EFFECTS OF LIGHT AND SUBSTRATE ON THE BENTHIC DIATOMS IN AN OLIGOTROPHIC LAKE: A COMPARISON BETWEEN NATURAL AND ARTIFICIAL SUBSTRATES¹

Abstract

Benthic diatoms form a particularly important community in oligotrophic lakes, but factors influencing their distribution are not well known. This study reports the depth distribution of living motile and total diatoms (living plus dead diatoms) on both natural (from sand to fine organic mud) and artificial substrates in an oligotrophic lake. On artificial substrates, motile diatom densities peaked in abundance (24-30 cells · mm(-2) ) between 0.6 and 1.9 m depth; on natural sediment surfaces, motile diatoms were generally more numerous and peaked in abundance (925 cells · mm(-2) ) at 1.3 m depth. Total diatom densities on artificial substrates were highest (1260 valves · mm(-2) ) at 0.6 m depth, with very low values below 3 m depth; on natural sediment surfaces, total diatom abundances were generally much higher (21600 valves · mm(-2) ) at 3 m depth and declined gradually with depth. Significant relationships were found between light and diatom densities on the artificial substrate. Ordination analysis indicated that substrate type significantly correlated with the variation of diatom composition on artificial and natural substrates. Our results suggest that in oligotrophic lakes, light influences benthic diatom abundance, whereas substrate type has more influence on benthic diatom composition.

Epiphytic diatoms in lotic and lentic waters - diversity and representation of species complexes

“…In general, the relationship between epiphyton and water chemistry has been demonstrated many times (ács et al 1991, 1994kitner & Poulíčková 2003;Blanco et al 2004;HájKová et al 2011) and submerged macrophytes have been recommended for routine monitoring (Kelly et al 1998;Blanco et al 2004). We found significant relationship to selected environmental variables (water streaming, pH) in congruence with other studies (PotaPova & cHarles 2003;kitner & Poulíčková 2003;kovács et al 2006;FránKová et al 2009;yang & FloWer 2012). However, the results of this method of water quality status assessment are strongly influenced by following stones and sediments in streams and by macrophytes and sediments in shallow lakes and ponds.…”

Recovery of acidified surface waters from acidification in the United Kingdom after twenty years of chemical and biological monitoring (1988–2008)

“…have built on biological and chemical monitoring data (Layer et al, 2011;Ledger and Hildrew, 141 2005;Woodward and Layer, 2007;Yang and Flower, 2012). Understanding and modelling the 142 speciation and toxicity of heavy metals have been the focus of several studies using AWMN data…”

Towards threshold-based management of freshwater ecosystems in the context of climate change

“…Higher temperature increases the release of nitrogen from soil, and lower stream flows decrease the dilution capacity of rivers (Whitehead et al, 2006). However, the impact on eutrophication is not straightforward due to the complex interaction between nutrient, light, temperature, residence time and flow conditions (Jeppesen et al, 2005;Yang and Flower, 2012). Increased surface water temperature can indirectly lead to stronger stratification and regeneration of water column nutrients, which can intensify eutrophication (Rabalais et al, 2009).…”