How Plants Power the Partnership Between Corals and Algae

Jenn Hoskins
20th March, 2024

How Plants Power the Partnership Between Corals and Algae

Image Source: Natural Science News, 2024

Key Findings

  • In a Stanford study, sea anemones need algae that can photosynthesize to establish a lasting partnership
  • Algae that couldn't photosynthesize were taken in by anemones but eventually lost, showing light is vital
  • Anemones can host multiple algae regardless of size, suggesting size isn't a barrier to symbiosis
Coral reefs are vital to marine ecosystems, but their survival is threatened by environmental changes. At the heart of a coral's ability to thrive is a symbiotic relationship with tiny algae called dinoflagellates, from the family Symbiodiniaceae. These algae live inside the coral's cells and provide essential nutrients through photosynthesis. Understanding how this partnership is established and maintained is crucial for coral conservation efforts. Recent research from Stanford University School of Medicine[1] has shed light on the symbiotic relationship between corals and their algal partners, using the sea anemone Aiptasia as a model. Aiptasia shares many characteristics with corals, making it an excellent subject for studying coral biology in the lab. The study found that the successful establishment of symbiosis between the anemone and the algae depends on the algae's ability to photosynthesize. In other words, the algae need to be able to convert sunlight into energy to be accepted and maintained within the host. When algae were introduced to the anemone in the dark, they were taken up but did not reproduce and were eventually lost, indicating that light and photosynthesis are critical for the long-term survival of the symbiotic relationship. Furthermore, the researchers observed that not all algal strains are compatible with the anemone. Some strains were unable to enter the host's cells, while others could enter but failed to multiply and were slowly expelled. This suggests that the establishment of symbiosis is a selective process, where the anemone can discern and favor certain algal strains over others. Interestingly, the study also addressed the question of whether physical size limits the algae's ability to be hosted by the anemone's cells. The findings revealed that size was not a discriminating factor, as the host cells were capable of accommodating multiple algal cells, regardless of their size. These insights build upon earlier studies that have explored the complex interactions within the coral symbiotic relationship. For instance, prior research[2] has shown that certain bacteria associated with the Symbiodiniaceae can enhance the algae's photosynthetic health and stress response. This suggests that the coral microbiome, including bacteria, plays a role in the fitness of the algae and, by extension, the health of the coral. Additionally, studies have highlighted the importance of nitrogen availability in the coral-algal symbiosis[3]. The presence of algal symbionts was found to increase the abundance of denitrifiers, bacteria that help maintain nitrogen balance within the coral. This delicate balance of nutrients is crucial for the symbiotic relationship. Another study[4] revealed that specific bacteria can influence the metabolism of Symbiodiniaceae. For example, the presence of certain bacterial genera correlated with increased levels of monosaccharides and the phytohormone indole-3-acetic acid (IAA), which in turn, boosted the growth of the algae. The research from Stanford University not only adds to our understanding of the coral-algal symbiosis but also highlights the importance of photosynthesis in maintaining this relationship. By uncovering the mechanisms behind symbiosis establishment and maintenance, scientists can better understand how to support coral health in changing marine environments. The study's findings emphasize the complexity of the coral microbiome and the intricate dance of interactions that must occur for corals to grow and survive. With the increasing pressures of climate change and other anthropogenic factors, research like this is more critical than ever, providing potential pathways to bolster coral resilience and inform conservation strategies.

EcologyPlant ScienceMarine Biology

References

Main Study

1) Photosynthesis and other factors affecting the establishment and maintenance of cnidarian-dinoflagellate symbiosis.

Published 18th March, 2024

https://doi.org/10.1098/rstb.2023.0079

Related Studies

2) Symbiodiniaceae photophysiology and stress resilience is enhanced by microbial associations.

https://doi.org/10.1038/s41598-023-48020-9

3) Presence of algal symbionts affects denitrifying bacterial communities in the sea anemone Aiptasia coral model.

https://doi.org/10.1038/s43705-022-00190-9

4) Coral endosymbiont growth is enhanced by metabolic interactions with bacteria.

https://doi.org/10.1038/s41467-023-42663-y


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