MEPS 609:151-161 (2019)  -  DOI: https://doi.org/10.3354/meps12845

ABSTRACT: Species coexistence is a critical determinant of biodiversity and community structure, yet resource partitioning mechanisms that facilitate coexistence remain understudied for many taxa, including cephalopods. Octopus vulgaris and Macrotritopus defilippi cohabit a shallow-water lagoon in South Florida. Temporal and spatial distribution as well as habitat association were examined as potential resource partitioning mechanisms to facilitate coexistence between these species. Methods included in situ visual observations, marking locations of octopus-occupied dens, and photoquadrats of octopus dens and surrounding habitats. Den locations were marked year-round for 3 yr to determine consistency of spatial distribution and temporal trends. Octopus abundance was highest during spring and lowest during fall for both species, indicating that temporal partitioning (in terms of seasonality) is likely not a mechanism of coexistence. O. vulgaris and M. defilippi had the highest densities of occupied dens in the same general shallow areas of the lagoon; thus there was no evidence of spatial partitioning. Although octopuses spatially overlapped in the same general area, multiple substrate categories were available, and each species’ den and surrounding habitat was associated with different substrates. O. vulgaris was associated mostly with hard bottom and inhabited hard-structured dens while M. defilippi was associated with soft sandy bottom and inhabited burrows in the sand as dens. Fine-scale habitat partitioning is made possible by this lagoon’s heterogeneous microenvironments, which aid in explaining coexistence of these 2 octopus species.

KEY WORDS: Resource partitioning · Cephalopods · Spatial distribution · Seasonal abundance · Den ecology · Habitat heterogeneity