Unpredictability in seagrass restoration: analysing the role of positive feedback and environmental stress on Zostera noltii transplants

Autor: Laura L. Govers, Roy van de Voort, Wouter Suykerbuyk, Tjeerd J. Bouma, Marieke M. van Katwijk, Dick J. de Jong, Paul T. Giesen, Wim Giesen, Kris Giesen
Rok vydání: 2016
Předmět:
Zdroj: Journal of Applied Ecology, 53, 3, pp. 774-784
Journal of Applied Ecology, 53, 774-784
ISSN: 0021-8901
Popis: 1. Restoration of key species in dynamic coastal ecosystems benefits from reduction in environmentalstress. This can be realized by promoting positive feedback (intrinsic processes) orby reducing extrinsic negative forcing.2. In a seagrass (Zostera noltii) restoration project in the south-western Netherlands, weinvestigated transplantation success in relation to intrinsic processes (i.e. comparing sods vs.single shoots, transplant size, transplant configuration and transplant density) and extrinsicforcing (i.e. bioturbation by Arenicola marina, desiccation and exposure to water dynamics).In total, 2600 m2 of seagrass sods were mechanically transplanted to six intertidal flats overthe course of 5 years.3. In total, 43% of sod transplants (2?25 m2) survived at the long term, whereas single shoottransplants failed within the first 3 months. The use of larger, or more compact (sod), transplantconfigurations had no long-term effect on survival, and initial densities did not affecttransplantation success either. Reducing desiccation stress increased the transplantation successduring the first growing season. Shielding transplants from bioturbating lugworms had apositive effect on long-term survival.4. Seagrass abundance in summer was related to spring abundance, whereas winter survivalwas not related to prior seagrass abundance. At four of the six intertidal flats, transplantsgradually decreased in size over time. At the other two, extensive colonization occurredaround the transplant areas in some years and was still partly present in 2015. A correlationwith the studied environmental parameters was not found.5. Synthesis and applications. Intrinsic processes favour transplantation development duringthe growing season, allowing positive feedback. Extrinsic processes favour the development ata longer time-scale (i.e. reduction in bioturbation, thus breaking the positive feedback of thebare state). Most surprisingly, the starting colonization of two out of six tidal flats could not berelated to environmental factors (hydrodynamics, light, emergence time, sediment characteristics,macro-algae and grazing). Environmental managers can improve transplantation successby restoring the positive feedback, reducing stress, but also via risk spreading by performingtransplants over wider areas. They thereby accept the complexity of processes and unpredictabletemporal and spatial variation in which transplantation sites turn out to be successful.
Databáze: OpenAIRE
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