Effect Of Increase In Salinity Research Articles

Reproductive trade-offs of the estuarine copepod Eurytemora affinis under different thermal and haline regimes

Copepod females invest a quantity of resources in their reproduction. Depending on several biotic and abiotic factors and their evolutionary history a trade-off can be commonly observed between producing a large number of smaller offspring or a small number of larger offspring. In this study, a multi-generational approach was applied to determine whether a trade-off between clutch size and egg size existed in the copepod Eurytemora affinis under different controlled conditions of temperature and salinity. This protocol was based on the follow-up of reproductive (Clutch Size ‘CS’, Egg Diameter ‘ED’) and morphological (Prosome Length ‘PL’) traits during several generations. Copepods were acclimated to cold (7 °C) and warm (20 °C) temperatures, and then their reproductive output was tested at the higher temperature of 24 °C. CS and ED were positively correlated to PL, so as a first step linear regressions between each reproductive trait and female PL were performed. The residuals from the regression lines of CS and ED with PL were calculated to remove the effect of female size. When the normalized data (residuals) of CS and ED plotted together a negative relationship between egg size and egg number revealed the existence of a trade-off. Copepod populations initially acclimated to cold temperature are commonly characterized by relatively smaller CS and larger ED. Conversely, warm temperature adapted females produced relatively larger CS and smaller ED. After transfer to a temperature of 24 °C, the ED did not change but the CS showed high variability indicating stressful conditions and no trade-off was observed. These observations suggest that E. affinis is able to modulate its reproduction depending on the encountered temperature. It seems that this copepod species can shift between a K- and an r-strategy in response to colder or warmer conditions. In a late winter-early spring like cold temperature, copepod females seem to invest more on offspring quality by producing relatively larger eggs. This ecological strategy ensures a high recruitment of the spring generation that is responsible for the strength of the maximum population size usually observed in late spring-early summer (May–June). To the contrary, at summer-like temperature, where the population density decreases significantly in the Seine estuary, copepod females seem to switch from K to r strategy by favoring offspring number compared to offspring size. Finally, the use of a higher temperature of 24 °C seems to disrupt the observed reproductive trade-off even after several generations. These results suggest that a switching between K- or r-strategy of E. affinis depends highly on temperature effects. The effect of salinity increase during a summer-like temperature of 20 °C as well as after transfer to 24 °C decreased PL and CS but the ED did not change significantly.

Salinity Influences Plant-Pest-Predator Tritrophic Interactions.

Climate change-induced salinity intrusion into agricultural soils is known to negatively impact crop production and food security. However, the effects of salinity increase on plant-herbivore-natural enemy systems and repercussions for pest suppression services are largely unknown. Here, we examine the effects of increased salinity on communities of rice (Oryza sativa), brown planthopper (BPH), Nilaparvata lugens, and green mirid bug (GMB), Cyrtorhinus lividipennis, under greenhouse conditions. We found that elevated salinity significantly suppressed the growth of two rice cultivars. Meanwhile, BPH population size also generally decreased due to poor host plant quality induced by elevated salinity. The highest BPH density occurred at 2.0 dS/m salinity and declined thereafter with increasing salinity, irrespective of rice cultivar. The highest population density of GMB also occurred under control conditions and decreased significantly with increasing salinity. Higher salinity directly affected the rice crop by reducing plant quality measured with reference to biomass production and plant height, whereas inducing population developmental asynchrony between BPH and GMB observed at 2 dS/m salinity and potentially uncoupling prey-predator dynamics. Our results suggest that increased salinity has harmful effects on plants, herbivores, natural enemies, as well as plant-pest-predator interactions. The effects measured here suggest that the bottom-up effects of predatory insects on rice pests will likely decline in rice produced in coastal areas where salinity intrusion is common. Our findings indicate that elevated salinity influences tritrophic interactions in rice production landscapes, and further research should address resilient rice insect pest management combining multipests and predators in a changing environment.

Comparison between two MBR pilot plants treating synthetic shipboard slops: effect of salinity increase on biological performance, biomass activity and fouling tendency

Comparison between two MBR pilot plants treating synthetic shipboard slops: effect of salinity increase on biological performance, biomass activity and fouling tendency

Effect of increase in salinity on ANAMMOX–UASB reactor stability

ABSTRACTThe effect of salinity on the anaerobic ammonium oxidation (ANAMMOX) process in a UASB reactor was investigated by analysing ammonium, nitrite, nitrate and TN concentrations, and TN removal efficiency. Extracellular polymeric substances (EPSs) and specific ANAMMOX activity (SAA) were evaluated. Results showed the effluent deteriorated after salinity was increased from 8 to 13 g/L and from 13 to 18 g/L, and TN removal efficiency decreased from 80% to 30% and 80% to 50%, respectively. However, ANAMMOX performance recovered and TN removal efficiency increased to 80% after 40 days when the influent concentrations of and were 200 mg/L and salinity levels were at 13 and 18 g/L, respectively. The amount of EPSs decreased from 58.9 to 37.1 mg/g volatile suspended solids (VSS) when the reactor was shocked by salinity of 13 g/L, and then increased to 57.2 mg/g VSS when the reactor recovered and ran stably at 13 g/L. The amount of EPSs decreased from 57.2 to 49.1 mg/g VSS when the reactor was shocked by salinity of 18 g/L, and then increased to 60.7 mg/g VSS when the reactor recovered and ran stably at 18 g/L. The amount of EPS and the amounts of polysaccharide, protein and humus showed no evident difference when the reactor recovered from different levels of salinity shocks. Batch tests showed salinity shock load from 8 to 38 g/L inhibited the SAA. However, when the reactor recovered from salinity shocks, SAA was higher compared to that when the reactor was subjected to the same level of salinity shock.

