Embodied Resources in Fish and Shrimp Feeds

Global averages were obtained for amounts of energy, land, water, wildfish, nitrogen, and phosphorus embodied in aquaculture feed ingredients. These data allowed amounts of these embodied resources to be calculated for typical feed formulations for channel catfish, Ictalurus punctatus; hybrid catfish, I. punctatus♀ × I. furcatus♂; Vietnamese catfish, Pangasius spp.; Atlantic salmon, Salmo salar; rainbow trout, Oncorhynchus mykiss; tilapia, Oreochromis spp.; whiteleg shrimp, Litopenaeus vannamei; and black tiger shrimp, Penaeus monodon. Embodied resource use per m.t. of feed varied among species: energy, 4.90–12.48 GJ/m.t.; land, 0.082–0.312 ha/m.t.; water, 502–1227 m³/m.t.; wildfish, 0–2880 kg/m.t.; nitrogen, 3.08–8.63 kg/m.t.; phosphorus, 1.16–5.62 kg/m.t. These calculations did not account for variations in site‐specific factors related to embodied resources and feed composition and use. But they suggest that reducing feed conversion ratio (FCR) by 0.1 unit for the seven species (species groups) could potentially reduce feed use by around 1.1 million tonne (Mt) while conserving 9.8 million GJ of energy, 270,000 ha of agricultural land, 1.4 billion m³ of freshwater, and 1.24 Mt of wildfish. Reduction of the FCR is a powerful means of lessening farm‐level production costs and negative impacts of feed production and use.     

Mechanical site preparation effects on understory plant diversity in the Piedmont of the southern USA

Diversity of understory vegetation was compared among four intensities of site preparation and an adjacent 50-year-old pine-hardwood forest. The study site was a six-year-old loblolly pine (Pines taeda) plantation in the lower Piedmont of Georgia. Species richness and Shannon diversity indices were used to evaluate vine and woody (trees and shrubs) species diversity. Biomass distribution was compared among four plant categories: vines, forbs, grasses, and woody. Moderate intensity treatments (chainsaw and shear and chop) consistently ranked highest overall in diversity, with the mature pine-hardwood forest ranking lowest. Distribution of the four plant categories was not significantly affected by intensity of site preparation.Alabama Agricultural Experiment Station Series No. 9-892325P.     

Use of middle infrared radiation to estimate the leaf area index of a boreal forest

The leaf area index (LAI) of boreal forest can be estimated using reflected radiation recorded by satellite sensors. Measurements of visible and near infrared radiation are commonly used in the normalized difference vegetation index (NDVI) to estimate LAI. However, research, mainly in tropical forest, has demonstrated that LAI is related more closely to radiation of middle infrared wavelengths than of visible wavelengths. This paper derives a vegetation index, VI3, based on radiation from vegetation recorded at near and middle infrared wavelengths. For a boreal forest canopy, the relationship between VI3 and LAI was observed to be much stronger than that between NDVI and LAI. In addition, the LAI estimated using VI3 accounted for about 76% of the variation in field estimates of LAI, compared with about 46% when using the NDVI. We conclude that information provided by middle infrared radiation should be considered when estimating the leaf area index of boreal forest.     

Organic Carbon and Dissolved Oxygen Budgets for a Commercial‐Size,In‐pond Raceway System

Intensive production of ictalurid catfish in the USA has increased over the past several years, and a better understanding of the amount of organic carbon (OC) and dissolved oxygen (DO) in these culture environments is needed. Budgets for OC and DO were estimated over a production season (March to November) for an in‐pond raceway system for channel catfish, Ictalurus punctatus, and hybrid catfish (channel catfish × blue catfish, Ictalurus furcatus), with co‐culture of paddlefish, Polyodon spathula, and Nile tilapia, Oreochromis niloticus. Feed input ranged from 45 to 263 kg/ha/d with an overall average of 80 kg/ha/d. Production of each kilogram of live catfish required 1.5 kg of feed and released into the water 0.70 kg of OC, and led to the synthesis of an additional 3.36 kg of OC by photosynthesis. Consequently, production of 1 kg of live catfish resulted in 4.06 kg OC, and harvest of catfish accounted for only 29.5% of OC applied from the feed. Removal of OC increased to 34.3% with the additional harvest of paddlefish and tilapia. OC was consumed in respiration, and some OC accumulated in sediment. Total respiration within the system exceeded the DO produced by photosynthesis, while diffusion and mechanical aeration aided in maintaining suitable DO levels for fish production.     

