Great attention gets paid to rainforests because of the diversity of life there. Diversity in the oceans is even greater.” – Sylvia Earle

What is biodiversity change? Two words: Bio and Diversity. Bios comes from the Greek and means ‘life’. Biodiversity is a variety of life. Biosiversity sustains life in the sea. To have a healthy fish population there needs to be a healthy predator population. Predators prey on the weak and sick, keeping it all in balance. But the diversity is changing. Rapidly! As humans, we are not a healthy predator anymore. We have become more like monsters, interfering with the system like we’re the last generation on earth.

Climate change, ocean acidification and plastic pollution all make it harder and harder for marine life to thrive. We speed up the degradation process with fertilisers, chemicals, pesticides, herbicides, sewage, oil, plastics running down from land, and nuclear disasters. This results into ‘dead zones.’which are zones in the ocean where no life exists at all anymore due to a lack of oxygen.

A 2017 published study by the Tropical Research Institute found that coral reefs are associated with more than half of the known tropical dead zones worldwide, concluding that the risk of dead-zone to reefs has been severely underestimated. The same study estimates the number of dead zones far greater (441 in the tropics, and 447 outside the tropics), than previous estimates (1).

Coral reefs are complex underwater ecosystems. Reefs are the “rainforests of the sea,” and home to many living beings. Half of the shallow coral reefs globally are gone or in a serious state of decline. In the Caribbean, 80% of the reefs are already believed to be dead. One in every eight birds is in danger, one in every four mammals, and one in every three amphibians. Seal populations are now less than 10% of what they once were in the North Atlantic 500 years ago (2).

With fewer species, the greater the challenge becomes to maintain a healthy ocean, food security and the health of everyone on earth. It’s a bit like the game Jenga, where the aim of the game is to make a tower as high as you can (more money and appetite satisfaction). You take a block (a fish species) out of the bottom foundation (the ecosystem) and put in on the top of the tower (our appetite). We can only do this so many times until the tower (the ecosystem) collapses. Fish species collapse when only a few fish are left and are not able to reproduce fast enough to replenish the population.

The primary cause of the changes in biodiversity is: overfishing. The next challenge to tackle!

26. Tropical dead zones and mass mortalities on coral reefs. Altieri, A. H., Harrison, S. B., Seemann, J., Collin, R., Diaz, R. J., & Knowlton, N. (2017). Tropical dead zones and mass mortalities on coral reefs. Proceedings of the National Academy of Sciences. 14, 2017, Proceedings of the National Academy of Sciences, Vol. 114, pp. 3660-3665.

27. Earle, Sylvia. A. The world is Blue: How our fate and the ocean’s are one. Washington : National Geographic, 2009.

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