Comparative Responses Of Dominant And Subordinate Periphytic Diatom Species To Environmental Gradients In Donghu Lake, China

An annual investigation on periphytic diatoms and physicochemical parameters was performed in Donghu Lake, China, to explore a suitable method to differentiate the dominant and subordinate taxa, and how they responded to the change of environmental factors. The results showed that: (1) a combined consideration of species frequency of occurrence and relative abundance for defining the dominant index was more appropriate than using solely relative abundance; (2) the dominant taxa Fragilaria capucina var. vaucheriae (Kutzing) Lange-Bertalot and Melosira varians Agardh responded insensitively to the environmental factors, whereas the subordinate species Fragilaria capucina Desmazieres var. capucina, Nitzschia amphibia Grunow, Achnanthidium exiguum (Grunow) Czarnecki and Melosira italica (Ehrenberg) Kutzing showed the potential to be indicators; F. capucina var. radians (Kutzing) Lange-Bertalot increased along the gradient of higher water temperature (WT) and nutrients concentration, however, Fragilaria bidens Heiberg and Cymbella affinis Kutzing were affected in the opposite direction. Our findings revealed that periphytic diatoms varied seasonally and were useful for assessing water quality of different trophic status. Especially the subordinate species showed the potential to be better indicators than the dominant species in Donghu Lake.