Alkalinity and Hardness: Critical but Elusive Concepts in Aquaculture

Total alkalinity and total hardness are familiar variables in aquatic animal production. Aquaculturists—both scientists and practitioners alike—have some understanding of the two variables and of methods for adjusting their concentrations. The chemistry and the biological effects of alkalinity and hardness, however, are more complex than generally realized or depicted in the aquaculture literature. Moreover, the discussions of alkalinity and hardness—alkalinity in particular—found in water chemistry texts are presented in a rigorous manner and without explanation of how the two variables relate to aquaculture. This review provides a thorough but less rigorous discussion of alkalinity and hardness specifically oriented toward aquaculture. Alkalinity and hardness are defined, their sources identified, and analytical methods explained. This is followed by a discussion of the roles of the two variables in aquaculture, including their relationships with carbon dioxide, pH, atmospheric pollution, ammonia, and other inorganic nitrogen compounds, phytoplankton communities, trace metals, animal physiology, and clay turbidity. Liming and other practices to manage alkalinity and hardness are explained. Changes in alkalinity and hardness concentrations that occur over time in aquaculture systems are discussed. Emphasis is placed on interactions among alkalinity, hardness, water quality, and aquacultural production.     

A comparative study of the cytological and reproductive behaviour of wheat and triticale subjected to two temperature regimes

Summary A comparison was made of the meiotic stability and reproductive behaviour ofTriticale hexaploide cv. Rosner andT. aestivum cv. Pitic in response to two temperature regimes (15° and 30°C) imposed continuously from premeiosis to maturity. Mean frequencies of MI open bivalents, univalents, and lagging chromosomes at AI were significantly higher in Rosner than in Pitic. Such irregularity would appear to arise from the asynchronous disjunction of chromosomes between Metaphase I and Anaphase I, resulting in meiotic disturbances and a high frequency of abnormal microspores. Despite such abnormalities, floret fertility was equivalent to that observed in Pitic, and the proportion of aneuploids recovered in the progeny, although greater than expected in wheat, was much lower than would be predicted. It is suggested that there is a strong certation effect in the transmission of aneuploid microspores and that the irregularities observed during microsporogenesis do not apply directly to megasporogenesis.No appreciable effect of temperature on meiotic chromosome behaviour during microsporogenesis was observed in either wheat or Triticale. In Triticale, high temperatures (30°C) substantially reduced spikelet fertility, and in contrast, low temperature (15°C) increased the frequency of aneuploids.Contribution No 232, Department of Plant Science, University of Manitoba, Winnipeg 19, Manitoba, Canada     

加拿大的小麦产业?

加拿大小麦是受出口驱动的产业,并处于激烈的世界市场竞争之中.加拿大小麦采取生产优质小麦的战略,这些优质小麦用于制作面包、面条和意大利面食,并且增加对普通小麦的充足供应.因此,加拿大小麦产业重点主要放在小麦的质量、等级、安全、清洁、品种多样化发展,以及提高售后服务的增加值上.……     

Novel trisaccharide fatty acid ester identified from the fruits of Morinda citrifolia (Noni)

Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2, 6-di-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose. The known compounds were identified as rutin and asperulosidic acid.     

Field measurements of CO2 enhancement and climate change in natural vegetation

It is generally assumed that healthy, natural ecosystems have the potential to sequester carbon under favorable environmental conditions. There is also evidence that CO₂ acts as a plant fertilizer. It is of interest to know if these assumptions are valid and how natural systems might respond under future scenarios of CO₂ increase and possible climate changes. Few measurements of the effects of CO₂ and global climate change have been made on “natural” ecosystems under realistic field conditions. Most measurements have been conducted in the synthetic environments of totally controlled greenhouses and growth chambers. Several lines of evidence indicate that controlled environment studies using plants growing in pots induce experimental artifacts that reduce confidence in the use of results for prediction of future global responses. Open top chambers are being used in several autecological field studies in an attempt to obtain more realistic field environments. A few field microcosm studies have been completed and a system for the free air release of CO₂ has been applied in cotton fields. Unfortunately, the requirement of large amounts of CO₂ and financial restrictions have precluded the initiation of larger scale field studies in natural vegetation. This paper lists and summarizes the best field studies available but draws heavily on studies from artificial environments and conditions in an attempt to summarize knowledge of global environmental change on forests and other non-agricultural ecosystems. Finally the paper concludes that there is a need for the development and application of equipment for field measurements in several representative natural ecosystems and makes specific recommendation of the creation of a tropical research center.