Introduction to Introduction to Barrier IslandBarrier Island

EcologyEcology

Biology 366 Ecology Biology 366 Ecology

16 April 200216 April 2002

Barrier Island TransectBarrier Island Transect

• Beach and DunesBeach and Dunes• Shrub Thicket and Maritime Shrub Thicket and Maritime

ForestForest• Freshwater WetlandsFreshwater Wetlands• Tidal MarshTidal Marsh• Estuarine Waters/Sand and Mud Estuarine Waters/Sand and Mud

FlatsFlats

Dune FormationDune Formation

Sand, moved by the process of saltation, accumulates around objects including vegetation and flotsam

Dune FormationDune Formation

SandSand WindWind ObjectObject

• Elements required for dune Elements required for dune formationformation

American American Beachgrass Beachgrass (Ammophil(Ammophil

a a breviligulatbreviligulat

a)a)

Sea OatsSea Oats (Uniola (Uniola paniculata)paniculata)

Panic Grass Panic Grass (Panicum (Panicum amarum)amarum)

SaltmeadoSaltmeadow w

Cordgrass Cordgrass (Spartina (Spartina patens)patens)

Strand Line or Wrack Strand Line or Wrack LineLine

• Line of debris Line of debris at spring tideat spring tide

• Debris is Debris is called called “wrack”“wrack”

• Most dunes Most dunes form hereform here

Strand Line or Wrack Strand Line or Wrack LineLine

• Large quantities Large quantities of sand moved of sand moved across strandacross strand

• Common on Common on prograding prograding (growing) (growing) beaches beaches

• Rare on eroding Rare on eroding beachesbeaches

Dune EnvironmentsDune Environments

• Youngest strand lines lie most Youngest strand lines lie most seawardseaward

• Multiple dune ridges form as Multiple dune ridges form as strand lines are colonizedstrand lines are colonized

Oldest - - - - - - > Youngest

Dune EnvironmentsDune Environments

• Dunes and colonizing plants Dunes and colonizing plants grow in concertgrow in concert

Year 3Year 3Year 2Year 2Year1Year1

Dune Environmental Dune Environmental Conditions Conditions

• Low soil Low soil nutrients nutrients (N and P) (N and P)

• Desiccating Desiccating windswinds

• Blowing Blowing sandsand

Dune Environmental Dune Environmental ConditionsConditions

• Air and soil Air and soil temperaturtemperatures are es are highly highly variablevariable

Dune ProcessesDune Processes

• Unvegetated Unvegetated dunes “migrate” dunes “migrate” or move from <1 or move from <1 m to >15 m m to >15 m annuallyannually

• Migrating dunes Migrating dunes engulf engulf surroundingssurroundings

Natural revegetation a long term Natural revegetation a long term processprocess

BlowoutsBlowouts

• Occur when Occur when vegetation vegetation mantle is mantle is destroyeddestroyed

• Difficult to stop, Difficult to stop, once startedonce started

• Creates Creates environment environment called “slack”called “slack”

blowoutblowout

Natural and Man-Natural and Man-induced Impacts on induced Impacts on

DunesDunes• Oceanic overwashOceanic overwash• ““erosion”erosion”• Off-road vehicle Off-road vehicle

(ORV) traffic(ORV) traffic• Sand fencing: Sand fencing:

wooden, brush, treeswooden, brush, trees

Washovers Washovers

Salt Aerosol ImpactsSalt Aerosol Impacts

Salt aerosol effects on plants

Salt aerosol source

this side

Source of Salt AerosolsSource of Salt Aerosols

Salt AerosolsSalt Aerosols

Salt Aerosol Impact on Salt Aerosol Impact on PlantsPlants

Source of salt aerosol (ocean side)

Salt Aerosol Impact on Salt Aerosol Impact on PlantsPlants

• Generally decreases Generally decreases from strand line, from strand line, landwardlandward

• Highest on foredunesHighest on foredunes• Lowest in slacks and Lowest in slacks and

lee of duneslee of dunes

Coastal Communities and Coastal Communities and ProcessesProcesses

• Beach and DunesBeach and Dunes• Shrub Thicket and Maritime ForestShrub Thicket and Maritime Forest• Freshwater WetlandsFreshwater Wetlands• Tidal MarshTidal Marsh• Estuarine Waters/Sand and Mud Estuarine Waters/Sand and Mud

