Species experience landscapes differently depending on their needs and behaviors, and on their trophic level. We expect species at high trophic levels in a community to be more sensitive to habitat fragmentation than species at lower trophic levels. But this depends on attributes such as resource breadth, dispersiveness, reproductive rate, and longevity, which may not be related to trophic leve...

In Prince Edward Island (PEI), shellfish (bivalves comprised of mussel and oyster) aquaculture production occurs in sheltered, generally shallow bays. The productive capacity of a bay for shellfish aquaculture is determined by many factors including the hydrodynamics of the bay and input of nutrients. There is considered to be a limit to the production (biomass) that can be extracted from an ar...

Multiple regression models were created to explain spatial and temporal variation in the δC and δN values of fish populations on the West Florida Shelf (eastern Gulf of Mexico, USA). Extensive trawl surveys from three time periods were used to acquire muscle samples from seven groundfish species. Isotopic variation (δCvar and δNvar) was calculated as the deviation from the isotopic mean of each...

In a food web, nutrients flow via trophic links. For this reason, trophic interactions have a fundamental character due to the principle of mass conservation. To further comply with this principle, we consider a food web model that includes nutrient cycling. Non-trophic effects amongst species of the food web are modelled as interaction modifications, i.e., a functional change in the trophic in...

We consider trophic networks, a kind of networks used in ecology to represent feeding interactions (what-eats-what) in an ecosystem. We observe that trophic networks can be naturally modelled as Petri nets and this suggests the possibility of exploiting Petri nets for the analysis and simulation of trophic networks. Some preliminary steps in this directions and some ideas for future development...

this research summarizes the data on benthic macro invertebrates collected from 25 points in the urmia lake wetlands during november 2008 to february 2009. the purpose of the study was to assess the effects of elevated salinity and nutrient (nitrogen and phosphorus) levels on macro invertebrate abundance and composition. a total of 32 taxa were collected, and the common taxa, including chironom...

in order to increase the knowledge of saurida tumbil biology and ecology, an investigation of food habits of this species was conducted from october 2010 to september 2011 in bushehr coastal waters, persian gulf. 485 fish stomach contents were studied. in this study the frequency of occurrence of prey, feeding intensity index, the index is empty stomachs, the mean trophic levels and the rate of...

Diazotrophic inputs by Trichodesmium have been shown to support production in tropical and subtropical marine environments, but the importance of Trichodesmium in the Gulf of Mexico has not been widely investigated. Here, we use stable carbon (δ13C) and nitrogen (δ15N) isotopes to determine whether diazotrophy impacts the isotope baselines of pelagic food webs in the northern Gulf of Mexico. Ph...

Trophic structure, or the distribution of biomass among producers and consumers, determines key ecosystem values, such as the abundance of infectious, harvestable or conservation target species, and the storage and cycling of carbon and nutrients. There has been much debate on what controls ecosystem trophic structure, yet the answer is still elusive. Here we show that the nutritional quality o...