born of new water

7/29/2019 Born of New Water

http://slidepdf.com/reader/full/born-of-new-water 1/8

teX~andllhatos byDirkJ . Stevenson



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



" 1 "1

(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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I ' I I I I I 'I' II

.",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



-.-.--- ..~

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.



~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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born of new water

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