Holding wild Snow crab,Chionoecetes opilio: effects of stocking density and feeding on survival and injury

In this study the effects of different stocking densities on survival, injury and weight of captive male snow crab were examined. The first experiment (I) was carried out in square plastic tanks (700 L) with stocking densities of 100 (L), 150 (M) and 200 kg m^?3 (H) for 30 days. In a second experiment (II) snow crabs were kept at a stocking density of 50 kg m^?3 and were either fed (F) or not fed (S) for the same period of 35 days. The last experiment (III), was carried out with stocking densities of 25 kg m^?3 for 21 days with two groups, one with inactivated claw and one without rubber bands, with three replicates per treatment. In the first experiment mortality (H = 27, M = 26 and L = 36%) and occurrence of injuries (H = 27, M = 20 and L = 16%) were high in all groups. The weight loss during the experimental period was; H = 15.3, M = 10.9 and L = 15.5 g, and was not significant different between the groups. In experiment II the mortality (F = 13% and S = 14%) and injuries were lower (F = 12% and S = 17%). The average weight increased in the fed treatment and decreased in the starved treatments. In the last experiment there was no mortality in any of the groups and the levels of injury were low (5% and 7%). The results show that adult male snow crab cannot be stored at densities equal to or higher than 25 kg m^?3 for 3 weeks without risk of mortality.     

Measuring density effects on growth and survival of two size classes of juvenile sea urchins (Strongylocentrotus droebachiensis) held in sea‐based holding systems and impacts on holding system design and management

Assessing density in intensive sea urchin culture systems by measuring the percentage coverage of available surface area is an effective means of calculating the available space within a holding system, the proximity of the animals in the system to each other and the probable effects of the stocking density. The results of this study show that density plays a critical role in regard to both somatic growth (increase in test diameter measured in millimetres) as well as mortality of juvenile sea urchins ranging in size from 5 mm to 26 mm test diameter (the size range tested in the current experiments). These effects appear to be greater for smaller urchins. The critical percentage coverage densities are in the order of 50%‐60% coverage for juvenile sea urchins, and the authors advise farmers growing Strongylocentrotus droebachiensis to maintain stocking densities below this point and to reduce the stocking densities as and when stocks reach these critical density points. Percentage cover must be constantly monitored as the results from this study indicate that the growth rates of juvenile urchins can alter percentage coverage rapidly and reductions in density may be required as frequently as every 3‐4 months at the early juvenile stage. Holding system design should take these factors into account and incorporate a method of rapidly reducing stocking densities with minimal stress and handling of sea urchin stocks.     

Segment-based coancestry,additive relationship and genetic variance within and between the Norwegian and the Swedish Fjord horse populations

ABSTRACT

The Fjord horse originates from Norway but forms a global population due to several small populations in foreign countries. There exists no information about the additive relationship and the genetic variance between these subpopulations. By collecting blood samples from Norwegian and Swedish Fjord horses, a sample of 311 Norwegian and 102 Swedish horses gave 485,918 SNPs available for analysis. Their inbreeding coefficients were calculated and compared to the pairwise coancestry and the shared genomic segments. The effective population size was almost similar with the two methods in the Norwegian Fjord horse population (63 and 71), but very different in the Swedish population (269 and 1136) and unprecise due to a much smaller number of observations. The study showed that coancestry from shared genomic segments can be used to estimate additive genetic relationship and genetic variation within and between the global populations of the Fjord horse.     

Use of reflex indicators for measuring vitality and mortality of the snow crab (Chionoecetes opilio) in captivity

The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process.     

The role of dietary methionine concentrations on growth,metabolism and N‐retention in cobia (Rachycentron canadum) at elevated water temperatures

This study determined impacts of dietary methionine concentrations at two temperatures on growth, feeding efficiency and N‐metabolites in juvenile cobia. Methionine concentrations of the experimental diets were deficient (M9; 9 g/kg), sufficient (M12; 12 g/kg) and surplus (M16, 16 g/kg). Water temperature was normal (30°C) or elevated (34°C). Twenty cobia in triplicate tanks were fed the experimental diets for 6 weeks. Both methionine and temperature affected cobia's growth and feeding efficiency. Cobia fed M9 performed lower than the fish fed M12 and M16 diets. Additionally, cobia reared at 34°C performed poorer than at 30°C, probably due to lower voluntary feed intake in the fish reared at 34°C. Protein efficiency ratio and protein productive value in cobia fed M9 diet were less than M12 or M16 diets. This was confirmed with the improved retentions of indispensable amino acids (AAs). No interactions between methionine and temperature were observed in growth and protein accretion. At 30°C, CF improved, while HSI and VSI declined upon methionine supplementation levels. Of which an interaction between temperature and methionine was present. Plasma, muscle and liver free AA and N‐metabolites were affected by methionine and temperature. Furthermore, temperature affected cobia's lipid class composition, resulting in increased phospholipids and cholesterol at 34°C.     

