Post on 10-Jul-2015
Managing for seagrass
resilience: feedbacks and
scales
Paul Maxwell
Kate O’Brien, Angus Ferguson, James Udy, Gary Kendrick, Peter Scanes, Kieryn Kilminster, Michelle Waycott, Bill Dennison, Len
McKenzie, Matt Adams, Jimena Samper-Villarreal, Kathryn McMahon, Mitch Lyons, Vanessa Lucieer, Lynda Radke
AMSA Conference, 10th July 2013
Ecosystems are complex
Sudden shifts occur in many ecosystems
AMSA Conference, 10th July 2013
Ecosystems are complex
Sudden shifts occur in many ecosystems
Coral Reefs (Hughes et al 2010, TREE)
AMSA Conference, 10th July 2013
AMSA Conference, 10th July 2013
Ecosystems are complex
Sudden shifts occur in many ecosystems
Rangelands (Walker et al 1981, Ecology)
Coral Reefs (Hughes et al 2010, TREE)
Seagrass collapse – Dutch Wadden Sea
Source: de Jonge et al 1993
1920’s 1950’s 1972 1988
Biomass (gCm-2)
Area (km2)
Seagrass collapsed in 1930’s
200
0
100
50
150
AMSA Conference, 10th July 2013
Seagrass collapse – Multiple stressors, multiple scales
AMSA Conference, 10th July 2013
Seagrass collapse – Multiple stressors, multiple scales
Wasting disease – Cellular scale (ultimate source of collapse)
AMSA Conference, 10th July 2013
Seagrass collapse – Multiple stressors, multiple scales
Wasting disease – Cellular scale (ultimate source of collapse)
Change in tidal regime over course of three centuries (de Jonge et al 1993)
“Afsluitdijk”
AMSA Conference, 10th July 2013
Seagrass collapse – Multiple stressors, multiple scales
Wasting disease – Cellular scale (ultimate source of collapse)
Change in tidal regime over course of three centuries (de Jonge et al 1993)
100
120
140
160
180
200
1860 1880 1900 1920 1940 1960 1980
Tid
al ra
ng
e (
cm
)“Afsluitdijk”
AMSA Conference, 10th July 2013
Seagrass collapse – Multiple stressors, multiple scales
Wasting disease – Cellular scale (ultimate source of collapse)
Change in tidal regime over course of three centuries (de Jonge et al 1993)
100
120
140
160
180
200
1860 1880 1900 1920 1940 1960 1980
Tid
al ra
ng
e (
cm
)
Coupled with decadal increases in sedimentation (de Jonge et al 1993)
“Afsluitdijk”
0
50
100
150
200
1965 1970 1975 1980 1985 1990
TS
S (
mg
/l)
Site 1
Site 2
AMSA Conference, 10th July 2013
No recovery
AMSA Conference, 10th July 2013
No recovery
No significant recovery despite:
• 120 million Euros spent in past 20 years
• Eelgrass recovered in much of the North Atlantic range
AMSA Conference, 10th July 2013
No recovery
No significant recovery despite:
• 120 million Euros spent in past 20 years
• Eelgrass recovered in much of the North Atlantic range
Why haven’t things improved?
