CLUES CAN SOLVE ECOLOGICAL MYSTERIES
October 2, 2011
use special techniques on invisible clues such as fingerprints, ballistics,
and DNA to unravel the full story of what happened in a crime. Ecologists
use visible clues such as footprints, tree rings, and hidden camera footage
to reveal information about particular plants or animals. Do they also
have procedures for investigating less obvious evidence?
A. Like crime
fighters, medical professionals, and military personnel, ecologists use
a suite of tactics and techniques to acquire information about a subject
of interest. In fact, ecological research relies on many of the methodologies
developed in these other arenas, including molecular DNA analyses, x-radiology,
and satellite imagery.
basic environmental clues, known as spoor, were used in the earliest primitive
human societies and are still used by modern-day ecologists and hunters.
A footprint in the sand, deer tracks in the woods, feathers on the ground
all are spoor that provide information to confirm that a certain type
of animal was present. Such clues can be used to assess how long ago the
animal was there and what activity it might have been engaged in. Dead
leaves on a forest floor offer evidence of the presence of vines or shrubs
that might not be readily observed when they are leafless in fall and
winter. Scat (animal droppings) can be an especially valuable environmental
clue. Not only does it reveal the existence of the animal itself but the
contents may include fur, berries, or scales that denote the presence
of other unseen animals and plants in the vicinity.
of modern technology is widespread in many fields of ecology. Environmental
chemists use highly sensitive laboratory equipment to determine what compounds
and isotopes are in contaminated soils and polluted waters, as well as
in plants and animals themselves, such as fish with dangerously high levels
of mercury. High mercury content in bottom sediments, water, and fish
cannot be revealed by human sight, touch, smell, or taste. Mass spectrometry
and other sophisticated procedures uncover otherwise invisible environmental
clues that lead to public protection thanks to EPA regulatory guidelines.
Advisory warnings from the EPA not to eat fish from certain rivers are
based on such analyses.
use the standard medical tool of x radiography to study reptile egg shells
that contain sufficient calcium to be detected by x-ray photography. All
crocodilians and turtles and most snakes and lizards lay eggs. Research
ecologists use portable x-ray machines in the field that enable them to
gather pertinent data about the number and size of eggs, and then return
the animal unharmed to its habitat. The nondestructive sampling technique
is especially important in ecological studies in which the loss of a single
specimen of an endangered species is undesirable. Studies in New Zealand
on the internationally endangered tuatara, which looks like a large lizard,
relied on x-ray photography to obtain information on egg production. Investigators
used x-ray photography to gather critical information on egg production
necessary for understanding population growth patterns in these unusual
animals that are on the verge of extinction.
and geographic information systems that are essential for military operations
worldwide are now commonly used by ecologists in a variety of studies.
Combining these techniques with radiotelemetry, in which the location
of individual research animals can be tracked, allows researchers to plot
movement patterns over particular time periods. A GPS unit permits precise
pinpointing of locations that can then be examined on GIS maps constructed
from satellite imagery. The ecologist can identify critical habitats where
mobile species such as deer, coyotes, and tortoises spend the most time.
Land-use patterns and changes in ground cover and habitats due to forest
fires, floods, pathogens, or other landscape-level phenomena can also
instrumentation and gadgetry are valuable in studying nature, but basic
environmental clues--finding a shed snake skin, seeing a tree gnawed by
a beaver, identifying the footprint of a bobcat--offer a gratifying wildlife
experience. And even the simplest environmental clues can tell us something
about the animals and plants in the world around us.
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