Do tissue carbon and nitrogen limit population growth of weevils introduced to control waterhyacinth at a site in the Sacramento-San Joaquin Delta, California?

Waterhyacinth (Eichhornia crassipes(Mart.) Solms), is a serious problem in the Sacramento Delta. Two weevil species (Neochetina bruchi Hustache and N. eichhorniae Warner) have been introduced as biological control agents. The purpose of this study was to test the hypothesis that nitrogen (N) in the tissue of waterhyacinth was not sufficient to support weevil growth and reproduction. Because it grows better on plants with high N content and because it has a greater impact on the growth of high N plants, N. bruchi may be a more effective biological control agent in the Sacramento Delta.

Reducing non-point DOC and nitrogen exports from rice fields: A pilot study and quantitative survey to determine the effects of different hydrologic management practices : Deliverable 15.3 Final Report

Rice cultivation at any level in the Sacramento–San Joaquin Delta (existing or expanded) compels the need to quantify surface and subsurface loads of dissolved organic carbon (DOC), disinfection byproduct precursors (DBPPs) and nitrogen. This information can be used to develop Best Management Practices (BMPs) to reduce export of these constituents in order to improve drinking water quality. Although rice cultivation in the Delta is relatively limited, several factors outside of this research could contribute to increased rice acreage in the Delta: • Recently developed rice varieties seem more suitable for the Delta climate than earlier varieties which required warmer conditions; • Previous economic analyses (Appendix A.10) suggest rice is more profitable than corn, a dominant land use in the Delta; • Recent studies on wetlands at Twitchell Island suggest rice production can help mitigate oxidative subsidence (Miller et al. 2000); • The different oxidative states that result from flooding in rice as compared to those found in crops that require drained soils may help control crop specific weeds and nematodes when rice is incorporated into a crop rotation; and • Providing flooded conditions during a greater part of the year than other crops may benefit water birds. ... (PDF contains 249 pages)

Studies on the nutrition of brackish water catfish - Chrysichthys nigrodigitatus . 1. Preliminary investigations on the probable use of vegetable oil in catfish feeds

Four groups of brackishwater catfish were fed four diets: N.F. (NIOMR formula 1 feed), A. B. and C. for seven weeks. Feeds N.F., A., B and C. contained 1.21% fish oil + 5.59% vegetable oil; 1.21% fish oil + 7.39% vegetable oil; 1.21% fish oil + 9.09% vegetable oil; 1.21% fish oil + 10.89% vegetable oil respectively. Results of feeding trial showed that growth was best in the group fed diets containing 10.89% vegetable oil and least in those containing 9.09% vegetable oil

The contribution of fish intake, aquaculture, and small-scale fisheries to improving nutrition security: a literature review

Much of fish consumed by the poor are caught by household members and traded in local markets. These fish are rarely or poorly included in national statistics, and it is therefore difficult to estimate precisely the real contribution of fish to the rural poor households. This report is the first global overview of the role played by fish in improving nutrition. Fish consumption patterns of the poor, the nutritional value of fish, and small-scale fisheries and aquaculture activities are considered. It also highlights the gap in knowledge where more research is needed.

WEFTA interlaboratory comparison on nitrogen determination by Kjeldahl digestion in fishery products and standard substances

14 Laboratorien aus 12 europäischen Ländern nahmen an einer Laborvergleichsuntersuchung zur Stickstoffbestimmung in Fischerzeugnissen und Standardsubstanzen nach Kjeldahl teil. 13 Laboratorien erzielten dabei Ergebnisse, die alle in engen Grenzen um die gefundenen Mittelwerte streuten. Der von den einzelnen Teilnehmern erzielte Variationskoeffizient war mit etwa 0,5 % gering. Auch die Standardsubstanzen mit bekanntem Stickstoffgehalt konnten überwiegend mit hinreichender Genauigkeit (98 % der vom Hertsteller angegebenen Gehalte) analysiert werden. Der ideale Kjeldahlaufschluß ist durch kurze Aufschlußzeiten (ca. 120 min), eine Aufschlußtemperatur bei 430° C und durch die Wahl des für die jeweilige Matrix geeigneten Katalysators gekennzeichnet.

On the nutrition of the predatory cladocerans Leptodora and Bythotrephes. [Translation of: Byulleten' Institute Biologii Vodokhranilishch 6, pp. 21-22, 1960]

Results of the investigation on certain problems of the nutrition of Leptodora and Bythotrephes in Rybinsk Reservoir (Russia) are reviewed. To clarify the composition of the food of Leptodora and Bythotrephes in this period, experiments were provided on their nutrition by cyclopids and rotifers.

On the nutrition of Polyphemus pediculus (L.). [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 12(15) 170-174, 1966.]

