By: Ana Frescas
Threat against the coastal ecosystems is happening right now by the cultural eutrophication. Nutrient load along the coastal zone has gone up within the past 50 years approximately. This has caused different symptoms to occur such as algal blooms (rapid growth of algae), and bottom water hypoxia (reducing the oxygen in the body of water). By high hypoxic conditions fish have died. Which results in hypoxia reducing the abundance in infauna within the area, and algal blooms in the composition of phytoplankton which produces bio-toxins that harm the organisms as well as the humans.
https://pubs-acs-org.tamiu.idm.oclc.org/doi/pdf/10.1021/acs.est.8b02971
Figure 1. Different hydrological conditions (flooding, flooding relaxation, and hyper saline) showing the water column oxygen consumption mechanisms using Baffin Bay as an example.
There were two coastal lagoons within Texas examined which were the Baffin Bay and Oso Bay, since both of them have an increase in nutrients as well as chlorophyll a concentration. Dissolved oxygen (DO) consumption is found to be integrated in the water column which accounts for the 67-73% of the total DO consumption between the two coastal lagoons rich in nutrients, located in the northwestern Gulf of Mexico. DO is temperature dependent to diverse extend, long-term warming of the environment can deteriorate the low-oxygen condition, since warming cannot just decrease DO solubility but also it can increase the water-column stratification and the rate of respiration. By the low condition of DO due to increased water residence time, which will give the organic matter a longer hang on to the lagoon systems.
Reference:
Wang, H., Hu, X., Wetz, M.S., and Hayes, K.C. 2018. Oxygen Consumption and Organic Matter Remineralization in Two Subtropical, Eutrophic Coastal Embayments. Environ. Sci. Technol. pp A-K. DOI: 10.1021/acs.est.8b02971
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