FlatsFlats

Shrub Thicket Shrub Thicket EnvironmentsEnvironments

• Early colonizers Early colonizers (survive low (survive low nutrients)nutrients)

• Best examples are Best examples are in dune slacksin dune slacks

• Reduced salt Reduced salt aerosol aerosol environment environment allows arborescent allows arborescent vegetation to vegetation to flourishflourish

Wax Myrtle Wax Myrtle (Myrica (Myrica pennsylvanica)pennsylvanica)

• Northern Bayberry Northern Bayberry is common in is common in thickets from Cape thickets from Cape Hatteras northward Hatteras northward into New Englandinto New England

• Bayberry candles Bayberry candles are made from the are made from the waxy coating on waxy coating on the berriesthe berries

Yaupon Yaupon (Ilex vomitoria)(Ilex vomitoria)

Maritime Forest Maritime Forest EnvironmentsEnvironments

• Develop under the Develop under the influence of salt influence of salt aerosolsaerosols

• Restricted Restricted distributiondistribution

• Shear edge created Shear edge created by salt aerosolsby salt aerosols

Maritime Forest Maritime Forest EnvironmentsEnvironments

• Species adapted Species adapted to:to:– Low salt aerosolsLow salt aerosols– low soil nutrientslow soil nutrients– sandy soilssandy soils

• Salt aerosols Salt aerosols control location control location and structure of and structure of the maritime the maritime forestforest

Maritime Forest Maritime Forest EnvironmentsEnvironments

• Vines are commonVines are common• Tree leaves small, thick, Tree leaves small, thick,

evergreenevergreen

Live Oak (Quercus virginiana)Live Oak (Quercus virginiana)

Bear oak (Quercus Bear oak (Quercus illicifolia) common along illicifolia) common along New England maritime-New England maritime-influence forestsinfluence forests

Southern Red Oak Southern Red Oak (Quercus falcata)(Quercus falcata)

Common in Mid-Atlantic maritime forestsCommon in Mid-Atlantic maritime forests

Red Cedar Red Cedar (Juniperus virginiana)(Juniperus virginiana)

Salt aerosol damageSalt aerosol damage

oceanocean

American Holly (Ilex American Holly (Ilex opaca)opaca)

Loblolly Pine Loblolly Pine (Pinus (Pinus taeda)taeda)

Loblolly pine is the most common pine in the maritime forest. It typically is successional and is replaced by live or laurel oak in the southeastern US.

Dogwood (Cornus florida)Dogwood (Cornus florida)

Poison Ivy Poison Ivy

(Rhus toxicodendron)(Rhus toxicodendron)

Woodbine (Parthenocissus quinquefolia)Woodbine (Parthenocissus quinquefolia)

Development of Maritime Development of Maritime ForestsForests

• Develop on Develop on coastal dune coastal dune systemssystems

• Sterile sandy Sterile sandy soilssoils

• Hummocky Hummocky topographytopography

• Begin as Begin as scattered shrubsscattered shrubs

Impact of hurricanes on maritime forest vegetation. Pines are typically snapped off; cabbage palms survive. Live oak and magnolia have branches and leaves ripped off.

Natural Impacts on Maritime ForestsNatural Impacts on Maritime Forests

Large migrating dunes are capable of overwhelming shrub and forest vegetation

Significant Human Significant Human ImpactsImpacts

• Fragmentation occurs when Fragmentation occurs when development occurs within a development occurs within a continuous forestcontinuous forest

Forest opened to Forest opened to salt aerosol salt aerosol impacts when impacts when development development occursoccurs

Freshwater Wetland Freshwater Wetland EnvironmentsEnvironments

• Ponds, Ponds, swamps, swamps, marshesmarshes

• Form where Form where water table water table intersects intersects ground ground surfacesurface

Freshwater Wetland Freshwater Wetland EnvironmentsEnvironments

• Receive Receive groundwater groundwater input from input from adjacent adjacent dunesdunes

• Influenced by Influenced by groundwater groundwater and rainfalland rainfall

Water flows from adjacent dunes into slough between dunes

Freshwater WetlandsFreshwater Wetlands

• Cattails (Typha spp.)Cattails (Typha spp.)• Bulrush (Scirpus spp.)Bulrush (Scirpus spp.)

