions of coastal ocean hydrography
and hydrodynamics at fine scales of space and time and regional spatial extents. This allows hydrography and hydrodynamics to
be placed at the foundation of a seascape ecology in the way that geography and
geophysics appropriately serve as the foundation of terrestrial landscape
ecology. IOOS not only provides the
ocean data required to develop seascape ecology but also the infrastructure and
expertise to operationalize it for regional ecosystem assessment and adaptive co-management.
Finally, regional IOOS associations are cooperative partnerships of academic,
government and private industry experts from diverse fields and interests. As a
result the IOOS "culture" can foster the collaborative development of
an interdisciplinary seascape science that is more likely to lead to effective
and less adversarial strategies of regional ecosystem co-management that operate
at space-time scales more closely matching those of the ecosystem itself.
2.
Seascapes are not landscapes
In
1984 Paul Risser and colleagues (Risser et al, 1984) summarized workshop
deliberations to develop a modern framework for the science of landscape
ecology using theoretical and empirical underpinnings of a broad scale
spatially explicit ecology useful for terrestrial resource management. The foundations of this synthesis rested on (1)
developments in satellite remote sensing that allowed researchers to place fine
scale ecological studies in broader spatial contexts; (2) advances in
ecological theory that elucidated the role of dispersal and connectivity in
determining regional community dynamics; and (3) the advent of modern computing
that allowed researchers to store, analyze, and model large amounts of spatially
and temporally explicit data and explore relationships between the changing
landscape patterns and the processes potentially causing them. Landscape ecology rests primarily upon the
patch mosaic paradigm of habitat in which patches are defined by sharp
gradients in vegetation and geomorphology (but see Cushman et al. 2010). Geography and geological processes, particularly soil development, that control
fundamental processes including primary productivity are the foundations of
landscape classification. In terrestrial ecosystems, most organisms and
processes are decoupled from the atmosphere by gravity and physiological
adaptation to extreme variations in atmospheric properties, including
temperature. As a result, the primary
features of terrestrial habitats and ecosystems are physical structures created
by landform and plant communities that can be modified by disturbance.
Community compositions are determined by climate (Wiens, 2007). However, the role of the atmospheric fluid is
of secondary importance and the space-time scales of terrestrial ecosystems [~
velocity, 0.1 cm sec-1] are orders of magnitude slower than the
atmosphere [100 cm sec-1] and approximately the same speed as soil
regeneration (Steele, 1991; Mamayev, 1996. Fig 1).
 |
| Figure 1. Ecosystems on land (above) operate at space-time scales orders of magnitude slower than turbulent features of the atmosphere while variability in marine ecosystems (below) matches the scales of variability of turbulence in the ocean fluid. (From Steele, 1991 and Mamayev, 1996) |
In contrast, the
ocean is highly viscous and has a density close to that of living tissues. Most marine organisms are therefore nearly
buoyant in a fluid with dynamics that control their motions and those of other
important particles including essential ecosystem building blocks. Since the basic processes of cellular
metabolism evolved in the sea, most living tissues are nearly isosmotic with
seawater. This contrasts starkly with terrestrial organisms whose intracellular
concentrations of solutes and water are dramatically different than the
atmosphere. Finally the specific heat
capacity and thermal conductivity of seawater are about four and twenty-three
times that of atmosphere by weight, respectively. As a result, marine organisms experience much
slower rates and ranges of temperature change than do terrestrial organisms.
Temperature is tyrannical in the oceans where oxygen required for endothermic
heat generation is limited and warm-blooded organisms are rare. Temperature regulates
critical rates across all levels of ecological organization from the cell to
marine ecosystems.
Processes
controlling primary productivity on land and the sea are also fundamentally
different. In the oceans nutrients
required by plants constant fall out of sunlit surface waters where
photosynthesis is possible. As a result,
tiny, fast living plants with high surface to volume ratios are entirely dependent
on the oceans “plumbing” to deliver nutrients into the sunlit surface layers
from sometimes remote land or deep waters sources. Phytoplankton have fast
population dynamics to which other members of marine food webs must respond. In
contrast, primary productivity on land depends on slow, local nutrient
regeneration in soil at the interface with a nearly transparent atmosphere
where sunlight is rarely in short supply.
As a result, plants at the base of terrestrial food web are often
immobile, long lived, and have slow population dynamics to which higher trophic
levels respond.
