Zeegrasrestoraties in Nederland

Transcriptie

1 Zeegrasrestoraties in Nederland Herintroductie in Waddenzee Mitigatie in Oosterschelde Plannen in Waddenzee Dick de Jong, Victor de Jonge, Fred Schmitz, Karin Hermus, Lucien Hanssen, Arthur Bos, Tjisse van der Heide, Tjeerd Bouma, Wim Giesen, Wouter Suykerbuyk, Laura Govers, Paul Erftemeijer, Luca van Duren Marieke van Katwijk Radboud University Nijmegen Biobouwersdag 15 april 2011

2 Harmsen 1936 Van Katwijk et al van Katwijk et al Seagrass zonation in tidal systems NW Europe Desiccation Water dynamics Desiccation Light Zostera marina Zostera marina Zostera noltii intertidal subtidal

3 Zostera marina Projects Zostera marina Zostera noltii Wadden Sea ( ) Zostera marina (+ Z. noltii) Eastern Scheldt ( ) Zostera noltii Wadden Sea ( ): Zostera marina

4 Wadden Sea Seagrass Light Nutrients Salinity Tidal depth Hydrodynamics Sediment type Various interactive effects Donor suitability Plant morphology -- Ecology Field experiments Outdoor mesocosms Laboratory Flume Review: van Katwijk et al Environment Restoration projects restore natural values find suitable sites -habitat requirements -habitat characteristics 50 KM

5 Ecological findings Z. marina Ammonium toxicity (water layer) High salinity: high nutrients unfavorable (multistress) Negative effect of hydrodynamics Importance of suitability donor population Macroalgal suffocation reduces seed production Ecosystem engineering Bos & van Katwijk 2007, Bos et al. 2007, Van der Heide et al. 2007, 2008, 2009, 2010a, b van Katwijk et al. 1997, 1998,1999, 2000, 2009, 2010a, b van Katwijk & Hermus 2000, van Katwijk & Wijgergangs 2004

6 Wadden Sea Seagrass Ecology Positive feedbacks Ecosystem engineering Light Nutrients Salinity Tidal depth Hydrodynamics Donor population Sediment type Morphology Various interactive effects Field experiments Outdoor mesocosms Laboratory Flume Review: van Katwijk et al Environment Other organisms Ecosystem engineering 50 KM

7 Biobouwers 5 cases 1. Sediment modification 2. Self-facilitation water clarity 3. Self-facilitation hydrodynamics 4. Facilitation hydrodyn.: mussel beds 5. Bioturbation

8 July: 6 wk after transplantation August: 11 wk September: 14 wk Sediment modification by intertidal, annual Zostera marina Transplantation experiment Comparing more situations: high plant density: muddification low plant density + very sheltered: sandification - accretion - fines > Bos et al. ECSS 2007 van Katwijk et al. ECSS 2010 muddification October: 21 wk locally increased turbulence reduced water dynamics

9 self-facilitation: water clarity 1930s: loss of ha Zostera marina (subtidal) Zostera marina Zostera marina era noltii 10 km

10 (van der Heide et al Ecosystems) self-facilitation: water clarity 1930s: loss of ha Zostera marina (subtidal) RESTORATION??? shoot density Simple growth model + - Monod equations, seagrass literature water clarity - waves+currents Geomorphological + hydrodynamic formulas

11 self-facilitation: water clarity 1930s: loss of ha Zostera marina (subtidal) RESTORATION??? van der Heide et al. 2007: first study to show possible alternative stable states in seagrass systems state 1: seagrass, water is clear state 2: no seagrass, water is turbid

12 Zostera marina self-facilitation: hydrodynamics Zostera marina Zostera noltii Zostera marina 50 KM

13 Zostera marina self-facilitation: hydrodynamics Two densities 30 cm 50 cm Exposed: high density ++ Sheltered: density no effect Transplantation Photo: Bos Donor population Bos & van Katwijk MEPS KM

14 Zostera marina facilitation by mussel beds: hydrodynamics Transplant behind mussel beds Photo: Bos Mussel bed increases seagrass survival rate Donor population Transplantation Bos & van Katwijk MEPS KM

15 Flume experiments (self-) facilitation related to hydrodynamics confirmed Bouma et al. subm.

16 Back to the field Maybe. seagrass mussels Water dynamics Salt marsh Z. noltii Z. Marina flexible Mussel bed Z. Marina robust