Tidal Marsh Tidal Marsh EnvironmentsEnvironments

• Develop in Develop in areas areas protected from protected from wave attackwave attack

• TopographicallTopographically flat, incised y flat, incised with drainage with drainage creekscreeks

Tidal Marsh Tidal Marsh EnvironmentsEnvironments

• Alternately Alternately exposed exposed and covered and covered by tides by tides dailydaily

• ““Pulse-Pulse-stable” stable” environmenenvironmentsts

Tidal Marsh Tidal Marsh EnvironmentEnvironment

• Saltmeadow Saltmeadow Cordgrass Cordgrass (Spartina patens)(Spartina patens)

• Smooth Smooth Cordgrass Cordgrass (Spartina (Spartina alterniflora)alterniflora)

ZonationZonation

• Cordgrass Cordgrass dominant dominant above and above and below mean below mean tide leveltide level

• Many other Many other species species dominant dominant above average above average high tideshigh tides

Black Needlerush Black Needlerush (Juncus roemerianus) (Juncus roemerianus)

Black Needlerush is common at the upper edge of the tidal marsh where the tide floods only occasionally

Black NeedlerushBlack Needlerush

Sea Ox-eye Sea Ox-eye (Borrichia (Borrichia frutescens)frutescens)

Sea Lavender

(Limonium carolinianum)

Glassworts Glassworts (Salicornia (Salicornia

spp.)spp.)

These succulent plants grow in the most saline environments in the tidal marsh area

Formation of Tidal Formation of Tidal MarshMarsh

• Sand and mudflats Sand and mudflats colonized by smooth colonized by smooth cordgrasscordgrass– must reach critical must reach critical

elevation elevation– seed falls on flatsseed falls on flats– spread by rhizomesspread by rhizomes

Typical environments colonized by smooth cordgrass primarily by seeds

Formation of Tidal Formation of Tidal MarshMarsh

Sand flats are colonized by clumps of smooth cordgrass. Alternatively, the sand flats can be colonized by germinating seeds of smooth cordgrass.

Colonization by Spartina alterniflora

Formation of Tidal Formation of Tidal MarshMarsh

• Sand flats Sand flats may become may become uniformly uniformly vegetated in vegetated in 2-5 years2-5 years

• Creeks Creeks become become incised as incised as community community maturesmatures

Human ImpactsHuman Impacts

• Finger Finger canals (now canals (now outlawed in outlawed in all states)all states)

• Point and Point and non-point non-point source source runoffrunoff

Mudflats and SandflatsMudflats and Sandflats• No rooted aquatic No rooted aquatic

vegetationvegetation• Significant infauna Significant infauna

(clams, worms, etc.)(clams, worms, etc.)• Important habitat Important habitat

for organisms in for organisms in intertidal intertidal environmentsenvironments

Submerged Aquatic Submerged Aquatic VegetationVegetation

• Typically composed of Typically composed of seagrassesseagrasses– Marine flowering plantsMarine flowering plants– 13 genera; 58 species 13 genera; 58 species

worldwideworldwide

• Grow in shallow subtidal Grow in shallow subtidal or intertidal water on or intertidal water on soft muds and sandy soft muds and sandy sediments (some on sediments (some on rocky substrates)rocky substrates)

• Evolved from terrestrial Evolved from terrestrial grassesgrasses

Turtle Grass, Thalassia

testudinum

Lifestyle Requirements Lifestyle Requirements for Seagrassesfor Seagrasses

• Must be adapted to saline waters (true Must be adapted to saline waters (true halophyte)halophyte)

• Must be able to grow completely submergedMust be able to grow completely submerged• Must be securely anchored in the substrate Must be securely anchored in the substrate

