Little was known about what factors caused the spread of the devastating Morbillivirus. Our findings suggest that synchronised breathing is one of the factors responsible for the spread within bottlenose dolphin populations. Their important social habits are contributing to the spread of the disease.
Our findings could also help us to protect vulnerable populations, for example one thing we know is that dolphins increase synchronised breathing when in the presence of boats, so reducing this stress when we know that the infection is present could help.
A 'sentinel' species
Bottlenose dolphins are a ‘sentinel’ species, that is, how they are faring acts as a signal for the health or not, of the whole ecosystem. Dolphins are under increased pressures from human introduced changes such as warming oceans and the introduction and spread of new diseases carried on plastics and other materials in the ocean. Incidences of Morbillivirus has led to mass deaths in populations around the globe, including more than 1,650 dolphins found along the US Atlantic coast over a two year period, populations were estimated to have diminished by more than 40%.
Modelling behaviour based on observations and social mixing of two dolphin populations (the Potomac-Chesapeake Bay region of the US, where the dolphins are seasonal and migratory and share the larger area with other dolphin groups, and Shark Bay, Australia, where the dolphins are resident and do not migrate). The findings, borne out by stranded dolphin rates, showed that the most at-risk were the juvenile and adult male members of both communities.
Research also suggested that infection rate was higher if a juvenile introduced the infection into the group. This is probably because juveniles synchronise their breathing most often- more with their own age group- to create those bonds useful in later life. The spread of infection within the group is slightly less when introduced by adults. Least at risk of sharing were adult females and calves.
This research has important implications to predict which individuals in a group are most at risk during epidemic outbreaks, especially useful in vulnerable species such Guiana dolphins that are also at threat from morbillivirus.
The paper, Breathing in sync: how a social behavior structures respiratory epidemic risk in bottlenose dolphins is published in ****.
Synchronized breathing
