Many ectothermic marine animals that respire underwater are under strain from increasing sea water temperatures as a result of climate change. In this blog post I will be outlining how human impacts have led to a global increase in sea water temperatures, resulting in an overall decrease in body size of many fish and therefore the food supply worldwide (Baudron, 2014).
Seawater temperatures have been rising since the 20th century. The main reason behind this warming is a process known as the greenhouse effect. A process where the heat radiated onto our earth is reflected back into space. Naturally occurring gasses in the atmosphere trap some of this energy and reflect it back causing heating of the earth. However, this greenhouse effect has been largely intensified by the immense use of fossil fuels by humans since the Industrial Revolution (Global Warming 101 | National Geographic, 2007). Fossil fuels are used in many different sectors worldwide, we depend on them to heat our homes, power industry and manufacturing, provide us with electricity and run our vehicles. In the united states 81% of its total energy used comes from fossil fuels. You can imagine the extent of how much fossil fuel is being burnt and the negative implications its having on our planet (The National Academies of Sciences, Engineering, Medicine, 2018). Global seawater temperatures have increased by 0.1oC (0.18oF) over the past century, this may seem a small change however, it’s caused large issues to the size of many fish in our oceans (National Geographic, 2010).
This increase in the temperature of seawater as a result of the greenhouse effect causes an increase in oxygen demand for ectothermic organisms. However, when sea water is heated oxygen supply decreases. This therefore causes an imbalance in the supply and demand of oxygen to the fish. This imbalance will restrain aerobic scope, thereby impairing individual performance. As a result of this, ectothermic organisms experiencing higher temperatures will have smaller body sizes. This is known as the temperature size rule (Baudron, 2014). A simulation combining both temperature predictions for the future and ecophysiological understandings predict that by 2050, the average body weight of ectothermic fish will have decreased by 14-24%. This is due to the temperature size rule alongside small sized species replacing large sized species (Cheung, 2013).
Fish is a vital source of food for people from all around the world, with about one billion people worldwide relying on fish as their primary source of animal protein we need to ensure we do all we can to protect their habitat. We need to work together to create a sustainable environment by promoting the use of renewable energy in our society to slow down the heating of our oceans. Some of the main ways households, businesses and the government can reduce their fossil fuel consumption could be through the use of solar power, wind power, power from tides, geothermal energy and also human power (5 Alternatives to fossil fuels – Renewable Energy Sources of Today, 2015). There are also many smaller days to day steps you can also take to reduce the amount of greenhouse emissions. These include Reduce, Reuse, Recycle, using less heating and air conditioning, using bicycles, turning lights off and planting a tree. I hope after reading this blog you will understand the importance of reducing your greenhouse gas emissions to as little as possible, to protect not only our marine animals but also our worldwide food supply. If you would like to read further on how you can reduce your carbon footprint, please follow the link bellow.
Baudron, A. R., Needle, C. L., Rijnsdorp, A. D., & Tara Marshall, C. (2014). Warming temperatures and smaller body sizes: synchronous changes in growth of North Sea fishes. Global change biology, 20(4), 1023-1031
Cheung WWL, Sarmiento JL, Dunne J et al. (2013a) Shrinking of fishes exacerbates impacts of global ocean change on marine ecosystems. Nature Climate Change, 3, 254-258.
Institute Of Ecolonomics. 2015. 5 Alternatives to fossil fuels – Renewable Energy Sources of Today. [ONLINE] Available at: http://ecolonomics.org/5-alternatives-to-fossil-fuels-renewable-energy-sources-of-today/ [Accessed 19th February 2018]
National Geographic. (2007) Global Warming 101 | National Geographic. [Online Video]. 18th May 2007. Available from: https://www.youtube.com/watch?v=oJAbATJCugs&t=73s [Accessed 19th February 2018]
National Geographic. 2010. Sea Temperature Rise. [ONLINE] Available at: https://www.nationalgeographic.com/environment/oceans/critical-issues-sea-temperature-rise/ [Accessed 19th February 2018]
The National Academies of Sciences, Engineering, Medicine. 2018. Fossil Fuels. [ONLINE] Available at: http://needtoknow.nas.edu/energy/energy-sources/fossil-fuels/ [Accessed 19th February 2018]