An ecosystem simulation model was developed to investigate potential mechanisms controlling the size-structured phytoplankton and nutrient dynamics in the mesohaline zone of the York River estuary. The model included 12 state variables in a unit volume (m3) describing the distribution of carbon and nutrients (nitrogen, phosphorus) in the surface mixed layer. General size-scale relationships and...

1. A year-round study was conducted in a mesotrophic reservoir to determine the dynamics of zooplankton populations as a function of food availability (edible phytoplankton), nutrient concentration, temperature and hydraulic regime. 2. Rotifer biomass was correlated with soluble reactive phosphorus (SRP) concentration. The abundance of the rotifers Keratella cochlearis and Anuraeopsis fissa wer...

A modelling procedure of hourly time discretisation is developed in order to study the effects of episodic rainfall events to the dynamics of coastal marine environments. This methodology was applied on the gulf of Gera, Island of Lesvos, Greece, a semi-enclosed and shallow ecosystem surrounded by an intensively cultivated watershed. The simulation of biological and chemical processes in the wa...

The bogs in Northern Michigan are unusual ecosystems that contain a thick layer of peat that separates the surface vegetation from the nutrient-rich groundwater below it. Because of the thick layer of peat, nutrient-poor rain is the sole source of water for the surface vegetation, which allows the bog to stay nutrient-poor. In order to measure nutrient dynamics throughout bogs, we decided to in...

The occurrence of cyanobacteria and microcystin is highly dynamic in natural environments and poses one of the biggest challenges to water resource management. While a number of drivers are known to be responsible for the occurrence of cyanobacterial blooms, the drivers of microcystin production are not adequately known. This study aims to quantify the effects of the changes in the structures o...

Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K...

A simple nutrient-phytoplankton model is used to explore the dynamics of phytoplankton blooms. The model exhibits excitable behaviour in the sense that a large scale outbreak can only be triggered when a critical nutrient threshold is exceeded. The model takes into account several features often neglected but whose combined effect proves very important: (i) rapid nutrient recycling associated w...

Droop models of nutrient-phytoplankton-zooplankton interaction with intratrophic predation of zooplankton are introduced and investigated. The models proposed in this study are open ecosystems which include both a constant and a periodic input nutrient models. A simple stochastic model mimics a randomly varying nutrient input is also presented. For the deterministic models it is shown analytica...

Coastal shallow lagoons are considered to be highly important systems, which have specific biogeochemical cycles and characteristics. The assessment of sediment-water interfaces is essential to understand nutrient dynamics and to evaluate the vulnerability to eutrophication, especially in regions of restricted water exchange (RRE), such as the Ria Formosa, which have natural conditions for the ...

The paradox of enrichment has been studied almost exclusively within communities or metacommunities, without explicit nutrient dynamics. Yet local recycling of materials from enriched ecosystems may affect the stability of connected ecosystems. Here we study the effect of nutrient, detritus, producer, and consumer spatial flows-combined with changes in regional enrichment-on the stability of a ...