AMSA Conference, 10th July 2013
Feedback processes control resistance and recovery
AMSA Conference, 10th July 2013
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Impact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Feedback
Processes
Impact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Feedback
Processes
Impact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Threshold
Feedback
Processes
Impact above thresholdImpact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Threshold
Feedback
ProcessesFeedback
Processes
Impact above thresholdImpact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Seagrass
response
Threshold
Feedback
ProcessesFeedback
Processes
Impact above thresholdImpact below threshold
Alternate RegimeRegime 1
Feedback processes control resistance and recovery
Trajectories between states are complicated
Seagrass present
Seagrass absent
Loss
trajectory
Stressor increasingAMSA Conference, 10th July 2013
Trajectories between states are complicated
Seagrass present
Seagrass absent
Loss
trajectory
Stressor increasingAMSA Conference, 10th July 2013
Trajectories between states are complicated
Seagrass present
Seagrass absent
Loss
trajectory
Stressor increasing
Changed
hydrologyIncreased
sedimentation
Wasting
disease
AMSA Conference, 10th July 2013
Trajectories between states are complicated
Seagrass present
Seagrass absent
Loss
trajectory
Recovery
trajectory
Stressor increasing
Changed
hydrologyIncreased
sedimentation
Wasting
disease
AMSA Conference, 10th July 2013
Trajectories between states are complicated
Seagrass present
Seagrass absent
Loss
trajectory
Recovery
trajectory
Stressor increasing
Changed
hydrologyIncreased
sedimentation
Wasting
disease
Sediment resuspension
Change current speed
AMSA Conference, 10th July 2013
Stressors, pressures and feedbacks affecting light
Stressors and pressures Seagrass responses(McMahon et al 2013)
Feedback processes(strategies for resistance and recovery)
AMSA Conference, 10th July 2013
Stressors, pressures and feedbacks affecting light
Cloud shading
Sediment
resuspension
Water clarity
Water depth
Self-shading
Sediment
runoff
Climatic
fluctuations
Planetary and
solar
fluctuations
Stressors and pressures
Local
disturbance
(boat anchors)
Dredging
Point source
nutrients
Algal blooms
Floods
Trawling
Catchment
clearing
Atmospheric
light
attenuation
(e.g. smog)
Seagrass responses(McMahon et al 2013)
Feedback processes(strategies for resistance and recovery)
AMSA Conference, 10th July 2013
Stressors, pressures and feedbacks affecting light
Cloud shading
Sediment
resuspension
Water clarity
Water depth
Self-shading
Sediment
runoff
Climatic
fluctuations
Planetary and
solar
fluctuations
Stressors and pressures
Local
disturbance
(boat anchors)
Dredging
Point source
nutrients
Algal blooms
Floods
Trawling
Catchment
clearing
Atmospheric
light
attenuation
(e.g. smog)
Seagrass responses(McMahon et al 2013)
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extension
Shoot density
Chlorophyll
contentLeaf extension
Leaf area
Above ground
biomass Below ground
biomass
Percent cover
Meadow area
Feedback processes(strategies for resistance and recovery)
Regional
seagrass
extent
AMSA Conference, 10th July 2013
Stressors, pressures and feedbacks affecting light
Cloud shading
Sediment
resuspension
Water clarity
Water depth
Self-shading
Sediment
runoff
Climatic
fluctuations
Planetary and
solar
fluctuations
Stressors and pressures
Local
disturbance
(boat anchors)
Dredging
Point source
nutrients
Algal blooms
Floods
Trawling
Catchment
clearing
Atmospheric
light
attenuation
(e.g. smog)
Seagrass responses(McMahon et al 2013)
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extension
Shoot density
Chlorophyll
