[1] A coupled physical-biological model of the waters off central Chile is used to investigate the nitrogen-phytoplankton-zooplankton response to ocean circulation driven by mean summertime winds. The circulation drives the upwelling of middepth water onto the continental shelf and reaches a quasistable rate between days 40 and 60 of the simulation. High-nutrient, low-phytoplankton biomass wate...

[1] We examine the interplay between iron supply, iron concentrations and phytoplankton communities in the Pacific Ocean. We present a theoretical framework which considers the competition for iron and nitrogen resources between phytoplankton to explain where nitrogen fixing autotrophs (diazotrophs, which require higher iron quotas, and have slower maximum growth) can co-exist with other phytop...

Temporal variability in lake phytoplankton is controlled largely by a complex interplay between hydrodynamic and chemical factors, and food web interactions. We explored mechanisms underlying phytoplankton interannual variability in Lake Washington (USA), using a 25-yr time series of water quality data (1975-1999). Time-series analysis and PCA were used to decompose chlorophyll data into modes ...

Phytoplankton constitute the main algal biomass in pelagic ecosystems and, therefore, play a fundamental role in the functioning of the marine trophic web. Information on long-term trends in marine phytoplankton may help to distinguish between biological responses to natural oscillations in climate and global warming, and to evaluate possible regional effects of eutrophication. The aim of this ...

The stoichiometric composition of autotrophs can vary greatly in response to variation in light and nutrient availability, and can mediate ecological processes such as C sequestration, growth of herbivores, and nutrient cycling. We investigated light and nutrient eVects on phytoplankton stoichiometry, employing Wve experiments on intact phytoplankton assemblages from three lakes varying in prod...

Phytoplankton size class variation is a good indicator of water dynamics changes, alga blooms or ecosystem change, for it usually corresponds to different phytoplankton group composition. Remote sensing technique is a very effective method for studying phytoplankton at large scale by virtue of synoptic view and large area cover. Here we detected seasonal and annual phytoplankton size class vari...

We experimentally investigated the effects of different pre-treatments of the sediment, and the effect of daily addition of fresh phytoplankton, on the growth and survival of 1-year-old (1+) individuals of the deposit feeder Monoporeia affinis (Amphipoda). We used three different types of sieved sediment: pre-frozen muddy clay, non-pre-frozen muddy clay, and fine sand. The muddy clay contained ...

Simulation modeling provides a means for testing the limits of our quantitative understanding of the factors that control phytoplankton biomass, growth rate, and primary productivity in the sea. We simulated the annual cycles of chlorophyll a (Chl a) concentration, primary productivity, nitrogen export, phytoplankton carbon to nitrogen (C : N) and carbon to Chl a ratios (C : Chl a) using a phys...

Several pelagic fish populations in the upper San Francisco Estuary have recently declined to historically low abundances, prompting an interest in the status of their food supply. Previous studies have indicated that the primary food supply for metazoans in the Delta is phytoplankton productivity, and the long-term decrease in phytoplankton over the last few decades may very well play a role i...

Potential increases of phytoplankton concentrations in river systems due to global warming and changing climate could pose a serious threat to the anthropogenic use of surface waters. Nevertheless, the extent of the effect of climatic alterations on phytoplankton concentrations in river systems has not yet been analysed in detail. In this study, we assess the impact of a change in precipitation...