In order to investigate the factors controlling viral abundance, 22 lakes In Quebec were surveyed. We measured viral and bacterial abundance, bacterial production, chlorophyll a, total phosphorus and DOC (dissolved organic carbon) concentrations. Regression models built with these data were compared to models based on literature data, which to date have been collected largely from marine sites ...

Dissolved organic phosphorus (DOP) is increasingly recognized as an important phosphorus source to marine primary producers. Despite its importance, the production rate and fate of DOP is poorly understood. In this study, patterns of DOP production were evaluated by tracking the evolution of DOP during simulated phytoplankton blooms initiated with nutrient amended surface waters, relative to co...

Lake Riñihue is the last in a chain of glacially derived oligotrophic lakes in southern Chile and was the subject of limnological research by Dr. Hugo Campos and co-workers at the Universidad Austral de Chile, Valdivia, Chile, since the 1970’s. Prof. Campos died in the field in 1998, and this paper now presents a review of these data with comments on methodology relevant to trophic parameters o...

Biomanipulation by fish removal has been used in many shallow lakes as a method to improve lake water quality. Here, we present and analyse 30 years of chemical and biological data from the shallow and 16 ha large Lake Væng, Denmark, which has been biomanipulated twice with a 20-year interval by removing roach (Rutilus rutilus) and bream (Abramis brama). After both biomanipulations, Lake Væng s...

The four large Swedish lakes Vänern, Vättern, Mälaren and Hjälmaren differ in many respects, not least in drainage area characteristics and basin morphometry (1). The differences also include water quality. Since nutrient chemistry of phosphorus (P) and nitrogen (N) in the lakes is of major concern, it has been treated by several authors (2–13). The hydrochemical studies started in 1964 and in ...

The influence of ambient water quality on the settlement of barnacles and the green alga Enteromorpha spp. to an artificial substratum in the estuaries of Sydney, Australia, was investigated to test the efficacy of both groups of organisms as indicators of changes in water quality due to urban stormwater runoff and/or sewage overflows. Wooden settlement panels were immersed for 4 months on 17 o...

We have measured the relationship between chlorophyll and carbon in phytoplankton cultures and natural populations of phytoplankton using simple standard extraction procedures without correction for degradation products. During exponential growth oi four cultures oi unicellular and colonial green algae and one diatom, chlorophy!l varied from 1.22 to 6.08% of the phytoplankton carbon content (i ...

In light of recent suggestions concerning the relaxation of controls on phosphorus loading in Lake Erie, and in consideration of our current lack of baseline information on microbial communities in this system, a two-part analysis of the microbial ecology of the lake has been conducted. A comprehensive survey of the surface waters collected data on phytoplankton abundance, bacterial productivit...

Bacterial community activity and structure are thought to be directly or indirectly related to phytoplankton development and, in particular, to the phytoplankton species dominating specific algal blooms. To test this hypothesis, we performed a mesocosm experiment designed to generate blooms of different types of phytoplankton through the additions of silicate, urea and phosphorus to oligotrophi...

This study examined the relative influence of nutrients (nitrogen and phosphorus) and habitat on algal biomass in five agricultural regions of the United States. Sites were selected to capture a range of nutrient conditions, with 136 sites distributed over five study areas. Samples were collected in either 2003 or 2004, and analyzed for nutrients (nitrogen and phosphorous) and algal biomass (ch...