HALIFAX -- The COVID-19 pandemic may not be limited to land mammals, according to new research.

A new study from scientists at Halifax’s Dalhousie University predicts that certain species of whales, dolphins, seals and other endangered marine mammals could be highly susceptible to infection from COVID-19.

The scientists say there have been no documented cases of COVID-19 in marine mammals to date, but both dolphins and beluga whales have been infected with related coronaviruses in the past.

“Many of these species are threatened or critically endangered,” says Graham Dellaire, director of research in the Department of Pathology at Dalhousie. “In the past, these animals have been infected by related coronaviruses that have caused both mild disease as well as life-threatening liver and lung damage.”

The team predicts that the majority of whale, dolphin and porpoise species -- 18 out of 21 -- have the same, or higher, susceptibility to the virus as humans, while eight out of nine seal species are also predicted to be highly susceptible to SARS-CoV-2.

There is also the concern that, because marine mammals are social, once one animal is infected it could threaten the entire population.

The scientists say the virus could be spread to the animals through improperly-treated human sewage and wastewater.

“Our major concern is in developing nations, where there is already a disparity in public health and the wastewater treatment infrastructure required to handle the COVID-19 crisis,” says Saby Mathavarajah, a Dalhousie pre-doctoral fellow who co-authored the report. “Monitoring susceptible species in these high-risk areas around the world will be pertinent for protecting wildlife during and post-pandemic.”

Studies have shown that SARS-CoV-2 is excreted in feces and can survive in water for up to 25 days, raising the possibility that wastewater could spread COVID-19. 

The study points to examples of the virus being detected in untreated sewage in Spain, Italy and France.

The researchers say they hope their findings can help shape policy decisions regarding wastewater management around the world and protect at-risk marine mammal species that may be exposed to COVID-19. 

The study was published Monday in the journal Science of the Total Environment.