8 Signs the Animal Kingdom Is Out of Whack
Jasmin Malik Chua
Special to LiveScience
LiveScience.com July 18, 2008
polar bear clinging to a melting iceberg may the poster child for
global warming, but rising temperatures, pollution and other human
activity are also affecting the animal kingdom in far subtler ways.
Like the proverbial canary in the coal mine, the natural world could be
giving us other signs that human intervention has knocked it way off
Some recent examples:
Earlier Migration: Several bird species are making their annual
northward jaunt slightly ahead of schedule in recent springs, as the
East Coast of the United States heats up, according to a study detailed
in the June issue of the journal Global Change Biology. The report
confirms similar studies dating back to 2006. Early birds may not sound
like a huge deal, but scientists warn that long-distance migrators who
start out in South America, and therefore lack cues about the timing of
spring in Northern Hemisphere destinations, will be less able to keep
pace with the changing climate. "Trees and shrubs are further along in
their development, and different groups of insects are out," said lead
author Abraham Miller-Rushing of Boston University. "Spring is coming
earlier for most other plants and animals, but not for the
long-distance migratory birds. Thus, these long-distance migrant birds
may need to learn to eat different sources of food or face other
challenges because of the changes in timing."
Jellyfish Rule: An outbreak of jellyfish in oceans across the planet
has resulted from the stinging creatures hitching rides on ships that
circumnavigate the globe. In fact, studies suggest that almost a
quarter of all marine species in international harbors are alien
transplants, thanks to human-assisted dispersal.
Food Web Contaminated. Scientists said last month that they found toxic
pollutants in nine deep-sea species of cephalopods, a class of mollusks
that includes octopuses, squid, cuttlefish and nautiluses. Among the
contaminants were at least two banned in the United States in the
1970s: dichloro-diphenyl-trichloroethane (DDT) and polychlorinated
biphenyls (PCBs). Scientists say it's further evidence that
contaminants make their way deep into the marine food web.
Heading for the Hills: Thirty species of reptiles and amphibians have
fled uphill to cooler climes as global warming has caused the mercury
to rise. We could see a rash of extinctions occurring between 2050 and
2100, scientists say, because higher ground will eventually run out.
Penguins in Peril: A rapid population decline among penguins because,
in addition to a warming planet, they face the triple whammy of oil
pollution, depletion of fisheries and aggressive coastline development.
"Penguins are among those species that show us that we are making
fundamental changes to our world," said Dee Boersma, a University of
Washington biology professor who has studied the flightless birds for
more than 25 years. "The fate of all species is to go extinct, but
there are some species that go extinct before their time and we are
facing that possibility with some penguins.
Sea-Life Shift: Scientists see a notable shift in the composition of
coastal marine animal communities, caused in part by changing ocean
temperatures, from vertebrates (fish) to invertebrates (lobsters,
squid, and crabs), as well as from bottom-feeders to species that feed
higher in the water column. Meanwhile, warm-water species have
superseded larger, cool-water species in population size.
Migrating Parasite: The parasite Angiostronglyus vasorum, commonly
known as "French heartworm," is migrating northward because of rising
temperatures. Normally found in southwestern England, the parasite has
been detected in dogs admitted to animal hospitals in Scotland.
Climbing temperatures in the country have also resulted in a sudden
proliferation of slugs and snails.
Food Shortages: Plant-loving animals in extremely seasonal environments
such as the Arctic struggle to feed themselves because global warming
causes their food supply to peak in availability before they can reach
breeding grounds. "Think of it like this," said Eric Post, a biologist
at Penn State. "You've been out on the town with friends, and on the
way home you want to stop off for a bite to eat, but the restaurant
you've always gone to has closed early. So you try for one around the
corner that's always open a little longer. But when you get to that
one, it too is closed. For herbivores, the fact that there are several
'restaurants' - their food patches - dispersed across the landscape
isn't useful if they all begin closing at the same time in addition to
closing earlier in the season."