Variation in abundance and spatial distribution of ecomorphs of the sea urchins,Echinometra sp.nov A and E.sp.nov C on a Fijian reef

摘要

This paper presents novel spatial distribution and abundance patterns of ecomorphs of Echinometra sp.nov A and E.sp.nov C (hereafter referred to as E.sp.A and E.sp.C,and collectively as Echinometra spp.).Echinometra spp.were surveyed on the Nukubuco Reef,to determine the within-reef variations in size-frequency and density at several spatial scales [between positions (east versus west),zones (crest versus flat),sites and quadrats].The scales of variation were greatest for both species between positions and zones.Echinometra sp.A was more readily found on the calmer flats while E.sp.C preferred the high-energy crests.The distribution of ecomorphs of Echinometra spp.varied between habitats (position x zone).Echinometra sp.A ecomorphs were more abundant on all locations and showed different size-class distributions compared with E.sp.C.Greater urchin numbers were observed on both zones of the eastern position than the western position.Echinometra sp.A showed marginal aggregation pattern while E.sp.C showed a stronger tendency to cluster.