Consideration of nitrogen fixation adds a positive nonlinear feedback to plankton ecosystem models. We investigate the consequences of this feedback for secondary phytoplankton blooms and the response of phytoplankton dynamics to physical forcing. The dynamics of phytoplankton, Trichodesmium (the nitrogen fixer), and nutrients is modeled with a system of three differential equations. The model ...

Phytoplankton requires light for photosynthesis, but most phytoplankton species are heavier than water and sink. How can these sinking species persist? Here we show, by means of an advection-di usion-reaction equation of light-limited phytoplankton, that the answer lies in the turbulent motion of water that re-disperses phytoplankton over the vertical water column. More speci cally, we show tha...

I use numerical and analytical techniques to study the dynamics of various models of plankton food webs with and without resource fluctuations. Plankton are ideal organisms because they are very small, fast-reproducing organisms so they can easily be used in laboratory experiments to verify any results. We can study simple food webs to develop a better understanding of more complex food webs. T...

To assess the effects of fluctuating prey availability on predator population dynamics and grazing impact on phytoplankton, we measured growth and grazing rates of three heterotrophic dinoflagellate species-Oxyrrhis marina, Gyrodinium dominans and Gyrodinium spirale-before and after depriving them of phytoplankton prey. All three dinoflagellate species survived long periods (> 10 d) without alg...

Index words: Saginaw Bay Phytoplankton Zebra mussels Dynamic modeling Community composition Invasive species Microcystis Phosphorus loads Colonization of the Laurentian Great Lakes by the invasive mussel Dreissena polymorpha was a significant ecological disturbance. The invasion reached Saginaw Bay, Lake Huron, in 1991 and initially cleared the waters and lowered algal biomass. However, an unex...

While several studies have suggested that bacterium-phytoplankton interactions have the potential to dramatically influence harmful algal bloom dynamics, little is known about how bacteria and phytoplankton communities interact at the species composition level. The objective of the current study was to determine whether there are specific associations between diverse phytoplankton and the bacte...

From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin). We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceanographic regime, namely changes in frequency and inten...

A comprehensive study on phytoplankton dynamics in the coastal waters of Kalpakkam showed a considerable increase (almost 3 fold) in phytoplankton species composition (185 species) as compared to the earlier findings (60 species). Despite such a massive change in floristic composition, 4-10 times reduction in total cell count was observed during the present study, which varied between 1.7 x 10 ...