Possibilities for Increased Carbon Sequestration through the Implementation of Rational Forest Management in Russia

Huge areas of the Russian forests suffer from insufficient forest management. A scenario has been developed for an improved management program that would be implemented over the next 40 years. Possible options have been aggregated into three interlinked groups: increase in forest productivity through improvement of the forest conditions and the structure of the Forest Fund, decrease of carbon release by mitigation of disturbance regimes, and improvement of landscape management. One prerequisite in developing this scenario was that the cost of sequestering one ton of carbon should not exceed US$3 (1992 dollar value). In this article a simple model is described to illustrate the following possibilities for increased carbon fixation by improved forest management: large-scale reforestation and afforestation, replacement of stands with low productivity and replacement of so called soft deciduous species and “climax” stands, and implementation of rational silviculture (thinning). The results indicate a potential for an increase in carbon fixation in Russian forest ecosystems of 24.4 Pg over 100 years, after the first year that the actions discussed are implemented. The net sink of carbon was determined to be 16.5 Pg in the “low” estimate and 42.5 Pg in the “high” estimate. There are, however, many uncertainties in the data and there are difficulties in adequately modeling the possibilities for implementation under current conditions in Russia. In spite of these uncertainties, we conclude that there is great potential for economically justified increased carbon fixation through improved forest management in Russia.     

Effects of metal pollution on the earthwormdendrobaena rubida (Sav.) in acidified soils

Survival of adultDendrobaena rubida, cocoon production, cocoon viability, and growth of juveniles were examined in laboratory experiments when the worms were reared in acidified and metal polluted soils. Solutions of Cu, Cd and Pb were added to give total concentrations of 10, 100 and 500 μg g^?1 in soils with a pH of 4.5, 5.5 and 6.5. Adult tissues, hatchlings and cocoons were analyzed for metals. D. rubida survived poorly in soils with low pH, especially in combination with Pb or Cu, which accumulated in seminal vesicles and cerebral ganglion. Cocoon production was halved when pH was lowered from 6.5 to 4.5 and metals reduced the cocoon number even more in the most acid soils. Hatching success was lower than 20 % in acidified soils. In contrast, the number of hatchlings increased when pH decreased and peaked in soils polluted with Cd. While low pH reduced the embryonic development time, metals prolonged it. Juveniles grew slowly and died early at low pH.     

Respiration and growth of a fungus, Mortierella isabellina, in response to grazing by Onychiurus armatus (Collembola)

Colonies of the fungus Mortierella isabellina (Oudem) were grazed by the collembolan Onychiurus armatus (Tullb.) for short periods interrupted by incubation without grazing in laboratory experiments. The grazed fungus had a lower respiration than ungrazed when Collembola were present on the mycelium. Fungal respiration was significantly increased with grazing when Collembola were periodically removed from the mycelium. Metal contamination of the substrate increased fungal respiration, regardless of grazing. Length of fungal mycelium was significantly greater in a natural soil in the presence of Collembola but reduced in a metal-polluted soil. Factors that may determine the impact of grazing on fungi are discussed.     

Effects of Plant and Soil Factors on Growth of Young Apple and Blackcurrant Plants

Abstract

Shoot growth as affected by plant size at planting, peat application in the planting hole, pruning, drip-irrigation and, for apple, specific apple replant disease (SARD) was investigated in apple (cv. Elstar) and blackcurrant (cvs Ben Lomond and Ben Nevis), using a multifactorial design. In the first year after planting, peat application and drip-irrigation enhanced shoot growth in both species, with a further interactional increase when both treatments were applied. The extension growth of apple, in contrast to blackcurrant, was positively related to plant size, and the strength of the relationship was distinctly improved when growth conditions were good. Pruning had only small effects on total shoot growth, with a trend towards an increase when growth conditions were poor.     

Is the winter period a severe bottleneck of anadromous riverine Arctic charr parr?

Abstract –  Winter growth and survival of wild individually tagged juvenile Arctic charr (1+ age) from a riverine anadromous stock, were studied in a small ice-covered (∼6 months) ground water brook (temperature ∼1 °C) connected to Skibotnelva in subarctic northern Norway. The overall winter survival was estimated to be 68% from late October 2005 to early May 2006. The recaptured charr were not significantly different in initial length or weight compared with the nonrecaptured fish suggesting low size-dependent mortality. The majority (98%) of the recaptured charr showed significant increase in size, with a mean increment of 62% from their initial bodyweight and 12% of the charr parr had more than doubled their weight. The mean specific growth rate was calculated to be slightly lower (0.27) than estimated values from a growth model (∼0.35). In addition, the condition factor increased significantly during the field experiment. These results are the first individual growth data on riverine anadromous Arctic charr parr under natural winter conditions, and indicate that charr can grow relatively fast during periods with low temperature and also that ground water brooks can be good over-wintering habitat for juvenile Arctic charr. These results suggest that the winter period is perhaps a less severe bottleneck than previously recognised for the cold-adapted Arctic charr.