نتایج جستجو برای: grazing food chain

تعداد نتایج: 568347  

Journal: :iranian journal of toxicology 0
mehdi khoshnamvand phd student environmental sciences, research center of eco-environmental sciences, university of chinese academy of sciences, beijing, china. kamran almasieh department of environmental sciences, university of kurdistan, sanandaj, iran. shahra m kaboodvandpour department of environmental sciences, university of kurdistan, sanandaj, iran.

background: the present study was carried out to track and calculate biomagnification factor (bmf) of total mercury (t-hg) between two different trophic levels (i.e., plankton and a planktivorous fish) in a fresh water grazing food chain. methods: experimental organisms were planktonic biomass and silver carp (hypophthalmichthys molitrix) as a planktivorous fish. silver carp samples were obtain...

2013
Peter Houk Craig Musburger

Coral reef assemblages, trophic interactions, and food web stability were examined across a remote and densely populated atoll, in the Republic of the Marshall Islands (RMI). The biomass of sharks, large-bodied piscivores, and secondary invertebrate consumers was expectedly larger in the absence of major human populations. Less intuitively, we report a doubling in the density and biomass of sma...

Journal: :Ecology 2008
David L Strayer Michael L Pace Nina F Caraco Jonathan J Cole Stuart E G Findlay

Inputs of fresh water and grazing both can control aquatic food webs, but little is known about the relative strengths of and interactions between these controls. We use long-term data on the food web of the freshwater Hudson River estuary to investigate the importance of, and interactions between, inputs of fresh water and grazing by the invasive zebra mussel (Dreissena polymorpha). Both fresh...

Journal: :Aquatic toxicology 2007
Scott G Lynn David J Price Wesley J Birge Susan S Kilham

The objective of this study was to examine the importance of nutrient status of a diatom (Stephanodiscus minutulus) to the uptake of PCB congener #54 (2,2',6,6'-tetrachlorobiphenyl) and the subsequent transfer of PCB to a pelagic grazing zooplankton (Daphnia pulicaria). The algae, which were grown under different nutrient treatments, were then fed to a zooplankton to examine the subsequent food...

Journal: :تحقیقات نظام سلامت 0
حسن هاشمی مرکز تحقیقات محیط زیست دانشگاه علوم پزشکی اصفهان، اصفهان، ایران صبا سپهوند کارشناسی ارشد جغرافیای پزشکی، دانشکده ادبیات و علوم انسانی،دانشگاه اصفهان،اصفهان کبری هاشمی کارشناس مهندسی منابع طبیعی- شیلات– گرایش تکثیر و پرورش آبزیان، دانشکده علوم دریایی، دانشگاه دریانوردی و علوم دریایی چابهار

climate change around the world is now a reality that has adverse effects on the environment and human health. there is little information about the effect of climate change on food systems, especially seafood from the farm to the table. the aim of this study was to review the fundamental effects of climate change on seafood safety and human health. climate change is expected to increase chemic...

حسین شمس, , سعید محتشم‌نیا, , مجید آقامحسنی فشمی, , محمد جنگجو, , احسان شهریاری, , حسن احمدی, , حسین ارزانی, , علی اصغر درویش صفت, , محمد جعفری, ,

Range suitability and its grazing capability are the most important criteria in rangeland analysis and monitoring. Determination and monitoring of factors affecting on range suitability and diagnosis of them are important .All range ecosystem components affect range suitability. Which among them physical and vegetational factors, forage production, water resources and sensitivity to erosion wer...

2008
Daniel S. Hamermesh

Using the 2006 American Time Use Survey and its Food and Health Module I show that over half of adult Americans report grazing (secondary eating/drinking) on a typical day, with grazing time averaging over 2/3 of primary eating/drinking time. An economic model predicts that higher wage rates will lead to substitution of grazing for primary eating/drinking, especially by changing the relative nu...

Journal: :Journal of animal science 2009
M Shibata K Matsumoto M Oe M Ohnishi-Kameyama K Ojima I Nakajima S Muroya K Chikuni

The objective of this study was to investigate the differences in the muscle proteome of grass-fed and grain-fed cattle. Eight Japanese Black Cattle 10 mo of age were separated randomly into 2 groups: 1) grazing (grass-fed) and 2) concentrate (grain-fed) groups. All cattle were first housed individually in a stall barn and fed a combination of concentrate ad libitum and Italian ryegrass hay unt...

Journal: :Applied and environmental microbiology 2011
Jude K Apple Suzanne L Strom Brian Palenik Bianca Brahamsha

Grazing mortality of the marine phytoplankton Synechococcus is dominated by planktonic protists, yet rates of consumption and factors regulating grazer-Synechococcus interactions are poorly understood. One aspect of predator-prey interactions for which little is known are the mechanisms by which Synechococcus avoids or resists predation and, in turn, how this relates to the ability of Synechoco...

Journal: :The Proceedings of the Nutrition Society 2003
J M Wilkinson J Hill C J C Phillips

The main factors affecting the accumulation of potentially-toxic metals (PTM) by grazing animals are the presence of the metal, its concentration in herbage and at the soil surface, and the duration of exposure to the contaminated pasture and soil. In addition, the elapsed time between the contamination of the pasture and grazing, the quantity of soil ingested together with herbage, the mechani...

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