Unveiling the Mysteries of Coral Life Through Submarine Microscopy

Unveiling the Mysteries of Coral Life Through Submarine Microscopy

The Benthic Underwater Microscope (BUM), a groundbreaking tool developed by researchers at the Scripps Institution of Oceanography - University of California San Diego (UCSD), is shedding light on the competitive and aggressive behaviour of corals. This innovative device, comprising an underwater computer operated by a diver and a special microscopic imaging unit, is instrumental in discovering and learning about the microscopic aspects of the marine environment.

Recent findings using the BUM have focused on the fine-scale interactions among coral colonies, revealing dynamic competitive mechanisms that shape reef community structure. Although these findings are not explicitly mentioned in the latest search results, current research highlights several related insights about coral interactions and reef fish behaviour influencing coral competition.

Corals and reef fish engage in complex territorial and competitive behaviours. For instance, bicolor damselfish (*Stegastes partitus*) exhibit aggression mainly to defend space and food resources, which indirectly influences coral dynamics by controlling algal growth on reefs and competing fish populations. Coral reef fish use sophisticated coloration and behavioural strategies as part of their competitive and defensive repertoire, which affects reef ecology and indirectly modulates coral competition by maintaining a balance between algae and coral growth.

Advances in underwater imaging, such as the BUM, allow scientists to observe these interactions at high resolution *in situ*, revealing previously unseen aggressive behaviours and spatial competition at the micro-scale among coral polyps and their neighbours. This technique helps researchers visualize how corals actively compete for space and resources by extending specialized structures or deploying chemical defenses directly against competing corals.

The microscopic imaging unit of BUM includes a high-magnification soft lens that focuses similar to the human eye, a bright LED focus ring for lighting, and is capable of recording tiny underwater organisms in their natural habitat. It can operate around 30ft (9m) deep, with the potential to reach depths of 100ft (30m).

One of the studies conducted with BUM focuses on corals off the coast of the Red Sea, where it captured two different coral species competing for space on the seafloor, showing chemical enzymes being secreted to destroy the other species. During high ocean temperatures, BUM recorded that the algae that lives inside the polyps of corals ejects itself, which can lead to coral bleaching.

However, when the same species were close to each other, this aggressive behaviour did not occur, suggesting that corals do not compete with their own species. This finding, while not directly related to the competitive behaviour with other species, adds to our understanding of coral dynamics within their ecosystems.

The BUM has the potential to reveal new insights about marine life, which could aid in preserving ocean ecosystems. Researchers are studying various marine behaviours using the BUM to help preserve ocean ecosystems, including studying the coordinated behaviour between polyps of the same colony and the colonization of bleached corals by algae. Andrew Mullen and his colleagues at Scripps Institution of Oceanography - UCSD are continuing to study other marine behaviours with BUM.

In sum, while the direct application of the BUM in studying coral aggression is emerging, current research supports that coral competitive behaviour involves direct physical and chemical interactions observable at fine scales, and these behaviours are closely linked with reef fish territoriality and ecosystem dynamics. The BUM enables novel, detailed insights into such interactions, enhancing our understanding of coral competition and reef biodiversity maintenance.

1. The Benthic Underwater Microscope (BUM) is illuminating competitive and aggressive behavior among corals, a revelation achieved through the microscopic aspects of the marine environment.
2. In-situ observation using the BUM has focused on the fine-scale interactions among coral colonies, exposing intricate competitive mechanisms that craft reef community structure.
3. Coral reef fish display complex territorial and competitive behaviors, employing coloration and behavioral strategies as part of their repertoire, thereby impacting reef ecology and indirectly modulating coral competition.
4. The BUM's microscopic imaging unit features a high-magnification soft lens that focuses like the human eye and a bright LED focus ring for lighting, enabling the recording of tiny underwater organisms within their natural habitat.
5. A study using BUM off the coast of the Red Sea capturedtwo different coral species competing for space on the seafloor, showcasing chemical enzymes being secreted to obliterate the other species.
6. During high ocean temperatures, BUM recordings demonstrate algae ejection from coral polyps, which can trigger coral bleaching.
7. When the same coral species coexist, aggressive behavior is absent, implying corals do not compete with their own species.
8. Leveraging the unique capabilities of the BUM, scientists endeavor to expose new marine behaviors that could assist in preserving ocean ecosystems, promoting not only the study of coral behavior but also the exploration of other facets of marine life.

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