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Paul Maxwell, AMSA 2013. Managing Seagrass Resilience: feedbacks and scales
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Paul Maxwell, AMSA 2013. Managing Seagrass Resilience: feedbacks and scales

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"I’m a phd student from Griffith University. Today I’m presenting the outcomes of a workshop I was lucky enough to attend which was funded by ACEAS, the Australian Centre for Ecological Analysis and …

"I’m a phd student from Griffith University. Today I’m presenting the outcomes of a workshop I was lucky enough to attend which was funded by ACEAS, the Australian Centre for Ecological Analysis and Synthesis. I’m presenting on behalf of a host of co-authors who are listed here. I thank them for the opportunity to present on their behalf." -Paul Maxwell

The aim of the ACEAS workshop was to generate a framework that outlines how a sea grasses response to impact operates on multiple scales and how understanding that scale is vital for understanding how seagrass ecosystems develop, maintain and enhance their resilience to disturbances.

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  • I’m a phd student from Griffith University. Today I’m presenting the outcomes of a workshop I was lucky enough to attend which was funded by ACEAS, the Australian Centre for Ecological Analysis and Synthesis. I’m presenting on behalf of a host of co-authors who are listed here. I thank them for the opportunity to present on their behalf. The aim of the ACEAs workshop was to generate a framework that outlines how a seagrasses response to impact operates on multiple scales and how understanding that scale is vital for understanding how seagrass ecosystems develop, maintain and enhance their resilience to disturbances.
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    • 1. 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
    • 2. Ecosystems are complex Sudden shifts occur in many ecosystems AMSA Conference, 10th July 2013
    • 3. Ecosystems are complex Sudden shifts occur in many ecosystems Coral Reefs (Hughes et al 2010, TREE) AMSA Conference, 10th July 2013
    • 4. 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)
    • 5. 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
    • 6. Seagrass collapse – Multiple stressors, multiple scales AMSA Conference, 10th July 2013
    • 7. Seagrass collapse – Multiple stressors, multiple scales Wasting disease – Cellular scale (ultimate source of collapse) AMSA Conference, 10th July 2013
    • 8. 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
    • 9. 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 Tidalrange(cm) “Afsluitdijk” AMSA Conference, 10th July 2013
    • 10. 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 Tidalrange(cm) Coupled with decadal increases in sedimentation (de Jonge et al 1993) “Afsluitdijk” 0 50 100 150 200 1965 1970 1975 1980 1985 1990 TSS(mg/l) Site 1 Site 2 AMSA Conference, 10th July 2013
    • 11. No recovery AMSA Conference, 10th July 2013
    • 12. 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
    • 13. 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
    • 14. Feedback processes control resistance and recovery AMSA Conference, 10th July 2013
    • 15. Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 16. Seagrass response Impact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 17. Seagrass response Feedback Processes Impact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 18. Seagrass response Feedback Processes Impact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 19. Seagrass response Threshold Feedback Processes Impact above thresholdImpact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 20. Seagrass response Threshold Feedback Processes Feedback Processes Impact above thresholdImpact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 21. Seagrass response Threshold Feedback Processes Feedback Processes Impact above thresholdImpact below threshold Alternate RegimeRegime 1 Feedback processes control resistance and recovery
    • 22. Trajectories between states are complicated Seagrass present Seagrass absent Loss trajectory Stressor increasing AMSA Conference, 10th July 2013
    • 23. Trajectories between states are complicated Seagrass present Seagrass absent Loss trajectory Stressor increasing AMSA Conference, 10th July 2013
    • 24. Trajectories between states are complicated Seagrass present Seagrass absent Loss trajectory Stressor increasing Changed hydrology Increased sedimentation Wasting disease AMSA Conference, 10th July 2013
    • 25. Trajectories between states are complicated Seagrass present Seagrass absent Loss trajectory Recovery trajectory Stressor increasing Changed hydrology Increased sedimentation Wasting disease AMSA Conference, 10th July 2013
    • 26. Trajectories between states are complicated Seagrass present Seagrass absent Loss trajectory Recovery trajectory Stressor increasing Changed hydrology Increased sedimentation Wasting disease Sediment resuspension Change current speed AMSA Conference, 10th July 2013
    • 27. 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
    • 28. 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
    • 29. 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 content Leaf 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
    • 30. 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 content Leaf 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
    • 31. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium AMSA Conference, 10th July 2013
    • 32. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium AMSA Conference, 10th July 2013
    • 33. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium AMSA Conference, 10th July 2013
    • 34. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium Physiological scale AMSA Conference, 10th July 2013
    • 35. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium Physiological scale Morphological scale AMSA Conference, 10th July 2013
    • 36. Outcome 1: Scale provides order ETRmax Shoot C:N Rhizome carbohydrates Shoot production Root extension Shoot density Chlorophyll content Leaf extension Leaf area Above ground biomass Below ground biomass Percent cover Flowering intensity Meadow area Regional seagrass extent second 10000 km 1 mm 10 m 10 cm 1km Seagrass responses (McMahon et al 2013) 100 km minute hour day month week year century millennium Physiological scale Morphological scale Landscape scale AMSA Conference, 10th July 2013
    • 37. second 10000 km 1 mm 10 m 10 cm 1km 100 km minute hour day month week year century Physiological scale Morphological scale Landscape scale millennium 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
    • 38. Outcome 2: Species specific modes of resistance and recovery Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) AMSA Conference, 10th July 2013
    • 39. Outcome 2: Species specific modes of resistance and recovery OPPORTUNISTIC SPECIESPERSISTENT SPECIES EPHEMERAL SPECIESNO SEAGRASS Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) AMSA Conference, 10th July 2013
    • 40. Outcome 2: Species specific modes of resistance and recovery OPPORTUNISTIC SPECIESPERSISTENT SPECIES EPHEMERAL SPECIESNO SEAGRASS Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) P. australis (east) Enhalus acoroides P. sinuosa Thalassia spp. AMSA Conference, 10th July 2013
    • 41. Outcome 2: Species specific modes of resistance and recovery OPPORTUNISTIC SPECIESPERSISTENT SPECIES EPHEMERAL SPECIESNO SEAGRASS Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) 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
    • 42. Outcome 2: Species specific modes of resistance and recovery OPPORTUNISTIC SPECIESPERSISTENT SPECIES EPHEMERAL SPECIESNO SEAGRASS Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) 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
    • 43. Outcome 2: Species specific modes of resistance and recovery OPPORTUNISTIC SPECIESPERSISTENT SPECIES EPHEMERAL SPECIESNO SEAGRASS Speed of recovery (event recurrence time/species recovery time) Resistancetodisturbance (survivaltime/eventduration) 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
    • 44. Outcome 3: Thresholds of feedback processes Time Seagrassresponse DISTURBANCE (Shootdensity,biomass) AMSA Conference, 10th July 2013
    • 45. Outcome 3: Thresholds of feedback processes Time Seagrassresponse DISTURBANCE (Shootdensity,biomass) AMSA Conference, 10th July 2013
    • 46. Outcome 3: Thresholds of feedback processes Time Seagrassresponse DISTURBANCE Threshold for feedback efficiency (Shootdensity,biomass) AMSA Conference, 10th July 2013
    • 47. Outcome 3: Thresholds of feedback processes Time Seagrassresponse DISTURBANCE Recovery from disturbance Threshold for feedback efficiency (Shootdensity,biomass) AMSA Conference, 10th July 2013
    • 48. Time DISTURBANCE Poorer conditions Better conditions Seagrassresponse (Shootdensity,biomass) Outcome 3: Thresholds of feedback processes AMSA Conference, 10th July 2013
    • 49. Time DISTURBANCE Seagrassresponse (Shootdensity,biomass) - sedimentation - tidal regime (wasting disease) Poorer conditions Better conditions Outcome 3: Thresholds of feedback processes AMSA Conference, 10th July 2013
    • 50. Time DISTURBANCE Seagrassresponse (Shootdensity,biomass) - sedimentation - tidal regime (wasting disease) Poorer conditions Better conditions Outcome 3: Thresholds of feedback processes AMSA Conference, 10th July 2013
    • 51. Time DISTURBANCE Change of state possible Seagrassresponse (Shootdensity,biomass) - sedimentation - tidal regime (wasting disease) Poorer conditions Better conditions Outcome 3: Thresholds of feedback processes AMSA Conference, 10th July 2013
    • 52. Time DISTURBANCE Change of state possible Manage to keep seagrass units at each scale above threshold Seagrassresponse (Shootdensity,biomass) - sedimentation - tidal regime (wasting disease) Poorer conditions Better conditions Outcome 3: Thresholds of feedback processes
    • 53. Implications for management Physiological scale Morphological scale Landscape scale MANAGEMENT PRIORITIES MONITORING STRATEGIESAMSA Conference, 10th July 2013
    • 54. 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
    • 55. 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
    • 56. 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
    • 57. 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
    • 58. 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
    • 59. 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
    • 60. Thank you AMSA Conference, 10th July 2013

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