Dune flora and fauna

Maia McGuireFlorida Sea Grant Extension

Beach zonation

http://glf.dfo-mpo.gc.ca

Cross section of a beach

http:// lighthouse.tamucc.edu

Barrier islands are dynamic!

• Their topography and vegetative profiles result from the interaction of plant growth habits and physical processes– Wind-driven sand movement– Salt spray deposition– Wave driven erosion, accretion, and overwash

Wind effects

• Dunes are built as stems of dune grasses increase the surface roughness, causing the wind to slow and to drop sand grains being moved across the beach

• Only winds blowing onshore will cause dune formation

• Like sand, salt spray is carried only by winds blowing onshore across the open water

Wave effects

• Accretion• Erosion• Overwash

• Continuous processes-longshore sand transport

• Single events-winter storms and hurricanes

Sand Dunes

Physical role of sand dunes

• Dunes provide protection from storm-induced waves and erosion (e.g. during hurricanes)

• Dunes are dynamic—they want to shift with long-term processes

The role of plants in dunes

• Dune plants help trap blowing sand, causing sand to create a mound which grows over time.

Vegetation

• Plant species occur in zones parallel to the coast– Upper beach and foredune: most directly affected

by wind and waves– Transitional zone/backdunes: same coastal

stresses, just at a lower intensity– Stable dunes: the most stable, oldest portion of

the barrier island

Challenges for dune plants

• Salty, windy, dry environment– Risk of desiccation

• Few nutrients• Unstable/shifting sand

Adaptations of dune plants

• Many are succulents (have moisture within their leaves)

• Many have very long roots to reach for moisture and nutrients

• Flexible stems help withstand wind

• Hairy leaves help trap moisture

• Deep roots cannot prevent erosion

Beach elder

Sea oats

Beach/Dune sunflower

Railroad vine

Beach morning glory

Beach croton

Pricklypear cactus

Beach pennywort (“Dollarweed”)

Dune plant ecology

• Many have both sexual and asexual reproduction

• If sections of pricklypear are knocked off, they can sprout

• Sea oats, beach pennywort, railroad vine, beach morning glory spread using rhizomes

Activity

• Leaf rubbings and leaf prints

Dunes as animal habitat

• Back dunes are important habitat for many Florida reptiles and some mammals

coastalwildlifeclub.org

Gopher tortoise

• Tortoise = turtle that lives on land• Tortoise can pull its legs and head into its shell

for protection• Gopher tortoise is protected in Florida

Gopher tortoise

• Digs long burrows using its front legs• One tortoise may use several burrows• Gopher tortoises mostly eat plants, including

pricklypears• Many other animals can share the burrows

(e.g. rattlesnakes, mice, opossums, and rabbits)

• Burrows average 30 feet long

Turtle anatomy

• Carapace (upper shell)• Plastron (lower shell)• Scutes (plates that make up the shell)– Medial, lateral, marginal

http://zygote.swarthmore.edu/turtle.html

Activity

• Gopher tortoise activity book

Snakes

• E.g. diamondback rattlesnake• Body covered in scales (like a fish!)• Snakes have no legs…they use

their belly scales to move along the ground.

• Suggestion: Contact Jax herpetological society to see if someone can bring snakes into the classrooms…

Activity

• Spinning snake

Anastasia beach mouse

• Endangered species• Found only on Anastasia Island

Beach mice

• Live in burrows—usually dig their own, although they may use abandoned ghost crab burrows

• Eat seeds (e.g. sea oats)—can help spread dune plants by carrying seeds from one location to another