Effects of high temperature on the growth of European whitefish (Coregonus lavaretus L.)     

Sten Ivar Siikavuopio  Rune Knudsen  Per Arne Amundsen  Bjørn Steinar Sæther  Philip James 《Aquaculture Research》2012,44(1):8-12

The effect of three different temperatures on growth in a first progeny generation, hatchery reared, subarctic population of European whitefish (Coregonus lavaretus L.) were investigated. The whitefish (start weight 444 g, ±SD 125 g) were reared for 60 days at three constant temperatures; 15, 18 and 21°C and under ambient light regimes for 70°N latitude. The results showed that temperature had a significant influence on the growth of the fish with the highest increase in weight increment occurring at 18°C (mean final weight 656 g ± SD 151 g) compared with the growth of fish held at 15°C (mean final weight 591 g ± SD 143 g) and 21°C (mean final weight 505 g ± SD 121 g). The cumulative per cent mortality of the fish during the experimental period increased with increasing temperature, from 10% at 15°C to 30% at 21°C. The present study indicates that the optimal temperature for farming of European whitefish is somewhere between 15 and 18°C rather than between 18 and 21°C.  相似文献   

Mini-cuttings technique: a new ex vitro method for clonal propagation of sweetgum   总被引：1，自引：1，他引：0  

Ivar Wendling  Gilvano Ebling Brondani  Leonardo Ferreira Dutra  Fabrício Augusto Hansel 《New Forests》2010,39(3):343-353

An efficient production system, which can quickly produce high quality plants, is shown in this study of Liquidambar styraciflua. The mini-cuttings technique was used for ex vitro clonal propagation of three sweetgum clones. The semi-hydroponics system for production of propagules was also tested, and the concentration of indole-3-butyric acid (IBA) for rooting was evaluated. Three adult clones, produced according to conventional cutting processes, were used as mini-stumps and maintained in semi-hydroponics systems of medium size sand. Ten collections of sprouts were prepared to evaluate the production of semi-hydroponics systems (mini-clonal hedges). Sprouts from collection number six were used at different concentrations of IBA solution (0; 500; 1,000; 3,000 and 6,000 mg l⁻¹) to test the mini-cuttings technique. The high survival rates of mini-stumps after ten collections (96.3%), and high annual production per square meter (~2,953 mini-cuttings) showed that the mini-clonal hedges are viable to conduct sweetgum mini-stumps. The formation of 62.5% of healthy plants after hardening under outdoor conditions showed that sweetgum could be successfully propagated by the mini-cuttings technique.  相似文献   

Sub‐lethal effects of the neurotoxic pyrethroid insecticide Fastac® 50EC on the general motor and locomotor activities of the non‐targeted beneficial carabid beetle Platynus assimilis (Coleoptera: Carabidae)     

Ene Tooming  Enno Merivee  Anne Must  Ivar Sibul  Ingrid Williams 《Pest management science》2014,70(6):959-966

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Maturation and related aspects in clonal forestry—part II: reinvigoration,rejuvenation and juvenility maintenance     

Ivar Wendling  Stephen J. Trueman  Aloisio Xavier 《New Forests》2014,45(4):473-486

Several techniques have been developed for reinvigorating, rejuvenating or maintaining the juvenility of plants. None of these techniques is as effective as natural rejuvenation whereby the most mature plant parts, the reproductive organs, produce the most juvenile plant parts, the embryos, through gametogenesis and sexual reproduction. The most common criteria for identifying reinvigoration or rejuvenation are based on morphology, morphogenic capacity and the ability to produce cones or flowers. Doubts remain over whether true rejuvenation (reduced ontogenetic age) can be achieved by artificial methods such as serial vegetative propagation, or whether these methods merely provide reinvigoration (reduced physiological age) by temporarily removing environmental and physiological constraints to growth. Rejuvenation and reinvigoration are difficult to distinguish from each other but there is some evidence that artificial methods provide at least partial rejuvenation of plants. This review examines methods for delaying the maturation of juvenile plants and for reducing the ontogenetic or physiological age of more-mature plants. The review discusses theoretical and practical aspects of juvenility, rejuvenation and reinvigoration in clonal forestry, and identifies research areas in maturation that could lead to more-effective methods for establishing high-productivity plantations.  相似文献   

Tests of Mendelian segregation and linkage-group relationships among 31 microsatellite loci in red drum, Sciaenops ocellatus     

Sten Karlsson  Liang Ma  Eric Saillant  John Rush Gold 《Aquaculture International》2007,15(5):383-391

Two families (parents and full-sibling progeny) of red drum (Sciaenops ocellatus) were assayed for genotypes at 31 nuclear-encoded microsatellites. Tests of expected Mendelian segregation at 29 of the microsatellites were non-significant following Bonferroni correction; occurrence of null alleles was inferred at the remaining two microsatellites. Nine of the 24 possible linkage groups (range 2–5 microsatellites per linkage group) were identified. Significant differences in recombination rates were found both between sexes and between families. The microsatellite linkage groups generated in this study represent the beginning of a genetic map for red drum, an economically important marine fish in the southeastern region of the United States of America.  相似文献   

Absorption, assimilation and catabolism of individual free amino acids by larval Atlantic halibut (Hippoglossus hippoglossus)     

