Kaja von Rotz

Antarctic Krill, a small crustacean found in the Southern Ocean of Antarctica. With its quantity, behavior and nutritional values, Krill is a crucial fish for the Antarctic’s marine ecosystem. Besides that, Krill is used to produce high quality fish feed, fish oil and medical products. In the following blog post I am going to talk about beneficial qualities of Krill, the commercial fishery and how Krill is influeced by climate change. 

Beneficial qualities of Antarctic Krill for the Southern Ocean

Antarctic Krill feeds on phytoplankton, which grows under sea ice. As the sea ice melts in summer, the layers get thinner, and sunlight can pass through. With surrounding carbon, phytoplankton can photosynthesize, grow in biomass and provide a food source for the Krill species (cf. Attenborough, 2019). Within a short time, the Krill population can increase in size and form gigantic swarms with millions of individuals. With a quantity between 300 and 500 million tons, Antarctic Krill makes up the largest biomass of any multicellular wild animal species (Meyer, 2020). They provide a vital food source for predator species such as whales, seals, seabirds, penguins, squid and fish. Even the largest animal on the planet, the blue whale depends on a 5-centimeter large crustacean, as his main food source (cf. ‘Antarctic Krill’, n.d.-a). As a keystone species, Antarctic Krill plays an important role in the Southern Ocean food web (‘Antarctic Krill’, n.d.-b).

In winter, when the conditions in the Southern Ocean are way harsher, the food source for Antarctic Krill is limited. They get through these winter months by sizing down their body. In this way, they can use their own proteins to survive without the need of an external food source. They endure starvation up to two hundred days. After this time, the ice melts and phytoplankton can grow again. Now they can regain their body mass until the next winter arrives (cf. ‘Antarctic Krill’, n.d.-a).

Furthermore, Antarctic Krill has a positive impact on the carbon cycle. As they feed, they absorb the carbon captured by phytoplankton. During nighttime they migrate to deeper sea levels to discrete their waste. The carbon stored in their waste will stay on ocean grounds for a very long time. The estimated quantity captured and transported to the deep sea is up to 23 million tons of carbon per year, which is equivalent to the amount of released carbon by 35 million cars. If the Antarctic Krill gets eaten by its predators, they absorb the carbon stored in Krill. The carbon often stays in their bodies for decades. When they die, their body sinks to the ocean ground and will be eaten by deep sea organisms. In this way the carbon stays captured for a long time and won’t be released in the atmosphere any time soon (cf. Kavanagh, 2019).

 Commercial Krill fishery

In the 1970s Antarctic Krill fishery began, as they found out, that it is an excellent source of protein. As early as 1970 they discovered, that besides being a good source of protein, Krill oil is rich in Omega-3 fatty acids. Initially Krill fishery focused on human consumption, later, however, the majority of the catch was used for the production of high-quality animal feed. Besides that, a small amount is used to produce krill oil as a human health supplement (cf. Nicol, 2016).

Since 1982, as a result of Krill exploitation, the commercial fishery for Krill is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) (Meyer, 2020). The Commission recognized the potential threat to Antarctic marine life through Krill fishery and they established a precautionary approach to manage future Krill fishing (Nicol, 2016).

According to Bettina Meyer (2020) the demand for products made from Krill will most likely grow. This is mainly due to two industries. Firstly, the request for fish feed such as fish meals and marine byproducts will increase. Secondly, there will be a rise in demand for high value pharma- and nutraceutical products made from Krill oil and Krill meal (cf. Meyer, 2020).

 Effects of climate change on Antarctic Krill

Climate change caused by human activities has a major impact on all areas on planet Earth, including the Southern Ocean. Due to rising temperatures the large ice masses of Antarctica are slowly melting. With disappearing sea ice, the optimal spot for phytoplankton to grow disappears too. This has a major impact on the abundance of Antarctic Krill. Without a food source, Krill will most likely disappear too. This leads to a movement towards the Antarctic continental shelves, where the temperatures are lower and the conditions for Antarctic Krill are better. Antarctic Krill populations move southwards, and their habitat gets smaller, which results in a decreasing number of individuals (cf. Amos, 2019). This impacts the predator species as well. For example, there will be more fights within the predator species, because of limited food resources. This will have a negative influence on the size of the predator species as well (cf. Meyer, 2020). Climate change triggers a chain of reactions with negative impacts.

A problem the Krill fishery is facing today is that Antarctic Krill populations decrease in size from year to year because of climate change. Catch limits should be adjusted according to current climate models or the current stock size to protect Krill populations. If there are no restrictions on Krill fishing, rising temperatures because of climate change will also have a negative impact on the entire Antarctic marine ecosystem (cf. Meyer, 2020). According to Stephen Nicol (2016) the CCAMLR already implemented a precautionary management regime to protect Antarctic Krill and other species.

 Conclusion

Despite their tiny size, Antarctic Krill play a huge role in the Antarctic marine ecosystem. As a main food source for most large predator species in the Southern Ocean they ensure their survival, they influence the carbon cycle in a positive way by acting as a carbon sink and they have commercial value for different industries. In today’s warmer climate, they face a lot of challenges and threats because of us humans. Therefore, it is our responsibility to protect the Antarctic marine ecosystem at any cost.

Bibliography

Amos, J. (2019). Antarctic krill: Key food source moves south. Retrieved from https://www.bbc.com/news/science-environment-46953652

Antarctic Krill. (n.d.-a). Retrieved from https://www.antarctica.gov.au/about-antarctica/animals/krill/

Antarctic Krill. (n.d.-b). Retrieved from https://oceana.org/marine-life/antarctic-krill/

Attenborough, D. (2019). Frozen Worlds. Retrieved from https://www.ourplanet.com/en/explore/frozen-worlds/

Kavanagh, A. (2019). Tiny Antarctic Krill Play Big Role in Climate Mitigation. Retrieved from https://www.pewtrusts.org/de/research-and-analysis/articles/2019/10/18/tiny-antarctic-krill-play-big-role-in-climate-mitigation

Meyer, B. (2020). Successful ecosystem-based management of Antarctic krill should address uncertainties in krill recruitment, behaviour and ecological adaptation. Retrieved from https://www.nature.com/articles/s43247-020-00026-1#:~:text=Antarctic krill (Euphausia superba%2C hereafter,species on the planet3.

Nicol, S. (2016). The Fishery for Antarctic Krill: Its Current Status and Management Regime. Retrieved from https://link.springer.com/chapter/10.1007/978-3-319-29279-3_11

(Illustration missing, BW)