Barrier
islands are an
important modern coastal depositional system. This study consists of a
transect
across the Padre Island National Seashore on the Texas Gulf Coast, from
Malaquite Beach to Bird Island Basin. Data collected included location
and behavior
of burrowing invertebrates, location of dominant plant taxa, and
sedimentary
structures. For the purpose of this study the island was divided into
beach,
foredune ridge, central island deflation flats, central island
vegetated
aeolian flats, and back-barrier lagoon margin environments.
Burrowing organisms such as
the Callichirus
islagrande
and Ocypode
quadrata
occupy the foreshore and back beach, respectively. Callichirus is
colonial along the foreshore,
with maximum burrow abundance occurring within the low tide swash
zone.
Ocypode is solitary in the
back beach
area. The burrow diameter and depth
increase towards the foredune ridge, while burrow abundance
decreases.
The fiddler crab Uca rapax is restricted to the
back barrier environment. Burrows found
in the central island are produced by insects and small mammals.
From the beach foredune
ridge to the back of the barrier island, the sedimentary structures are
generally disrupted by heavy vegetation and burrowing organisms. The
active
dunes, however, are not completely covered in vegetation and the
sedimentary
structures are observable. Although the surface of a barrier island is
rarely
preserved in the ancient rock record, it is important to understand the
different element of this modern depositional system to understand its
preservation potential.