Climate change making
oceans unhealthier
Warmer temperatures are
creating conditions conducive to population booms in other microorganisms that
carry and transmit diseases to humans and other species.
The trend is evident in the oceans as well as on land, raising
the risks of disease outbreaks and epidemics around the world, including in
places where they have not been risks historically.
Microscopic in size,
marine prokaryotes are nonetheless the largest living biomass in the world ocean.
While analysis of long-term ecological and paleontological data
indicates that climate change has an impact on populations of eukaryotes,
microorganisms that have a cell nucleus and well defined cell walls, little is
known about the effect of rising sea surface temperatures on prokaryotes, the
report authors point out in the research abstract.
Having evolved earlier in evolutionary history, prokaryotes, which lack cell nucleii or well defined cell walls, are considered evolutionary precursors to eukaryotes.
In a landmark research paper,
an international team of researchers for the first time report that rising sea
surface temperatures are strongly associated with booms in populations and
infections caused by Vibrio cholerae and other members of this genus of
bacteria.
Ocean temperatures
and pathogen populations
Lead author Rita R. Colwell has devoted her career as a microbiologist
to studying Vibrio cholerae and
other members of the genus. A member of the faculty at the University of
Maryland Pathogen Research Institute and Center of Bioinformatics and
Computational Biology, Colwell has been conducting groundbreaking scientific
research on Vibrio bacteria for decades.
Commonly found in ocean
waters, Vibrio do better in warm, coastal waters. Vibrio cholerae carries
and transmits cholera, while other species carry other diseases and can cause
food poisoning in humans.
Investigating whether or
not links exist between Vibrio population booms, infections and ocean
temperature, the researchers analyzed seawater samples dating back to 1958
collected in the North Atlantic Ocean as part of the Sir Alister Hardy Foundation
for Ocean Science’s (SAHFOS) Continuous Plankton Recorder
survey over the past half century.
Colwell and fellow researchers from SAHFOS, the University of
Genoa, Italy, the U.K.’s Plymouth University and others concluded that rising
sea surface temperatures coincide and show strong associations with surges in
the number of Vibrio bacteria and infections.
The resulting increase in
food and health risks are higher in northern waters where ocean water
temperatures are rising faster than global averages. That includes cities,
towns, and communities situated around the Baltic Sea in northern Europe, where
there has been little risk of infections until now.
“They are now reporting more Vibrio in their waters,” Colwell was quoted in a New Scientist report. “Not because it wasn’t there before, but because the water was too cold [for them to bloom]. Vibrio responds very quickly to temperature.”
The U.S. Centers for
Disease Control and Prevention (CDC) has gathered evidence that the same thing,
including outbreaks, is taking place in Alaskan coastal waters, according to
the news report.
Colwell notes that
scientists could develop a computer model to help predict the occurrence of
Vibrio outbreaks by incorporating satellite data on sea surface temperatures
into the research team’s model.
Another microbiologist points to other factors, such as nutrient
levels, salinity and population counts of other phytoplankton and zooplankton,
that require consideration in order for any such new model to be effective.