Ecology of South Florida (EVR 3013) LECTURE 24

MARINE COMMUNITIES I
SEA GRASSES

BISCAYNE BAY
The bay
At sunset is
An old silver mirror
In which Evening looks to apply
Her rouge. 		 The bay
At mid-day is
A zircon, its blue-green
Eyes quick to catch the tropic skies
At play.
Aleda Norma Davis (1931) [in Jones and O'Sullivan 1995]
HANDOUTS: 1. Species List for sea grass community

I. INTRODUCTION

A. Sea grasses are not true grasses

B. Distribution

Worldwide 2 families, 12 genera, 45 species

C. Productivity

Among the most productive of nearshore coastal communities

II. PHYSICAL FEATURES

A. Distribution

  1. 10,000 km2 in Gulf of Mexico (75% in Florida)
  2. 5,500 km2 in Florida Bay and surrounding waters
  3. Cover 80% of the bottom between Cape Sable, North Biscayne Bay and Dry Tortugas

B. Physical Attributes

  1. Not found on high energy shores
  2. Best developed where sediment transport is low
  3. Best-developed where tidal flow is significant
  4. Limited to about 10m depth

III. PLANTS

A. Vascular Plants

diversity very low

1. Thalassia testudidum

Turtle grass--Hydrocharitaceae--long, ribbon-like leaves, 4-12 mm wide and 10-35 cm long.  This is the most important species.

2. Syringodium filiforme

Manatee grass--Cymodaceae--leaves 1 mm wide to 50 cm long.

3. Haludole wrightii

Shoal grass--Cymodaceae--blades 1-3 mm wide and 10-20 cm long, early colonizers of disturbed sites

4. Halophila engelmanii

Sea grass--Hydrocharitaceae

B. Algae

very diverse

C. Plant Species List For Sea Grass Beds


1. Sea Grasses

Turtle grass Thalassia testudinum
Manatee Grass Cymodacea filiforme

2. Algae

Umbrella Algae  Acetabularia crenulata
Green Fleece Coduium decorticum
Disk algae Halimeda incrassata
Mermaid's Shaving Brush Penicillus captitatus
Sargassum Sargassum natans
Sea lettuce Ulva lactuca

IV. ANIMALS

A. Diversity and abundance very high

B. Animal species list for Sea Grass Beds


1. Birds
American coot  Fulica americana
Osprey Pandion haliaetusSSC
Laughing gull Larus atricilla
Ring-billed gull Larus delawarensis
Royal tern Stern maxima
Double-crested cormorant Phalacrocorax auritus
Brown pelican Pelicanus occidentalisSSC

2. Reptiles
Green sea turtle Chelonia mydasT
American crocodile Crocodylus acutusT
Loggerhead turtle Caretta carettaT

3. Fish
Bonefish Albula vulpes
Snook Centropomus undecimalis
Mangrove snapper Lutjanus griseus
Tarpon Megalops atlanticus
Mullet Mugil cephalus
Red drum Scieanops ocellatus
Great Barracuda Sphyraena barracuda

4. Mammals
Florida manatee Trichechus manatusT
Bottle-nose dolphin Tursiops truncatus

5. Sponges
Loggerhead sponge Spheciospongia vesparium
Vase sponge Icinia campana

6. Jellyfish
Portuguese man-of-war Physalia physalia

7. Gastropods
Horse conch Leuroploca gigantea[state shell]
Queen conch Strombus gigasSSC

8. Bivalves

Oyster Crassotrea virginica

9. Crustaceans
Blue crab Callinectes sapidus
Spiny lobster Panulirus argus
Pink shrimp Peneaus duorarum
White shrimp Penaeus setiferus

10. Sea urchins
Long-spined sea urchin Diadema antillarum
For superscript by species name: C = commercially exploited, SSC = species of special concern, T = threatened. Florida Game and Freshwater Fish Commission listings. EX = exotic.

V. BIOTIC RELATIONS

A. Endemics

None

B. Exotics

None

C. Diversity

Plants low, animals high

D. Zonation

VI. ECOLOGICAL PROCESSES

A. Importance

1. High production and growth

Leaves grow 5 mm per day on average and up to 10 mm per day

2. Food and feeding pathways

2 pathways--direct and detrital, export to other communities

3. Shelter

nursery beds

4. Habitat stabilization

stabilize sediments in two ways, slow water currents near sediment water-interface, roots and rhizomes bind sediments

5. Nutrient effect

Epiphytes fix nitrogen, take up nutrients through the sediments

B. Productivity

1. Haludole

1.1 g C/m2/day {up to 240 C m-2 year-1]

2. Syringodium

0.8 - 3 g C m2/day [up to 720 C m-2 year-1]

3. Thalassia

0.9 - 16 g C m2/day [up to 3840 C m-2 year-1]

4. Florida Bay

up to 1100, [70% from turtle grass and 20% from algae, plus 10% in water column]

C. Succession

1. Colonizers

Typically algae. (Halimeda, Penicellus, Udotea and Rhipocephalus)

2. Haludule wrightii

Colonizes next, from seed or rhizome

3. Climax

Syringodium then Thalassia

VII. HUMAN EFFECTS

A. pre-Columbian

Fishing

B. 18th and 19th century

1. Fishing

2. Dredging

3. Change in water quality

C. 20th century

1. Importance

Sport and commercial fishing
  1. Spiny lobster
  2. Pink shrimp
  3. Striped mullet
  4. Blue Crab
  5. Tarpon
  6. Snook
  7. Mangrove snapper

2. Effects

  1. Change in water quality
  2. Change in water quantity
  3. Dredge and fill
Back to start,  Back to lecture 20,  21,  22,  23,  On to lecture 25,   26,  27

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