Flowering plants Flowering plants (Angiosperms)(Angiosperms)• 250,000 species. Most are land 250,000 species. Most are land

plants (trees, flowers, shrubs, plants (trees, flowers, shrubs, grasses etc)grasses etc)

• Only three groups are adapted to life Only three groups are adapted to life in coastal areas either totally or in coastal areas either totally or partially submerged:partially submerged:– SeagrassesSeagrasses– MangrovesMangroves– Salt-marsh plantsSalt-marsh plants

Seagrass bed

Salt-marsh

Mangroves

What are seagrasses?What are seagrasses?

• Seagrasses are not “true” grassesSeagrasses are not “true” grasses• Seagrasses are found totally Seagrasses are found totally

submerged in shallow coastal waterssubmerged in shallow coastal waters• Seagrasses provide important habitat Seagrasses provide important habitat

for marine organismsfor marine organisms• 55 different species of seagrasses 55 different species of seagrasses

worldwideworldwide• 7 species off the coast of Florida7 species off the coast of Florida

•Seagrass communities provide habitat for a variety of marine animals.•Some animals feed directly on the plants while others feed on the variety of organisms that live on and among the seagrass•Large predators also visit the seagrass beds in search of prey

Classification of SeagrassesClassification of Seagrasses

• Kingdom PLANTAEKingdom PLANTAE– Vascular PlantsVascular Plants

• Subclass MonocotyldoneaeSubclass Monocotyldoneae

Family Family Potamogtonaceae Potamogtonaceae

Family Family HydrocharitaceaeHydrocharitaceae

Manateegrass

Turtle grass

• Seagrasses have Seagrasses have stems (rhizomes) stems (rhizomes) which spread which spread horizontally under the horizontally under the sediment.sediment.

• Leaves and roots grow Leaves and roots grow from the rhizomes from the rhizomes and anchor the plantand anchor the plant

• Flowers are small and Flowers are small and inconspicuousinconspicuous

• Pollen often released Pollen often released in thread-like strands in thread-like strands and transported by and transported by the waterthe water

Examples of Seagrass Examples of Seagrass speciesspecies• Turtle Grass Turtle Grass

((Thalassia Thalassia testudinumtestudinum))– Most common in Most common in

Florida and BahamasFlorida and Bahamas– Flat, ribbon-like Flat, ribbon-like

blades with blunt tipsblades with blunt tips– Blades up to 14 inches Blades up to 14 inches

long and ½ inch widelong and ½ inch wide

Turtle Grass (continued)Turtle Grass (continued)

• Turtle grass typically Turtle grass typically occurs from low tide occurs from low tide level to a depth of level to a depth of 10m (33ft)10m (33ft)

• Typically found on Typically found on sandy or rubble-sandy or rubble-covered bottomscovered bottoms

• Name refers to green Name refers to green sea turtles that often sea turtles that often graze on large fields of graze on large fields of ThalassiaThalassia

Manatee Grass (Manatee Grass (Syringodium Syringodium filiformefiliforme))

• Second most common Second most common seagrass in Florida seagrass in Florida and Bahamasand Bahamas

• Blades up to 20 inches Blades up to 20 inches long and cylindricallong and cylindrical

• Roots barely below the Roots barely below the substratesubstrate

• Favorite food of Favorite food of manateemanatee

Star Grass (Star Grass (Halophila Halophila engelmanniengelmanni))

• Found on sandy or Found on sandy or muddy bottoms up muddy bottoms up to 130 ft deepto 130 ft deep

• Leaves in “star-Leaves in “star-like” whorllike” whorl

• blades have blades have distinct midribs distinct midribs and veins and fine and veins and fine tooth edgestooth edges

Eel Grass (Eel Grass (Zostera marinaZostera marina))

• Most widely Most widely distributeddistributed

• Found in shallow, Found in shallow, well protected bays well protected bays and estuaries of and estuaries of cooler North cooler North Atlantic and PacificAtlantic and Pacific

Zonation and DistributionZonation and Distribution

• Zonation determined by:Zonation determined by:– SalinitySalinity– LightLight– Air exposureAir exposure

•55 species worldwide•Over half of these off Australia•The most extensive seagrass community in the world is off South Florida

Seagrasses provide:Seagrasses provide:

• Sediment stabilizationSediment stabilization

• Water ClarityWater Clarity

• Productivity and ShelterProductivity and Shelter

• Seagrasses stabilize sediments and prevent Seagrasses stabilize sediments and prevent erosionerosion

• Seagrasses take up dissolved nutrients and Seagrasses take up dissolved nutrients and trap sediments resulting in high water claritytrap sediments resulting in high water clarity

• The leaves cut down on wave action and The leaves cut down on wave action and decrease turbulence causing fine sediment to decrease turbulence causing fine sediment to be depositedbe deposited

ProductivityProductivity• Seagrass areas are the most productive Seagrass areas are the most productive

communities in the oceancommunities in the ocean

• Herbivores – feed directly on the seagrassHerbivores – feed directly on the seagrass

• Infauna – organisms that live in the sediment Infauna – organisms that live in the sediment of the seagrass area of the seagrass area

• Epiphytes – organisms that live on the blades Epiphytes – organisms that live on the blades of the seagrassof the seagrass

• Epifauna (epibethic organisms)-organisms that Epifauna (epibethic organisms)-organisms that live on the surface of the bottom sedimentslive on the surface of the bottom sediments

Sea anemone in the turtle grass

Epiphyte on the turtlegrass

Queen Conchs in Turtle grass

Sea urchin epifauna

Sea cucumber epifauna

Lobsters hiding in the seagrass

Seagrass beds provide nursery areas and feeding grounds for many species of reef fish