Born of New Water
Transcript of Born of New Water
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teX~andllhatos byDirkJ . Stevenson
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in cyclicwaves" by ecologist Charles Wharton-is
meaningful to both isolated wetland ecosystems and to
upland habitats nearby. Think of all the red-shouldered
hawks, wading birds, Eastern kingsnakes and raccoons
that find energy in the form of amphibian dinners!
A f,l
~ ragically, many of OUT isolated wetlands or
the upland habitats surrounding them havebeen
lost or degraded because of development, loggingor agriculture. Remember, the frogs, toads and
salamanders that breed at cypress ponds and Carolina
baysspend most of their lives (more than 90percent)
in the upland habitats that surround these wetlands.
Remarkably, these little newts and frogs commonly
crawl or hop up to 1,000meters from their breeding
ponds to reach suitable shelter or foraging habitat.
Field studies of Eastern spadefoots, gopher frogs and
ambystomatid salamanders-vall of whichmay live
more than ten years in thewild-have demonstrated
that individuals return to the same ponds to breed
throughout their livesand often inhabit the same
terrestrial home ranges outside of the breeding season.
Because of habitat loss, several of South Carolina's
Eastern spadefoot (above) and gopher (left) frogs
are explosive breeders, with a brief breeding event
triggered by a large rainfall. These frogs live in the
uplands most of the year but are drawn to mate
in ponds filled temporarily by rain.
isolated wetland amphibian species are declining and in
big trouble. The federally listed flatwoods salamander
and the state-listed gopher frog require open, grassy
cypresswetlands within longleaf pine flatwoods-
disappearing habitats that depend on growing-season
fires to function naturally. According to SteveBennett,
herpetologist with the S.C. Department of Natural
Resources, the state monitors flatwoods salamander
and gopher frog populations on public lands in
collaboration with the U.S. Forest Service and the U.S.
Fish andWildlife Service.Long before I became aware of science, these
beautiful wetlands creatures had abig impact onmylife, especially inmy choice ofa career. Now thatI'm a
scientist, I realize mygrandfather was agood fisherman
because he could read the rhythms of nature and
anticipate what the fishwould be doing tomorrow. My
memorable time with himwas afine foundation.for
someone interested in the natural world. Taketime
to notice the amphibians of isolated wetlands. They
have interesting stories to tell and are among the many
splendid jewels of natural South Carolina. ~
Dirk1tevenson is a herpetologist and free-lance writerliving in southeastern Georgia.
J anuary-February 2009 23
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During the breeding season from late winter to earlyspring) male Eastern newts can be easily identified by their enlarged hind
legs, used for gripping females. F emales lay between 200 and 400 single, jelly-covered eggs on submerged vegetation each
season) leaving them to survive on their own. Both males and females reach sexual maturity around the age of three.
over herbaceous cover that iseasy on the eyes-clumpsof hatpins, sedges, blue flag iris, maidencane. In the
spring, flooded sitesmay be decorated by the gorgeous
yellowblossoms of the floating bladderwort. Water
levels in these wetlands drop dramatically during
our dryspring months when new plant growth and
rising temperatures cause evapotranspiration rates
to skyrocket, Lichen lines onthe cypress trunks
correspond to maximum depth watermarks; most of
these wetlands are onemeter deep when full.
The amphibian species restricted tobreeding
in isolated, ephemeral wetlands cannot withstand
the level of predation typical ofmore permanent
wetlands. Gelatinous amphibian eggs and soft-bodied,slow-swimming tadpoles and salamander larvae are
defenseless morsels for many predators. Periodic
drying removes many organisms-like fishandinvertebrates-that like to snack on the aquatic stages
of frogs, toads and salamanders.
Heavy, soaking autumn-winter rains bring the ground
puppies to the surface. At dusk, they emerge from the
earth likewater-logged worms and trek purposefully,
enmasse, to the basins of small, isolated wetlands,
where courtship occurs. They arejoined bynewts and
several handsome chorus frog species that are also cool-
weather breeders. Like all salamander larvae, those of
the bushy-gilled tiger salamander are carnivores. Small
tiger larvae slurp insects and minute crustaceans, while
larger ones eat fairy shrimp and even the larvae of other
amphibians. ByMayor June, they have their limbs and
their gills begin toresorb-metamorphosis isunder way.
In years when isolated wetlands remain flooded,
asuite of spring-summer breeders arrives. Frogs,
particularly treefrogs, characterize wet summers in
South Carolina. Everyone should wade acypress pond
on awet June night and enjoy the cacophonous din
of afull-blown frog congress composed of dozens ofhammering pinewoods treefrogs, along with ahealthy
mix of peeping oak toads and bleating narrowmouth(Continued onpage 22.)
J a n ua r y- F e br u ar y 2 0Q9 19
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(Continued from page 19.)
toads. During your walk, expect encounters with barred
owls and banded water snakes-they areboth fond of
feasting on frogs.
