Abstract
Spatial patterns formed through the process of self-organization are found in nature across a variety of ecosystems. Pattern formation may reduce the costs of competition while maximizing the benefits of group living, and thus promote ecosystem persistence. This leads to the prediction that self-organizing to obtain locally intermediate densities will be the optimal solution to balance costs and benefits. However, despite much evidence documenting pattern formation in natural ecosystems, there is limited empirical evidence of how these patterns both influence and are influenced by tradeoffs between costs and benefits. Using mussels as a model system, we coupled field observations in mussel-culture plots with manipulative laboratory experiments to address the following hypotheses: 1) labyrinthine spatial patterns, characteristically found at intermediate to high patch densities, are the most persistent over time; this is because labyrinthine patterns 2) result in adequately heavy patches that can maximize resistance to dislodgement while 3) increasing water turbulence with spacing, which will maximize food delivery processes. In the field, we observed that labyrinthine ‘stripes’ patterns are indeed the most persistent over time, confirming our first hypothesis. Furthermore, with laboratory experiments, we found the ‘stripes’ pattern to be highly resistant to dislodgement, confirming the second hypothesis. Finally, with regards to the third hypothesis, we found positive effects of this pattern on local turbulence. These results suggest that the mechanisms of intraspecific facilitation not only depend on initial organism densities, but may also be influenced by spatial patterning. We hence recommend taking into account spatial patterns to maximize productivity and persistence in shellfish-cultivation practices and to increase the restoration success of ecosystems with self-organizing properties.
| Original language | English |
|---|---|
| Pages (from-to) | 1805-1815 |
| Journal | Oikos |
| Volume | 128 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - 8 Aug 2019 |
Funding
) and minimizing competition have been shown for other ecosystem engineers, such as the saltmarsh plant We showed that the survival of an ecosystem‐engineering species in a physically stressful environment not only depends on their density (Bouma et al. 2009), but also on the spatial pattern in which they are distributed. In mussels, organising as a labyrinth was found to confer the advantages of group living while minimizing competition between conspecifics. We demonstrated that not organizing in spatial patterns, whether at low or high densities, was not sustainable. Tradeoffs between being the right shape and size to maximize facilitation in terms of decreasing dislodgment risk (de Paoli et al. Spartina anglica . In ). However, as behavioral organization in shapes is known to be both environment‐ and density‐dependent (Gascoigne et al. 2005, Bouma et al. 2009, Capelle et al. 2014), we can say that these processes are inherently interlinked, and density could be used as a good proxy to maximize cultivation methods. S. anglica systems, dislodgement is decreased by greater shoot densities, but densely packed tussocks limit light penetration. Moreover, this investment in density limits investment in lateral expansion (Van Hulzen et al. ). Here, using patterns observed in real‐world mussel beds, we provide a solid and process‐oriented experimental test on the benefits of (presumably self‐organized) patterning for mussels, and highlight its importance for both restoration practices and the optimization of culturing techniques (Guichard ). Results from this study can also be used to plan restoration of degraded habitats, including drivers to develop optimal ‘facilitative’ patterns. This should lead towards low‐maintenance restoration for ecosystems with self‐organizing properties that can persist over time with limited human intervention (Silliman et al. 2015). The theoretical emergent properties of spatial self‐organization proposed for patterned ecosystems as diverse as arid bushlands, patterned peatlands and mussel beds have been subject to very limited experimental verification (de Paoli et al. Acknowledgements – We are thankful to Jaco de Smit and Manuel d'Angelo for help with hydrodynamic measurements and development of MATLAB code and to Lotte de Wit for help with flume measurements. Funding – This study is part of the INNOPRO project and has received funding from the European Union, through the European Maritime and Fisheries Fund (EMFF) and from the Producers’ Organization of the Dutch mussel culture (POM). Conflicts of interests – The authors declare no conflict of interests. Author contributions – CB, BC and JJC contributed to the design and execution of sampling and experiments, all authors contributed to the data analysis and writing of the manuscript.
Keywords
- benthic dynamics
- density-dependent
- facilitation
- habitat complexity
- mussel beds
- self-organization