(some species are anchored to rocky substrates)(some species are anchored to rocky substrates)• Must be able to flower, fruit and produce seeds Must be able to flower, fruit and produce seeds

in waterin water• Leaves and stems lack waxy cuticle typical of Leaves and stems lack waxy cuticle typical of

terrestrial plantsterrestrial plants• Typically possess aerenchyma tissue for Typically possess aerenchyma tissue for

bouyancybouyancy

OccurrenceOccurrence• Worldwide in distributionWorldwide in distribution• In US, found on Atlantic, Pacific, and Gulf In US, found on Atlantic, Pacific, and Gulf

coasts coasts • 90% of seagrasses in US are in Gulf of 90% of seagrasses in US are in Gulf of

MexicoMexico– Major beds in Chesapeake Bay, Florida, Texas Major beds in Chesapeake Bay, Florida, Texas

and Californiaand California

• Occur primarily in “beds,” typically patchy Occur primarily in “beds,” typically patchy in naturein nature

• Grasses typically found in 10-15 m of Grasses typically found in 10-15 m of water, but have been found down to 130 water, but have been found down to 130 feetfeet

Ecology of Seagrass Ecology of Seagrass BedsBeds

• Seagrass beds are important to:Seagrass beds are important to:– Grazers—manatees, ducks, etc.Grazers—manatees, ducks, etc.– Epiphyte grazers—feed on seagrass Epiphyte grazers—feed on seagrass epiphytes—sea urchins, fish, etc.epiphytes—sea urchins, fish, etc.– Detritus feeders—feed on decaying Detritus feeders—feed on decaying organic matterorganic matter– Shelter for conch, starfish, sand Shelter for conch, starfish, sand dollars, etcdollars, etc

• Substrate and food for bay barnacles, Substrate and food for bay barnacles, sea squirts, sponges, isopods, sea squirts, sponges, isopods, amphipods, snails, seahorses, amphipods, snails, seahorses, anchovies, silversides, shrimp, blue anchovies, silversides, shrimp, blue crabs, waterfowl and otherscrabs, waterfowl and others

Ecology of Seagrass Ecology of Seagrass BedsBeds

• Bind sediments with extensive rhizomes Bind sediments with extensive rhizomes and rootsand roots

• Baffle waves and currentsBaffle waves and currents• Trap sediments/clear the water columnTrap sediments/clear the water column

• Improve water quality by taking up Improve water quality by taking up nutrients (epiphytes do the same)nutrients (epiphytes do the same)

• Important in oxygenating waterImportant in oxygenating water• Seagrass systems protected under Seagrass systems protected under

federal “no-net-loss” policy for federal “no-net-loss” policy for wetlandswetlands

Vulnerability of Vulnerability of Seagrass BedsSeagrass Beds

• Conditions resulting in reduction of Conditions resulting in reduction of seagrass bedsseagrass beds– Nutrient loadingNutrient loading– Light reductionLight reduction– Physical destructionPhysical destruction

• Rate of loss: weeks to monthsRate of loss: weeks to months• Rate of recovery: yearsRate of recovery: years

– Vegetatively slow recoveryVegetatively slow recovery– Seeding shows more rapid recoverySeeding shows more rapid recovery

Propeller scars on seagrass beds near Windley Key, Florida Keys

Common Seagrasses of Common Seagrasses of the Eastern and Gulf USthe Eastern and Gulf US

Manatee GrassSyringodium filiforme

Shoal GrassHalodule wrightii

Widgeon GrassRuppia maritima

Turtle GrassThalassia testudinum

Eel GrassZostera marina

Paddle Grass Halophila decipiens

Causes of Decline in Causes of Decline in SeagrassesSeagrasses

• Dredge and fill Dredge and fill operationsoperations

• Mooring scarsMooring scars• Propeller scarsPropeller scars• Vessel wakesVessel wakes• Jet skisJet skis• Fish and Fish and

shellfish shellfish harvesting harvesting techniquestechniques

• Sewage outfallsSewage outfalls• Thermal pollution Thermal pollution • DiseaseDisease• StormsStorms• Ice scourIce scour• Epiphyte loadEpiphyte load• Burrowing shrimpBurrowing shrimp• Green algaeGreen algae