Individual-based simulation of the spatial and temporal dynamics of macroinvertebrate functional groups provides insights into benthic community assembly mechanisms

Abstract

The complexity and scales of the processes that shape communities of marine benthic macroinvertebrates has limited our understanding of their assembly mechanisms and the potential to make projections of their spatial and temporal dynamics. Individual-based models can shed light on community assembly mechanisms, by allowing observed spatiotemporal patterns to emerge from first principles about the modeled organisms. Previous work in the Rance estuary (Brittany, France) revealed the principal functional components of its benthic macroinvertebrate communities and derived a set of functional relationships between them. These elements were combined here for the development of a dynamic and spatially explicit model that operates at two spatial scales. At the fine scale, modeling each individual’s life cycle allowed the representation of recruitment, inter- and intra-group competition, biogenic habitat modification and predation mortality. Larval dispersal and environmental filtering due to the tidal characteristics of the Rance estuary were represented at the coarse scale. The two scales were dynamically linked and the model was parameterized on the basis of theoretical expectations and expert knowledge. The model was able to reproduce some patterns of α- and β-diversity that were observed in the Rance estuary in 1995. Model analysis demonstrated the role of local and regional processes, particularly early post-settlement mortality and spatially restricted dispersal, in shaping marine benthos. It also indicated biogenic habitat modification as a promising area for future research. The combination of this mechanism with different substrate types, along with the representation of physical disturbances and more trophic categories, could increase the model’s realism. The precise parameterization and validation of the model is expected to extend its scope from the exploration of community assembly mechanisms to the formulation of predictions about the responses of community structure and functioning to environmental change.

Effects of Benthic Protection Extent on Recovery Dynamics of a Conceptual Seafloor Community

“…The use of a seafloor disturbance model enabled the testing of a large number of management strategies, across large spatial and temporal scales, on the disturbance and recovery dynamics of a conceptual seafloor community based on ecological principles about the modeled organisms (Alexandridis et al, 2018). However, several assumptions were made to ensure a parsimonious model.…”

“…The functional group approach used here provided a practical way of reducing the number of interacting organisms (underpinned by well-known ecological principles derived from empirical studies) ensuring a parsimonious model. Closely related models have been shown to accurately reflect trends in benthic community over time (e.g., Lundquist et al (2010), Alexandridis et al (2018). Further, the use of functional groups has the added benefit that they allow the disturbance and recovery dynamics to be generalized to other geographical locations (Lundquist et al, 2018) and possibly other habitat types with similar recovery times [e.g., other biogenic habitats (Lundquist et al, 2010)].…”