contentLeaf extension
Leaf area
Above ground
biomass Below ground
biomass
Percent cover
Meadow area
Feedback processes(strategies for resistance and recovery)
Algal grazing
rates
Regional
seagrass
extent
Seagrass
grazing rates
Genetic
variability
Trapping of
sediments
Nutrient
filtration
Reduced
water velocity
Sediment
stabilisation
Seagrass
succession
Flowering
intensity
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extension
Shoot density
Chlorophyll
contentLeaf extension
Leaf area
Above ground
biomass Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extension
Shoot density
Chlorophyll
contentLeaf extension
Leaf area
Above ground
biomass
Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extensionShoot density
Chlorophyll
content
Leaf extension
Leaf area
Above ground
biomass
Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extensionShoot density
Chlorophyll
content
Leaf extension
Leaf area
Above ground
biomass
Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
Physiological
scale
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extensionShoot density
Chlorophyll
content
Leaf extension
Leaf area
Above ground
biomass
Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
Physiological
scale
Morphological
scale
AMSA Conference, 10th July 2013
Outcome 1: Scale provides order
ETRmax
Shoot C:N
Rhizome
carbohydrates
Shoot
production
Root
extensionShoot density
Chlorophyll
content
Leaf extension
Leaf area
Above ground
biomass
Below ground
biomass
Percent cover
Flowering
intensity
Meadow area
Regional
seagrass
extent
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
Seagrass responses(McMahon et al 2013)
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ry
mill
en
niu
m
Physiological
scale
Morphological
scale
Landscape
scale
AMSA Conference, 10th July 2013
se
co
nd
10000
km
1 mm
10 m
10 cm
1km
100 km
min
ute
hour
day
mo
nth
we
ek
ye
ar
ce
ntu
ryPhysiological
scale
Morphological
scale
Landscape
scale
mill
en
niu
m
First outcome:
Managing and monitoring seagrass
ecosystems, need to understand
scale of stressor and response
Outcome 1: Scale provides order
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
OPPORTUNISTIC SPECIESPERSISTENT SPECIES
EPHEMERAL SPECIESNO SEAGRASS
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
OPPORTUNISTIC SPECIESPERSISTENT SPECIES
EPHEMERAL SPECIESNO SEAGRASS
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
P. australis (east)
Enhalus acoroides
P. sinuosa
Thalassia spp.
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
OPPORTUNISTIC SPECIESPERSISTENT SPECIES
EPHEMERAL SPECIESNO SEAGRASS
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
P. australis (east)
Enhalus acoroides
P. sinuosa
Thalassia spp.
Syringodium spp.
H. spinuosa
Halodule spp.
Ruppia spp.
H. ovalis
H. decipiens
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
OPPORTUNISTIC SPECIESPERSISTENT SPECIES
EPHEMERAL SPECIESNO SEAGRASS
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
P. australis (east)
Enhalus acoroides
P. sinuosa Thalassodendron spp.
Thalassia spp.
P. corriacea
P. australis (west)
Cymodocea spp.
Zostera spp.
Amphibolis spp.
Syringodium spp.
H. spinuosa
Halodule spp.
Ruppia spp.
H. ovalis
H. decipiens
AMSA Conference, 10th July 2013
Outcome 2: Species specific modes of resistance and recovery
OPPORTUNISTIC SPECIESPERSISTENT SPECIES
EPHEMERAL SPECIESNO SEAGRASS
Speed of recovery(event recurrence time/species recovery time)
Re
sis
tan
ce to d
istu
rba
nce
( su
rviv
al tim
e/e
ve
nt d
ura
tio
n)
P. australis (east)
Enhalus acoroides
P. sinuosa Thalassodendron spp.
Thalassia spp.
P. corriacea
P. australis (west)
Cymodocea spp.
Zostera spp.
Amphibolis spp.
Syringodium spp.
H. spinuosa
Halodule spp.
Ruppia spp.
