Increasing mussel transplantation success by initiating self-facilitating feedback mechanisms

Abstract

Transplantation success of ecosystem-engineering species can be low in dynamic environments, as such ecosystem-engineers often require density-dependent positive feedback mechanisms to overcome environmental stressors. These self-facilitating feedback mechanisms play an important role in self-organization, whereby complex systems tend to organize and create patterns in order to ameliorating physical and/or biological stressors. In this study we used biodegradable structures to ameliorate self-facilitating feedback mechanisms to overcome environmental stressors in the initial post-transplantation phase. The biodegradable structures tested are an innovation of the traditional Seed Mussel Collectors (SMCs) used in mussel cultivation. The so-called “BioShell-SMC” does not contain any plastic, but is made up of a coconut fiber rope surrounded by empty cockle shells and held together by a biodegradable net based on a compound of aliphatic polyesters. We tested if the survival of two size classes of blue mussel (Mytilus edulis) transplants, on a tidal flat in the Oosterschelde estuary in the Netherlands, increased when mussel seed was transplanted attached to the BioShell-SMCs instead of single mussels in combination with empty cockle shells. The results of this study revealed that the survival of larger mussel seed significantly improved when attached to the BioShell-SMC compared to those transplanted loosely. Factors contributing to the difference in mussel loss between BioShell-SMC mussels and loosely transplanted mussels include predation, competition and dislodgement due to hydrodynamic forces. For small mussel seed, mussel biomass decreased strongly in the first three days of the experiment, irrespective of transplantation method. This is due the small size of the mussels in combination with low mussel densities. Overall, this study highlights the potential of using biodegradable structures to initiate self-facilitating feedback mechanisms in establishment of ecosystem engineers in dynamic environments.