Due to the tight coupling of physiology,
movement of organisms and other critical ecological processes to the oceans
fluid, the fluid is the primary driver structuring seascapes and regulating seascape processes. As a result, ecological processes in the ocean operate at
approximately the same space-time scales (~velocities [~1 cm sec-1])
as ocean turbulence (Steele 1991, & Mamayev, 1996). Bottom features are important to some marine
organisms. However the functional importance of bottom features as surfaces
concentrating advected materials, sites of energy acquisition and/or
conservation in the contexts of fluid flows, predation refugia in regions where
preference for water properties such as temperature, salinity and oxygen are
shared between predator and prey; are frequently primarily defined by fluid processes and
properties.
In summary,
differences in the nature of the ocean and atmospheric fluid and adaptations of
organisms to those fluids produce at least two critical differences in the
characteristics of seascapes and landscapes.
Firstly, habitats in the sea have much faster spatial dynamics: their
locations, volumes and quality change quickly at rates defined by the
space-time scales of organisms responses to highly dynamic properties and
processes of the oceans fluid that are driven in turn by atmospheric and planetary
forcing in the form of percipiation, wind, temperature and tides. Secondly,
because the ocean fluid is so viscous, horizontal and vertical currents driven
by atmospheric and planetary forcing, transport essential habitat resources
from sometimes remote sources and concentrate them in particular areas and
times. In such cases habitats are not just locations in space supported by local
resources, but nodes of networked resources and processes many of which are derived from distant "upstream" sources . For
these and other reasons relationships between habitat dynamics and processes regulating
populations, including density dependent processes, are fundamentally different
in the sea and on land. Differences in the nature of habitat in the
ocean and on land are in fact responsible for the order of magnitude
differences in rates of change in species distribution and abundance in the sea
and on land (~10 km yr-1 vs ~ 1 km yr-1) associated
with recent rapid changes in climate (Chueng et al., 2009; Sorte et al., 2010).
3.
The role of IOOS in seascape ecology
The
presence of Integrated Ocean Observation Systems IOOS, including its
infrastructure, data, models and the expertise of its diverse partners, now
allows for the development of seascape ecology with a regional spatial scope
that reflects the realities of the ocean.
Like landscape ecology's modern synthesis (Risser, 1984), an IOOS
informed seascape ecology could provide the theoretical and empirical
underpinnings for the broad scale spatially and temporally explicit ecology required
for the regional assessment and management of ocean resources. Seascape science will integrate the fields
of fisheries oceanography, marine habitat ecology, and ecosystem science with
hydrography and hydrodynamics at its foundation, just as terrestrial landscape
ecology rests appropriately on the foundation of geography and geophysics.
4.
Toward an IOOS informed seascape ecology
With the support of the NOAA office of Science and Technology and North East Fisheries Science Center Cooperative Research Program we
have taken advantage of the IOOS collaborative culture to form an
interdisciplinary workgroup of habitat scientists, oceanographers, fishery
managers, social scientists, and fishermen from academia, government and
industry to develop ecologically informed habitat models for the purpose of addressing
issues of related to the dynamics and assessment of habitats and populations of
butterfish (Peprilus triacanthus) and
longfin squid (Doryteuthis
pealeii) fishery.
We held workshops to combine scientists’ and fishermen’s knowledge into
a single model of butterfish habitat made using National Marine Fisheries
Service (NOAA/NMFS) surveys of organisms and hydrography, and satellite and high-frequency radar
measurements of ocean properties and processes provided by the Mid-Atlantic
Regional Association Coastal Ocean Observing System (MARACOOS), a regional
component of IOOS (Manderson et al., 2011).
During the workshops scientists and fishermen each made “mental models”
that included environmental variables each group considered important in defining
habitat. Over lunch the two models were constructed and evaluated using
cross-validation in a butterfish "smackdown". Following lunch we discussed results of the “smackdown”
and the ecological mechanisms potentially responsible for habitat associations described
by scientists and fishermen. Following
the workshops we developed the model that combined the ecological expertise of
fisherman and scientists.