H. ovalis
H. decipiens
AMSA Conference, 10th July 2013
Outcome 3: Thresholds of feedback processes
Time
Seagra
ss r
esponse
DISTURBANCE(S
ho
ot d
en
sity,
bio
ma
ss)
AMSA Conference, 10th July 2013
Outcome 3: Thresholds of feedback processes
Time
Seagra
ss r
esponse
DISTURBANCE(S
ho
ot d
en
sity,
bio
ma
ss)
AMSA Conference, 10th July 2013
Outcome 3: Thresholds of feedback processes
Time
Seagra
ss r
esponse
DISTURBANCE
Threshold for
feedback efficiency
(Sh
oo
t d
en
sity,
bio
ma
ss)
AMSA Conference, 10th July 2013
Outcome 3: Thresholds of feedback processes
Time
Seagra
ss r
esponse
DISTURBANCE
Recovery from
disturbance
Threshold for
feedback efficiency
(Sh
oo
t d
en
sity,
bio
ma
ss)
AMSA Conference, 10th July 2013
Time
DISTURBANCE
Poorer
conditions
Better
conditionsSeagra
ss r
esponse
(Sh
oo
t d
en
sity,
bio
ma
ss)
Outcome 3: Thresholds of feedback processes
AMSA Conference, 10th July 2013
Time
DISTURBANCE
Seagra
ss r
esponse
(Sh
oo
t d
en
sity,
bio
ma
ss)
- sedimentation
- tidal regime
(wasting disease)
Poorer
conditions
Better
conditions
Outcome 3: Thresholds of feedback processes
AMSA Conference, 10th July 2013
Time
DISTURBANCE
Seagra
ss r
esponse
(Sh
oo
t d
en
sity,
bio
ma
ss)
- sedimentation
- tidal regime
(wasting disease)
Poorer
conditions
Better
conditions
Outcome 3: Thresholds of feedback processes
AMSA Conference, 10th July 2013
Time
DISTURBANCE
Change of state
possible
Seagra
ss r
esponse
(Sh
oo
t d
en
sity,
bio
ma
ss)
- sedimentation
- tidal regime
(wasting disease)
Poorer
conditions
Better
conditions
Outcome 3: Thresholds of feedback processes
AMSA Conference, 10th July 2013
Time
DISTURBANCE
Change of state
possible
Manage to keep seagrass units at each scale above threshold
Seagra
ss r
esponse
(Sh
oo
t d
en
sity,
bio
ma
ss)
- sedimentation
- tidal regime
(wasting disease)
Poorer
conditions
Better
conditions
Outcome 3: Thresholds of feedback processes
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
MANAGEMENT PRIORITIES
MONITORING STRATEGIESAMSA Conference, 10th July 2013
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
AMSA Conference, 10th July 2013
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
Investigatory
monitoring
- physiological indicators of stress
- reproductive output
- physiological feedback processes
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
Investigatory
monitoring
- physiological indicators of stress
- reproductive output
- physiological feedback processes
Manage environmental
conditions
- regional management of
water quality
- catchment management
- reduce sedimentation
- reduce nutrient loading
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
Investigatory
monitoring
- physiological indicators of stress
- reproductive output
- physiological feedback processes
Manage environmental
conditions
- regional management of
water quality
- catchment management
- reduce sedimentation
- reduce nutrient loading
Seasonal or annual
monitoring
- mapping meadow change
- patch dynamics
- species distribution
- seagrass biomass
- morphological feedback
processes
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
Investigatory
monitoring
- physiological indicators of stress
- reproductive output
- physiological feedback processes
Manage environmental
conditions
- regional management of
water quality
- catchment management
- reduce sedimentation
- reduce nutrient loading
Seasonal or annual
monitoring
- mapping meadow change
- patch dynamics
- species distribution
- seagrass biomass
- morphological feedback
processes
Manage ecosystem
integrity
- habitat protection (MPA’s)
- habitat and species
connectivity
Implications for management
Physiological
scale
Morphological
scale
Landscape
scale
Facilitate seagrass
recovery
MANAGEMENT PRIORITIES
MONITORING STRATEGIES
- reduce plant stress
- maximise seed dispersal
- improve conditions to
maximise photo efficiency
Investigatory
monitoring
- physiological indicators of stress
- reproductive output
- physiological feedback processes
Manage environmental
conditions
- regional management of
water quality
- catchment management
- reduce sedimentation
- reduce nutrient loading
Seasonal or annual
monitoring
- mapping meadow change
- patch dynamics
- species distribution
- seagrass biomass
- morphological feedback
processes
Manage ecosystem
integrity
- habitat protection (MPA’s)
- habitat and species
connectivity
Periodic monitoring
- broad scale and long term
assessments
- remote sensing
- ecosystem models
- landscape feedback
processes
Thank you
AMSA Conference, 10th July 2013