Featured Research

from universities, journals, and other organizations

How A Little Bit Of Cold Can Kill A Big Manatee, And What It Might Mean For The Species

Date:
August 5, 2003
Source:
Harbor Branch Oceanographic Institution
Summary:
researchers from Harbor Branch Oceanographic and other institutions have discovered for the first time the causes of "cold stress syndrome" in Florida manatees.

While Florida may be warm enough even in the coldest winter months to attract sun-seeking tourists, when the thermometer does dip, it can prove deadly for endangered Florida manatees. Just why these plus-size animals would succumb in water cooled to just 68 degrees Fahrenheit has remained a mystery. Now, researchers from HARBOR BRANCH Oceanographic and other institutions have discovered for the first time the causes of this "cold stress syndrome" in Florida manatees.

Related Articles


The work, described in the current edition of the journal Aquatic Mammals, could significantly improve treatment for cold-stressed manatees. It could also help decide an ongoing controversial debate regarding the manatee's state endangered species status and aid in the development of plans to minimize the effects of power plant shutdowns on the manatees who have grown to depend on the warm water they release.

During cold spells, sick, sometimes emaciated manatees at times wash up along the coast of Florida afflicted with a puzzling combination of skin sores and infections that clinicians historically treated as separate ailments. In the new paper, lead author Dr. Gregory Bossart, Director of the Division of Marine Mammal Research and Conservation at HARBOR BRANCH, and colleagues, explain how long-term exposure to cold water can be responsible for this multi-faceted condition.

The team found that the cold stress syndrome stems from a cascade of physiological events and diseases initiated by cold water and manatees' limited ability to adapt to low temperature extremes. The study suggests that the animal's metabolism slows, leading to digestion problems, decreased appetite, and associated weight loss. These events, along with the possible release of certain hormones, weaken manatees' immune systems, making them vulnerable to environmental toxins as well as a variety of diseases, including pneumonia, intestinal infections, and perhaps even a manatee virus similar to one that causes human cervical cancer. This progression and its results are surprising given that manatees are known for their outstanding immune systems.

"This syndrome opens up the manatees to the long-term pathologic effects that can predispose the population to many other problems," says Dr. Bossart, who has studied both clinical marine mammal medicine and pathology and human pathology.

In the study, investigators performed necropsies--the animal form of an autopsy--on 12 manatees thought to have died from cold stress syndrome during the exceptionally harsh winter months between November 2000 and April 2001. Researchers found that each manatee showed signs of starvation, including a thinned blubber layer and an overall sunken appearance. In addition, at least 75 percent of the animals had an abnormally low number of disease-fighting white blood cells called lymphocytes, various skin and intestinal lesions, heart degeneration and pneumonia.

Knowledge that the cold can cause even more devastating and extensive effects than previously realized could help managers decide how to deal with the closing and deregulation of aging and under-used power plants. More than 500 manatees have been spotted basking in the heated water near a single power plant on one winter day, according to Winifred Perkins, manager of environmental relations at the Florida Power and Light Company. Historically, manatees migrated only to relatively warm freshwater springs or far enough south to avoid colder water, but now reports indicate that over 60% of the population has grown accustomed to instead spending winters near balmy discharges from industrial plants. As outdated power plants are shut down these electric blankets are removed and some manatees are not able to find substitutes in time.

Manatees already die each year from the cold, and the fear is that future power plant closings and replacement with more efficient facilities that don't churn out heated water could increase the number of deaths. "Some of these power plants provide warm water for up to hundreds of manatees and when you shut one down you could be talking about losing a substantial portion of the remaining population," says Dr. Bossart. In the past, manatee deaths are thought to have been caused by shutdowns of a power plant in Jacksonville and a paper mill in Fernandina Beach.

Florida officials are considering various means to address the problems surrounding manatee dependence on industrial outfalls. Potential solutions range from strict management of power plant closings to the creation of a network of artificial warm water refuges to replace decommissioned facilities. In the meantime, this new understanding of cold stress should improve efforts to treat and rehabilitate rescued manatees with the syndrome. Instead of dealing with each symptom in the sick manatees, and potentially releasing animals in need of further care, Dr. Bossart says now rehabilitators can deal with the overall syndrome, which is physically far-reaching and can last for months.

The study comes at a critical time when the Florida Fish and Wildlife Conservation Commission is discussing whether to down-list the Florida manatee classification with the state government from endangered to threatened. Although the downgrade would not impact current manatee protections such as slow speed boating zones and manatee sanctuaries, some environmentalists fear the change could give the public the impression that the manatee population is safely stabilized, eventually leading to loosened protection measures. Proponents of down-listing point to an increase in the population from about 1,500 in 1991 to the current rough estimate of 3,000.

However, the inevitable shutdown of power plants should be taken into account in the debate over the manatee's endangered status, according to the study authors, because the closings could dramatically increase mortality in a population that already suffers from various threats such as boat collisions and red tide poisoning. Furthermore, Dr. Bossart says the cold stress syndrome could cause future reproductive and health problems for those manatees that survive the initial cold exposure but are not brought into rehabilitation facilities. The state wildlife commission is expected to decide on the status issue this November.


Story Source:

The above story is based on materials provided by Harbor Branch Oceanographic Institution. Note: Materials may be edited for content and length.


Cite This Page:

Harbor Branch Oceanographic Institution. "How A Little Bit Of Cold Can Kill A Big Manatee, And What It Might Mean For The Species." ScienceDaily. ScienceDaily, 5 August 2003. <www.sciencedaily.com/releases/2003/08/030805071937.htm>.
Harbor Branch Oceanographic Institution. (2003, August 5). How A Little Bit Of Cold Can Kill A Big Manatee, And What It Might Mean For The Species. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2003/08/030805071937.htm
Harbor Branch Oceanographic Institution. "How A Little Bit Of Cold Can Kill A Big Manatee, And What It Might Mean For The Species." ScienceDaily. www.sciencedaily.com/releases/2003/08/030805071937.htm (accessed October 24, 2014).

Share This



More Plants & Animals News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins