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<DIV class=article-heading>Cold weather, Deepwater Horizon and an influx of cold
fresh water combined to cause record cetacean mortality.</DIV>
<DIV class=article-heading><FONT size=4>Perfect storm hit Gulf of Mexico
dolphins</FONT></DIV></HGROUP>
<DIV><SPAN class=vcard><A class=fn
href="http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724#auth-1">Melissa
Gaskill</A></SPAN></DIV>
<DIV class=pubdate-and-corrections><TIME datetime="2012-07-19" pubdate>Nature
News Alert, 19 July 2012</DIV>
<DIV class=pubdate-and-corrections><A
href="http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724">http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724</A></DIV>
<DIV class=pubdate-and-corrections> </DIV>
<DIV class=pubdate-and-corrections>
<DIV class=article-tools>Bottlenose dolphins in the northern Gulf of Mexico were
hit by a triple whammy of events, leading to an unusually high death rate in
early 2011, a paper published in <I>PLoS ONE</I> suggests<SUP><A id=ref-link-1
class=ref-link
title="Carmichael, R. H., Graham, W. M., Aven, A., Worthy, G. & Howden, S. PLoS ONE 10.1371/journal.pone.0041155 (2012)."
href="http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724#b1">1</A></SUP>.</DIV>
<P>Between January and April 2011, 186 bottlenose dolphins (<I>Tursiops
truncatus</I>) washed ashore in the northern Gulf of Mexico. Of these, 86 were
near-term or newborn, nearly double the historical average. Dolphin deaths are
being monitored by an ongoing Unusual Mortality Event (UME) survey, which began
in response to high numbers of adult dolphins dying during a period of sustained
cold weather in early 2010.</TIME></P></DIV></HEADER><SECTION>
<DIV class=section>
<DIV class="content no-heading cleared main-content">
<DIV style="WIDTH: 302px" class="img img-right">
<DIV
style="PADDING-BOTTOM: 1px; PADDING-LEFT: 1px; PADDING-RIGHT: 1px; PADDING-TOP: 1px"
class=img-content><FONT size=1><IMG alt=""
src="http://www.nature.com/polopoly_fs/7.5383.1342691393!/image/1.11011_42-25804018.jpg_gen/derivatives/landscape_300/1.11011_42-25804018.jpg">
</FONT></DIV>
<DIV
style="PADDING-BOTTOM: 1px; PADDING-LEFT: 1px; PADDING-RIGHT: 1px; PADDING-TOP: 1px"
class=caption><FONT size=1>Dolphins in the Gulf of Mexico have been weakened by
the oil spill and some unusually cold winters.</FONT></DIV>
<DIV
style="PADDING-BOTTOM: 1px; PADDING-LEFT: 1px; PADDING-RIGHT: 1px; PADDING-TOP: 1px"
class=credit><FONT size=1>Julie Dermansky/Corbis</FONT></DIV></DIV></DIV>
<DIV class=article-tools> </DIV>
<DIV class=article-tools>The <I>PLoS ONE </I>study suggests that the cold
weather was the first of three factors that weakened the dolphin population and
contributed to the high death rate. The second was the Deepwater Horizon oil
spill that followed in April. And the third was large volumes of cold fresh
water from melting snow entering Mobile Bay — an inlet in the Gulf of Mexico —
in 2011.</DIV>
<P class="content no-heading cleared main-content">Dolphins naturally encounter
seasonal temperature and freshwater fluctuations, says lead author Ruth
Carmichael, a marine scientist at Dauphin Island Sea Lab in Alabama, and neither
factor alone would necessarily cause strandings or death. But the cold
freshwater pulses may have been the proverbial straw that broke the camel’s
back, if the dolphin population was already weakened due to depleted food
resources caused by preceding events, such as oil in the northern Gulf food
chain<SUP><A id=ref-link-2 class=ref-link
title="Graham, W. M. et al. Environ. Res. Lett. 5, 045301 (2010)."
href="http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724#b2">2</A>,
<A id=ref-link-3 class=ref-link
title="Mitra, S. et al. Geophys. Res. Lett. 39, L01605 (2012)."
href="http://www.nature.com/news/perfect-storm-hit-gulf-of-mexico-dolphins-1.11011?WT.ec_id=NEWS-20120724#b3">3</A></SUP>,
or bacterial infection.</P>
<P class="content no-heading cleared main-content">Between June 2010 and January
2012, 12 of the 51 stranded dolphins tested for <I>Brucella</I> bacteria gave
positive results, according to Teri Rowles, coordinator of the National Oceanic
and Atmospheric Administration (NOAA) Marine Mammal Health and Stranding
Response Program in Silver Spring, Maryland. <I>Brucella</I>, which is present
in some healthy animals, can cause pneumonia, encephalitis, skin and bone
infections, and abortion in dolphins.</P></DIV>
<DIV class="content no-heading cleared main-content">“Studies show that dolphins
were in poor condition after Deepwater Horizon and some particularly cold
winters, and we know from theNOAA analysis that some had <I>Brucella</I>,” says
Carmichael. “For animals already stressed and in poor condition, this freight
train of cold fresh water could certainly have affected the timing of
mortality.” The cold water pulsed into Mobile Bay during the spring birthing
period, and the greatest number of newborn strandings were found close to this
area. Since dolphins have a gestation period of 12 months, some of the stranded
newborns would have been conceived during the oil spill, which could have
affected their ability to survive.</DIV>
<DIV class=section>
<P class="content no-heading cleared main-content">“It’s a common fact that
animals in good shape nutritionally are much more able to withstand change and
stress,” says marine biologist Moby Solangi, executive director of the Institute
for Marine Mammal Studies in Gulfport, Mississippi. “With multiple environmental
challenges, we may not be able to say it was one thing or another. We do know
that dolphins in the northern Gulf have been subjected to a number of
environmental challenges in the past few years, and we do know that each one of
those challenges will have affected their ability to deal with the others.”</P>
<P class="content no-heading cleared main-content">As is often the case with
strandings, few of the dolphins were recovered in good enough condition to
determine the cause of death, Rowles says. Nor do scientists have full data on
the causes of death from those that have been analyzed. The UME survey is still
ongoing, and final data and analysis are typically not available until 18 months
after an event.</P>
<P class="content no-heading cleared main-content">Carmichael hopes that the
study will encourage scientists to consider the physical and chemical
environments in which events such as strandings happen, as these could affect
the way species respond to stresses. </P>
<P class="content no-heading cleared main-content">“It’s important to understand
links between events that are human related and can potentially be managed, and
those that just happen and that we may or may not be able to manage,” she
says.</P>
<DL class=citation>
<DT><A href="javascript:;" jQuery16407126570012800896="8"><STRONG><FONT
color=#000000>References</FONT></STRONG></A><SPAN class="vcard author"><SPAN
class=fn></SPAN></SPAN></DT>
<DT><SPAN class="vcard author"><SPAN class=fn></SPAN></SPAN> </DT>
<DT><SPAN class="vcard author"><SPAN class=fn>Carmichael, R. H.</SPAN></SPAN>,
<SPAN class="vcard author"><SPAN class=fn>Graham, W. M.</SPAN></SPAN>, <SPAN
class="vcard author"><SPAN class=fn>Aven, A.</SPAN></SPAN>, <SPAN
class="vcard author"><SPAN class=fn>Worthy, G.</SPAN></SPAN> & <SPAN
class="vcard author"><SPAN class=fn>Howden, S.</SPAN></SPAN> <SPAN
class=source-title>PLoS ONE 10.1371/journal.pone.</SPAN>0041155 (<SPAN
class=year>2012</SPAN>).</DT>
<DT><A
href="http://dx.doi.org/10.1371/journal.pone.0041155">Article</A> <A
class="context-link show" href="javascript:;">Show context</A><SPAN
class="vcard author"><SPAN class=fn></SPAN></SPAN></DT>
<DT><SPAN class="vcard author"><SPAN class=fn>Graham, W. M.</SPAN></SPAN>
<I>et al</I>. <SPAN class=source-title>Environ. Res. Lett.</SPAN> <SPAN
class=volume>5</SPAN>, 045301 (<SPAN class=year>2010</SPAN>).</DT>
<DT><A
href="http://dx.doi.org/10.1088/1748-9326/5/4/045301">Article</A> <A
href="http://chemport.cas.org/cgi-bin/sdcgi?APP=ftslink&action=reflink&origin=npg&version=1.0&coi=1:CAS:528:DC%2BC3cXhsVeqt7nJ&pissn=0028-0836&md5=6c8e80ae86399800ea912d1dfa9a3b75">ChemPort</A> <A
class="context-link show" href="javascript:;">Show context</A><SPAN
class="vcard author"><SPAN class=fn></SPAN></SPAN></DT>
<DT><SPAN class="vcard author"><SPAN class=fn>Mitra, S.</SPAN></SPAN> <I>et
al</I>. <SPAN class=source-title>Geophys. Res. Lett.</SPAN> <SPAN
class=volume>39</SPAN>, L01605 (<SPAN class=year>2012</SPAN>).</DT>
<DT><A href="http://dx.doi.org/10.1029/2011GL049505">Article</A> <A
class="context-link show" href="javascript:;">Show
context</A> </DT></DL></DIV></FONT><BR>
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