17 Review: van Katwijk et al Wadden Sea restoration results Zostera noltii: succesful > 13 years Zmarina 8 yr max (macroalgae) Zostera marina: never transplanted: strong feedbacks related to turbidity 50 KM

18 Restoration results Sheltered: Excellent survival 1 st year Seed production minimum Relatively exposed: Very good survival 1 st year Excellent seed production NO RECRUITMENT IN THE NEXT YEAR sheltered site exposed site van Katwijk et al. 2010b

19 Restoration results Sheltered year-to-year: Excellent survival 1 st year Seed production Recruitment next year only when low macroalgae Relatively exposed: Low macroalgal cover Very good survival 1 st year Excellent seed production No recruitment next year High macroalgal cover High macroalgal cover Scouring? Bad year Good year Bos & van Katwijk 2007 van Katwijk et al. 2009

20 Eastern Scheldt Seagrass mitigation Wadden Sea Restoration 50 KM EU-regulations 50 KM

21 Seagrass mitigation Eastern Scheldt EU habitat directive: mitigate Approach: Large scale: save all seagrass (z.noltii) TRANSPLANTATION Scientific: ensure optimal survival knowledge development Radboud University Nijmegen, The Netherlands Rijkswaterstaat Netherlands Institute of Ecology Projectbureau Zeeweringen: 325 km dike reinforcement Site-selection: Seagrass history present Cause of disappearance known and removed (temporary changes after construction works) Locally reduce negative effect of bioturbating lugworms for a good start Bioturbation Photo: Wim Giesen

22 Anti-lugworm measures 1. Shell layer 2. Nets

23 Locations and setup transplantations DM Exposed 2007 Shell/ Control DM Exposed 2008 Shell/ Control KKZ KKZ Sheltered Sheltered Shell/NET Donor 2007, 2008 (Viane) Shell/ Control Control KKN Intermed Shell/ Control RH Intermed Shell/ Control Dortsman N. DM 12 plots plots 2008 KKN plots 2008 KKZ 24 plots plots m 1.5 m 10 m 1.5 m Roelshoek (RH) 16 plots 2008 Plot Zeegraspatch 2010: KKN 2011: RH 2012: Viane

24 Transplantation remove seagrass at donor location Mitigation location prepare apply shells transport lugworm treatment has visual effect on relief place seagrass

25 # scheuten/patch 5000 Transplantations & 2008 in Aug/Sep Shoots per patch O S O S O S N O S O S O S DN07 DN08 KN08 KZ07 KZ08 RH08

26 Propagation Roelshoek Dijk

27 Some first results...

28 Plannen zeegrasaanplant Waddenzee Rijkswaterstaat Waddenvereniging Deltares Radboud Universiteit NIOO/Z Yerseke Methode: zaadstengels in zakken aan boeien (Buoy deployed seeding, Pickerell et al. 2005)

29 Plannen zeegrasaanplant Waddenzee Grotere schaal ivm positieve terugkoppelingen Methode BuD: zaadstengels in zakken aan boeien Zaadstengels (die anders grotendeels weg zouden spoelen, 80-90%) worden verzameld in Sylt Uitgeplant op 3 plekken in Waddenzee met maximaal kans op succes: historie van zeegras, hoge score op zeegraskansenkaart, redelijk succes bij eerdere aanplanten ondanks kleinere schaal (Balgzand) bergingskom met minder waterexport zodat minder zaadstengelverlies (Oostelijke WZ, wrschl Schier en Groningse kust)

30 Plannen zeegrasaanplant Waddenzee Twee maal aanplanten (2011 en 2012) Drie jaar monitoren ( ) zeegrasopkomst in augustus (en kenmerken) meest bepalende factoren (zodat resultaten verklaard kunnen worden) uit expert judgement en literatuur

31 Plannen zeegrasaanplant Waddenzee Bepalende factor voor succes, lokaal (op hoofdlijnen is de locatie bepaald door historie van zeegras en zeegraskansenkaart <- hydrodynamiek, droogvalduur, saliniteit, nutrienten): sedimentdynamiek - ervaring Oosterschelde, o.a. bioturbatie - proeven in de Waddenzee (vk & Hermus 2000), zelfde resultaat in VS (Fonseca ea) - verspreidingskaarten Waddenzee (Kohlus & Reise 2008)