Manipulation of growth to reduce mercury concentrations in sport fish on a whole-system scale

2012 ◽  
Vol 69 (1) ◽  
pp. 122-135 ◽  
Author(s):  
Jesse M. Lepak ◽  
Kristoph-Dietrich Kinzli ◽  
Eric R. Fetherman ◽  
William M. Pate ◽  
Adam G. Hansen ◽  
...  
Keyword(s):  
Energy Content ◽  
Northern Pike ◽  
Fish Population ◽  
High Energy ◽  
Forage Fish ◽  
Food Web Structure ◽  
High Quality ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Web Structure ◽  
Sport Fish

Altering food web structure has been shown to influence mercury (Hg) concentrations in sport fish. Here, we describe a whole-system manipulation designed to assess the effectiveness of stocking relatively high-quality, low-Hg prey (rainbow trout, Oncorhynchus mykiss ) as a means of increasing northern pike ( Esox lucius ) growth to reduce Hg concentrations. A replicated pond experiment served as a reference for the lake experiment and provided information to parameterize bioenergetics simulations. Results indicate that stocking relatively high-quality, low-Hg prey is a rapid and effective method to reduce sport fish Hg concentrations by up to 50% through an increase in individual northern pike biomass. Large northern pike, the fish that tend to be the most contaminated, were affected most by the manipulation. The observed declines in northern pike Hg concentrations indicate that stocking might be used to reduce Hg concentrations in sport fish prior to harvest. However, after 1 year, northern pike Hg concentrations rebounded, suggesting that reductions would be temporary without continuous stocking. Thus, perhaps the most effective method of perpetually reducing sport fish Hg concentrations would be to manage for the development of a naturally reproducing forage fish population with relatively high energy content and low Hg concentrations.

scholarly journals High quality cassava peel® production and its utilization in pig production: A review

2019 ◽  
Vol 46 (3) ◽  
pp. 205-218
Author(s):  
A. O. K. Adesehinwa ◽  
T. A. Amole ◽  
E. Ajayi ◽  
B. A. Makanjuola ◽  
I. Okike
Keyword(s):  
Energy Content ◽  
High Energy ◽  
Blood Parameters ◽  
Proximate Analysis ◽  
Growing Pigs ◽  
Weaned Pigs ◽  
High Quality ◽  
Cassava Peels ◽  
Cassava Peel ◽  
Good Substitute

The cassava peel has been investigated as a good source of energy for various categories of livestock and it has been reported as a good substitute for maize for all classes of pigs.International Livestock Research Institute (ILRI) has transformed fresh cassava peels intohigh quality, safe and hygienic livestock feed, known as High Quality Cassava Peel®. HighQuality Cassava Peel® was produced by sorting, grating, pressing, sieving and drying offresh cassava peels. Sorting of the fresh (harvested the same day) cassava peels was done by removal of the stumps, large sized woody tubers and other foreign materials before grating, to gradually reduce the particle size, ensure rapid dewatering, drying and easy handling of the sorted peels. Next is the pressing of the grated peels in woven bags using a hydraulic jack and wooden planks. The resultant cassava peel cake after pressing around 30- 35% moisture had shelf life of 5- 7 days. The pressed cassava peel cake was re-grated to loosen it into a free flowing material that can be subjected to sieving to separate the fine mash (lower fiber, high energy content) from the coarse mash (higher fiber, lower energy content). The resultant fine or coarse mash was further dried by toasting or sun-drying to a moisture level of 10-12%. The final product with 10–12% moisture content was bagged and stored safely for 4- 6 months without any spoilage. Proximate analysis of the HQCP® further clarified its quality over that of other processed cassava peels. Series of trials conducted have proved High Quality Cassava Peel as a good substitute for significant portion of maize in the diet of growing and weaned pigs without any adverse effect on the performance and blood parameters determined in each of the studies. The results of the studies conducted on the utilization of the high quality cassava peel as a substitute for maize in the diet of weaned and growing pigs have shown the efficacy of HQCP® to replace significant quantities of maize in their diet. High Quality Cassava Peel demonstrated potential for replacement of up to 15% of the 40% maize inclusion in the diet of weaned pigs and 30% in the diet of growing pigs with or without direct fed microbial (DFM) supplementation. No significant effect of DFM was noticed in the utilization of HQCP® by both weaned and growing pigs. All the hematological and serum biochemical parameters determined were within the normal range for healthypigs. Based on the outcome of the feeding trials, HQCP® has been proved to replace asubstantial portion of maize in the diet of weaned and growing pigs, thereby bringing about a decrease in the cost of production

scholarly journals Multiple species drive flexible lake food webs with warming

2018 ◽  
Author(s):  
Timothy J. Bartley ◽  
Tyler D. Tunney ◽  
Nigel P. Lester ◽  
Brian J. Shuter ◽  
Robert H. Hanner ◽  
...  
Keyword(s):  
Climate Change ◽  
Temperature Gradient ◽  
Food Webs ◽  
Lake Trout ◽  
Trophic Levels ◽  
Forage Fish ◽  
Food Web Structure ◽  
Web Structure ◽  
Nearshore Habitat ◽  
Multiple Species

