Periphyton biofilms are natural mixtures comprised of photoautotrophic and heterotrophic complex microorganisms. In this work, the inhibition effects of periphyton biofilms on cyanobacterial blooms were studied in pilot and field trials. Results show that the cyanobacterial species responsible for the blooms had an upper nutrient concentration threshold, below which it could not effectively com...

Forest disturbance can alter light and nutrient regimes in small streams, which in turn may influence grazer–periphyton interactions within the stream community. To investigate the influence of forest disturbance on grazer–periphyton interactions, we tested the effects of light, nutrients, and grazing by tadpoles of the tailed frog (Ascaphus truei) on periphyton standing crop and tadpole growth...

Periphyton is a key component of shallow littoral zones of lakes and streams because it is an important source of primary production and a food resource for herbivores. Meiofauna are abundant in periphyton, but macroinvertebrate grazer (macrograzers) effects on periphytic meiofauna have not been studied so far. We used a spatially structured field experiment (hierarchical nested design consisti...

Stomach contents of Simulium perflavum Roubaud larvae were analyzed and compared with plankton and periphyton collected in five streams, in Central Amazonia (Manaus and Presidente Figueiredo counties), in Sep./Oct.1996 (dry season) and Feb./Mar. 1997 (rainy season). A total of 1,400 last-instar larvae were dissected; the stomach contents were analyzed using different methods: fresh and after ox...

Trophic accumulation of mercury (Hg) in aquatic ecosystems is of global concern due to health effects associated with eating fish with elevated Hg levels. The methylated form of Hg bioaccumulates so it is important to understand how inorganic Hg is transformed to methylmercury in the environment. Here, a new site for Hg methylation, the periphyton communities that are prevalent in the Florida E...

1. The biochemical composition of primary food resources may affect secondary production, growth, reproduction and other physiological responses in consumers and may be an important driver of food-web dynamics. Changes in land use, riparian clearing and non-point nutrient inputs to streams have the potential to alter the biochemical composition of periphyton, and characterising this relationshi...

The photosynthesis-irradiance (P-Z) relationship was examined in 10 intact periphyton communities from sites in eight streams that differed in ambient light, nutrient concentrations, and grazing pressure. Algal biomass ranged from 2.3 to 86 pg Chl a cm -* and taxonomic composition differed. Photoassimilation of 14C was measured in the laboratory at six light levels for each community. Photosynt...

Periphyton and macrophytes alter water velocity in streams, influencing movement of solutes and providing microhabitat for other organisms. How assemblages with different growth form and architecture influence water velocity attenuation across mm to dm scales is not well described. A thermistor microprobe was used to measure water velocity through 4 morphologically distinct stream periphyton as...

Periphyton from rice-fish environment of Apatani Plateau, Arunachal Pradesh, India was studied for diversity and productivity (Chlorophylla and biomass) on artificial (glass slide) and natural (rice stem) substrates. Periphyton from rice stems, especially, from cultivars locally known as ‘Amo’ were collected from a depth of 7.0-8.0 cm from surface water and 5.0 cm above from the field bottom. G...

We used a subsidy–stress model as a basis for predicting macroinvertebrate community response to a steep gradient of P enrichment in the Florida Everglades, a P-limited wetland ecosystem. We tested the hypothesis that consumers were resource limited and their biomass would show a subsidy response (increase) to low-to-moderate levels of P enrichment, but a stress response (decrease) at high leve...