Algae-fueled Bacteria Causing Coral Demise
In a groundbreaking discovery, scientists at the University of California (UC) San Diego and UC Santa Barbara have unveiled a microbial mechanism that contributes to the decline of coral reefs. This mechanism involves harmful algal blooms (HABs) that are fueled by nutrient pollution, such as agricultural runoff, sewage, and other waste[1].
These harmful algal blooms (HABs) grow excessively due to human activities, creating hostile conditions that stress and eventually kill corals. The algae block sunlight essential for the symbiotic algae that live within corals, and when the algae die, microbial decomposition further depletes oxygen, inducing hypoxia (oxygen deficiency) that harms corals and marine life[1].
The team's research, published in the June 5 online version of the scientific journal Ecology Letters, found that corals with neighboring algae died, while coral without neighboring algae did not[1]. An addition of an antibiotic prevented coral death in the presence of algae, indicating that bacteria fed by the algae are the agents of coral death[1].
From a biological perspective, coral reefs are more productive and support more species than any other marine ecosystem on the planet[2]. They are particularly important to humans because they support abundant fisheries and generate a large tourism industry. However, these vital ecosystems are losing their ability to recover due to threats such as global warming and pollution[3].
Sala, the leader of the Line Islands Expedition and an associate professor at UC San Diego's Scripps Institution of Oceanography, stated that addressing individual threats is not enough to ensure healthy coral reefs[3]. He emphasized the need to tackle the root causes of these issues, such as nutrient pollution and overfishing.
The research was supported by the Gordon and Betty Moore Foundation, the Moore Family Foundation, National Geographic Society’s Committee for Research and Exploration, Ivan Gayler, SDSU Foundation, College of Sciences, and several private donors[4]. A video titled "The Maintenance of Coral Reef Health" describes the research and can be viewed at coralreefmultimedia.org[4].
Despite the challenges faced by coral reefs, there is hope that it is not too late to stop the destruction of these vital ecosystems. Many scientists are excited to begin working towards reef restoration and recovery in heavily degraded areas[5].
[1] Source: Ecology Letters (June 5, 2023) [2] Source: National Oceanic and Atmospheric Administration (NOAA) [3] Source: UC San Diego News Centre (June 5, 2023) [4] Source: UC San Diego News Centre (June 5, 2023) [5] Source: UC San Diego News Centre (June 5, 2023)
- The decline of coral reefs, a vital marine ecosystem, raises concerns not only for environmental-science but also for the health-and-wellness of humans, as they support abundant fisheries and an extensive tourism industry.
- The recent discovery by scientists of a microbial mechanism contributing to coral reef decline, involving harmful algal blooms, highlights the impact of climate-change, as nutrient pollution, such as agricultural runoff, sewage, and waste, fuel these harmful blooms.
- As we strive to ensure the health of marine biodiversity, it's crucial to invest in the science that uncovers the root causes of these issues, such as nutrient pollution and overfishing, to promote the overall well-being of both the environment and human societies.
