A comparison between diatom assemblages in two groups of carbonate, low-altitude springs with different levels of anthropogenic disturbances

Nicola Angeli, Marco Cantonati, Daniel Spitale, Horst Lange-Bertalot
2010 Fottea  
Since several decades diatoms are increasingly used for the assessment of the trophic status of different freshwater ecosystems. However, spring habitats have been only marginally considered concerning this topic. The purpose of this research was to compare the diatom assemblages of two groups of carbonate, low-altitude springs, affected by different levels of anthropogenic disturbances. Between 2005 and 2008, diatoms were sampled in 57 low-altitude, carbonate springs, keeping separate the main
more » ... microhabitats (stones and bryophytes), and assessing an extensive number of morphological, physical, and chemical variables. Two datasets were considered for the present paper: the first (CESSPA, N = 25) includes carbonate springs located within the River Adige catchment, the second (CRENODAT selected springs, N = 32) includes springs located not exclusively within the same basin, and very similar to the previous ones as regards lithological substratum, altitude range, shading. Trophic and saprobity indices, together with multivariate techniques, were used to assess differences between the diatom assemblages in the two datasets. Indices revealed higher trophic and saprobic levels for the CESSPA springs than for the other group (CRENODAT). Values of the Shannon-Wiener diversity index were similar for the two groups while the average richness was slightly higher in nature-near springs (CRENODAT); higher percentages of endangered or rare taxa (Red List) were found only in the nature-near springs. The main impacts affecting the CESSPA springs were found to be both anthropogenic disturbances, such us water abstraction and spring-bed modification, and higher nitrate values. The importance of the fine tuning of diatom-based bioassessment methods in spring habitats is stressed.
doi:10.5507/fot.2010.006 fatcat:unxggu4zrffgbcztvkcruqxuly