Dominant species, functional assemblages and frequency of equilibrium phases in late summer phytoplankton assemblages in Hungarian small shallow lakes

Abstract

Late summer phytoplankton associations were studied qualitatively and quantitatively in 80 Hungarian lakes altogether (mostly shallow salt lakes, reservoirs, oxbows, gravel pit lakes). Equilibrium phases sensu Sommer et al. (1993) were found only in 17 lakes. Most of them were under some kind (high salt content or very low level of nutrients) of stress factor. It is concluded that environmental stress forces phytoplankton communities towards equilibrium. No relationship between occurrence of equilibria and trophic state was found. Species number of nonequilibrated lakes was almost three times as high as those in equilibrium. Of the 31 recently described (Reynolds et al., 2002) phytoplankton assemblages most of those were recognized that are likely to occur in shallow lakes. Separation of a functional group W S from W2 for Synura dominated lakes is suggested. It seemed also necessary to raise a group (Y Ph ) for lakes dominated by Phacotus. Sorting of Dinophyta species into different already described functional groups is desirable.

Stability and change of phytoplankton communities in a highly dynamic environment—the case of large, shallow Lake Balaton (Hungary)

“…This is an important difference compared to deep lakes, where environmental stability associated with thermal stratification supports less disturbed successional sequences, which frequently result in prolonged dominance of one or another K-selected stress tolerant species (Reynolds, 1997). This difference between deep and shallow lakes explain the observation of Padisá k et al (2003) that equilibrium phases sensu Sommer et al (1993) were relatively infrequent (17 out of 80) in shallow lakes during summer.…”

Phytoplankton structure and diversity in the eutrophic-hypereutrophic reservoir Paso de las Piedras, Argentina

“…In our research, only some short periods within Cyanobacteria and Cyanobacteria II periods match Sommer's criteria for steady state. In this regard, Padisák et al (2003) found that equilibrium phases in phytoplankton assemblages were relatively rare and that stressed ecosystems are quite likely to support equilibrated phytoplankton communities.…”

Use of Phytoplankton Assemblages for Monitoring Ecological Status of Lakes within the Water Framework Directive: The Assemblage Index

“…Recently, Reynolds et al (2002) published an extended description of phytoplankton assemblages that can be understood as functional groups: groups of species with more or less precisely defined demands for several different combinations of physical, chemical and biological properties (depth of mixing layer, light, temperature, P, N, Si, CO 2 and grazing pressure) of the lake environment. At present, 33 functional groups are described (Reynolds et al, 2002;Padisa´k et al, 2003b), each having alphanumerical symbols (codons).…”