Ocean Acidification is defined as the phenomenon of the rise of seawater acidity. In other words, the lowering of seawater pH due to the suspension of chemical substances like carbon dioxide, acids, etc., is called open acidification. The rise in the level of carbon dioxide in seawater is mainly caused due to activities like deforestation, the combustion process of fossil fuels, agriculture, and lack of proper land use. According to the past research studies and experiments conducted, the increase in the acid content in seawater has had a drastic impact on the biological and physiological structure of numerous marine organisms and has also instigated fluctuation in the population of several species. On the other hand, industries like fisheries and tourism will be affected on a large scale as human beings are completely dependent on the marine ecosystem through such activities.
There are various causes for the increase in the carbon dioxide level in seawater. The primary ones are - the suspension of atmospheric carbon dioxide, global warming, and the increase in other natural ocean acidification processes.
The increase in the net amount of carbon dioxide in the atmosphere leads to an increase in the rate of suspension of atmospheric carbon dioxide in the seawater. Thus, this leads to the lowering of the pH level of the seawater. Overall it affects the carbon chemistry of the seawater. Suspension of atmospheric carbon dioxide can increase the level of algal toxins and pathogens and other forms of dissolved inorganic carbons.
Additionally, acid rain can directly affect the pH level of seawater. Global warming directly affects the process of vertical mixing of seawater, leading to a lack of interchange of atmospheric oxygen, which can harm the marine ecosystem.
The negative effects of acidified seawater and the presence of high levels of CO2 in seawater on the marine ecosystem depend on various factors like- the concentration of the water, the time for which the particular organism was exposed to the contaminated water, the type of species and the way these factors transformed the evolution stages of the species.
Thus, the high concentration of chemical substances in seawater will naturally affect the oxygen level in the seawater. The lack of availability of oxygen and the increase in the level of carbon dioxide will directly impact the functioning of the respiratory system of marine species. This factor will reduce the oxygen content in the bloodstream of the organism and affect the functioning of the organs, especially the functioning of the pH-sensitive tissues (oxygen binding proteins that are pH-sensitive- haemoglobin and haemocyanin). Furthermore, organisms require energy for carrying out other metabolic activities like damage repair and blood circulation. If the ventilation system of these organisms does not function efficiently, it may have a drastic impact on the appetite of the organism, as well as the quality of the blood purified by the respiratory system. For example, Copepod sensitivity is a terminology that defines the characteristic changes that occur in the early phase of the organisms and not in the adult stage. This characterization differs for different populations of similar species.
Lack of availability of oxygen and an increase in the amount of carbon dioxide in the seawater may lead to an increase in the number of algae, toxins, and pathogens both at surface level and underwater. Thus, organisms present in the marine ecosystem may die, or their body parts might get damaged due to the factor increase in the algal blooms, the successive event being the deposition and descending process of the dead algae.
In conclusion, the high level of acidification of seawater and the abundance of carbon dioxide in it, which in turn increases the temperature of the water, affects the species present in the marine ecosystem both internally by damaging their body’s metabolic activities or externally, by damaging their body parts by the means of fostering algal blooms and the growth of other pathogens. This may lead to the loss of a large number of unique species present in the marine ecosystem. It may also affect various activities like fisheries, tourism, research, etc., for which humanity is totally dependent on the marine ecosystem.
- Nikshitha