Many sides of the biology of Polyphemus pediculus are adequately studied at the present time. Most complicated is the question of its feeding. Dissection does not give an idea of the composition of the food, since Polyphemus strongly grinds its food with its mandibles. For clarification of the composition of the food of Polyphemus pediculus, the authors carried out in July and August 1962 a series of experiments with the application of radio-carbon methods in order to judge the degree of utilization of one or other foods by the quantity of C14, accumulated in the body of the crustacean after feeding. Particular attention in these experiments was given to the question of the possibility of the utilization by polyphemus of plant food - bacteria, algae and detritus.

Tests of some specific effect substances in duck nutrition. Translation from: Biologisace a chemisaze vyzivy svirat 5, 43-48, 1969.]

There is a constantly increasing collection of manufactured substances, whose effectiveness in the sustenance of ducks is under investigation. The author examines the effects of some substances already previously tested and also there were examined substances which had not hitherto been studied. The use of different supplements for late autumn fattening is studied through various experiments.

Nitrogen and phosphorus forms in water and the food requirements of algae. [Translation from: Wiadomosci Ekologiczne 19 238-244, 1973. ]

When dissolved in water, compounds of nitrogen and phosphorus ought to contain the basic assimilated food requirements for autotrophic plants and therefore autotrophic algae. This article summarises the occurrence of nitrogen in water, how species of algae utilize nitrogen and phosphorus forms for growth and the capacities of algae to adapt to environments of different nutrient wealth. This topic has unquestionable importance not only for the purpose of survival of a species but also in deciding indirectly about the stability of ecosystems.

Ratio of natural isotopes of nitrogen. I. Primary results: soils of Dombes [Translation from: Revue d'Ecologie et de Biologie du Sol 14, 279-287, 1977]

Utilization of the heavy isotope of nitrogen as a tracer has found numerous applications in soil biology. It allows better definition of different stages of the nitrogen cycle, in particular the immobilization-mineralization cycle. In this work, the authors report the results of calculations of natural isotope ratios of nitrogen in samples of water, soil and vegetation prevailing in Dombes and discuss the possibilities of errors and coefficients of fractionation.

The effect of oxygen concentration in water on the growth and nitrogen metabolism in the fry of rainbow trout [Translation from: Rybnoe Khoziaistvo,V.33, 74-75, 1957]

To ascertain the effect of various concentrations of oxygen in water on the fry of rainbow trout experiments were made with aquaria at various concentrations of oxygen. The food supplied was chironomid larvae (Chironomus plumosus). A surplus of food was supplied to the fry. Indices are given of the reaction of the fry to different temperatures.

A study of the nutrition of the Rotifer Asplanchna, with the help of Carbon 14 [Translation from: Byulleten ' Instituta Biologii Vodokhranilishch, No. 12, pp.17-20, 1962]

Laboratory research was done in order to study the feeding of larval Cricotopus silvestris F. in relation to characters of structure of oral apparatus. Results of the experiments are summarised and the oral apparatus morhologically described.

Trends in nitrate-nitrogen, nitrite-nitrogen and phosphorus concentration in Ebonyi river, Nigeria

A baseline study of the limnological integrity of Ebonyi River, a tropical lotic system in south-eastern Nigeria was conducted between September 2006 and February 2008 to assess its potential in enhancing fisheries production for the benefit of the rural poor, who depend on the resources of the river for survival. The parameters measured were nitrate-nitrogen, nitrite-nitrogen and phosphate-phosphorus. Results show that nitrate varied between 40.43mg/L in September 2006 and 1.73mg/L in December 2007, Showing significant difference (P<0.01) among months. The values recorded for nitrites varied between 0.2mg/L in September 2006 and 0.4mg/L in February 2008, showing significant (P<0.01) variation among months. Values recorded for phosphorus was highest (0.05mg/L) in the month of October 2006 while the least mean value (0.32mg/L) was recorded in the month of May 2007 and showed significant (p<0.01) variation in monthly means. It was concluded that the values of the measured parameters falls within tolerable range for enhanced fisheries development in the area. KEYWORDS: Limnology, Tropical, River, Monthly, Mean, Variation

Fisheries production in Asia: its role in food security and nutrition

This paper reviews the status and some management issues of fisheries production in Asia, as well as the supply and demand situation. Its food security and nutritional roles and opportunities for value addition are also discussed.

Can nitrogen pollution from aquaculture be reduced?

Nitrogen is essential for the normal growth of fish. It is an important ingredient in fish feed but is very expensive. There is evidence that nitrogen loading from feeding and metabolic activities of fish can cause pollution of the receiving waters. This paper reviews nitrogen losses and nitrogen retention in fish and suggests ways of reducing nitrogen loading to the environment for a sustainable aquaculture program.