Salinity is one of the most critical environmental parameters regarding fish physiology, modifying food intake and growth performance in many fish species. The present study has investigated the ...effects of different salinity levels on growth performance, feeding and survival of Asian seabass Lates calcarifer juveniles. Asian seabass juveniles were reared at 0 (T1), 5 (T2), 22 (T3), 36 (T4), and 42 (T5) ppt salinity. Approximately eight hundred thirty fish individuals with an average weight of 1.24±0.52 g were randomly distributed (166 fish/Tank) in 5 concrete tanks (each tank 30×6×4 ft, volume 19,122 L) for forty days. Juveniles were initially fed 42% crude protein-containing diets at a rate of 6% of their body weight per day. The results showed that salinity level had a significant effect on the weight gain (WG), average daily weight gain (ADWG), specific growth rate (SGR), feed conversion ratio (FCR), survival rate (SR), total biomass and health indices (p<0.05). The highest WG (39.11±1.49 g), ADWG (1.00±0.12 g), SGR (8.74±0.03% d-1) and lowest FCR (0.96±0.20) were observed with T3 treatment, which was significantly higher compared to other treatment groups (p<0.05). Among the health indices, the highest hepatosomatic index and viscerosomatic index were found with T3 treatment, significantly higher than the other groups (p<0.05). No significant differences were found among the treatments in terms of survival rate (p>0.05), but the maximum survival rate (98.89±0.0%) was observed in the T3 and T2 treatments. The maximum level of crude proteins (19.99±1.4%) was found in the whole-body biochemical composition of Asian seabass juveniles in the T3 treatment group. The second-order polynomial regression showed that 20 ppt salinity is optimum for the best growth of Asian seabass. Thus, the present study recommends 20 to 36 ppt salinity for the commercial farming of Asian seabass under a closed aquaculture system.
Few studies have attempted to determine experimentally the relative importance of direct and indirect effects of host plants on herbivorous insects in the field. This study identifies important ...direct and indirect effects of a coastal plant on its most common insect herbivore and assesses the relative importance of those effects. The direct effects of increased interstitial soil salinity and nitrogen on the abundance of Pissonotus quadripustulatus (Homoptera: Delphacidae), which feeds on Borrichia frutescens (Asteraceae), are reported. Also reported are the indirect effects of these treatments on parasitism of P. quadripustulatus eggs laid in plant stems by the fairfly parasitoid Anagrus sp. nr. armatus (Hymenoptera: Mymaridae). Soil salinity was experimentally elevated by the addition of salt pellets, and plant foliar nitrogen was increased by the addition of fertilizer. Both salt and fertilizer increased the abundance of P. quadripustulatus. There was a significant salt × fertilizer interaction, suggesting that salt stress may be more important when plants are more nitrogen limited. Salt, by increasing the frequency of tough B. frutescens stems, decreased the rate at which Anagrus parasitized P. quadripustulatus eggs. Fertilizer, by increasing the frequency of B. frutescens stems that were softer and easier to penetrate, increased the rate of parasitism. Changes in parasitism, however, did not affect P. quadripustulatus density. Tests for density dependence showed that the results reported here were attributable to application of the treatments and not to spatial density dependence. This study suggests that, in a stressful salt-marsh system, the direct effects of plant quality on herbivores are more important than indirect effects of plant morphology mediated by natural enemies.
The effects of salinity on long-term tropical atmospheric and oceanic variability are investigated using a pair of two-dimensional coupled ocean-cloud resolving atmosphere simulations. A zero ...vertical velocity and a constant zonal wind are imposed in cloud resolving atmosphere model. The experiment with salinity is compared to the experiment without salinity. The model is integrated for 51 days. The comparison between the experiments with and without salinity effects shows negative differences in ocean mixed-layer temperature and precipitable water as well as positive differences in atmospheric temperature. The budgets of ocean mixed-layer heat and atmospheric mass-weighted mean temperature and precipitable water are analyzed. The ocean thermal forcing and thermal entrainment determine the negative difference in the mixed-layer temperature. Surface evaporation and condensation are responsible for the negative precipitable water difference whereas radiative heating and latent heat account for the positive air temperature difference.
Salinity differenes between samples and standards may be a source of error in the determination of strontium in seawater by atomic absorption spectrophotometry. lf calibration is by reference to ...artificially prepared standards, these standards must match the sample solutions in salinity. For this reason, recently published values for strontium in the marine environment, determined by atomic absorption, are probably low.
Respiration rates and $Q_{10}\text{'}{\rm s}$ of 1-day-old brine shrimp nauplii were affected significantly by radiation, the salinity of the water, and the interaction between the two factors. ...Respiration rates were measured in salinities from 5 to 200%. Irradiated nauplii received doses of 60 Co radiation of 10,000 to 80,000 rads. In general, respiration rates of irradiated nauplii were significantly lower than those of unirradiated nauplii at salinities of 5, 50, and 200%, but were higher at 100 and 150%. When nauplii were in the highest salinity, 200%, each increase in radiation above 10,000 rads caused a corresponding decrease in the rate of respiration. Similarly, at each salinity the nauplii exposed to the highest radiation dose, 80,000 rads, had the lowest rate of respiration. The highest levels of radiation and salinity acted synergistically and depressed the respiration rate to the lowest point. The greatest effect on $Q_{10}\text{'}{\rm s}$ was at the highest salinity. At this salinity, Q10 values for all irradiated nauplii were significantly lower than for controls or for irradiated nauplii at other salinities.
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