Diatoms of three bodies of water from wetlands Jilotepec-Ixtlahuaca, Estado de Mexico

Abstract

The taxonomic and environmental characteristics of the diatom flora found in three bodies of water in the wetlands of Jilotepec-Ixtlahuaca, Estado de Mexico are described. Six samplings were made (January-October, 2001). Benthic and planktonic diatoms growth were collected.The samples were analyzed with a Light Microscope (LM) and a Scanning Electron Microscope (SEM). 45 species and 3 infraspecific taxa belonging to 32 genera were identified. Aulacoseira granulata, Cymbella affinis, Gomphonema acuminatum, G. angustatum, Pinnularia microstauron, Synedra ulna y Stephanodiscus niagarae were the dominat species. Craticula halophila, Cymatopleura solea, and Neidium iridis were rare species. Epithemia turgida, Eunotia curvata and Rhopalodia sp. were species specific to the permanent pond. Achnanthes pinnata, Cyclostephanos dubius, Eunotia faba and Planothidium ellipticum are new records for theTrans Mexican Volcanic Belt. We found a living population of S. niagarae from wetlands, suggesting that this species had once a much wider distribution towards the southern region of North America. 89% of the species were limnophilous with an indifferent and rheophilous tendency. 67% of the taxa were associated to the diversity of substrates and did not exhibit marked seasonality. Species richness was higher during dry season. Craticula halophila, Encyonema caespitosum, Frustulia vulgaris y Sellaphora pupula were found during the rainy season. All of the species were found to be meso-eurytherms with temperate affinity. pH was slightly basic (7.8), 65% of the species were alkaliphilous. Eunotia faba, acidophilous-circumneutral, Eunotia curvata and Surirella tenera circumneutral-indifferent. Stephanodiscus niagarae in association with Aulacoseira granulata, Fragilaria capucina and F. crotonensis showed a tendency to eutrophic condition. All of the species were characterized as being from freshwater and oligohalobous. Results from environmental analysis show that the water from study area has a low mineral content