Higher food abundance reduces the catchability of cod (Gadus morhua) to longlines on the Faroe Plateau

The cod fishery at the Faroes has been managed since 1996 by an effort management system where it is assumed that there is a direct relationship between fishing mortality and fishing effort. We show that this relationship is weak. Due to a factor five variation in the primary production on the Faroe Plateau, the annual growth rate of cod may vary by a factor of five. Commercial catch-per-unit-effort data in combination with stock assessment estimates showed that there was a negative correlation between the annual growth rate of cod and their catchability with longlines, as well as with the total fishing mortality of cod on the Faroe Plateau. Furthermore, mark-recapture experiments showed that longline-caught cod in comparison with trawl-caught cod had a lower condition factor, a lower stomach content of natural prey, and a higher content of longline baits. During the feeding season in September–December, longline-caught cod exhibited a larger displacement distance than trawl-caught cod. These results were largely confirmed by storage tag data. Consequently, during low-productive periods, (i) the longline-dominated cod fishery at the Faroes exerted fishing mortalities that by far exceeded safe biological limits, and (ii) longline catch-per-unit-effort series might overestimate stock size considerably.     

Factors associated with colostrum quality in individual cows from dairy herds in the Waikato region of New Zealand

AIMS: To examine associations between various cow-level factors and quality of first-milking colostrum (measured as Brix), and to evaluate herd-level associations between vaccination against calf diarrhoea and colostrum quality, in cows from dairy herds in the Waikato region of New Zealand.

METHODS: A single colostrum sample was collected, by complete udder evacuation, from each of 20 cows from 29 dairy herds in the Waikato region of New Zealand during the 2016 spring calving period. Vaccination pre-partum with a calf diarrhoea vaccine was used in 15 herds. Each colostrum sample was tested using a digital Brix refractometer. The body condition score of each cow was recorded at the time of sample collection and farmers provided records of clinical mastitis and facial eczema from the previous 12 months, as well as the age and breed of cows. Associations between cow-level variables in non-vaccinated herds and Brix were examined using a multivariable linear mixed model and estimated marginal means obtained for different categories.

RESULTS: Mean Brix of 281 samples from cows in non-vaccinated herds was 18.7 (SD 0.26)%; 63/281 (22.4%) samples had Brix ≥22% and 152/281 (54.1%) had Brix ≥18%. Mean Brix of colostrum samples from cows aged ≥6 years (20.2 (95% CI=19.1–21.2)%) was higher than for samples from 2-year-old cows (18.6 (95% CI=17.3–19.9)%) (p=0.005). Colostrum that was collected at the first milking on the day of calving had higher Brix (20.0 (95% CI=19.1–20.9)%) than colostrum collected from cows that calved the previous day (17.5 (95% CI=16.5–18.4)%) (p<0.001). Mean Brix of colostrum samples from cows which produced ≥8?L (18.2 (95% CI=17.1–19.2)%) tended to be lower than from cows which produced <8?L first-milking colostrum (19.1 (95% CI=18.3–20.0)%) (p=0.08). Among vaccinating herds, 9/15 (60%) had ≥60% colostrum samples with Brix ≥18% compared with 4/14 (29%) of non-vaccinating herds (p=0.04).

CONCLUSIONS AND CLINICAL RELEVANCE: Colostrum quality, as measured by Brix, was associated with the total volume of first-milking colostrum, interval from calving to colostrum collection and cow age. Vaccination against calf diarrhoea was associated with a higher proportion of colostrum samples with adequate Brix. Careful selection of colostrum donor cows should ensure newborn calves are fed adequate quality colostrum which should be beneficial in preventing failure of passive transfer of IgG. Testing of colostrum from individual cows with a Brix refractometer is advocated for the selection of colostrum for feeding newborn calves.     

啤酒废水的单株降解与菌株鉴定研究

分别测定了从啤酒废水分离的15株细菌降解啤酒废水的能力,通过方差分析和多重比较发现,COD去除率50%以上的优势菌株有A1、A5、A9、A13、A14和A156种。根据其形态特征及生理生化特征鉴定,它们分别属于芽孢杆菌属、芽孢杆菌属、微球菌属、微杆菌属、棒状杆菌属和微杆菌属。该6种菌株可进一步优化组合进行啤酒废水降解研究。     

