Virus causes coral bleaching
24th April 2007
A virus that kills algae on coral reefs may be causing
widespread bleaching, according to breakthrough research performed
by scientists at Plymouth Marine Laboratory (PML) and the
University of Plymouth (UoP).
The virus, which kills tiny symbiotic algae essential for the
survival of corals, could explain the bleaching. This bleaching is
now reported in over 50 countries, across three major oceans and
shows that viruses play an important role in coral reef
dynamics.
Coral bleaching, usually triggered by a rise in seawater
temperature, can lead to mass mortality of corals and a consequent
reduction in the biodiversity of coral reefs. Mass bleaching events
in 1998 and 2002 led to destruction of up to 90% of corals in some
areas of the Great Barrier Reef and Indian Ocean and climate change
is widely believed to be responsible for the increased frequency
and distribution of bleaching. Until this significant discovery the
underlying cause and the mechanisms involved were largely
unknown.
Jayme Lohr, the lead author and a PhD student at PML said: “This
is a very exciting breakthrough that could explain coral bleaching.
I have shown that the symbiotic algae contain a latent virus - it
is only when they are stressed by temperature or UV light that the
virus multiplies.”
Dr Willie Wilson, Jayme’s supervisor from PML, commented that:
“The virus is latent in the algae. It is only when the coral is
stressed by temperature or UV light that it starts to infect the
symbiotic algae. It provides a plausible explanation for some of
the rapid bleaching we see in coral reefs.”
Dr Colin Munn, who was also part of the research at the UoP,
explained: “It could be compared to the situation of herpes in
humans, where stress can trigger cold sores because a latent virus
starts to multiply. This is another significant piece of evidence
as to why this bleaching occurs as it would appear that climate
change alone is not responsible for the destruction of coral
reefs.”