Lancaster (UK): According to recently conducted research at Lancaster University, large-scale coral bleaching episodes make it much harder for a bunch of reef fish species to identify their rivals.
Researchers studying reefs in five Indo-Pacific locations discovered that after severe coral loss caused by bleaching, butterflyfish individuals' ability to recognise rival species and act appropriately was hampered. They are now making worse decisions, making it more difficult to avoid picking pointless battles and wasting valuable, finite energy. The researchers behind the study believe that these changes could have an impact on species survival as global warming increases the likelihood of coral loss.
The researchers behind the study believe that these changes could have an impact on species survival as global warming increases the likelihood of coral loss.
"By recognising a competitor, individual fish can make decisions about whether to escalate, or retreat from, a contest - conserving valuable energy and avoiding injuries," said Dr Sally Keith, Senior Lecturer in Marine Biology at Lancaster University and lead author of the study.
These ground rules evolved for a specific playing field, but that field is changing. Repeated disturbances, such as bleaching events, change the abundance and identity of corals, which serve as a food source for butterflyfish. It's unclear whether these fish can update their rule book quickly enough to rebalance their decisions."
The researchers took more than 3,700 observations of 38 species of butterflyfish on reefs before and after coral bleaching event, and compared their behaviours.
After coral mortality caused by the bleaching event, signalling between fish of different species was less common, with encounters escalating to chases in more than 90% of cases - up from 72% before the event. Researchers also found the distance of these chases increased following bleaching, with fish expending more energy chasing away potential competitors than they would have done previously. The researchers believe the environmental disturbances are affecting fish recognition and responses because the bleaching events, in which many coral die, are forcing fish species to change and diversify their diets and territories. Therefore, these large-scale environmental changes are disrupting long-established and co-evolved relationships that allow multiple fish species to coexist.
Dr Keith said: "By looking at how behaviour responds to real-life changes in the environment, and by seeing that those changes are the same regardless of location, we can start to predict how ecological communities might change into the future. These relatively small miscalculations in where to best invest energy could ultimately push them over the edge."
The findings are outlined in the paper 'Rapid resource depletion on coral reefs disrupts competitor recognition processes among butterfly species', which has been published by the journal Proceedings of the Royal Society B.
The paper's authors are Dr Sally Keith, Dr Lisa Bostrom-Einarsson, Dr Ian Hartley of Lancaster University, Dr Jean-Paul Hobbs or the University of Queensland, and Prof Nathan Sanders of the University of Michigan. —ANI