An improved coverslip method for investigating epipelic diatoms

Abstract

The traditional coverslip method for harvesting motile diatoms was improved and standardized by determining optimum times for diatom harvesting; by using opaque Petri dish bases as experimental chambers; and by preparing coverslips by burning. Three experiments were conducted to evaluate the harvesting efficiency of the coverslip method. Experiment 1 was performed to reveal the spatial distribution of epipelic diatoms on the coverslips after exposure periods ranging from 2 to 36 h. The transect count results were supplemented using an Inverse Distance Weighted algorithm and showed that after 8 h exposure the epipelic diatoms began to accumulate at the coverslip margin. Therefore, 8 h was identified as the optimum time for the coverslip method to capture epipelic diatoms efficiently for the samples. However, the optimum time could vary between sites because of differences in diatom composition, light intensity and other environmental conditions. Experiment 2 revealed that the numbers of epipelic diatoms harvested from opaque chambers were 15.6% higher than those harvested from transparent chambers, indicating that opaque sides and base reduce multi-directional diatom migration. Experiment 3 indicated that the burning method was more efficient than the traditional method (directly counting fresh diatoms) because it makes identification easier and yields higher densities of diatoms. All experiments demonstrated that the coverslip method harvested more epipelic diatoms, made identification easier than the traditional method, enabling permanent slides to be created. In addition, the method makes it possible to estimate in situ epipelic cell densities, if the sediment area is known.

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

“…Diatom abundances were expressed quantitatively using a modified coverslip method (Yang et al. 2010) so that the motile epipelic diatoms could be discriminated from the total diatom abundances.…”

“…Wetted lens tissue squares (2 · 2 cm) were placed on each tube and orientated towards the light source to encourage motile diatoms to migrate out of the substrate biofilm. After Yang et al (2010), the lens tissue squares were exposed for 8 h (8 a.m.-4 p.m.) before careful removal. The sample lens tissues were then extracted for Chl a using degassed acetone overnight at 4°C (USEPA 1995).…”

“…Different quantitative methods were used to count the motile diatoms and total diatoms on the artificial and natural substrates. To harvest the motile living diatoms, the traditional lens tissue method (Eaton and Moss 1966) was modified by standarizing the sample container, optimizing the exposure time and improving the slide making technique (Yang et al. 2010).…”

Short Communication: The diversity of epipelic diatoms as an indicator of shrimp pond environmental quality in Lampung Province, Indonesia

“…Bicarbonate anions are used by algae as a carbon source for photosynthesis, thus its availability greatly affects aquatic algae existence. Yang et al (2010) demonstrated that CO 2 concentration affects the existence of epipelic diatoms in aquatic environments. A sufficient quantity of dissolved organic material is needed by the algae.…”