Scott L. Applebaum  Ivar Rnnestad 《Aquaculture (Amsterdam, Netherlands)》2004,230(1-4):313-322

Following the completion of the lecithotrophic phase, most marine larvae rely on an incompletely developed digestive tract to absorb amino acids (AA) and other nutrients needed for rapid growth. Despite their undeveloped state, larvae must absorb nutrients in sufficient amounts to fuel exceptionally high rates of growth. This study examined the ability of larval Atlantic halibut to absorb, assimilate and catabolise dispensable (alanine, glutamate) and indispensable (arginine, lysine) dietary free amino acids (FAA) using tube-fed AA solutions with ¹⁴C tracers. Absorption of FAA was rapid with an average of 71% absorbed from the gut within 30 min after tube feeding. Evacuation of FAA by larvae was low, averaging only 6% of tube-fed dose. Dispensable amino acids (DAA) were catabolised in greater proportion (17%) than indispensable FAA (54%). Saturation of FAA transporters was not attained under the present conditions (20 mM, 20% midgut filling). Absorption rates did not differ significantly between the four FAA.  相似文献   

Seawater adaptation in atlantic salmon (Salmo salar L.) at different experimental temperatures and photoperiods     

Sten Knutsson  Torfinn Grav 《Aquaculture (Amsterdam, Netherlands)》1976,8(2):169-187

A study was made of the effect of gradually increasing day length at different temperatures on the smolting process and on growth of Atlantic salmon during smolting.The experiment consisted of ten experimental groups: a combination of three photoperiod- with three temperature-groups and a tenth control group.Size was found to be the most important factor in seawater adaptation of underyearling Atlantic salmon. Optimal growth in the experimental temperature and photoperiod regimes occurred at 15°C and at the photoperiod with the longest period of increasing day length.At the time for seaward migration, the most pronounced effect of photoperiod on seawater adaptation occurred at 11°C. At this temperature there was a significantly higher percentage of survivors at the photoperiod with the longest period of increasing day length.  相似文献   

Interpretation of ontogenetic changes in composition studies of fish eggs and larvae: presenting relative data can lead to erroneous conclusions     

Ivar Rønnestad Senior scientist 《Aquaculture Nutrition》1995,1(4):199-199

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The effects of stocking density on gonad growth, survival and feed intake of adult green sea urchin (Strongylocentrotus droebachiensis)     

Sten I. Siikavuopio  Trine Dale  Atle Mortensen 《Aquaculture (Amsterdam, Netherlands)》2007,262(1):78-85

In this study the effects of different stocking densities on survival, gonad growth and feed intake in adult green sea urchin (Strongylocentrotus droebachiensis) were examined. Two size groups of sea urchins with respective initial mean weight of 45 g (S) and 70 g (L) were used. The experiments were carried out in 755 l plastic tanks divided into chambers by vertical fibreglass lamellae. In the two experiments stocking densities of 6, 12, 14 and 16 kg m^− 2 (Exp I) and 3, 6 and 8 kg m^− 2 (Exp II) were used. Sea urchins reared individually in compartmentalised raceways were used as controls in both experiments. All groups were fed a formulated moist feed ad libitum for 60 days at 8 °C (± 0.5). Mortality was observed in all groups, except for the control group and the lowest density group of large sea urchins (3 kg m^− 2, L). Both mortality and occurrence of injuries increased significantly with increasing stocking density in both experiments and for both size groups. In the highest density groups mortality was 60% (L) and 80% (S). There was a significant increase in gonad index during the experimental period in both experiments. Increased stocking density had a significantly negative effect on gonad growth in both size groups while feed intake was unaffected. The results show that adult S. droebachiensis can maintain high survival rate and high gonad growth at stocking densities up 6 kg m^− 2 in holding facilities of the design used in the present study.  相似文献   

Vascular plants as a surrogate species group in complementary site selection for bryophytes, macrolichens, spiders, carabids, staphylinids, snails, and wood living polypore fungi in a northern forest   总被引：1，自引：0，他引：1  

Magne Sætersdal  Ivar Gjerde  Per G. Ihlen  Reidun Pommeresche  Torstein Solhøy 《Biological conservation》2004,115(1):21-31

Vascular plants were investigated as a potential surrogate group in complementary small scale site selection, such as woodland key habitats in Scandinavia. We compared the response of vascular plants to environmental gradients to that of seven other plant, fungal and animal groups within a forest reserve in western Norway using data from 59 plots of 0.25 ha. We also examined whether the spatial changes in species (beta-2 index) of vascular plants matched that of the other groups. All seven groups responded to the same gradients in nutrient richness and humidity as the vascular plants. Furthermore, changes in species composition of vascular plants were reflected in comparable degrees of change among the “target“ groups. The lower the degree of change in species composition between plots in the “target“ groups relative to that of vascular plants, the higher the percentage “target“ species encompassed in a complementary selection of sites based on vascular plants. We conclude that in practical site selection of small scale sites of conservation value, such as woodland key habitats, vascular plants may be used in combination with an inventory of important habitats for rare and/or redlisted forest species, such as dead wood, old trees, deciduous trees, and cliffs.  相似文献