Colorful corals may be calling crucial algae back home

[Judi Lynn]

By Nick Lavars
May 21, 2020

https://assets.newatlas.com/dims4/default/d538b06/2147483647/strip/true/crop/2000x1333+0+0/resize/1200x800!/format/webp/quality/90/?url=http%3A%2F%2Fnewatlas-brightspot.s3.amazonaws.com%2Fbd%2F33%2F26ef89a5474e986a149a73a4c81a%2Fdepositphotos-44989073-l-2015.jpg

Scientists have unraveled the mystery behind a form of "colorful bleaching" in coral reefsshalamov/Depositphotos
VIEW 2 IMAGES

One of the ways coral reacts to abnormal sea temperatures is by expelling tiny algae that lives in its tissues, a process that drives the type of bleaching events that have devastated Australia’s Great Barrier Reef in recent years. But not all corals respond by turning ghostly white, with some instead becoming shimmering arrays of bright neon colors. The authors of a new study believe this is an attempt to lure the much-needed algae back home.

A lot of the coral species that make up structures like Australia’s Great Barrier Reef survive by way of a delicate symbiotic relationship with this algae, which shelter in their cells and provides them with energy via photosynthesis. When sea temperatures rise, it causes this relationship to break down, with the algae abandoning their homes to leave the coral white, withering and in danger of dying.

In what has been a mystery to scientists, however, some of these algae-free coral respond by exhibiting a variety of bright colors instead. To study this phenomenon, scientists at the University of Southampton conducted laboratory experiments at their coral aquarium facility, through which they found these corals produce a type of protective “sunscreen” layer that presents as these colorful displays.

This is a consequence of a business as usual approach on part of the corals, the team found. In the absence of the all-important algae to absorb light, it bounces around inside the coral tissue to give it its white appearance, But when these corals are able to continue some of their normal functions, this internal light instead boosts the production of colorful photoprotective pigments, which act a lure for the returning algae.

More:
https://newatlas.com/biology/bleached-corals-colorful-lure-algae/