~ outhem leopard frogs and Eastern spadefoot
frogsmaybreed year-round if depressions havejust
filled with "new water." The bright -eyed spadefoot is
noteworthy: "frog-strangler" torrents are necessary
to stimulate these subterranean hermits to surface
and breed. Spadefoots will breed in that gentle swale
in your lawnand similar siteswhere water only pools
during extreme rain events. Themewing groan issued
bycallingmales carries for more than ahalf-mile and is
unforgettable. The classic Life Histories of the F rogs ofOkefinokee Swamp, Georgia)byA.H. Wright, describes
this croaking as "like the groan made by adeep-voiced
man having atooth pulled," and, my favorite, "like
the laments of hellbound souls." Adapted to the most
ephemeral waters, spadefoot development fromegg to
newly transformed toadlet is completed in twoweeks.
For isolated wetland-breeding amphibians,
reproduction is tied to pond hydroperiod, which in
22 South. Carolina Wildlife
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Narrowmoutli toads (above) and Southern leopard
frogs (left) will breed throughout the summer; possiblymating multiple times per year when water levels are
sufficient in the temporary ponds that bring males and
females together.
turn depends on rainfall. They are described as "boom
or bust" species because they experience great annual
variation in reproductive success-depending on
when or if their breeding pond fills and how long it
remains inundated. A banner year with large numberscompleting larval development (and transforming into
juveniles) may be followed byseveral poor years without
reproduction-because of drought or large numbers of
predators and competitors sharing the pond.
Weknow from landmark field studies conducted by
Savannah River Ecology Laboratory herpetologists
near Aiken that large annual fluctuations in population
sizeare ahallmark of isolated wetland amphibians.
Long-term monitoring efforts at SREL havemade
huge contributions toour understanding of these
amphibians and their habitats; some breeding sites have
been continuously monitored for more than twenty-fiveyears. These studies have generated impressive
numbers: in asingle breeding season, 12,000adult
marbled salamanders traveled to "Ginger's Bay," a
small Carolina bay wetland; at another bay, more than
75,000amphibian larvae completed development in a
single year before moving into adjacent woodlands. This
flowofbiomass into and away from isolated wetlands-
eloquently referred to as "grand movements of life
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.",solated, ephemeral wetlands are the primary
breeding habitat for many of South Carolina's
amphibians, including five species of mole salamanders:
the spotted, tiger, flatwoods, Mabee's and molesalamanders. These wetlands are small, embedded
depressions-surrounded by uplands-that lack
surface water or ground water connections to other
wetlands. Filled by rainwater alone, they have seasonal
or irregular hydroperiods-which is to say the basins
of these wetlands are not always flooded. In fact,
they typically dry annually. You may have heard such
wetlands referred to as temporary ponds, high ponds or
18Sou th Ca r ol in a W i fd li f~
Population declines among tiger salamanders
because of habitat destruction have made
this a species of concern nationally. Almost
entirely terrestrial as adults, tiger salamanders
only return to the water to breed, predictably
returning to their birthplace to mate and layeggs. Larvae, characterized by large external gills
and a prominent caudal fin, remain in the water
and develop limbs soon after hatching.
wet-weather ponds.
The low country of our coastal plain isdotted with
tens of thousands of isolated wetlands. From alow-
flying aircraft, they appear as islands of swamp within asea of pinelands. Most isolated wetlands are quite small
(0.1 acre to 3 acres) and round or elliptical in shape.
They are classified according to origin and vegetation.
Many different types of isolated wetlands occur in
South Carolina, predominately cypress ponds and
Carolina bays.
Walk inside an isolated wetland and you are apt to
find a scattered canopy of pond cypress or black gum
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Barking treefrogs give their "barking" calls from
treetops except when involved in breeding activities)
when they seek out temporary ponds for mating.
F loatingin open water; males call females using a
distinctive breeding call. After mating, females lay
eggs in the wate" where the tadpoles (inset far left)
hatch and remain until they develop limbs and climb
into surrounding trees.
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~y grandpa called them ground puppies.
Hunting nightcrawler bait for his catfish lines, wewould
occasionally unearth strange, colorful creatures from
the dark soil. They were smooth-skinned and pop-eyed,
their pudgy bodies adorned with yellow spots or black-
and-white bands. They looked weird, likethey belonged
underground. An adolescent with aburgeoning
fondness for squirmy critters, I was instantly
smitten. They were ambystomatid salamanders(family Ambystomatidae, genusAmbystoma )-also known as the mole salamanders-an
interesting group of burrowing amphibians thatbreed in isolated, ephemeral wetlands.
J iVhenwater fills lowlands like this dry cypress pond,
a diverse assemblage of amphibians moves in for
breeding. Among the animals that have evolved to
breed in temporary ponds are the members of the
mole salamander family (inset far left), including
the federally threatened flatwoods salamander (insetleft) and the marbled salamander (above). Marbled
salamanders, unlike most others) lay eggs in a dry
pond and guard them unti l it fi l ls.
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