AbstractClimate change is rewiring the food webs that determine the fate of diverse ecosystems. Mobile generalist consumers are responding to climate change by rapidly shifting their behaviour and foraging, driving food webs to flex. Although these responsive generalists form a key stabilizing module in food web structure, the extent to which they are present throughout whole food webs is largely unknown. Here, we show that multiple species comprising key trophic roles drive flexible lake food webs with warming. By examining lakes that span a 7°C air temperature gradient, we found significant reductions in nearshore derived carbon and nearshore habitat use with increased temperature in three of four fish species. We also found evidence that the response of lake trout to increased temperatures may reduce their biomass and cascade to release their preferred prey, the pelagic forage fish cisco. Our results suggest that climate warming will shift lake food webs toward increased reliance on offshore habitats and resources. We argue that species across trophic levels broadly couple lake macrohabitats, suggesting that potentially stabilizing responsive consumers are present throughout food webs. However, climate change appears to limit their ability to responsively forage, critically undermining a repeated stabilizing mechanism in food webs.

Effects of northern pike (Esox lucius) additions on pollutant accumulation and food web structure, as determined by δ13 C and δ15 N , in a eutrophic and an oligotrophic lake

1999 ◽  
Vol 56 (11) ◽  
pp. 2193-2202 ◽  
Author(s):  
Karen A Kidd ◽  
Michael J Paterson ◽  
Raymond H Hesslein ◽  
Derek CG Muir ◽  
Robert E Hecky
Keyword(s):  
Food Web ◽  
Fathead Minnow ◽  
Pimephales Promelas ◽  
Eutrophic Lake ◽  
Northern Pike ◽  
Esox Lucius ◽  
Oligotrophic Lake ◽  
Food Web Structure ◽  
Pike Esox Lucius ◽  
Web Structure

In May 1993 and 1994, northern pike (Esox lucius) were added to eutrophic Lake 227 and oligotrophic Lake 110 at the Experimental Lakes Area in northwestern Ontario. Both lakes were previously dominated by cyprinids, and northern pike additions significantly decreased cyprinid densities in both lakes. Food web relationships were determined pre- and post-manipulation using stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of zooplankton, benthic invertebrates, and fishes. In Lake 110, fathead minnow (Pimephales promelas) shifted from a zooplanktivorous to a zoobenthivorous diet as indicated by a shift in isotopic composition to more depleted δ15N and enriched δ13C values after northern pike additions. It was not possible to direct predator-induced shifts in cyprinid diets in Lake 227. Concentrations of mercury and organochlorines (sum of polychlorinated biphenyls (ΣPCB), dichlorodiphenyltrichloroethane (ΣDDT), and hexachlorocyclohexane (ΣHCH)) in these fish did not change markedly after northern pike introductions despite the shifts in diet for fathead minnow from Lake 110. However, concentrations of all contaminants were lower in biota from eutrophic Lake 227 when compared with Lake 110, which is consistent with previous studies. Our results indicate that nutrient availability, rather than short-term changes in food web structure, determined contaminant concentrations in fish and other biota from these lakes.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

scholarly journals Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3193
Author(s):  
Ana L. Santos ◽  
Maria-João Cebola ◽  
Diogo M. F. Santos
Keyword(s):  
Energy Content ◽  
Water Electrolysis ◽  
High Energy ◽  
Operating Conditions ◽  
Energy Sources ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
New Energy ◽  
Recent Developments ◽  
Cell Components

Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. This review examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis. This process is far from being new, but research shows that there is still plenty of room for improvement. The efficiency of an electrolyzer mainly relates to the overpotential and resistances in the cell. This work shows that the path to better electrolyzer efficiency is through the optimization of the cell components and operating conditions. Following a brief introduction to the thermodynamics and kinetics of water electrolysis, the most recent developments on several parameters (e.g., electrocatalysts, electrolyte composition, separator, interelectrode distance) are highlighted.

Invasive rodents have multiple indirect effects on seabird island invertebrate food web structure

2017 ◽  
Vol 27 (4) ◽  
pp. 1190-1198 ◽  
Author(s):  
Joshua J. Thoresen ◽  
David Towns ◽  
Sebastian Leuzinger ◽  
Mel Durrett ◽  
Christa P. H. Mulder ◽  
...  
Keyword(s):  
Food Web ◽  
Indirect Effects ◽  
Food Web Structure ◽  
Web Structure ◽  
Invasive Rodents
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