Earthworm distribution and abundance predicted by a process-based model

Earthworms are significant ecosystem engineers and are an important component of the diet of many vertebrates and invertebrates, so the ability to predict their distribution and abundance would have wide application in ecology, conservation and land management. Earthworm viability is known to be affected by the availability and quality of food resources, soil water conditions and temperature, but has not yet been modelled mechanistically to link effects on individuals to field population responses. Here we present a novel model capable of predicting the effects of land management and environmental conditions on the distribution and abundance of Aporrectodea caliginosa, the dominant earthworm species in agroecosystems. Our process-based approach uses individual based modelling (IBM), in which each individual has its own energy budget. Individual earthworm energy budgets follow established principles of physiological ecology and are parameterised for A. caliginosa from experimental measurements under optimal conditions. Under suboptimal conditions (e.g. food limitation, low soil temperatures and water contents) reproduction is prioritised over growth. Good model agreement to independent laboratory data on individual cocoon production and growth of body mass, under variable feeding and temperature conditions support our representation of A. caliginosa physiology through energy budgets. Our mechanistic model is able to accurately predict A. caliginosa distribution and abundance in spatially heterogeneous soil profiles representative of field study conditions. Essential here is the explicit modelling of earthworm behaviour in the soil profile. Local earthworm movement responds to a trade-off between food availability and soil water conditions, and this determines the spatiotemporal distribution of the population in the soil profile. Importantly, multiple environmental variables can be manipulated simultaneously in the model to explore earthworm population exposure and effects to combinations of stressors. Potential applications include prediction of the population-level effects of pesticides and changes in soil management e.g. conservation tillage and climate change.     

碧螺春茶树单株的选择研究

[目的]以洞庭碧螺春专用茶树品种选育为目标,开展碧螺春优质茶树[Camellia sinensis(L.)O.Ktze.]单株选择研究。[方法]根据茶叶品质、产量、芽叶发育期、抗性等性状指标,筛选洞庭群体种优良单株。[结果]d-x-1、d-x-8、d-x-24单株的感官审评总得分和单个香气得分均较对照和其他株系高,春茶开采期比其他株系稍早(d-x-24稍晚2 d),春茶发芽密度高于对照和其他株系,鲜叶产量、百芽重、抗逆性等与对照和其他株系相差不多。总体上,这3个株系综合性状比对照和其他株系优异。[结论]筛选出d-x-1、d-x-8和d-x-24共3个优质碧螺春茶树新株系,为碧螺春品种选育奠定了基础。     

作物有效营养面积及最佳营养面积研究

通过无肥区和施肥区不同土壤营养面积的试验得出 :黑土垄作区甜菜的有效营养面积是 3 7.8～ 5 3 .4× 67cm ;最佳营养面积是 2 7.3～ 2 9.7× 67cm。无肥区植株有较小的有效营养面积和最佳营养面积 ,施肥区植株有较大的有效营养面积和最佳营养面积。土壤营养面积过小 ,个体生长影响较大 ,会改变其生物学生长规律 ,S型生长曲线不明显     

扎龙自然保护区丹顶鹤繁殖期的个体行为

采用目标取样法和所有事件取样法研究了4对野生丹顶鹤在繁殖期的各种行为。结果表明：丹顶鹤的行为类型主要有觅食、静栖、警戒、游走、修饰、繁殖（包括求偶、交配、筑巢、产卵、孵化、育雏）。丹顶鹤为保证繁殖成功而建立领域，在繁殖期的不同阶段，其行为存在一定的变化：在产卵前期，觅食行为显示的强度最高；在孵化期，繁殖行为显示的强度最高，静栖行为显示的强度下降，警戒行为显示的强度则显著升高。     

黄海主要桡足类的生物量

本文采用个体重量计数法对黄海海区及各分区水域中的浮游桡足类的生物量及其组成进行了统计分析.结果表明,在浮游桡足类的生物量中起重要作用的有小拟哲水蚤Paracalanus parvus,大同长腹剑水蚤0ithona similis,中华哲水蚤Calanus sinicus,短角长腹剑水蚤0ithona brevicornis,强额拟哲水蚤Paracalanus crassirolris,双刺纺锤水蚤Acartia bifilasa,近缘大眼剑水蚤Corycaeus affinis及克氏纺锤水蚤Acartca clausi等8种.其中除中华哲水蚤体型较大外,其它7种均属中小型浮游桡足类.且其生物量的大部分是由2～4种桡足类的生物量所组成.     

覆麦草和遮光对夏季章丘大葱营养生长的影响

以章丘大葱大梧桐品种为试材,研究了夏季栽培中覆麦草和遮光对大葱株高和单株鲜重的影响。结果表明:7～9月各处理的株高和单株鲜重差异显著,覆麦草不利于大葱的长高和增重,而遮光可明显促进大葱生长,不覆麦草、遮光50%的处理株高平均值与对照差异不显著,但平均单株鲜重比对照高63.82%,增产潜力较大。多因素方差分析表明:覆麦草、遮光及两者交互效应对大葱株高和单株鲜重有极显著影响(P<0.01)。     

合作输出对提高英语写作能力影响的实证研究

基于对两人合作写作与个人独立写作的对比研究,发现英语写作教学中合作输出对提高学生英语写作能力的作用显著大于个人独立写作。合作写作可以激发学习者就写作策略、主题思想、篇章结构、遣词造句等方面进行讨论,达到取长补短的目的,从而有效提高输出效果,提高写作水平,同时又增进了友谊和团队合作精神。