Off-road-vehicle impact on beach fauna studied
URI researchers examine harm to beach invertebrates caused by vehicles
KINGSTON, R.I. -- April 7, 2000 -- "Most people walk the beach and
think that nothing lives there but a few birds," said Howard Ginsberg,
a research ecologist with the U.S. Geological Survey based at the University
of Rhode Island. "But the beach is filled with life, both marine organisms
and terrestrial creatures. You just don't notice them."
And that's the problem. Since people don't notice these creatures, they
also don't notice the impact they have on them. Off-road-vehicles, in particular,
likely have a significant impact, both on the creatures themselves and on
the shorebirds that feed on them.
The Cape Cod National Seashore, administered by the National Park
Service and located along the outer Cape, recently concluded a "negotiated
rulemaking" process to develop rules for off-road-vehicle traffic on
the beach. Part of the agreement calls for the park to monitor the effects
of vehicles on the ecology of the beach.
So Ginsberg and URI graduate student Jacqueline Steinback of East
Falmouth, Mass., are working with the National Park Service on a $173,000
grant to study the impact of vehicles on the fauna of the Cape Cod National
Seashore.
"Sandy beaches are ephemeral," notes Ginsberg. "They
change every time the tide comes in. And the creatures that live there
have to deal with constant inundation by seawater and exposure to strong
winds. It's a harsh environment."
The various beach invertebrates have evolved a variety of adaptations
for dealing with their unusual habitat. Some burrow into the sand to escape
the elements, while others migrate back and forth between the beach grass
and the wrack (the vegetation that accumulates at the high tide line).
Some eat fresh wrack, others feed on the dried wrack at the highest high
tide line, and still others are predators.
"The dynamics of the fauna on sandy beaches have never been described,
so there are lots of unanswered questions," explained Ginsberg. "Are
these creatures truly ephemeral blown onto the beach haphazardly from
wherever or is it a true community with a structure to the interactions
among them?"
So far Ginsberg thinks there is some degree of consistency in the interactions
among beach fauna, which suggests a structured community. "But we
just aren't sure yet."
In a related study completed in 1999, Steinback recorded 217 species
of invertebrates living on one beach on Fire Island, N.Y. Most were
amphipods which she describes as "semi-terrestrial crustaceans"
beetles, mites, worms, flies and spiders. Almost all are tiny, short-lived
animals that are primarily active at night. "And none of them are
harmful to people," notes the URI student.
Steinback's Fire Island study found that off-road-vehicles do not harm
the beach creatures directly, but instead the vehicles disturb the creatures'
habitat in significant ways.
"When vehicles drive over the wrack, their tires break up the vegetation,
which makes the wrack dry out faster," explained Steinback. "That
changes the abundance of species on the beach. In the high traffic areas,
I found far fewer of the species that feed on fresh wrack and more of the
species that feed on dry wrack."
Since many of the animals depend on a moist environment, Steinback's
research suggests that the indirect result of off-road-vehicle traffic is
that many creatures are at a high risk of drying out and dying. Her studies
this summer on the Cape Cod National Seashore will hopefully shed additional
light on the subject.
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For Information: Howard Ginsberg 874-4537, Todd McLeish
874-7892
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