Seasonal variations of rotifers from a high altitude urban shallow water body, La Cantera Oriente (Mexico City,Mexico)

摘要

La Cantera Oriente is a shallow freshwater volcanic water body located at an altitude of 2 270 m above sea level in the Ecological Reserve of San Angel Pedregal of Mexico City (Mexico).In order to ensure the conservation of its biological heritage including zooplankton,the present work was undertaken to quantify the seasonal changes in the diversity and density ofrotifers and the selected physicochemical variables during 2013-2014.Qualitative analysis of the zooplankton samples yielded 68 rotifer species which represented 24 genera in 15 families.Brachionus calyciflorus Pallas,1766,B.quadridentatus Hermann,1783,Polyarthra vulgaris Carlin,1943,Lecane closterocerca (Schmarda,1859) and Keratella cochlearis (Gosse,1851) were the most common species.Preston plots of species frequency-density revealed that as many as 30％ of the rotifer taxa were dominant throughout the year.The species with high population densities were Brachionus quadridentatus,Lecane closterocerca,Keratella cochlearis,and Lepadella patella;their peak densities were 2 000,1 000,180 and 90 ind./L,all occurring in summer.Canonical correspondence analysis showed that Platyias quadricornis was related to the concentration of phosphates available in the environment and the conductivity,while B.quadridentatus was positively correlated with chlorophyll-a.The trophic status of the lake was eutrophic based on Chl-a content but oligotrophic with relation to the Brachionus:Trichocerca ratio.