Ocean Acidification and its major impacts in Bay of Bengal, Bangladesh
Ocean acidification (OA) is an effect of climate change. OA can be defined as a long-term decrease in seawater pH, principally due to an anthropogenic increase in atmospheric carbon dioxide (CO2). The ocean absorbs approximately (~30%) of CO2 added to the atmosphere from human activities including fossil fuel burning, cement manufacture, deforestation, and land-use change. CO2 dissolves in water, forms carbonic acid (H2CO3), and causes decreases in ocean pH (due to an increase in hydrogen ion concentration or H+(Kibria, 2015). Human’s too much CO2 emission is one of the main driving forces of OA.
Atmospheric CO2 concentrations are expected to reach 467–555 ppm by the Year 2050 that would cause surface ocean pH to decline, on average, to 7.8 in the Year 2050 (Cooley et al. 2009c).
it is rapidly changing the carbonate system in the Bay of Bengal. The recent study reveals that pH value in the Bay of Bengal on average is around 7.73.the pH value has dropped by 0.2 between 2012 to 1994 (pH 7.95).there is also is on an increasing trend.
the CO2 concentration is increasing continuously. This suggests that there will have significant consequences for marine organisms that build skeleton or shells by carbonates like coral reefs, coccolithophores, oysters, pteropod, benthic mollusks, etc. so the distribution and abundance of marine organisms have greatly decreased.
Impacts of Ocean acidification (OA)
- Impact on biodiversity and food web
Marine Plankton is the base of the marine food chain upon all other marine life depends. Ocean acidification could affect the marine food chain and lead to substantial changes in oceanic biodiversity which may threaten protein supply and food security for millions of people as well as the multi-billion dollar fishing industry(IUCN, 2015). Ocean acidification may directly affect some marine species that supply many services to humans. For instance, mollusks and crustaceans support valuable commercial and recreational fisheries (Cooley and Doney, 2009a). Lowering the pH of the ocean results in coral bleaching, slow growth, and decrease coral biodiversity. Among the 66 coral species in 1997, only 40 species were recorded in 2008, which indicates 26 coral species lost in 11 years, posing a serious threat to the coral biodiversity in the northern Bay of Bengal Bangladesh(Hossain, Sharifuzzaman, Chowdhury, Sarker, & Chowdhury, 2015). When the entire marine and coastal food web may have to face acidic seawater, the food web and food chain will be at risk. This entire biodiversity will be disrupted shortly if these horrible situations will continue.
2.Impact on coastal ecosystem
Coastal ecosystems, like most other ocean ecosystems, are feeling the effects of anthropogenic problems such as climate change, ocean acidification, and eutrophication due to excessive nutrient runoff. (IUCN, 2015) .bangladesh has an area of 47,201km2 which is 32% of the total land area of the country. The coastline of Bangladesh is about 710 km long. Most of the coastal beaches are muddy with rich biodiversity. OA may affect the benthic ecosystem of the onshore, offshore, and nearshore. ocean acidification affects the fertilization rates of sea urchin embryos and the size and formation of sea urchin larvae (Kurihara et al. 2004).
3.Impact on shellfish and coral reef
OA affects the organisms that use CaCO3 for their skeleton and shell-like pteropod and coral reef. Sea urchins, nematodes, bivalves and echinoderms, algae, diatoms .gastropods demonstrated reduced growth with acidification; up to 62% reduce growth found for sea urchins with acidification(Hendriks, Duarte, & Álvarez, 2010). Increased acidity in ocean water is affecting the size and weight of shells and skeletons, and similar sort of problem is widespread across marine species. Different species-specific responses among mollusks have been observed, but the majority of molluscs due to ocean acidification ate neutral to negative (Cooley et al. 2012). , the net effect of ocean acidification on coral reef ecosystems will probably be negative as many warm-water corals will be heavily impacted by the combined effects of increasing sea-surface temperatures (coral bleaching) and decreasing carbonate saturation states of surface waters in the coming decades (Guinotte et al., 2009).
4.Impact on livelihood and food security
Bangladesh has large coastal resource-dependent communities. Millions of people of Bangladesh depend on marine fisheries for a protein source, food, and employment. OA is affecting marine fisheries of Bangladesh and will intensify. Ocean acidification is likely to affect organisms that support subsistence, commercial, and recreational fisheries, thereby impacting the ability of those ecosystems to provide services upon which humans have been dependent (Cooley et al. 2009). The oceanic ecosystem supports rich and diverse fisheries that form an integral component of the ecosystem and are associated with economic and other societal benefits (IUCN, 2015). ultimately OA will create an adverse impact on health, coastal natural resources, and employment in the coastal area of Bangladesh.
Conclusion
This review has covered almost available research papers related to ocean acidification of bay of Bengal and tried to investigate recent status and impacts on marine ecosystems, livelihood, and food security. Ocean acidification is one aspect of global climate change. Anything we do to mitigate climate change today will benefit the future of the ocean as well. OA has direct and indirect consequences that are accelerated by climate change. OA of Bay of Bengal has increased rapidly over the decades and probably will continue to intensify if global CO2 emissions are not reduced.
References
Guinotte, J., Sano, L., Grant, V. S., Day-miller, E., Hastie, B., Keener-chavis, P., … Wharton, J. (2009). Hall-Spencer&Rauer09, 25(1).
Hendriks, I. E., Duarte, C. M., & Álvarez, M. (2010). The vulnerability of marine biodiversity to ocean acidification: A meta-analysis. Estuarine, Coastal, and Shelf Science, 86(2), 157–164. https://doi.org/10.1016/j.ecss.2009.11.022
Hossain, M. S., Sharifuzzaman, S. M., Chowdhury, S. R., Sarker, S., & Chowdhury, S. N. (2015). Ocean Acidification Threatens Marine Ecosystems and Livelihood Security in Bangladesh. Institute of Marine Sciences and Fisheries, University of Chittagong, Bangladesh. Retrieved from http://iocwestpac.org/OA1/4 Bangladesh_Shahadat Hossain.pdf
IUCN. (2015). Vulnerability of the Bay of Bengal to Ocean Acidification. Retrieved from https://portals.iucn.org/library/sites/library/files/documents/2015-049.pdf
Report, T. (2016). Ocean Acidification and Its Impact on Marine Biodiversity , Seafood Security & Livelihoods- A Short Review, (SEPTEMBER 2015), 1–8. https://doi.org/10.13140/RG.2.1.5138.4808
Cooley, S.R., and S.C. Doney. 2009a. Anticipating ocean acidification’s economic consequences for commercial fisheries. Environmental Research Letters 4, 024007.
Cooley, S. R. and Doney, S. C. 2009b. Ocean acidifications impact on fisheries and societies: A U. S. perspective. The Journal of Marine Educaitn. 25(1): 15–19.
Cooley, S. R., Kite-Powell, H. L. and Doney, S. C. 2009. Ocean acidification’s potential to alter global marine ecosystem services. Oceanography. 22: 172–181.
Kurihara, H., S. Shimode, and Y. Shirayama. (2004). Sub-lethal effects of elevated concentration of CO2 on planktonic copepods.
