Download Marine Plants

Marine Plants
 Macroscopic, multicellular organisms that are usually large enough to
pick up and examine
 Require sunlight - confined to the photic zone
 Restricted to shallow waters
 Play an important role as a the trophic level organism
 Reproduction may be either sexual or asexual
Seaweed - a group of larger marine plants attached to the bottom in
relatively shallow waters.
 Common in intertidal regions
 Can be found up to 200 meters deep
 Some can tolerate extreme surf action
 Provide food, protection from waves, shade and a substrate for animals to
attach.
Four divisions of Marine Plants
1.
2.
3.
4.
Phaeophyta (Brown Algae)
Rhodophyta (Red Algae)
Chlorophyta (Green Algae)
Anthophyta (Flowering plants)
Division Chlorophyta - Green Algae
 Varies in structure - from simple filaments to flat sheets
 Usually less than 1/2 meter long
 Few species compared to red or brown algae
Division Phaeophyta- Brown Algae
 Photosynthetic pigment - xanthophyll (pigment is golden in color) and
chlorophyll (green pigment)
 A typical brown algae is a drab-olive green
 Example - Kelp
Division Rhodophyta - Red Algae
 Has a pigment called Phycobilin - red and blue pigment and chlorophyll
(green pigment)
 This division can vary in color from a bright green to brown to reddish
purple.
 Usually do not exceed 1 meter in length.
Structure of Algae
 Lack roots, flowers, seeds and true leaves.
 Wide range of shapes and sizes
 Mature plants have:
1. Blades,
2. Stipes
3. Holdfasts
Blade - Flattened, broad leaf like structure that can branch
-It houses the photosynthetic cells (although the stipe and
holdfast can also photosynthesize)
Pneumatocysts - gas filled floats that help lift the blades
toward the sunlight. Ex. Sargassum
Stipe - the "stem"
-considered to be the shock absorber in the plant
Holdfast - is the structure that attaches the plant to the substrate
Division Anthophyta - Marine Flowering Plants
 Found in bays, estuaries, along sea shores
 Have leaves stems and roots
Submergent Plant Communities Seagrass beds - halophtyes (thrive in salty environments)
 Submerged vegetation that exists in the intertidal and subtidal areas
of the embayments
 Found in shallow water - because of their need for sunlight
Why are seagrass beds important?
1. Provide a feeding grounds for marine organisms
2. Refuges for commercially important benthic invertebrates and some fish
3. Provide a breeding ground for juvenile fish
4. Filter excess nutrients in the run-off water
5. Provide oxygen
6. Stabilize the sediment
In Alabama, there are two types of sea grass that are found:
1. Thalassia - (turtle grass)- the only flowering sea grass
2. Zostera (eel grass)
Seagrass can reproduce both sexually and asexually
Asexually
 Use rhizomes that produce shoots, a root anchors each shoot, and
clones are formed (genetically identical to the parent)
 A seagrass meadow may actually be a single individual connected
by rhizomes.
Sexually- via seeds
 Seeds are retained by special blades on female plant
 The male plant releases sperm into the water and fertilizes the seed
 Seeds are then released and distributed by the current.
Emergent Plant Communities - Mangroves and Salt Marshes
Mangroves - warm climate
 Have a number of specialization's
that allow them to survive in a salty
wet environment- considered to be a
halophyte
 Common in southern Florida
 Three species that are common:
Red, black and white mangroves
 All three types are pollinated by
bees and crabs
 Each tree produces a propagule
(a seed that grows while still on a tree).
Once the propagule matures, it drops off the
tree and may either be carried by the current
or settle near the parent. The propagule can
float for several months.
Red Mangroves -are found closest to the sea. Prop roots extend from the tree and allow the
tree to anchor and take up nutrients. The prop root also allows the tree to
breath when the tide comes in.
 Lenticels - specialized cells in the prop root that open up during low
tide and allows air to diffuse into the plant. During high tide, the
lenticel closes
 have a chemical defense mechanism against insects and other animals
Black Mangroves -Pneumatophores - are roots of this tree that are aerial, extending out of
the ground used for gas exchange. They can be up to 30 cm long.
-The roots of the Black mangrove contain chlorophyl and can
photosynthesize.
-"Salt Glands" - are specialized cells that can excrete salt from the upper
surface of the leaves. This helps decrease the salt content of the water
inside the tree.
- have a chemical defense mechanism against insects and other animals
White Mangroves
-does not have aerial roots
-usually the most landward species of mangroves
-also has salt glands
Salt Marshes - Cooler Climates
 In Alabama, we have salt marshes that have Spartina (Cord Grass). This
plant is submerged during high tide.
 They provide a feeding ground and a hiding place for juvenile fish and
crabs during tidal periods.
 Spartina also has a salt gland that allow the plant to secrete salt on it's
leaves.
Salt Marsh in Virginia