Anti-fouling agents have the ability to prevent the settlement and growth of marine organism in submerged habitats as well as impacting primary production levels. Both sinking rate and the physio-chemistry of marine diatoms are impacted on by the presence of diuron. Diuron is a photosystem II inhibitor which prevents electron transfer.
Two species in particular were looked at, Thalassiosira pseudonana (single-celled species) and Skeletonema marinoi-dohrnii (complex chain forming species). Cultures were grown and maintained for both species and then used for various experiments.
Sinking rates decreased significantly in both diatom species with exposure to diuron at 50% effective concentration for growth. Furthermore, photosynthetic performance of both diatoms also significantly decreased. Number of cells per chain of S.marinoi-dohrnii decreased significantly however T.pseudonana cell diameter remained constant. Lipid concentration increased in both species while water soluble protein concentration decreased in T.pseudonana after 72 hours.
These observed changes in composition are suggested to be the reason why sinking speed is decreased. The roll-on impact of the decreased sinking speed may in fact increase risk of diuron exposure and therefore exacerbate the problem even further. Furthermore, many diatom species have a resting stage cell under unfavorable environmental conditions. Reduced sinking rate will possibly prevent diatoms reaching this stage in time and negatively impacting upon the groth of the diatom. Previous studies have found that when photosystem II is impaired, the products of photosynthesis are not taken up as normal, and instead deposited as lipids. Therefore, higher neutral lipid levels may be a biological reaction to physiological stress. It was found that the correlation between the number of cells per chain and photosynthetic parameters in chain-forming diatoms suggest that there is an obligate reliance between chain length and sinking rate whereas single-celled diatoms sinking rate was determined by its biochemical composition.
paper reviewed:
Saranya, K., Sundaramanickam, A., Shekhar, S., Meena, M., Sathishkumar, R. S., & Balasubramanian, T. (2018). Biosorption of multi-heavy metals by coral associated phosphate solubilising bacteria Cronobacter muytjensii KSCAS2. Journal of Environmental Management, 222, 396-401. doi:10.1016/j.jenvman.2018.05.083
paper reviewed:
Saranya, K., Sundaramanickam, A., Shekhar, S., Meena, M., Sathishkumar, R. S., & Balasubramanian, T. (2018). Biosorption of multi-heavy metals by coral associated phosphate solubilising bacteria Cronobacter muytjensii KSCAS2. Journal of Environmental Management, 222, 396-401. doi:10.1016/j.jenvman.2018.05.083
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