Sea-Stars Suffocating

               While above the water humans are currently enduring a pandemic, under the water, starfish are undergoing an epidemic of their own. Across the pacific coast of North America, starfish are turning into a leathery goo as sea-star wasting disease suffocates and kills many species of starfish. Species such as the sunflower sea stars are being deemed critically endangered as the disease has overcome 90% of their population. The culprit of this epidemic? Climate change and microscopic bacterium.

Photo credit: Kit Harma

               Over time, the Earth’s average conditions have become warmer and warmer. This warming of the Earth has caused the temperatures of the oceans to rise. With this rise in ocean temperature comes an increase in the concentration of organic materials in the waters. Organic materials are defined in chemistry as being carbon-containing with covalent bonding. Certain bacteria called copiotrophs, which are bacteria found in areas with high levels of carbon that rapidly consume carbon for their respiration, begin to thrive continuously as the organic material concentrations keep rising. These bacteria respirate, consuming the organic materials in the water, as well as depleting the oxygen in the water.

               These bacteria also live on the outer surface of the starfish’s skin. When the waters become too warm and the organic matter concentrations reach levels too great, the bacteria reach numbers too high for the starfish to live. The bacteria in large proportions begin to use all of the oxygen up in the water surrounding the starfish to suffocate and die. Starfish don’t breathe like humans; however, they diffuse water over their skin through papulae, which are little skin gills. Without the oxygen to breathe, the starfish “drown,” and this triggers the wasting of the starfish.

               The problems these starfish face are stuck in a cycle of even more wasting and extinction. As more starfish die, more will start to waste. When they die, their organic materials will be consumed by the copiotrophs around them, causing the bacteria to thrive even more. Those bacteria will continue to suffocate the other starfish around them. Climate change is also predicted to get worse and worse, causing the waters to get warmer and warmer on average. Gasses like oxygen are dissolved in the water and the warmer it is, the less energy it will take for the oxygen to escape and leave the water. Conversely, the colder the water is, the tighter it holds onto the oxygen, making it harder for oxygen to escape the water. So with less oxygen in the water and warmer waters containing even more of these suffocating bacteria, the starfish of the world are in a dangerous position.

Photo Credit: MWRD

               There are some solutions that are being investigated to help save the starfish, however. One option that scientists are looking into is to pump oxygen into the water to give the starfish more to breathe with. Another direction that is being researched is the use of ultra-violet radiation to remove the excess organic matter from the waters. The UV radiation can cause organic materials to degrade and break apart. This is done by raising the energy states of the molecules, causing the formation of radicals (free singular electrons), which further break apart more and more bonds. By removing the excess organic matter from the water, the copiotroph populations would drop, helping the starfish populations maintain themselves. With no immediate solution in sight, increasing numbers of species of starfish will near extinction.

               For more information on sea-star wasting disease click here.

Written by Sean Shacklock.

Sources:

https://www.sciencenewsforstudents.org/article/bacteria-suffocating-sea-stars-wasting-disease-goo

https://www.nbcnews.com/science/environment/warming-oceans-may-be-choking-oxygen-starfish-causing-them-drown-n1253355

https://www.sciencedaily.com/releases/2021/01/210106133017.htm