Multispecies coexistence of branchiopods (Anostraca,Notostraca & Spinicaudata) in temporary ponds of Chaouia plain (western Morocco): sympatry or syntopy between usually allopatric species

The study of the structure of communities of Crustacean branchiopods Anostraca, Notostraca and Spinicaudata of temporary ponds in Morocco revealed the existence of a geographical area with a particularly diversified number of species. Over a few hectares, 11 species, among the 18 known in Morocco, are present. While most of them are usually allopatric and belong to distinct associations, indicative of particular ecological and climatic conditions, they can coexist in Chaouia plain, either in adjoining ponds (sympatric species) or in the same pond (syntopic species). In one pond we could find up to 10 phyllopods: 6 Anostraca, 2 Notostraca and 2 Spinicaudata.This faunistic diversity may result from abiotic features (the location of the ponds at the boundary of two climatic areas) and from a heterogeneous geological substratum, creating a patchwork of temporary ponds with various mesologic conditions.Secondarily, this diversity may result from different life history characteristics of each coexisting species. As all species hatch synchronically, coexistence is only possible if their growth rates and life span are different. This implies that horizontal and vertical distribution, and exploitation of food supplies in the habitat differ for each ecophase of the syntopic species (spatial and trophic exclusion).