Science Daily –
Repeat coral bleaching caused by rising sea temperatures has resulted in lasting changes to fish communities, according to a new long-term study in the Seychelles.
Large predator fish such as snappers and very small fish such as damselfish dramatically reduced in number and were largely replaced by seaweed-loving fish like rabbitfish.
Publishing in the journal Global Change Biology, researchers show clear evidence that coral bleaching back in 1998 has led to changes in biodiversity and permanent shifts in the range of fish species coexisting on coral reefs, which still remain in place today.
While some of the coral reefs surveyed, bounced back and recovered following the bleaching event, other reefs shifted to fields of seaweeds.
Changes in fish communities were most apparent on these seaweed dominated reefs, but the ‘herbivore’ fish that feed on seaweeds became a dominant part of the community on all the reefs in the study.
Researchers believe these same changes are likely to be found in similarly damaged reefs around the world and could be described as the ‘new normal’ state for post bleached reefs.
The Lancaster University-led research tracked reef recovery in the Seychelles for 16 years, before another major coral-bleaching event impacted the reefs in 2016. Despite the length of time between these two major coral bleaching events, fish populations failed to recover to their pre-bleaching condition.