Every year, millions of tourists flock to coral reefs to marvel at the bright colors, sculptural forms, and stunning diversity of organisms that live there. According to a study published today in PeerJ, the aesthetic appeal of these natural scenes is directly related to their ecological health.

In the study, a cross-disciplinary team of mathematicians, biologists, and art historians collaborated to develop a computer program that measures the beauty of coral reefs. People have long sought universal, objective criteria to explain why some things are beautiful and others are ugly. But applying such assessments to ecosystems is a rather new idea.

The researchers combed through previous studies of the aesthetics of paintings and photographs to identify a suite of 109 visual features contributing to beauty such as color, texture, regularity of shapes, and the relative sizes and positions of objects in the frame.

Then, they developed a computer program to scan photographs of coral reefs and evaluate these 109 features to come up with an aesthetic score for each image. They used this program to analyze roughly 2,100 randomly chosen photos of 9 different coral reefs in the Central Pacific and the Caribbean.

They compared the resulting aesthetic scores with data on the ecological status of each reef from the National Center for Ecological Analysis and Synthesis. The ecological data reflect the impacts of factors such as various types of fishing, pollution, invasive species, nutrient inputs, ocean acidification, and commercial activity in the area.

The reefs studied have varying levels of human disturbance, and their ecological scores are strikingly similar to their aesthetic ones, the researchers found.

“Our results suggest that our perception of aesthetics is well aligned with healthy, thriving ecosystems,” says Andreas Haas, a postdoctoral researcher at San Diego State University and the study’s lead author.

Since tourists like to visit beautiful reefs, the findings also mean that economic interests dovetail with ecological values.

The researchers acknowledge that some people might object to the idea that the wonder of coral reefs can be summed up tidily in a single number. But they say that their method could provide a tool for quick, inexpensive assessments of reef health, perhaps by analyzing geotagged snapshots of reefs uploaded to social media or Flickr.

By mining historical databases of reef photos, scientists could also reconstruct the baseline conditions and ecological trajectories of reefs, a goal that until now has proved elusive. As an example of this approach, the researchers analyzed photographs of the Carysfort reef in the Caribbean, taken over a span of 40 years between 1975 and 2014. The aesthetic value of these images has declined over time, reflecting the reef’s ecological degradation.

Aside from these practical applications, at a philosophical level there’s something reassuring about this harmony between aesthetics and ecology. Our human eyes intuitively pick up on and appreciate the appearance of healthy ecosystems. Though it may often seem otherwise, in some deep sense our preferences are in line with the planet’s. – Sarah DeWeerdt | November 10, 2015

Source: Haas A.F. et al. “Can we measure beauty? Computational evaluation of coral reef aesthetics.” PeerJ DOI: 10.7717/peerj.1390

Header image: Kingman reef, a healthy and beautiful reef in the Central Pacific. Credit: Jennifer E. Smith.