description of sea grass ecology

1. Seagrass Ecology
Estuarine seagrass ecosystems in
North Carolina and Florida

2. Seagrasses
• Angiosperms (flowering plants) that live
life entirely underwater
• Primary productivity is among the highest
measured (500 - 4000 g C/m2/year)
• Important feeding and refuge habitat for
fishery species (shrimp, scallops, fishes)
• Seagrasses act as sediment stablizers help to
filter water

3. Major polyhaline seagrass
species
Scientific name Common
name
Salinity range
(ppt)
Zostera marina eelgrass 7 - 35
Halodule wrightii shoal grass 12-35
Thalassia testudinum turtle grass Tolerance: 3.5 - 60
Optimum: 24-35
Syringodium filiforme manatee grass 24-35
Halophila spp. “Halophila” 35
Ruppia maritima widgeon grass 2 - 70

4. Major oligohaline aquatic
macrophytes
Scientific name Common Name Salinity range (ppt)
Vallisneria americanum wildcelery or freshwater
eelgrass
0 - 9
Potamogeton pectinatus Sago pondweed 0 - 9
Potamogeton perfoliatus redhead grass 0 - 9
Zanichellia palustris horned pondweed 0 -25
Myriophyllum spicatum Eurasian watermilfoil 0 -10
Najas guadalupensis bushy pondweed 1- 15

5. Seagrass productivity
Species Location Productivity
(gC/m
2
/day)
Thalassia testudinum Florida
Puerto Rico
0.9 -16
2.5 - 4.5
Syringodium filiforme Florida
Texas
0.8 - 3.0
0.6 - 9.0
Halodule wrightii North Carolina 0.5-2.0
Zostera marina North Carolina
Rhode Island
0.2-1.7
0.4-2.9

6. Habitat Complexity
• Habitat complexity is high in seagrass/SAV
• Predators are inhibited by complexity
because the prey have many places to hide
• Densities of many invertebrates (infaunal
and epifaunal) and small fishes are greater
in SAV than in nearby unvegetated areas
• Seagrass provides a refuge from predation

7. Types of animals in seagrass
• Infauna: bury in sediment.
– Polychaete worms, amphipods, clams, benefit from root and
rhizome mat which protects from predators
– deeper-living animals survive better than shallow-living
(Mercenaria > Chione)
• Epifauna: Live on surface of blades and sediment
– Meiofauna (harpacticoid copepods), macrofauna (amphipods.
isopods), tube-dwelling sessile polychaetes, gastropods, decapods
– Shoot and leaf complexity provides refuge
• Mobile fauna: Live in water over canopy
– fishes swim above canopy, dive into it when predator