Ecology and distribution of Aulacoseira species (Bacillariophyta) in tropical reservoirs from Brazil

Abstract

Ecological preferences and distribution of Aulacoseira species in southeastern Brazilian reservoirs with varying trophic states were studied. One hundred and fourteen plankton samples (winter and summer) from 57 sites located in 16 reservoirs were analysed. Ten water quality parameters were measured. Ten Aulacoseira species were identified using light, scanning and transmission electron microscopy, and new information on their ecological preferences is provided here. Our results indicate that trophic gradient is the main driver of species distribution. Principal components analysis and calculation of weighted average nutrient optima revealed three indicator taxa, Aulacoseira tenella characteristic for oligotrophic waters and two varieties of Aulacoseira granulata (nominate and var. angustissima) typical for eutrophic reservoirs. This is the first ecological study of Aulacoseira in Brazil, adding information on the distribution of this genus in the tropics, and highlighting the need for species-level identification and regional studies to improve the use of diatoms in water quality assessment.

Keywords:

• autecology
• bioindication
• centric diatoms
• South America
• taxonomy
• weighted average

Acknowledgements

We deeply appreciate the valuable assistance of personnel from the agency in charge of the public water supply in São Paulo – SABESP/RHMS (Companhia de Saneamento do Estado de São Paulo, Divisão de Recursos Hídricos Metropolitanos Sudoeste) and Votorantin Energia for their valuable logistical support during the fieldwork. We are also grateful to Prof. William de Queiróz (Universidade de Guarulhos, Laboratório de Geoprocessamento) for providing the illustration of the study area. We thank all the students and technicians from the Department of Ecology, Institute of Botany, involved in field and laboratory work. We acknowledge Dr Václav Houk, Dr Marina Potapova and Dr Luis Maurício Bini for providing helpful comments that improved the quality of our manuscript.

Additional information

Funding

This study was carried out within the framework of the AcquaSed project supported by funds from FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo, AcquaSed Project) [number 2009/53898-9]. DCB and CEMB thanks CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for Research Fellowships [number 310940/2013-3] and [number 309474/2010-8].