Distribution patterns and coexistence of six species of the amphipod genus Hyale

Abstract

The six phytal amphipod species of the genus Hyale that occur on the intertidal rocky shores of Coquimbo, Chile, show habitat segregation with respect to the wave-exposure gradient: H. maroubrae (small species, <0.6mm cephalon length) and H. rubra large species, 0.6mm cephalon length) occurred in protected environments, whereas H. grandicornis, H. hirtipalma and H. media (large species) and Hyale sp. (a small species) inhabited exposed environments. With the exception of Hyale sp., all species were also found in areas with intermediate exposure, but where they coexist, they show differential occurrence according to microhabitat utilization: in protected environments H. rubra was found exclusively on algal patches with high canopies, whereas H. maroubrae was abundant on patches with low canopies. In the exposed sectors, the species were found mainly on algal patches with low canopies; they showed pronounced segregation among patches, with Hyale sp. being restricted to turf-forming filamentous algal patches. The distribution and coexistence of Hyale may be controlled by predation and the proximity to the colonization sectors (subtidal), but interspecific competition is the main factor influencing the distribution and coexistence patterns. -from Authors