Evaluating Carbonate System Algorithms in a Nearshore System: Does Total Alkalinity Matter?

Current Trends of Analytical Techniques for Total Alkalinity Measurement in Water Samples: A Review

Increasing acidity of seawater caused by increasing anthropogenic carbon dioxide absorbed into the seawater attracted the interest of researchers due to increased concern on the deterioration of marine systems and food supply to humans. Total alkalinity (TA) is one of the important parameters in determining carbonate chemistry and is described as the capacity of the sample to neutralize acids. Over the last two decades, many analytical techniques have been developed to determine TA. This article presents a review of different analytical techniques including titration, colorimetric, spectrophotometric, and potentiometric analyses in measuring TA. Among these analytical techniques, potentiometry analysis, which utilizes electrode systems such as glass electrode and ion-selective electrode used as indicator electrodes, is the most used technique. Important features such as principle, limitations, and challenges of the involved technique are discussed in detail.

Shift in rhizospheric and endophytic bacterial communities of tomato caused by salinity and grafting

Saline water has to be used as an alternative resource in modern agriculture due to the increasing lack of fresh water. Approaches that promote the growth of crops under saline conditions have, therefore, become crucial. Grafting has been reported to be effective for this; however, the associated bacterial community remains unclear. To obtain a deeper understanding of the underlying microbial mechanisms, both grafted and non-grafted tomatoes were irrigated with three types of water having different electrical conductivity values. The experiment lasted 2.5 months, after which, the soil chemical properties and tomato heights were assessed. The rhizospheric and endophytic bacterial communities of samples from the different treatments were assessed by Illumina sequencing. The results showed that saline water significantly affected leaf-associated endophytic bacterial communities, whereas rhizosphere and root- and stem-associated bacterial communities were not affected. Increasing salinity increased the abundance of Gammaproteobacteria, but decreased the abundance of Actinobacteria, Alphaproteobacteria, Bacilli, and Acidobacteria at the class level of the leaf-associated bacterial community. Moreover, under higher salinity levels, grafting increased the diversity of the leaf-endophytic bacterial community. Overall, this study provides a comprehensive understanding of the rhizosphere and endophytic bacterial communities of tomato under saline conditions. The results highlight the importance of leaf-endophytic bacteria for salt response in plants. This is an important complementary finding to previous studies on the effect of salinity, which mainly focused on plant rhizosphere and root bacterial communities.

Can larvae of a marine fish adapt to ocean acidification? Evaluating the evolutionary potential of California Grunion (Leuresthes tenuis)

Ocean acidification can reduce the growth and survival of marine species during their larval stages. However, if populations have the genetic capacity to adapt and increase their tolerance of low pH and high pCO2 levels, this may offset the harmful effects of ocean acidification. By combining controlled breeding experiments with laboratory manipulations of seawater chemistry, we evaluated genetic variation in tolerance of ocean acidification conditions for a nearshore marine fish, the California Grunion (Leuresthes tenuis). Our results indicated that acidification conditions increased overall mortality rates of grunion larvae, but did not have a significant effect on growth. Groups of larvae varied widely with respect to mortality and growth rates in both ambient and acidified conditions. We demonstrate that the potential to evolve in response to ocean acidification is best described by considering additive genetic variation in fitness-related traits under both ambient and acidified conditions and by evaluating the genetic correlation between traits expressed in these environments. We used a multivariate animal model to estimate additive genetic (co)variance in larval growth and mortality rates under both ambient and acidified conditions (low pH/high pCO2). Our results suggest appreciable genetic variation in larval mortality rates (h 2 Ambient = 0.120; h 2 Acidified = 0.183; rG  = 0.460), but less genetic variation in growth (h 2 Ambient = 0.092; h 2 Acidified = 0.101; rG  = 0.135). Maternal effects on larval mortality rates accounted for 26%-36% of the variation in phenotypes, but maternal effects accounted for only 8% of the variation in growth. Collectively, our estimates of genetic variation and covariation suggest that populations of California Grunion have the capacity to adapt relatively quickly to long-term changes in ocean chemistry.