How do biodiversity patterns of river animals emerge from the distributions of common and rare species?

We studied the patterns of commonness and rarity for one vertebrate (fish) and four freshwater insect taxa (Ephemeroptera, Plecoptera, Trichoptera and Coleoptera) in southwestern France (57,000 km²), and we analysed the relationships between the location of sites and the contribution of commonness and rarity to species richness within a large stream system. Richness patterns in fish and aquatic insects were related to the location of sites within the stream system. The number of common and rare fish species increased from up- to downstream areas as a result of downstream additions of species. The number of common insect species peaked in the intermediate section of the river continuum, whereas rarity increased with decreasing elevation. In all taxa, common species gave a closer approximation to overall patterns of species richness than did rare ones. The biodiversity patterns of river animals emerged from convergence in the distributions of common and rare species (fish), or mostly from the distribution of common species (insects). However, in fish, Ephemeroptera and Plecoptera, the rarer species became almost equally, or more strongly correlated with overall species richness when increasing information along the common-to-rare and rare-to-common sequences. These patterns suggested that rarer species show a similar or stronger affinity, on a species-for-species basis, for high richness areas than do the commoner species. These schemes have implications for biodiversity assessments, as studies using common species richness to target important areas for monitoring or conservation efforts within stream systems will not necessarily identify areas important for rare species, and vice versa.     

A behavioural sensor for fish stress

Due to water turbidity, fish stress might be difficult to observe. Evaluation of fish stress by blood sampling requires removing a fish from the water, which is in itself a stressful event. Therefore, we designed and built a sensor to detect fish behaviour that reflects stress. The electronic sensor detected early signs of fish stress by scoring the fish's inactivity. LEDs and detectors are embedded on a steel wand that is held underwater by an operator. In this preliminary (feasibility) study, the new sensor was validated for Tilapia (Cichlidae) and Hybrid Striped Bass (Morone). We induced stressful situations in the fish tanks by manipulating oxygen and temperature levels.ResultsLowering the temperature and oxygen levels both significantly increased the average number of signals identified by the sensor, which indicate stress. The effect of reducing water temperature from 24 °C to 15 °C was three times stronger than was the effect of lowering the oxygen saturation level from 85% to 50%. The difference in the number of signals between the good and stressful conditions was statistically significant, amounting to approximately eight sensor signals, 10.57 compared to 2.49 respectively. Lowering the temperature increased the mean number of signals by 5.85 and 6.06 at 85% and 50% oxygen saturation respectively, whereas lowering oxygen levels increased the mean number of signals by 2.02 and 2.23 at 24 °C and 15 °C, respectively. The results indicate that the stress status of cultured fish can be evaluated using the proposed behavioural sensor. The new sensor may provide an earlier indication of a problem in a fish tank or pond than was heretofore possible. This early warning can enable the fish farmer to take action before many fish are harmed.     

Regulation of hepatic peroxisome proliferator‐activated receptor α expression but not adiponectin by dietary protein in finishing pigs

Soy protein regulates adiponectin and peroxisome proliferator‐activated receptor α (PPARα) in some species, but the effect of dietary soy protein on adiponectin and PPARα in the pig has not been studied. Therefore, the objective of this study was to determine whether soya bean meal reduction or replacement influences serum adiponectin, adiponectin mRNA, serum metabolites and the expression of PPARα and other genes involved in lipid deposition. Thirty‐three pigs (11 pigs per treatment) were subjected to one of three dietary treatments: (i) reduced crude protein (CP) diet containing soya bean meal (RCP‐Soy), (ii) high CP diet containing soya bean meal (HCP‐Soy) or (iii) high CP diet with corn gluten meal replacing soya bean meal (HCP‐CGM) for 35 days. Dietary treatment had no effect on overall growth performance, feed intake or measures of body composition. There was no effect of dietary treatment on serum adiponectin or leptin. Dietary treatment did not affect the abundance of the mRNAs for adiponectin, PPARα, PPARγ2, lipoprotein lipase or fatty acid synthase in adipose tissue. The mRNA expression of PPARα, PPARγ2, lipoprotein lipase or fatty acid synthetase in loin muscle was not affected by dietary treatment. In liver tissue, the relative abundance of PPARα mRNA was greater (p < 0.05) in pigs fed the HCP‐Soy diets when compared to pigs fed RCP‐Soy or HCP‐CGM diets. Hepatic mRNA expression of acyl‐CoA oxidase or fatty acid synthase was not affected by dietary treatment. Western blot analysis indicated that hepatic PPARα protein levels were decreased (p < 0.05) in pigs fed the RCP‐Soy diets when compared to pigs fed the HCP‐Soy diets. These data suggest that increasing the soy protein content of swine diets increases hepatic expression of PPARα without associated changes in body composition.     

