17 Effects of fine sediment and grazers on periphyton and nutrient cycling in a coastal river Michael Limm, Department of Integrative Biology University of California, Berkeley Excessive loading of fine sediment is one of the most serious impacts of land-use on stream ecosystems in arid and semi-arid environments. Detrimental direct effects of excessive fine sediment are well documented for fis...

A protocol was developed to extract, fractionate, and quantitatively analyze periphyton extracellular polymeric substances (EPS), which obtains both information on the molecular weight (M r) distribution and protein and polysaccharide content. The EPS were extracted from freshwater periphyton between July and December 2011. Organic carbon (OC) compounds from different EPS extracts were analyzed...

Phosphorus enrichment caused by runoff from agricultural areas has resulted in ecosystem-level changes in the northern Florida Everglades, including a loss of periphyton mats from nutrient-impacted areas. The potential for methanogenesis resulting from the anaerobic decomposition of cellulose and fermentation products, and the microorganisms responsible for these processes, were studied in mats...

The competitive interactions of two lotic snails, Elimia cahawbensis and Elimia carinifera, were examined in a second-order spring-fed stream. We first demonstrated food limitation in laboratory microcosms where snails grew faster when exposed to enhanced periphyton levels. We then tested the magnitude and relative strengths of intraand interspecific competition in similar stream and laboratory...

When external loading is small, as it is in Lake Tanganyika, the internal redistribution of nutrients can be important for ecosystem productivity. One conduit for this redistribution is fish. Research has been conducted on the transfer of nutrients into the pelagic or benthic ecosystems by benthic or pelagic fishes, respectively, but less attention has been paid to the recycling of nutrients by...

The changes imposed by dams on hydrological regime, water transparence and nutrient concentrations downstream affect biodiversity in relation to species richness and specific composition of the community. The aim of this work was evaluate this effect on periphyton, comparing richness and composition of periphytic algae in the Garças Lake, Upper Paraná River floodplain, between the years 1994, b...

INTRODUCTION We evaluated periphytic algal and microbial communities to assess the influence of human and cattle impact on Sierra water quality. METHODS 64 sites (lakes and streams from Lake Tahoe to Sequoia National Park, California) were sampled for suspended indicator bacteria and algae following standardized procedures. The potential for nonpoint pollution was divided into three categorie...

Mercury (Hg) methylation and methylmercury (MMHg) demethylation activity of periphyton biofilms from the industrially contaminated East Fork Poplar Creek, Tennessee (EFPC) were measured during 2014-2016 using stable Hg isotopic rate assays. 201HgII and MM202Hg were added to intact periphyton samples in ambient streamwater and the formation of MM201Hg and loss of MM202Hg were monitored over time...

1. To determine feeding links between primary producers, invertebrates and fish, stable isotope analyses and gut content analyses of fish were conducted on the components of four shallow, eutrophic to hypertrophic, plant-dominated lakes. 2. Although separation of basal resources was possible, the diets of both fish and invertebrates were broad, comprising food from different compartments (plank...