MEPS 608:149-163 (2019)  -  DOI: https://doi.org/10.3354/meps12808

ABSTRACT: Habitat geometry, especially when resulting from ecosystem-engineering species, is a key property of natural ecosystems. Habitat geometry influences the abundance and distribution of species through an interplay between habitat area and perimeter. However, few studies have tested the interacting effects of these distinct geometry parameters on community and ecosystem dynamics. We used experimental mussel (Mytilus spp.) beds as a model system to control and test for the effect of perimeter, area and their interaction on the diversity and abundance of macro-invertebrate species associated with mussel beds and on ecosystem functions (ammonium and oxygen fluxes). Live blue mussels were used to create artificial mussel transplants corresponding to 9 factorial combinations of area and perimeter, and both community and ecosystem effects were assessed after a 2 mo colonization period in the field. Our results showed an interacting and scale-dependent effect of area and perimeter on both community and ecosystem characteristics: area had a negative effect on taxonomic diversity of small-perimeter transplants, and perimeter had a negative effect on diversity of small-area transplants. At the ecosystem level, ammonium release increased with area in large-perimeter transplants. This study stresses the importance of integrating the explicit and interactive effects of multiple metrics of habitat shape for resolving the relationship between community dynamics and ecosystem functions in fragmented habitats.

KEY WORDS: Habitat shape · Area · Edge effect · Biodiversity · Ecosystem function · Functional groups · Nutrient fluxes · Mussels · Mytilus spp.