  We propose a general population dynamics model for two seagrass species
growing and interacting in two spatial dimensions. The model includes spatial
terms accounting for the clonal growth characteristics of seagrasses, and
coupling between species through the net mortality rate. We consider both
intraspecies and interspecies facilitative and competitive interactions,
allowing density-dependent interaction mechanisms. Here we study the case of
very similar species with reciprocal interactions, which allows reducing the
number of the model parameters to just four, and whose bifurcation structure
can be considered the backbone of the complete system. We find that the
parameter space can be divided into ten regions with qualitatively different
bifurcation diagrams. These regimes can be further grouped into just five
regimes with different ecological interpretations. Our analysis allows the
classifying of all possible density distributions and dynamical behaviors of
meadows with two coexisting species.
