Hurricane Effects on Marine Mammals

From: Dagmar Fertl (dfertl@geo-marine.com)
Date: Mon Oct 18 2004 - 18:04:46 EDT

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    Q: My daughter is in fourth grade and doing an independent learning project
    for her class on hurricanes and their impact. She has a couple questions:
            1. How are marine mammals affected by hurricanes?
            2. How do marine mammals breath during hurricanes?
    Thank you for any help you can provide.
    ********************************************************
    A: Dear daughter of Kathleen Center,

    No one really knows how marine mammals are affected by hurricanes. The
    impact of hurricanes on marine mammals would depend on what type of marine
    mammal you are talking about - large whale, small dolphin or porpoise, seal,
    sea lion, and even the manatee. People have observed dolphins surfing on the
    really large waves that are associated with hurricanes (much like people
    sometimes do). I think that there are some folks who have tried to correlate
    stranding events with intense storm activities, but this is difficult to do,
    since not all the bodies would be expected to wash up on beaches, and
    instead could be pushed out to sea. I would guess that there is a
    possibility that a hurricane could forcefully move a marine mammal from one
    location to another that it is not as familiar with. I would imagine that
    young marine mammals (and sick/dying individuals) would have the hardest
    time with a storm; I've seen sperm whale calves being tossed around on big
    waves while all the adults swam just below the water's surface. There is
    also the possibility that with changing oceanographic conditions, perhaps
    the animals can also sense the impending weather conditions and perhaps move
    into areas that do not experience as much turbulence.

    Marine mammals are really good at breathing during rough water conditions;
    the nostrils close very quickly, and their is a rapid exhalation and
    inhalation at the same time which means that there is probably not a big
    chance of water getting into the lungs (compared to humans who are miserable
    in such turbulent water conditions).

    The following is an excerpt from the Sirenia Project (U.S. Geological
    Survey) web page; these folks study manatees.

    "The effect of the 2004 hurricanes on manatee survival rates remains to be
    seen. Monitoring and research are in progress. On the one hand, manatees
    inhabit the tropical waters of Florida and the Caribbean and one would
    expect they would have evolved behaviors to cope with extreme violent
    storms. On the other hand, Florida manatees are endangered and living at
    the northern limit of their range. They often experience chronic and
    debilitating effects from injuries from watercraft collisions, cold weather,
    and degraded habitats, which may make them more vulnerable to extreme storm
    forces. Vulnerability of individual manatees also will depend on the
    destructiveness of the storm. Storms vary in intensity, size, the speed of
    forward motion, storm surge, and energy of waves and winds. Physical
    features of the coastline, which offer some measure of protection to
    manatees, also vary throughout Florida. The southwest Gulf coast and
    eastern Atlantic coast with extensive barrier islands may provide better
    protection than the sloping marsh coast lines of northwest Florida. Other
    factors can affect storm risk to manatee populations as well, such as the
    density of manatees in the strike area, the number of storms within a
    season, or coincidence with other mortality risks."

    Let me know if you have any additional questions.

    Regards,
    Dagmar Fertl



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