Saltmarsh ecosystem services under multiple stress Context-dependent effects of sediment deposition & increased inundation

Transcription

1 Saltmarsh ecosystem services under multiple stress Context-dependent effects of sediment deposition & increased inundation Carl Van Colen Joanne Wong, Steven Degraer, Laura Airoldi, Magda Vincx

2 Outline from Ewoud Monballiu who am I? who is involved? which challenge(s) faced us? (stressors) what was our assumption in order to tackle this challenge(s)? (research hypotheses) what happened: interventions, processes, applications, discoveries, (un)expected barriers, pivotal moments or breakthrough moments? (results) where we are now & what principles of working can be gleaned from this? my proposition is

3 Who am I (and what do I study)? Coastal habitats and ecosystems are affected by multiple stressors

4 Coastal benthic habitats are affected by multiple stressors Broad scale phenomena Local disturbances and environmental change Multiple stressors interact and result in changes in the intrinsic dynamics of ecosystems that may predispose the system to critical shifts Disentangling local vs. broad-scale drivers of change & potential interaction effects Mora et al PloS Biology. Predicted changes by 2100 due to greenhouse gas emissions

5 Who am I (and what do I study)? Ultimate research goal... Moving from hindsight to a more predictive science that is able to assist in the implementation of ecosystem-based management Methods Study context-dependency in ecological interactions that determine BDEF relationships & support resilience Spatial and temporal context-dependency Evolutionary adaptation Coastal habitats: estuaries, coastal lagoons, salt marshes, continental shelf seas Benthic communities: microbial communities benthic invertebrates (macrobenthos) nekton

6 Macrobenthos as a bio-indicator of environmental change Well suited for long-term comparative investigations since many of the constituent species are sessile or have low mobility relatively long-lived integrate effects of environmental change over time Macrobenthos-mediated ecosystem services Production services: food provisioning (direct, e.g. shell fish; indirect: provision of food/nutrients to higher trophic groups); raw materials (e.g. shells) Regulating services (removal of pollutants) Supporting services (nutrient cycling, biologically-mediated habitat)

7 Saltmarsh vegetation provide habitat & ecosystem services provide erosion control, sediment accretion and carbon sequestration

8 Who is involved? M. Alsebai Long-term variability and regime shifts in benthic communities S.Mestdagh Estuarine benthic-pelagic coupling E. Ong Stressors & benthos behavior J. Wong Management options of cumulative stressors in salt marshes X. Fang Estuarine benthic ecosystem functioning: Biogeochemical modelling V. Lo Salt marsh biodiversity and functioning: human pressures & Recovery pathways

9 158 ha - Ramsar list - Natura 2000 Dunes, salt marsh and creeks, tidal flats, salt pans, tidal pond. To be enlarged in the future (+120 ha). Case study 1: Sediment-benthos relationships in the Zwin coastal lagoon 2003: 95 samples + seasonal survey 12 stations (Tricolor study)

10 Case study 1: Sediment-benthos relationships in the Zwin coastal lagoon 2010: 60 samples (BEMONA and ZTAR project)

11 Case study 1: Sediment-benthos relationships in the Zwin coastal lagoon 2013: 60 samples (ZTAR project)

12 Probability of occurrence Biomass (g AFDW.m -2 ) Probability of occurrence Biomass (g AFDW.m -2 ) Probability of of occurrence Biomass Biomass (g (g AFDW.m AFDW.m -2-2 ) ) Probability of occurrence Biomass (g AFDW.m -2 ) Probability of occurre Biomass (g AFDW.m Probability of occurre Biomass (g AFDW.m 10 75% 75% Habitat preference: identification of critical thresholds 2 50% % 25% modelling occurrence and biomass of benthos as a function of sediment 2 50% 1 0% % % 75% 50% 25% S. H. plana diversicolor % 75% 50% 25% M. H. filiformis balthica % Median grain size (µm) % 75% 50% 25% 0% Median grain size (µm) S. plana % Median grain size (µm) 5 100% M. balthica - Highest probability of 4 75% occurrence < 200 µm 3 50% 2 25% 1 0% Biomass optima for Hediste and Scrobicularia < 150 µm - Biomass optimum for 300 µm probability of occurrence < 200 µm Median grain size (µm) Van Colen C. et al. (2014) Sediment-benthos relationships as a tool to assist in conservation practices in a coastal lagoon subjected to sediment change. Biodiversity and conservation