The effect of salinity increase on the photosynthesis, growth and survival of the Mediterranean seagrass Cymodocea nodosa

There are major concerns in the Mediterranean Sea over the effects of hypersaline effluents from seawater desalination plants on seagrass communities. However, knowledge concerning the specific physiological capacities of seagrasses to tolerate or resist salinity increases is still limited. In this study, changes in the photosynthetic characteristics, pigment content, leaf light absorption, growth and survival of the seagrass Cymodocea nodosa were examined across a range of simulated hypersaline conditions. To this end, large plant fragments were maintained under salinities of 37 (control ambient salinity), 39, 41 and 43 (practical salinity scale) in a laboratory mesocosm system for 47 days. At the end of the experimental period, net photosynthesis exhibited a modest, but significant, decline (12–17%) in all tested hypersaline conditions (39–43). At intermediate salinity levels (39–41), the decline in photosynthetic rates was mainly accounted for by substantial increases in respiratory losses (approximately 98% of the control), the negative effects of which on leaf carbon balance were offset by an improved capacity and efficiency of leaves to absorb light, mainly through changes in accessory pigments, but also in optical properties related to leaf anatomy. Conversely, inhibition of gross photosynthesis (by 19.6% compared to the control mean) in the most severe hypersaline conditions (43) reduced net photosynthesis. In this treatment, the respiration rate was limited in order to facilitate a positive carbon balance (similar to that of the control plants) and shoot survival, although vitality would probably be reduced if such metabolic alterations persisted. These results are consistent with the ecology of Mediterranean C. nodosa populations, which are considered to have high morphological and physiological plasticity and a capacity to grow in a wide variety of coastal environments with varying salinity levels. The results from this study support the premise that C. nodosa has a higher tolerance to hypersaline conditions than the highly sensitive Posidonia oceanica, the other dominant Mediterranean seagrass, which is limited to marine environments with stable salinities.

Environmental research on brine discharge optimization: A case study approach

Desalination plants constitute a new way of solving the shortage and degradation of Mediterranean hydric resources by providing a new source of water supply according to local demand, and, at the same time, being climatically independent. Since all desalination plants are located on the shoreline, environmental constraints have to do with water intake and sea outfall discharges. As for brine discharging, a wide range of case-study research is being carried out in order to solve technical uncertainties and provide our projects with preventive measures. The first of these case studies regards the prediction of brine discharge behaviour by using a reduced scale model to simulate the way it is likely to perform in a harbour. The second case-study deals with mixing brine with a thermal effluent in a pipeline to obtain a better dilution that might then minimize its impact on the area. The third case-study is aimed at protecting marine biodiversity by studying into the effects of salinity increase on the growth and survival of the seagrass Cymodocea nodosa.

Nutrient partitioning in the upper Canning River, Western Australia, and implications for the control of cyanobacterial blooms using salinity

The partitioning of N and P is examined between the submerged macrophytes, sediment and phytoplankton in a eutrophic freshwater impoundment on the Canning River, Western Australia. The importance of the macrophytes as a nutrient sink, and the effect of salinity increase on their growth were assessed. Summer cyanobacterial blooms in this system have led to a proposal to increase the salinity of this system to curtail or prevent the blooms. Uptake of N and P by Potamogeton crispus accounted for the major portion of the observed loss from the sediments. Luxury uptake of P, and N limitation, were indicated by tissue N:P ratios, with high biomass and tissue N and P concentrations indicating the capacity of this macrophyte to act as a nutrient sink in midsummer. Water column dissolved inorganic N (DIN) and filterable reactive phosphorous (FRP) was also reduced in midsummer. P. crispus showed significant reduction in growth at 8 ppt salinity, and Hydrilla verticillata at 6 ppt. Therefore, use of increased salinity to control freshwater cyanobacterial blooms is likely to reduce nutrient uptake by macrophytes, and may cause a change to phytoplankton dominance.

Effects of salinity increase on carotenoid accumulation in the green alga Dunaliella salina

The effect of sudden salinity increases on the kinetics of growth and carotenogenesis was studied in three geographically diverse isolates of Dunaliella saliva. A sudden increase in salinity results in a lag phase in growth and the length of this lag phase is dependent on the final salinity and the magnitude of the salinity change (no lag at 10–15% w/v NaCl, 4-day lag at 30% NaCl). There is also a lag before an increase in the total carotenoid content can be measured following the salinity up-shock, and the length of the lag depends largely on the initial salinity and the magnitude of the salinity up-shock, whereas the rate of carotenogenesis and the final carotenoid content reached depend on the final salinity. The increase in total carotenoid content is mainly due to β-carotene. Following the salinity up-shock (especially from 10% to 20% NaCl) the proportion of lutein as a percentage of total carotenoids decreases, whereas zeaxanthin increases. This suggests that the pathway synthesising lutein is more sensitive to salt or osmotic stress and is inhibited at higher salinities, thus leading to β-carotene formation. The proportion of α-carotene does not change.