Long-term separate and combined effects of environmental hypercapnia and hyperoxia in Atlantic salmon (Salmo salar L.) smolts   总被引：3，自引：1，他引：2  

Camilla Diesen Hosfeld  Annhild Engevik  Ted Mollan  Torleif Markussen Lunde  Rune Waagb  Anne Berit Olsen  Olav Breck  Sigurd Stefansson  Sveinung Fivelstad 《Aquaculture (Amsterdam, Netherlands)》2008,280(1-4):146-153

Atlantic salmon (Salmo salar L.) parr (mean start weight 50 g) were reared in freshwater (FW) and exposed to three levels of oxygen saturation measured in effluent water; control group (93% O₂, LO₂), medium (111% O₂, MO₂) and high (123% O₂, HO₂). Further three groups were exposed to similar water oxygen levels in combination with elevated carbon dioxide levels (17–18 mg L^– 1 CO₂), named LO₂–CO₂, MO₂–CO₂ and HO₂–CO₂, respectively. The experiment was run in duplicate tanks for 42 days, and the fish were subsequently transferred to the same seawater (SW) regime for 45 days for an assessment of post-smolt growth. As a consequence of the CO₂ addition, tank pH levels in the FW period were reduced from 6.7 to 5.9 for the hypercapnia groups compared to for the normcapnia groups. Water temperature in FW ranged between 6.4 and 9.0 °C. Citrate was added to the water to complex labile aluminium.In the CO₂ groups observed ventilation frequencies were significantly increased compared to the control (p < 0.05). This difference declined towards the end of the FW period, suggesting acclimation to elevated CO₂. The degree of oxygenation appeared to contribute to the acclimation as the lowest mean ventilation frequency on day 36 was found in the HO₂–CO₂ group and the highest in the LO₂–CO₂ group. Lower plasma chloride and sodium levels were observed in the CO₂ groups relative to the respective oxygenation groups during the FW period, while plasma chloride and sodium levels were normalised to equal levels for all groups after 44 days in SW. No significant differences were found among treatments for blood concentrations of red blood cells, haemoglobin, potassium and glucose during the experiment.By termination of the FW period, the HO₂ group had significantly higher body weight than all other groups (p < 0.05), with specific growth rate significantly higher than the CO₂ groups (p < 0.05). Further, the condition factor was significantly lower in all the CO₂ groups at the end of the FW period compared to the control and normcapnia groups (p < 0.05). Although variable among replicates, occurrence of nephrocalcinosis was 10 times higher in the hypercapnia groups than in the control and normcapnia groups. Mortality was negligible (< 2.0%) during the trial, and most of the mortality occurred following SW transfer.  相似文献   

Cultivar Effects on the Interaction between Free-Living Plant-Parasitic Nematodes and the Fungal Pathogen <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> in Potato     

Maria Viketoft  Annhild Andersson  Eva Edin 《American Journal of Potato Research》2017,94(4):314-322

Crop damage is associated with infection by plant pathogens but can also arise through abiotic factors. However, the plant pathogens are involved in biotic interactions with other plant pathogens, and these interactions may differ depending of the cultivar of the crop. Here, the interaction between the fungus Rhizoctonia solani (AG3) and free-living plant-parasitic nematodes was investigated in a pot experiment with different potato cultivars. No synergistic interaction between R. solani and plant-parasitic nematodes was found, instead there was an effect of treatment with lower tuber yield when nematodes occurred alone. There were differences among the cultivars regarding incidence of black scurf, dry weight of stems and tubers, and there was interactive effects between treatment and cultivar regarding dry weight of stolons and roots. Therefore, results concerning incidence and damage of R. solani and/or plant-parasitic nematodes found for one cultivar may not be applicable to other cultivars.  相似文献