This study concerns the effects of ions on the shell-secreting membrane of clam mantles. The average resting potentials were --47 mV for freshwater mantles and --60 mV for marine mantles. Elevation of potassium in the absence of chloride gave a maximal slope of depolarization equivalent to 59 mV for a 10-fold change in the marine form but much less in the freshwater form. In normal potassium, a...

This chapter discusses definitions and classification of estuaries. It presents both the classical and more flexible definitions of estuaries. Then it discusses separate classifications of estuaries based on water balance, geomorphology, water column stratification, and the stratification–circulation diagram – Hansen–Rattray approach and the Ekman–Kelvin numbers parameter space. The most widely...

Microbes are critical in carbon and nutrient cycling in freshwater ecosystems. Members of the Verrucomicrobia are ubiquitous in such systems, and yet their roles and ecophysiology are not well understood. In this study, we recovered 19 Verrucomicrobia draft genomes by sequencing 184 time-series metagenomes from a eutrophic lake and a humic bog that differ in carbon source and nutrient availabil...

Storm events impact freshwater microbial communities by transporting terrestrial viruses and other microbes to freshwater systems, and by potentially resuspending microbes from bottom sediments. The magnitude of these impacts on freshwater ecosystems is unknown and largely unexplored. Field studies carried out at two discrete sites in coastal Virginia (USA) were used to characterize the viral l...

The roles of several trophic groups of organisms (methanogens and sulfate- and nitrate-reducing bacteria) in the microbial degradation of methanethiol (MT) and dimethyl sulfide (DMS) were studied in freshwater sediments. The incubation of DMS- and MT-amended slurries revealed that methanogens are the dominant DMS and MT utilizers in sulfate-poor freshwater systems. In sediment slurries, which w...

Fisheries ABSTRACT: Anthropogenic effects including river regulation, watershed development, contamination, and fish introductions have substantially affected the majority of freshwater habitats in Europe and North America. This pattern of resource development and degradation is widespread in the tropics, and often little is known about the resources before they are lost. This article describes...

The salmon farming production chain is structured in four consecutive phases: freshwater, seawater, plant processing, and distribution and marketing. The phases interact in a pull manner, freshwater stocks fish to meet seawater’s demand, seawater produces to meet plant processing biomass demand, and the processing plant produces to satisfy consumers’ demand. Freshwater planning decisions are in...