As we celebrate World Oceans Week, which began June 8, we can pause during this time of social, environmental and economic upheaval caused by a land-based viral pandemic and imagine what this might mean for the world’s largest bodies of water, and their marine wildlife.
That’s what a group of internationally recognized experts from the Broad Institute at Harvard and MIT, the University of California at Davis and locally based Narwhal Tusk Research in Sharon among others recently did by asking the question, “Can the SARS-CoV-2 virus bind to ACE2 receptors in other animals?”
Coronaviruses are not new, but this one certainly wrenched the collective world attention.
The discovery was startling. It turns out that all of the primate populations — including endangered lowland gorillas — share exactly the same binding sites as humans.
More surprisingly, toothed whales including the narwhal also share a majority of the binding sites, making them highly susceptible to the virus.
The story gets interesting since narwhals, like other toothed whales, are ill-equipped genetically to ward off viral infections.
So what’s the evolutionary advantage of their viral receptors? They are essential in regulating blood pressure needed for these deep-diving whales.
No one imagined a scenario where coronaviruses might infect toothed whales. Yet coronaviruses have already been found in beluga, bottlenose dolphins and harbor seals.
Viral pandemics can be real for marine mammal species, as in 1988 and 2002 when a harbor seal infection of the distemper virus killed more than 50,000 animals.
Most of the 200,000 types of normally existing ocean viruses have restricted hosts and pathways, but we are mixing these with untreated waste of a planet that now has 7.8 billion people.
An endangered ocean
To examine potential transmission of a coronavirus to a narwhal, we need to examine viral survival in the Arctic Ocean and the possible pathways for the virus to reach the narwhal.
The Arctic Ocean is changing in almost every capacity at two to three times the rate of the rest of the planet. Changes include loss of polar ice sheet cover, increased CO2 absorption, ocean acidification, alterations in the binding chemistry of calcium, and changes in the distribution of marine mammal populations.
It is the world’s least saline ocean, layered with the Atlantic underneath, and has multiple bracken water inlets used by migratory marine mammals. Glacial run-off and summer ice melt add to the freshwater system that can influence marine life and likewise viral survival.
Blackwater waste
So how exactly would a narwhal catch a virus? Wastewater contamination may be the most likely variable. The SARS virus can survive four days in fecal material and more than a week in wastewater. Two recent medRxiv papers cited detectable fragments of the SARS-CoV-2 virus in the wastewater systems of seven European cities weeks before the outbreak of COVID-19, and viral titers of Boston’s wastewater were correlated to outbreak.
Potential transmission in the Arctic can occur in multiple ways, with “blackwater” waste from increasing boat traffic, commercial and cruise lines and wastewater run-off and substandard waste treatment facilities.
Research findings might assume immediate destruction of such viruses in ocean water, but the Arctic Ocean has bracken water inlets and is overall less saline than other world’s oceans.
Plastics are now in the Arctic food web; are viruses and bacteria the next threat?
Dr. Martin Nweeia is a full-time general dentist in Sharon, co-curator of the Smithsonian exhibit on narwhals, and on the faculty at Harvard and Case Western Reserve Universities Schools of Dental Medicine. He was recently featured on a Wilson Center Ground Truth Briefing on the SARS-CoV-2 viral transmission to cetaceans.