13 SPATIO-TEMPORAL DYNAMICS IN BENTHIC COMMUNITIES AND SEDIMENT PROPERTIES IN TWO CONTRASTING HABITATS B N 200 m Van Colen C. et al. (2014) Sediment-benthos relationships as a tool to assist in conservation practices in a coastal lagoon subjected to sediment change. Biodiversity and conservation

14 Organic matter (%) Biomass (g AFDW m-²) Median grain size (µm) Mud content (% < 63µm) A B Context-dependent sedimentological change (spatial segregation) - Coarsening of the inlet channel - Finer sediment in the high intertidal Benthos response to sediment change C Inlet channel High intertidal D Inlet channel Scrobicularia plana Macoma balthica Heteromastus filiformis Hediste diversicolor Total biomass High intertidal - Gradual infilling of the floodplain Increased access for ground predators Overall decrease in sediment organic matter, macrobenthos biomass & thus food supply for shorebirds and nekton foraging in the intertidal creeks Temporal variability in sediment composition, (a) median grain size, (b) mud content, (c) organic matter content; and (d) biomass of macrobenthos in the inlet channel and intertidal habitat surrounding the tidal pond. The top of the stacked bar represents the total biomass and the biomass of the four most dominant species in terms of biomass are depicted in different colors (see inset). Error bars are 95 % confidence intervals (note that mud content = 0 in 2010)

15 Abundance (average monthly total counts) TEMPORAL DYNAMICS IN SHOREBIRD ABUNDANCES IN THE ZWIN COASTAL LAGOON C. alpina 140 R. avosetta P. squatarola T. tadorna Temporal change in average winter (November-February) abundances of Calidris alpina (Dunlin), Pluvialis squatarola (Grey Plover), Recurvirostra avosetta (Avocet), and Tadorna tadorna (Shelduck) in the Zwin nature reserve between 2003 and Solid lines represent running average fits (n=2) through the average counts. Data are obtained from monthly density censuses of shorebirds performed during high tide for the complete nature reserve in November-February between November 2003 and February Survey counts for R. avosetta were occasionally missing for February 2006 and January Population densities significantly declined over time for T. tadorna (simple linear regression: F(1, 6) = 16.95; R² = 0.74; p = 0.006; Durbin-Watson test of serial correlation over time = D = 1.52, correlation = 0.10)

16 Shellduck feeding traces on microbial biofilm

17 Further actions: Monitoring nekton and benthos responses to restoration management in the Zwin coastal lagoon

18 Case study 2: Interactive effects of increased inundation and nutrient loading on Spartina maritima in the NE Adriatic Sea 9 years of Deegan et al. (2012) Coastal eutrophication as a driver of salt marsh loss. Nature 490: Excess in nutrients cause saltmarsh deterioration

19 Testing the joint effect of excess nutrients and increased inundation on Spartina Experiment using field mesocosms Stressors: excess nutrients & increased inundation Other factor: soil type Wong J. et al. (2015) Sediment-benthos relationships as a tool to assist in conservation practices in a coastal lagoon subjected to sediment change. Marine environmental research

20 8 scenarios of orthogonal combinations of two levels of: 1) Inundation low (ambient) vs. high (+10 cm = 20% more inundation: i.e scenario, Theseus 2009) 2) Nutrient low (ambient) vs. high (Osmocote fertiliser NPK: 1.5 mg/l) 3) Soil type low (~2%) vs. medium (~10%) organic Study site: Vallona lagoon Replication: n=8 Growth season July-September Vallona Lagoon

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22 - Dominant negative inundation effects on plant properties - Root growth worse when increased inundation is coupled with high nutrients Reduced vertical growth keep up with sea level rise Impact on erosion control?

23 Summary of the two case studies Sediment deposition and increased inundation affect saltmarsh ecosystem services - habitat quality for e.g. shorebirds - plant biomass carbon sequestration & erosion control - benthos & salt marsh mediated effects on regulating and supporting services BUT The magnitude and direction of stressor impact can be site-specific depending on environmental conditions - hydrodynamics - nutrient loading

24 PROPOSITION With current delays and limitations on the mitigation of global stressors, it is crucial to identify which factors can maintain ecosystem resilience at local scales. Investigating interactive effects of global and local stressors (or management actions, i.e. removal/reduction of a local stressor) across gradients in space and time can therefore assist in the implementation of conservation strategies. "The single most important problem is our misguided focus on identifying the single most important problem! - Jared Diamond

25 Acknowledgments Thank you for your attention! MARBIOL and UNIBO colleagues Research funded by the Research Foundation Flanders (FWO) Mares doctoral programme, ANB Contact: