Suggests
earlier springs and hotter summers foster increase in shell infections
By
David Malmquist
This shows the Millstone Nuclear Power Plant's continuous discharge of heated reactor coolant water directly into Long Island Sound at the rate of a billion gallons a day. |
An
earlier spring may sound nice, unless you’re a New England lobster.
New
findings reveal that as coastal waters in the northeastern U.S. continue to
warm—bottom temperatures in Long Island Sound have increased 0.7°F per decade
over the last 40 years—resident lobsters are becoming increasingly susceptible
to epizootic shell disease, a condition that has depleted the southern New
England population and severely impacted the
local lobster fishery.
The
findings stem from a collaboration between the Virginia Institute of Marine
Science and Dominion Energy’s Millstone Environmental Laboratory. The lab
maintains a unique, long-term record of lobster abundance and health in waters
near Dominion
Energy’s Millstone Power Station in Waterford, Connecticut.
The
research, funded by NOAA’s
Saltonstall-Kennedy Program and led by then postdoctoral associate
Maya Groner of VIMS, suggests that the increased prevalence of shell disease in
area lobsters stems from two factors—an earlier onset of warmth-induced spring
molting, and hotter summers.
EDITOR'S NOTE: this article makes no mention of the contribution made by one of the sponsor's of this research: the Millstone nuclear power plant just outside of New London. This plant discharges 1 BILLION gallons of heated reactor coolant water directly into Long Island Sound EVERY DAY. It's surprising the researchers didn't find cooked lobsters floating on top of the water.
While I don't doubt the impact of climate change and the warmer waters it brings to the lobster population, I think the research would be more credible if the impact of Millstone was included in the impact calculations.
Millstone, like many environmentally-destructive businesses, engages in "green-washing," funding nice programs and projects to distract from their polluting practices. For example, Millstone funds programs at the Mystic Aquarium. - Will Collette
“We used the lab’s mark-recapture dataset, now
going on 37 years, to investigate relationships between temperature, molting
phenology, and ESD [epizootic shell disease],” says Groner, currently a
research ecologist at the Prince William Sound Science Center in Alaska.
Phenology refers to the study of how plant and animal life is affected by
seasonal changes.
“Our
work shows that temperature
increases due to climate change have caused a phenological
shift in the molting patterns of lobsters, making them more susceptible to the
disease,” says Groner.
The team’s results pertain mostly to male and juvenile
lobsters, as females have a different molting pattern, typically molting every
two years in the region.
As
the name implies, epizootic shell
disease occurs when the bacterial populations that normally
inhabit the surface of a lobster’s carapace change and begin consuming the
cuticle, causing it to erode.
An earlier study by Hoenig, Groner,
Shields, and colleagues using the same Millstone dataset
showed that mortality due to epizootic shell disease can be as high as 70% in
diseased lobsters. “This type of dataset is extremely rare,” says Shields, “and
allowed us to determine that diseased lobsters have a much lower survival rate
than healthy ones.”
The
current study shows that when a diseased lobster molts, discarding and
replacing its shell in order to grow, it essentially sets the disease clock
back to zero. Thus when spring warmth—a seasonal cue for lobster
molting—arrives earlier in the year, lobsters also molt earlier in the year,
giving the disease a jumpstart on its progression into and through the summer
months.
The
researchers found that for every 1.8°F increase in the average May bottom-water
temperature, lobsters molted about 6 days earlier in spring.
In turn, during
early-molting years—defined as those in which at least 5% of lobsters were
observed to molt in May—disease prevalence in September doubled from about 15%
to more than 30% relative to later-molting years.
During the latter years, only
1% of lobsters were observed to molt in May, and the remainder in June or
subsequent months.
The
research team discovered that disease prevalence in October correlates even
more strongly with summer heat. In years with 90 days exceeding 68°F they
detected epizootic shell disease in around 65% of lobsters, but found only 40%
were diseased when the summer had 50 or fewer days above that threshold.
In
years with both warm springs and warm summers, disease could exceed 80%.
Indeed, 2012, one of the warmest years in recent history, had the highest
disease prevalence of all years for both juveniles and adult males.
Broader
impacts
In
addition to the observed impacts in Long Island Sound, the researchers say
their findings portend troubling possibilities for lobster populations
elsewhere in the rapidly warming
waters of New England.
“Recent increases
in the prevalence of ESD in the Gulf of Maine—home to the
largest lobster stock in the U.S.—have raised concerns that the disease is
expanding northward,” says Shields. “If summer temperatures in the Gulf reach
levels conducive to ESD within the next few decades—as expected under ‘business
as usual’ climate projections—we’re concerned that it will lead to earlier
molting in the spring and less molting during the summer, when lobsters are
most susceptible to the disease.”
If
that’s the case, he says, “then disease may increase substantially.”