Download Hurricanes article

What
happens to ecosystems during major
storms?
WIND DISLOCATION
Powerful winds from hurricanes and tropical storms can blow birds off
course and push them hundreds of miles away from their home habitat. Last
year, a North Carolina brown pelican was found on the roof of a night club
in Halifax, Nova Scotia. The news often covers the
appearance of rare species after a major storm. Sometimes younger or
weaker birds become separated from their flock and many can take weeks
to return home — if they can find the right foods on their way back.
During major storms, sea birds and waterfowl are most exposed.
Birds are not the only species affected by the winds. Sea mammals can be
harmed too. While many can seek shelter in open water or in near shore
shelter, some dolphins and manatees have actually been blown ashore
during major storms.
TREE LOSS
In 1992, Hurricane Andrew brought incredible wind velocities onshore and
knocked down as many as 80% of the trees on several coastal Louisiana
basins, such as the Atchafalaya. Tree loss during Hurricane Katrina in
2005 caused even more extensive damage. Loss of coastal forests and
trees can be devastating to dependent wildlife species and migratory
species. Many wildlife species have very specialized niches in these forests
that are lost to heavy winds. Specific foods can be taken away too. High
winds will often strip fruits, seeds and berries from bushes and trees.
DUNE AND BEACH LOSS
Storm surges, wave action, and winds can cause beach and dune erosion
and that can have severe effects of species. Many wildlife species live in
ecological niches in the sandy areas and dunes of coastal barrier island. In
some cases the storm can cause a beach area to disappear. Sea turtle
nests, for example, can be washed out, or a water surge, called a “wash
over” can submerge these nests or tern and plover nesting areas.
SALTWATER INTRUSION
The sustained and powerful winds of a hurricane will
cause salty ocean water to pile up and surge onshore. These “storm
surges” can be huge. Hurricane Irene’s surges brought water levels that
were as much as 8 feet above normal high tide and Katrina pushed a 30
foot high surge onto the coast. In addition to the physical damage this
causes, the salt contained in sea water dramatically shifts the delicate
balance of freshwater and brackish wetland areas. Creatures and
vegetation that are less salt-tolerant will be harmed and many will not
survive this influx of sea water. Marsh grasses, crabs, minnows, fish
hatchlings, insects, and myriad creatures of freshwater and estuarine
environments are harmed. The salt water intrusion in these some of these
areas does not drain off very quickly and can even harm or kill off
bottomland forests and other coastal trees.
FRESHWATER FLOODING
The reverse is true too. The heavy rains generated by hurricanes will dump
water in coastal area river basins (called watersheds) and this, in turn, can
send vast amounts of fresh water surging downstream into coastal bays and
estuaries. This upsets the delicate and finely tuned freshwater/salt water
balance that can be so vital for the health of these ecosystems. In
1972, Hurricane Agnes sent such massive amounts of freshwater into the
Chesapeake Bay. The normally brackish (partially salty) water was fresh
for months placing great pressure on the species living there.
TURBIDITY
Heavy rainfall in upstream areas also washes soil, sediment and many
pollutants into coastal and marine environments. After Hurricane Agnes, the
turbidly or cloudiness of the water became so severe in the Chesapeake
Bay that the native grasses growing on the bottom of Bay died off in huge
quantities. These grasses provided critical habitat from crabs, fish
spawning and many species. It took the Bay years to recover. Similarly,
sediment can wash over coral reefs, blocking needed sunlight and even
causing algae to grow.
MARINE AND AQUATIC SPECIES
When hurricane Andrew hit Louisiana more than 9
million fish were killed offshore. Similarly an assessment of the effect of
that same storm on the Everglades Basin in Florida showed that 182 million
fish were killed. Hurricane Katrina also had a huge effect on dolphin
species. Many dolphins were hurt during the storm and were rescued and
underwent rehabilitation.