[MARMAM] New publication on winter habitat preferences for Florida manatees

Cynthia Taylor ctaylor at sea2shore.org
Mon Mar 25 21:06:19 PDT 2013

Dear colleagues,

We are pleased to announce that the following paper on Florida manatees is
now available at http://dx.plos.org/10.1371/journal.pone.0058978:

D. W. Laist, C. Taylor, and J. E. Reynolds, III. (2013) Winter habitat
preferences for Florida manatees and vulnerability to cold. PLoS ONE8(3):
e58978. doi:10.1371/journal.pone.0058978


To survive cold winter periods most, if not all, Florida manatees rely on
warm-water refuges in the southern two-thirds of the Florida peninsula. Most
refuges are either warm-water discharges from power plant and natural
springs, or passive thermal basins that temporarily trap relatively warm
water for a week or more. Strong fidelity to one or more refuges has created
four relatively discrete Florida manatee subpopulations. Using statewide
winter counts of manatees from 1999 to 2011, we provide the first attempt to
quantify the proportion of animals using the three principal refuge types
(power plants, springs, and passive thermal basins) statewide and for each
subpopulation. Statewide across all years, 48.5% of all manatees were
counted at power plant outfalls, 17.5% at natural springs, and 34.9 % at
passive thermal basins or sites with no known warm-water features. Atlantic
Coast and Southwest Florida subpopulations comprised 82.2% of all manatees
counted (45.6% and 36.6%, respectively) with each subpopulation relying
principally on power plants (66.6% and 47.4%, respectively). The upper St.
Johns River and Northwest Florida subpopulations comprised 17.8% of all
manatees counted with almost all animals relying entirely on springs (99.2%
and 88.6% of those subpopulations, respectively). A record high count of
5,076 manatees in January 2010 revealed minimum sizes for the four
subpopulations of: 230 manatees in the upper St. Johns River; 2,548 on the
Atlantic Coast; 645 in Northwest Florida; and 1,774 in Southwest Florida.
Based on a comparison of carcass recovery locations for 713 manatees killed
by cold stress between 1999 and 2011 and the distribution of known refuges,
it appears that springs offer manatees the best protection against cold
stress. Long-term survival of Florida manatees will require improved efforts
to enhance and protect manatee access to and use of warm-water springs as
power plant outfalls are shut down.

David W. Laist
Senior Policy and Program Analyst
Marine Mammal Commission
4340 East-West Highway, Rm. 700

Bethesda, MD 20814
main office: 301-504-0087
fax: 301-504-0099
e-mail: dlaist at mmc.gov


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