نتایج جستجو برای: nutrient resource

تعداد نتایج: 278576  

Journal: :The American naturalist 2007
James E Cloern

The import of resources (food, nutrients) sustains biological production and food webs in resource-limited habitats. Resource export from donor habitats subsidizes production in recipient habitats, but the ecosystem-scale consequences of resource translocation are generally unknown. Here, I use a nutrient-phytoplankton-zooplankton model to show how dispersive connectivity between a shallow auto...

2017
Giovanni Putoto Renzo Pegoraro

2007
Timothy Besley Rohini Pande Vijayendra Rao

This paper uses data on elected village councils in South India to examine the politics of public resource allocation. We stress two facets of the political process –access to political authority, and the use of political power. We …nd compelling evidence that the pattern of policy re‡ects politicians’self-interest. Further, the extent and type of political opportunism in resource allocation is...

2009
S. Dutkiewicz M. J. Follows J. G. Bragg

[1] We examine the interplay between ecology and biogeochemical cycles in the context of a global three-dimensional ocean model where self-assembling phytoplankton communities emerge from a wide set of potentially viable cell types. We consider the complex model solutions in the light of resource competition theory. The emergent community structures and ecological regimes vary across different ...

Journal: :Ecology 2006
Edie Marsh-Matthews Raelynn Deaton

Theoretical models of the evolution of matrotrophy from a lecithotrophic ancestor suggest that resource availability plays a major role in selective scenarios favoring a change in offspring provisioning. We examined effects of feeding level on embryo provisioning in the livebearing fish Gambusia geiseri, a species with dual provisioning of embryos via both yolk sequestered in large eggs and pos...

2006
Jennifer L. Greenwood Amy D. Rosemond Holly S. Weyers

Most nutrient enrichment studies in aquatic systems have focused on autotrophic food webs in systems where primary producers dominate the resource base. We tested the heterotrophic response to longterm nutrient enrichment in a forested, headwater stream. Our study design consisted of 2 years of pretreatment data in a reference and treatment stream and 2 years of continuous nitrogen (N) + phosph...

Journal: :Proceedings. Biological sciences 2016
Muhammad Saleem Ingo Fetzer Hauke Harms Antonis Chatzinotas

Loading of water bodies with dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) affects their integrity and functioning. Microbial interactions mitigate the negative effects of high nutrient loads in these ecosystems. Despite numerous studies on how biodiversity mediates ecosystem functions, whether and how diversity and complexity of microbial food webs (horizontal, vertical) an...

2005
Scott Heckbert Alex Smajgl

Resource issues for the Great Barrier Reef (GBR) are characterised by heterogenous multiple users incurring diverse non-point source environmental impacts. Of particular concern is sediment and nutrient runoff caused by cattle grazing and sugar cane growing, among other practices in the lowland agricultural and upland grazing areas. In this paper we present a decision support tool for resource ...

2010
Rachel L. Vannette Mark D. Hunter

1. General theories of plant defence often fail to account for complex interactions between the resources required for defence expression. For example, the carbon that is used for carbon-based defence is acquired using nutrient-rich photosynthetic pigments, while nutrient gain itself requires substantial carbon allocation belowground. We should therefore expect the expression of plant defence t...

2015
Daniel L. Roelke Sofie Spatharis

Coastal marine systems are affected by seasonal variations in biogeochemical and physical processes, sometimes leading to alternating periods of reproductive growth limitation within an annual cycle. Transitions between these periods can be sudden or gradual. Human activities, such as reservoir construction and interbasin water transfers, influence these processes and can affect the type of tra...

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