Download Physical-biological Coupling in Marine Ecosystems

US GLOBEC
Before and After
Eileen Hofmann
Old Dominion University
Outline of Presentation
• Understanding prior to GLOBEC
• Advances in understanding physicalbiological interactions resulting from
GLOBEC science
• Moving forward from what has been
learned from GLOBEC
Pre-GLOBEC
• Recruitment to marine fish populations
depended on
• Critical period - variations in larval feeding
and nutrition
> larval feeding was viewed in terms of a direct link from
zooplankton to the consumer
• Aberrant drift - advection into favorable or
unfavorable environmental conditions
> the scales of the physical environment were known but
the details of the scales that were relevant to the
planktonic organism were essentially unexplored
Pre-GLOBEC
• Physical oceanography and biological studies
were essentially separate disciplines
> difficulties in attributing causes, effects and mechanism
• Studies restricted to a limited locations and
short times
> decadal and longer time variability not recognized as
driving forces
• Lack of linkage and cohesion between the
observational and modeling communities
Science Challenge
• To understand the dependence of marine
population dynamics on the physical structure
of the ocean and to link this to ecosystem
dynamics (NAS, Steele et al., 1987)
• GLOBEC Goal
“…. understand how climate change and
variability will translate into changes in the
structure and dynamics of marine ecosystems
and in fishery production”
Scales of Processes
• View that marine ecosystems operate along a
continuum defined by space and time
underpinned much of the research that was
undertaken during GLOBEC
• GLOBEC --> View has evolved to one in which
marine ecosystem variability and population
recruitment result from the integration of
processes across all scales and includes direct
as well as indirect interactions
Processes at all scales
influence variability of
marine organisms and
populations
Studies of marine
ecosystems require
integration of the
environmental drivers
and biological responses
Scales of Processes
• Pick out key scales
and follow these
through system
• Multiple optima in
ecosystems and
have begun to
understand
interactions that
produce these
Scales of spatial variation
Scale of aggregation depends
on view of system
Structure modifies the operation of the ecosystem
Scale of aggregations - exploited by different predators
Krill are important to different parts of the food web because of a spatial
structure that covers many scales
Longevity and overwinter survival allows spatial and temporal transfer
Makes energy available to predators
GLOBEC - Recruitment patterns
Why patterns occur and what are key processes?
Knowledge of scale interactions have resulted in
additional hypotheses about physical-biological
controls on recruitment
Alternative food
web structures
Implications for
production and
maintenance of
predators
Understand the
causes for change
and key processes
Development of conceptual frameworks for
recruitment that encompass multiple scales
Predators
Cod larvae
and early juveniles
Copepods
OCEAN CLIMATE
PARAMETERS
Transport
Temperature
Light conditions
Turbulence
Phytoplankton
Development of field and modeling programs to test
conceptual models of ecosystem structure and function
Modeling Physical-Biological
Interactions
• Modeling is central to GLOBEC science
• Built on scientific and technological advances,
such as realistic circulation models
• Integration of IBMs with circulation models
resulted in ability to determine transport
pathways, residence times, controls on growth
• Allowed identification of spawning areas,
recruitment regions, connectivity of populations
at a range of scales
Coastal Gulf
of Alaska
Realistic Regional
Circulation Models
Include sea ice, coupling
to atmospheric models
and larger scale models
West Antarctic
Peninsula
Georges Bank
Advection
Autochtonous – Allocthonous
production
Displaces production
Disconnects
Production - Mortality
Production - Export
Population connectivity at regional to circumpolar scales
Speirs et al.(2006)
Tian et al. (2009)
Spiers et al.
Thorpe et al. (2007)
Connection between spawning
and
recruitment regions
Inclusion of detailed biology
provides process understanding
Importance of comparative
studies
Physical-biological models
evolved to systems of
interconnected modules
Developed around data sets
from GLOBEC programs
NEMURO - minimum trophic
structure and biological
relationships … thought to
be essential in describing
ecosystem dynamics in the
North Pacific
deYoung et al. (2004)
Top down and bottom
up controls operate
simultaneously but
relative effect of each
is variable
GLOBEC
Target species
Approach
GLOBEC science evolved
to include humans
as part of the
marine food web
Perry et al. (2010)
Importance of top predators
including humans
Barange et al. (2010)
Physical-biological Interactions
GLOBEC Science
• Ecosystems result from interactions across
multiple scales
• Comparative studies provide insights beyond
those from single program
• Target species approach allowed picking out
key processes - compare with other systems
• Top predators, including humans, are integral
parts of food web
• Physical, biological, observational, and
observational communities focused on
integrated research programs
Future Directions
Next challenge
Provide meaningful forecasts and projections
of marine population variability and response to
climate change and human impacts
Climate/
JGOFS
Heat Distribution/
Biogeochemistry
Budgets/
Elemental cycles
Weather/
GLOBEC
Synoptic patterns/
Events/
Population dynamics Species
Link regional and
basin-scale models
Expand beyond
regional focus
Methods for
Down/Up
Scaling of
Physical-biological
Models
Climate Projections
Ecosystem Responses
Fogarty et al. (2008)
Temperature warming
and cod recruitment
Relevance to Global Ecosystems
Global carbon budget models
lack biological detail
Current models do not capture what is known about
ecosystems and harvesting/human impacts
What Needed?
• Sustained observations that support
predictions and forecasts
• Continued integration of observations and
models from outset of programs
• Explicit inclusion of human dimension
• Estimates of uncertainty and communication
of this to policy makers
• Educational outreach to public sector
Concluding Remarks
• GLOBEC science advanced state of models,
data sets, and conceptual understanding of
physical-biological interactions that underlie
marine population variability
• Provides basis to develop the integrative
research programs between the natural,
social, and economic sciences that are
needed to understand and sustain the world’s
ocean in an era of increasing change and
uncertainty