Once
the combined model was complete, we worked with fishing industry partners to design
an at-sea model evaluation using dynamic habitat model nowcasts provided by
MARACOOS. The combined model was
adjusted slightly to include variables that has slow spatial dynamics (seabed rugosity)
and fast dynamics (Sea surface temperature, water mass frontal boundaries) that
could be delivered in real-time by the ocean observing system.
 |
| Figure 2. Butterfish habitat preference predicted by the model during our 8-day evaluation. The warmer colors indicate areas of preferred habitat. The vessel track is shown in green. |
During
an 8-day trip on the F/V Karen Elizabeth, captained by Chris Roebuck, we
transmitted updated dynamic butterfish habitat model nowcasts to the vessel
(Fig 2). Our survey design involved sampling areas the nowcasts predicted “habitat
suitability” would be “high” and “low”.
In each 3 station set we also included a site where the fisherman, Captain
Roebuck, predicted butterfish would be abundant. We sampled station sets for fish and the
environment during the day and night in three canyon hotspots identified by the
model along the edge of the Mid Atlantic Bight continental shelf. Using this approach
we were able to formally incorporate fishermen’s knowledge into the design of
our field evaluation survey. Throughout the evaluation the crew on board the
Karen Elizabeth sent reports of preliminary results back to shore which we
published on an online blog.
The
evaluation survey showed us that the combined model could be used to identify regions
and times when butterfish concentrations were likely to be high at scales of
10s of kilometers. We learned that fishermen
understood species-habitat associations at scales much finer than could be
described by the data used to construct the model and thus the model itself.
Fishermen also knew locations and times where the animals were likely to occur
that are not typically sampled on scientific surveys including those used in
population assessments.
We
are further refining our mesoscale model with the help of the fishing industry for
the recalibration of indices of population trend based upon the amount of
habitat sampled in fisheries independent surveys. We are also designing prototype adaptive industry
based surveys of dynamic habitat guided by meso-scale habitat models that are intended
to supplement information collected on regional scale fishery-independent population
assessment surveys. These applications may prove especially useful for estimating
population trends of ecosystem keystone species when rapid changes in climate are
causing dramatic changes in fluid properties and processes and thus in the spatial
dynamics of ocean habitats.
5.
The Next Decade
Figure 3. Thermal niche model based on metabolic theory parameterized for butterfish which we coupled to daily Regional Ocean Model (ROMS) hindcasts of bottom water temperature in 2006 for the North West Atlantic (Cape Hatteras [lower left] to Canada [top right]) We are currently using similar prototype models to assess changes in the proportion of habitat available in the ecosystem and sampled in each year during population assessment surveys, design adaptive fields surveys, and to better understand the relationships between habitat dynamics and population dynamics for mobile species that thermoregulate by tracking the thermal dynamics of the seascape.
We are beginning to move beyond empirical
ecological models based upon regional fisheries data and observations toward mechanistic
ecological models that can be coupled to IOOS assimilative oceanographic models
describing critical features of ocean habitats (Fig. 3). Coupled mechanistic biophysical models will
allow us to describe dynamic ocean habitats throughout the water column and
avoid pitfalls associated with using correlative empirical models for
forecasting. Using oceanographic models will also allow us to investigate the
role of advection in delivering key habitat building blocks from sometimes
remote sources to locations and times where/when ocean habitats form. Mechanistic
seascape models that rest on the foundations of assimilative hydrodynamic models
will be particularly useful if climate change produces ocean conditions we have
never before observed.
We intend to continue to work with fishermen within the context of the
IOOS collaborative culture. Integrating their practical ecological knowledge
with academic knowledge of the sea should result the rapid development of accurate
seascape models. These models will first
be considered hypotheses that can be adaptively tested within ocean observing
systems. Once vetted in this way they
can be easily operationalized as tools for the space and time management of
human activities in dynamic ocean ecosystems. We believe this adaptive, iterative,
collaborative approach is the cost effective way to develop a seascape ecology with
a scope broad enough to meet requirements for resource management in the sea.
Rapid
changes in human demand and use patterns of marine resources combined with the
profound effects climate change is having on species distributions and the
structure of marine ecosystems have made the development of a regional scale
seascape ecology reflecting the dynamic realities of the ocean urgent. The foundations of the landscape ecology synthesis in the early 1980s rested
on developments in satellite remote sensing, advances in spatial ecology and the
advent of modern computing. The recent development of operational ocean observing
systems that integrate assimilative hydrodynamic models, and observations from
remote sensing and insitu platforms along with important advances in our
understanding of micro to macro-ecological process in the sea have made the
time ripe for a similar synthesis and the development of a robust science of
seascape ecology useful for the management of marine ecosystems.
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