Flora and Fauna of Northwest Florida

Biology Department

University of West Florida

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Barrier Islands

Barrier islands are sand deposits of recent geologic origin. Here in Northwest Florida, the Barrier Islands are comprised of almost pure milky quartz, leading some to claim they are the whitest sand beaches in the world. The sands have their origin in the piedmont, delivered to the Gulf by rivers, and reworked wind and waves. The "washing" of the sand results in it being "well-sorted", or of uniform grain size. The same process that gave us these clean washed sands also keeps the islands "moving" by a constant give and take from erosion and redistribution of sand. The redistribution of the sands by wind gives us dunes, which are colonized by plants that catch and stabilize the sand like Sea Oats and Bitter Panicum. Low areas between the dunes where the sand is blown away down to the ground water are called swales, and here we find some distinctive wetland plants like Red Root and the carnivorous Sundews.

The sand on the barrier islands have very low amounts of nutrients, do not retain water well, and are in general not shaded by large plants, creating a desert-like or xeric (hot-dry) environment. Many of the xeric-adapted plants found here (xerophytes) are also found inland in sandy dry habitats like the pine sand hills. However, the biggest factor determining the distribution of plants is salt. Salt comes from droplets thrown in the air by the surf, there is salt in much of the groundwater, and major storms (gales and hurricanes) flood parts of the island with salt water. Plants out on the beach and foredunes have the greatest salt tolerance, and diversity of plants increases as one walks into the island and into the protection of the back dune or secondary dune field area and into patches of maritime forest along the Sound and Bay side.

 

The surf zone where the waves crash on the beach make a unique habitat. We find some species of animals adapted to this high energy home that are found nowhere else, like the Coquina surf clams (Donax variabilis) and mole crabs (Emerita talpoida; locally called sand fleas). Both of these organsisms filter food out of the water as it washes up and down the surf zone. Mole crabs (at right) use their antennae as filters. Coquina are amazingly fast diggers, pullling themselves back into the sand as the water rushes over them. Many fish, like Florida Pompano, hang out in the deep trough that is formed by the returning water to eat the animals washed out of the surf zone sand. Sandpipers and other small shorebirds also feed on the animals in this part of the beach.

 

The incoming tide carries material up onto the beach and leaves it behind as a tide or wrack line (left). All kinds of stuff is found here (including our trash), and it is used as a cafeteria by many of the barrier island birds and animals. Only a couple of animals are resident on the beach itself, ghost crabs (Ocypode quadata; above) and beach fleas, and they both burrow into the sand to survive. The Ghost crab to the right is carrying out a ball of sand while digging a burrow. Most of the animal life on the islands is found in the secondary dune field, maritime forests, and back bay marshes where they can find water and escape the harsh conditions of the beach. Many, like the raccoon and fox, will patrol the wrack line at night as part of their "rounds".

 

Primary Dunes are large sand piles built up from sand blowing off the beach. Sea rocket (Cakile constricta), Sea Oats (Uniola paniculata; left), Seaside elder (Iva imbricata; above), and Bitter Panicum (Panicum amarum) are the major dune building plants here that capture and hold the blown sand, and grow to keep pace with the enlarging sand pile.

The secondary dune field is an intriguing mix of open bare sandy areas and patches of vegetation in and around wind built sand dunes. The scouring effects of storm water surges can be seen, as well as the continual effects of the wind. The "patches" of vegetation can be as small as tiny plants in the open sand like the Lachnocaulon minus (only 2 inches tall) shown at left, to broad vegetated areas seen above. Resident animals like the Six Lined Race Runner (Cnemidophorus sexlineatus sexlineatus,below) take cover and find food in these vegetated "islands" in the sand. Other species, like the Monarch Butterflies (Danaus plexippus, below), are transient visitors resting on the island during their Spring and Fall migrations across the Gulf of Mexico.

 

Swales are wetlands formed where the wind has scoured out the sand down to the water table or below. Here we find some typical freshwater wetland species, although the touch of salt in the air leads to some unique community assemblages.

Salt Sculpting of plants reflects the salt spray from the surf zone carried inland on the wind. Trees and shrubs in the secondary dune field have a characteristic aerodynamic appearance from the wind-borne salt constant killing new growth. Some trees and shrubs in this area are completely enclosed by dunes, with only the outer parts of the branches sticking out above the sand.

A Maritime Forest is sometimes found along the back side of the barrier island in the shelter of the secondary dune field. Live Oak, Myrtle Oak, and Sand Live Oak mixed with Slash Pine make up the canopy of these woodlands.

Back Bay/Sound shore can have fringing marshes or periodic cuspate spits that form points of land enclosing lagoons and salt marshes, as in this view of Big Sabine Point. This photo was taken from the crest of the last secondary dune looking north to Santa Rosa Sound.

 

Leave your footprints only (a guide to tracks in the sand)

Barrier Island Plant Species

This is a partial listing of some of the more conspicuous or important species. A study of the recovery of plant species on the Gulf Islands National Seashore's Fort Pickens area after Hurricanes ERIN and OPAL (1995) has resulted in a fairly comprehensive database of the plant species found there (descriptions and images). This database is SEARCHABLE by keywords that are descriptive of the plant type (habitat, flower color and season, leaf and stem type, etc.).

Plant Species

Beach & Fore Dune

Sea Oats

Uniola paniculata

Bitter Panicum

Panicum amarum

Sea Rocket

Cakile constricta

Seaside Elder

Iva imbricata

 

 

Primary & Secondary Dunes

Sea Oats

Uniola paniculata

Bitter Panicum

Panicum amarum

Woody Goldenrod

Chrysoma pauciflosculosa

Salt Meadow Hay

Spartina patens

Pennywort

Hydrocotyle bonariensis

Blue Stem

Schizachyrium maritinum

 

 

Secondary Dunes & Maritime forest

Beach Rosemary

Ceratiola ericoides

Sand Live Oak

Quercus geminata

Myrtle Oak

Quercus myrtifolia

Magnolia

Magnolia grandiflora

Sweet Bay Magnolia

Magnolia virginiana

Yaupon

Ilex vomitoria

Slash Pine

Pinus elliottii

Fetter Bush

Lyonia lucida

Saw Palmetto

Serenoa repens

 

 

Swales (dune blowouts)

Redroot

Lachnanthes caroliniana

Rushes and Sedges

spp.

Sundew

Drosera capillaris

 

Animal Species

Surf Zone

Coquina Surf Clam

Donax variabilis

Augers

Terebra spp.

Moles crabs

Emerita talpoida

Shorebirds

several genera & species

 

 

Wrack line & Beach

Beach Flea

Talorchestia sp.

Ghost Crab

Ocypode quadratus

Least Tern (nesting)

Sterna albifrons

Shorebirds

several genera & species

Seagulls

several general & species

Loggerhead Sea Turtle

Caretta caretta caretta

 

 

Dunes, ponds, & Back Bay

Raccoon

Procyon lotor

Fox

Vulpes vulpes

Skunk

Mephitis mephitis

Oppossum

Didelphis virginiana

Otter

Lutra canadensis

Santa Rosa Beach Mouse

Peromyscus polionotus leucocephalis

Ribbon Snake

Thamnophis s. sauritus

Six Lined Race Runner

 Cnemidophorous sexlineatus

Diamondback Rattlesnake

Crotalus adamanteus

Banded Water Snake

Nerodia fasciata fasciata

Monarch Butterfly

Danaus plexippus

 

 

Fishes in Swale Pools

Sheepshead minnow

Cyprinodon variegatus

Mosquitofish

Gambusia affinis