Underwater microscope reveals hidden coral secrets

Now scientists can gaz directly into the microscopic world of life reefs, thanks to a portable underwater microscope that reveals photosynthesis that takes place in real time in various coral cells.
The device, developed by researchers at the UC San Diego Scripps Institute of Oceanography, allows marine biologists to study coral health and bleaching processes without disturbing these fragile ecosystems.
Benthic underwater microscopy imaging PAM (BUMP) represents a significant technological advance in coral research, providing an unprecedented perspective on the symbiotic relationship between corals and small algae to keep them alive.
See invisible
Corals depend entirely on the microscopic algae that live inside the tissues – spreading 10 microns, or one-tenth of the width of human hair. These algae perform photosynthesis, converting sunlight into sugars rich in energy. When corals lose these algae due to stress, they bleach white and eventually starve to death.
“This microscope is a huge technological leap in the field of coral health assessment,” explained Ben-Zvi, a postdoctoral researcher at Scripps Oceanographic and lead author of the study. “We now have a tool that allows us to examine these microalgae in coral tissue, non-invasive and natural environments.”
Microscopes use pulse amplitude modulation (PAM) light technology to measure the effectiveness of photosynthesis in various algae in coral tissues – underwater was not previously observed on such scales.
Technological innovation
Concave and convex are based on early underwater microscopy technology, but add crucial new features:
- Almost micrometer resolution used to image single algae cells
- Real-time photosynthesis measurement using fluorescence technology
- 3D scanning function is adjusted through focus
- Portable design accessories in a carry-on suitcase
- Extend 20-hour battery life for underwater research
Coral behavior is surprising
In addition to measuring photosynthesis, the microscope also showed unexpected coral behavior. Ben-ZVI observed that corals constantly change their volume and shape, and individual polyps quickly contract tentacles to capture or remove transfer particles.
The team tested the instrument at coral reef sites in Hawaii, the Red Sea and Palmyra Atolls. In studies comparing shallow versus deep water corals, they found that shallow corals showed lower photosynthesis efficiency and higher variability, which may be due to more intense light conditions.
A technical detail not highlighted in the initial report: The system uses a dedicated LED array with Fresnel lens to accurately focus the lighting, allowing a short 50 millisecond type of exposure to minimize motion blur while reducing the potential stress of bright lights on the coral.
Real-world applications
“We get a lot of information about their health without interrupting nature,” Ben-ZVI noted. “It’s similar to a nurse who grabs your pulse and tells you about your performance.
The non-invasive approach of microscopy means that researchers don’t need to collect samples or even touch the coral they are studying. This preserves the natural ecosystem while collecting detailed health data.
Early results suggest that the instrument can detect warning signs before corals experience irreversible damage during climate change events such as ocean heat waves. These insights can help guide conservation strategies to better protect vulnerable reef systems.
Beyond Coral Reefs
“Since photosynthesis in the ocean is important for life on Earth, imagine the tool, including near the San Diego coast, including here,” said Jules Jaffe, a research oceanographer who co-developed the microscope.
Several Scripps researchers are already using BUMP to study the early stages of life in the giant kelp on the California coast. The technology may check any small marine life that photosynthesis is used and opens new windows to the marine ecosystem health.
As reefs face increasing pressures from climate change, having tools that can diagnose problems in coral natural habitats (in their natural habitats), is crucial for global conservation efforts.
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