Chapter 7

Multicellular Primary Producers

Seaweeds

Seaweeds!!! Come in all kinds of interestingShapes and sizes! • some are delicious! • some are poisonous • Some have weird names • Come in all sorts of colors

Seaweed Structure

• Thallus-body• Lack vascular tissue -Do not

have roots, stems, or leaves

• Holdfast -The structure that attaches the seaweed

to the substrate • Stipe-stem-like structure

Phylum Chlorophyta (green algae)• Contain chlorophylls a and b for photosynthesis• Most are freshwater • Ecologically important

– food source – Contribute to coral reef formation– Some are invasive

Green algae structure

• Most unicellular• Marine species have coenocytic thallus-

containing more than 1 nucleus– Occurs by cell growing– nucleus divides

but cell never divides

Reproduction of Algae

• Sexual • Gametes released from gametophyte 2 flagella• spores released from sporophyte- 4 flagella

Representative species

• Halimeda• Caluerpa-invasive

CFU: Green Algae

• Are green algae unicellular or multicellular • Autotrophic or heterotrophic • What is an important organelle in

photosynthesis • How does green algae grow in length?

– Same cell, division of nucleus • What is the function of the Stipe?

Red Algae

Phylum Rhodophyta (red algae)

• Primarily marine• Most diverse among seaweeds• Cholorphylls a and d, pigments:

phycoerythrins and phycocyanins • Not always red in color- can appear yellow to

black

Structure

• Multicellular and less than 1 meter long• Wide variety of shapes and organization

among species

Reproduction

• Can vary from simple to complex…but 2 unique features………..

1. Lack flagella on spores and gametes

2. 3 multicellular stages1. Carpospore-unique

to red algae

Ecological Roles

• Porphhra- used as food in oriental dishes• Seasonal food source for urchins, mollusks,

fish, and crustaceans• Some grow on other plants or animals• Help form base of coral reef• Agar- used as a thickening agent in foods such

as ice cream, pudding, and salad dressings• Used in cosmetics for creamy foundations

CFU: Red Algae

• Heterotrophic or Autotrophic?• Multicellular or unicellular • What are the two unique stages? • What organisms feed on red algae?

Brown Algae

Phaeophyta (brown algae)

• Mostly marine• Higher diversity than green but less diverse

than red• Size: from microscopic to kelps (100 meters)• Chlorophylls a and c and pigment fucoxanthin• Mostly in high latitudes• Large flat leaf-like blades with bladders help

bouy plant toward light• Representative species Sargassum, Fucus

reproduction

• Gametophyte is eliminated from life cycle (difference from Chlorophyta and

Rhodophyta)• Egg develops

root-like structures (rhizoids) after fertilization

Ecological role

• Habitats for a variety of marine life• Harvested for thickening agents used in

dentistry, cosmetic, and food industries• Previously iodine was extracted and put into

table salt (iodized salt) to prevent a goiter

Human Impacts • Excessive nutrients

– Runoff from fertilizer • Causes huge algae

blooms! – When algae dies off

decomposers consume majority of the oxygen in the environment

– Eutrophication • Kills off fish and marine

life

CFU: Algae

• What macromolecule allows algae to live in marine environments without swelling?

• What causes algae blooms? • What is this process called? • What are the harmful effects of algae blooms?

Sea grasses, salt marsh plants, mangroves

Salt Marsh Plants and Sea Grasses

• Salt marshes are in Estuaries – The kidneys of the coasts

• Nursery for small fish – 75% of commercial fish are hatched in estuaries

• Estuaries are severly affected by humans – Coastal development – Pollution – Eutrophication

• Protect us from storms

Phylum Anthophyta• Seagrasses, salt marsh plants, mangroves• Ecological Roles- Primary producers, habitats,

stabilizing sediments• Help slow down erosion • Have to deal with extreme changes in salinty

and oxygen Mixing of salt and fresh water Eutrophication

Sea grasses (marine flowering plants)

• Related to lilies• Reproduce by pollination of seed; Male and female flowers on

separate plants contain pollen• Literally look like grass • Food for manatees and sea turtles • Can live up to 100 meters below sea level

Sea Grasses in Florida

• 12 genra– Genra native to Florida

• Syringodium -manateegrass

• Halophila-paddlegrass• Thalassia- turtlegrass• Ruppia- • Halodule- shoalgrass

Salt Marsh Plants• Adapted to high levels of salinity and tidal action• Found in estuaries – level of succession based on salinity and tidal tolerance• Species native to Jacksonville

– Spartina Alternaflora– Batis Maritima– Spartina patens– Juncus– Salicornia virginica

Mangroves

• Found in south of St. Augustine to Key West• 3 genra local to Florida

– Rhizophora mangle –red mangle-----prop roots– Avicennia germinans – black mangle---

pneumatophores– Laguncularia racemosa- white mangle

• Distinctive by their root system and pods

Mangroves: Highly adaptive

• Use active transport to regulate water levels in their roots

• Live in anaerobic mud– Why they stand above

the water

• Protect coral reefs from eutrophication – Filter, kidney

Help Protect Coastal Development2004 Indian OceanTsunami

Mangrove reproduction

• Flowers pollinated by wind or bees• Embryo grows on the plant in a propagule

(similar to seed)• Propagule eventually falls from parent and is

carried by current until it settles and takes root

Black Mangrove

Red Mangrove

Red, White, and Black mangrove leaves

White Mangrove