Supplementation of dairy cows with a fish oil containing supplement and sunflower oil to increase the CLA content of milk produced at pasture

It has been shown that the cis 9, trans 11 isomer of conjugated linoleic acid (CLA) can be increased in milk by supplementation with fish oil and vegetable oils. Feeding a high level of oil, however, can impact negatively on gross milk composition. The principal aim of this study was to determine if relatively low levels of fish oil or sunflower oil, either alone or in combination, offered to dairy cows on pasture would increase the C18:2 cis 9, trans 11 CLA concentration in milk. Forty autumn-calved cows on a diet of grazed grass were assigned to 4 supplementation treatments: (i) No supplement (P), (ii) 255 g/day of sunflower oil (SO), (iii) 255 g/day of sunflower oil + 52.5 g/day of fish oil (SOFO), and (iv) 105 g/day of fish oil (FO). The fish oil was supplied in a proprietary product called Omega-3 Supplement which is a mixture of marine oils and an extracted oilseed meal and contains 500 g/kg of oil. The oils were fed in a concentrate mixture, which was offered at a rate of 3.0 kg/cow per day. The production of the cows was measured for 54 days and the milk fatty acid composition was determined on day 0 (immediately before the supplements were introduced) and on days 14, 28 and 42 after the treatments were imposed. Supplementation increased the yield of milk (P < 0.01), protein (P < 0.05) and lactose (P < 0.001), decreased milk fat (P < 0.05) and protein (P < 0.01) concentrations and increased (P < 0.01) lactose concentration. Type of oil did not significantly affect any production variable. The concentration of C18:1 trans 9 + C18:1 trans 11 (mainly C18:1 trans 11) (P < 0.001) and C18:2 cis 9, trans 11 CLA (P < 0.01) were greater on supplemented treatments than on P and the concentration of both were greater (P < 0.05) on FO than on SO. The results confirm that the concentration of C18:2 cis 9, trans 11 CLA can be increased further, from an already relatively high concentration in milk from pasture, by offering supplements containing a low level of fish oil either alone or in combination with sunflower oil.     

微波技术对大豆蛋白功能特性的影响

研究了微波辐照对大豆功能蛋白（FSP）溶解性、乳化性与起泡性的影响。结果表明，微波辐照能改善FSP溶解度、乳化活性、起泡能力与泡沫稳定性。试验中FSP溶解度可提高343．7％，乳化活性可提高2392．7％，起泡能力可提高196．9％，泡沫稳定性可提高82．76％。     

Comparative study of digestive enzymes in fish with different nutritional habits. Proteolytic and amylase activities

This work provides a comparative study of the proteolytic and amylase activities in six species of fish with different nutritional habits: rainbow trout (Oncorhynchus mykiss), gilthead seabream (Sparus aurata), European eel (Anguilla anguilla), common carp (Cyprinus carpio), goldfish (Carassius auratus), and tench (Tinca tinca). Trout and carp showed the highest digestive proteolytic activity. When proteolytic activity was determined in a wide range of pHs, the highest values in the digestive tract of all species were found at alkaline pHs, except in eel where activity could be detected only at acid pHs. Eel showed the lowest digestive proteolytic potential among all the species studied. With respect to amylase activity, the omnivorous species presented higher activity than did the carnivores. Among the carnivorous species, the lowest activity was found in trout. The ratio of total amylase:total proteolytic activity was higher in omnivorous fish species, the carp having the greatest value, whereas in trout this ratio was lower than one. Digestive enzyme activity declined as the incubation temperature decreased, but this trend varied depending on the fish species and the tissue analyzed.     

Review of opportunities for low stress and selective control of fish

Routine inspection and selective control of livestock is an integral part of animal agriculture benefiting both animal welfare and profitability. Appropriate developments in this field may therefore also be expected within fin-fish farming. Equipment enabling some subsurface inspection of fish stocks has recently appeared on the market but this is as yet unmatched by equipment which would enable subsurface selective interaction for the purpose of sampling, further inspection or selective application of remedial measures. Currently available non-selective fish control techniques are reviewed and some potential methods for selective control are considered. Since most forms of selective control must rely on fish’s response to signals the paper is organised on the basis of the sensory systems that might be used. A brief introduction to each system is given followed by a review of any current control techniques and possibilities for developing selective control systems.     

高产池塘混养鱼类关系的研究

应用灰色关联度分析法分析了影响顺德高产池塘鱼产量的主因子,并对顺德高产池塘的多品种混养鱼类关系进行分析,各种不同鱼类的放养对产量的关系为：草鱼放养量对鲢的净产量影响最大（Ｒ＝０．８２４２）其次为鳙放养对草鱼的净产量影响（Ｒ＝０．８０７５）最小为鲮的放养对鳙的净产量关系（Ｒ＝０．２１０２）鳙的放养为优势母因子,鲢的收获为优势子因子。