Response of epiphytic algae to nutrient loading and fish density in a shallow lake: a mesocosm experiment

Abstract

Studies on the effect of eutrophication on the ecology of shallow lakes, usually pay scant attention to changes within the epiphytic algal community, though the contribution of this to the ecosystem dynamics is transcendental. In order to test the influence of nutrient loadings and fish densities in the structure of algal epiphyton in a shallow lake, an experiment was performed using in situ mesocosms. Nutrient additions were related to significant decreases in the total epiphyton biovolume and that of bacillariophyceans and zygnematophyceans, but with increases in the abundance of cyanobacteria. The different response of algal groups at the higher nutrient concentrations (increases or decreases in their abundance and/or biovolume) can be related to their ecophysiological constraints such as different resistance to toxicant ammonium accumulation. Plant-associated macroinvertebrates numbers were positively correlated with total numbers of epiphyton. The presence of planktivorous fish enhanced the abundance and biovolume of all algal groups, except cyanobacteria. Fishes enhanced the abundance of plant-associated animals and of total epiphyton. Fish indirect effects (e.g., nutrients release) and their dietary particularities were among the factors that together with nutrients influenced epiphyton growth. The role of indirect effects of fishes and the importance of their dietary particularities are stressed as key factors to understand the processes controlling epiphyton ecology and the food web structure of shallow lakes.

The role of abiotic and biotic environmental factors in shaping epiphyton on common reed in shallow, hydrologically transformed, temperate lakes

“…Despite some differences among the lakes in the number of species and algal abundance, we found that the diversity of algal assemblages based on abundance did not differ one from the other and was lower than, for example, in the meso-eutrophic Lake Gulbinas (Karosienė and Kasperovičienė, 2008). However, the diversity based on the algal biomass was found to be the highest in the least eutrophicated lake, which is in accordance with the results of a mesocosm experiment by Blanco et al (2008). They revealed that species richness of epiphyton on the submerged Myriophyllum alterniflorum decreased significantly (from 15 to 32 taxa) with N and P enrichment.…”

“…The direct periphytic biomass consumption by omnivorous fish was showed in experimental study by Guariento et al (2010). Blanco et al (2008) showed that zooplanktivorous fish enhanced the abundance of Euglenophyceae and Zygnematophyceae, as well as algal species richness and diversity, by secreting biogenic substances. Our studies showed that the abundance of crustaceans being able to graze on algae was very low, and no significant relationship between them and epiphytic algae was found.…”

“…Furthermore, a meta-analysis of 85 experimental studies showed that grazing by invertebrates on algae were found to be greater than nutrient effects (Hillebrand, 2002). In general, the reports on the role of zooplankton and fish in shaping epiphyton communities are scarce and mostly experimental (Tall et al, 2006;Abe et al, 2007;Blanco et al, 2008;Guariento et al, 2010). Some anthropogenic disturbances, like man-made water level fluctuations (WLFs), eutrophication or water pollution are also important factors that influence epiphyton (Barbour et al, 1999;Kernan et al, 2010;Pfeiffer et al, 2015).…”

Relationships between benthic diatom assemblages’ structure and selected environmental parameters in Slovak water reservoirs (Slovakia, Europe)

“…abiotic spatial factors and catchment variables as landuse and hydromorphology (Gottschalk and Kahlert, 2012), physical and chemical quality of substratum Michelutti et al, 2003;Poulíčková et al, 2003Poulíčková et al, , 2004King et al, 2006;Ács et al, 2007;Bolla et al, 2010), light conditions (Kelly et al, 1998;King et al, 2006), seasonality (King et al, 2002(King et al, , 2006Bolla et al, 2010;Rimet et al, 2015), water chemistry (Hofmann, 1994;King et al, 2000;Schönfelder et al, 2002;Kitner and Poulíčková, 2003;Blanco et al, 2004;Ács et al, 2005;Stenger-Kovács et al, 2007;Jüttner et al, 2010;Gottschalk and Kahlert, 2012) and also other groups of organisms, such as indirect effect of fish (Blanco et al, 2008).…”

Biofilms as potential indicators of macrophyte-dominated lake health

“…Secondly, biofilms are sensitive to changes in environmental conditions. Thirdly, they potentially constitute an important step in the integration of biogeochemical cycles and dynamics of aquatic ecosystems (Schorer and Eisele 1997;Allan and Castillo 2007). Most important of all is that they play a key role in energy transduction and uptake or retention of nutrients (Sabater et al 2000).…”