I Multicellular Algae Seaweeds B Green Algae Chlorophyta

I. Multicellular Algae - Seaweeds B. Green Algae (Chlorophyta) • • • Mostly freshwater species (~700 marine species) Some species common in nearshore environments Structurally simple • • • Many unicellular or filamentous Photosynthetic pigments and energy storage products similar to higher plants • May have shared a common ancestor with plants • No pigments to mask green color Habitat • • Many live as epiphytes Some species bore into calcium carbonate shells

I. Multicellular Algae - Seaweeds B. Green Algae (Chlorophyta) • • Examples Enteromorpha • Often found in polluted areas; Used as bioassay tool Ulva (Sea Lettuce) • • Found in areas with high nutrient levels Valonia (Bubble Algae) • Caulerpa Ulva • Tropical and subtropical Caulerpa • • Invasive species (C. taxifolia) Codium (Dead Man’s Fingers) • • Multinucleated Halimeda • • Calcareous alga Valonia

Codium Fig. 6. 2 - Ulva Halimeda

I. Multicellular Algae - Seaweeds C. • • Brown Algae (Phaeophyta) • • Padina Mostly marine (~1500 species) Includes largest and most complex algae - kelps Especially abundant on rocky coasts in temperate and polar regions Dominant accessory pigment is fucoxanthin Imparts yellow-brown to brown color Structurally simple to complex Some with simple flat thalli (Padina) Others with complex structures • Holdfast, stipe, blade, pneumatocysts Includes fast growing species Some kelps can grow up to 50 cm per day! Most anchored to substrate Some float (Sargassum – Sargasso Sea) Common in intertidal zone Good at withstanding mechanical stress Tolerant of exposure and desiccation Sargassum

I. Multicellular Algae - Seaweeds C. Laminaria Brown Algae (Phaeophyta) • • Fig. 6. 5 - Fucus Examples Fucus (Rockweeds) • Intertidal and subtidal species; Ecologically important Laminaria (Kelp) • • • Some species consist of a single blade Commonly used for food Postelsia (Sea Palm) • • Usually on exposed rocky shorelines Laminaria

I. Multicellular Algae - Seaweeds C. Laminaria • • Brown Algae (Phaeophyta) • • Fucus Examples Fucus (Rockweeds) Intertidal and subtidal species; Ecologically important Laminaria (Kelp) Some species consist of a single blade Commonly used for food Postelsia (Sea Palm) Usually on exposed rocky shorelines Egregia (Feather Boa) Common on rocky Pacific coast Pelagophycus (Elk Kelp) Large float Macrocystis (Giant Kelp) May reach 100 m and grow up to 50 cm day-1 Most common in cold water Laminaria

Pelagophycus Macrocystis Egregia

I. Multicellular Algae - Seaweeds D. Red Algae (Rhodophyta) • • Mostly marine (~4000 species) Common in shallow water but also found in very deep water Contain accessory pigments called phycobilins Structurally less complex than brown algae • • • Most are filamentous Much smaller than large brown algae May be heterotrophic or parasitic May incorporate calcium carbonate into tissues (Why? ) • • • Sebdenia Coralline red algae May be important in formation and cementing of coral reefs May contribute to formation of carbonate sand Some encrusting, others arborescent Many are commercially important

Pelagophycus Halimeda Porphyra

I. Multicellular Algae - Seaweeds E. Life History 1. Asexual • • 2. Fragmentation – Especially in species with no holdfast Spores – Resistant dispersal stages • Zoospores – Flagella permit motility Sexual • • Rare in unicellular algae; common in multicellular forms • Gametes produced by meiosis Two types of life stages • Haploid (n) – gametophyte generation • Diploid (2 n) – sporophyte generation Alternation of generations between gametophyte and sporophyte stages Four basic patterns of sexual reproduction

Fig. 6. 11

I. Multicellular Algae - Seaweeds F. 1. 2. Economic Importance • • Food Source Harvested Mariculture • Red algae (Porphyra, Eucheuma) • Brown algae (Laminaria) Products a. • • • b. • Phycocolloids Algin (Extracted from kelp; harvested with boats) • Stabilizer, emulsifier for ice cream, cheese • Stabilizer to keep frostings and baked goods moist • Thickener, emulsifier for shampoo, shaving cream, plastics, rubber, paints, cosmetics, textiles Carrageenan (Extracted from red algae) • Emulsifier for dairy products, toothpaste, puddings Agar (Extracted from red algae) • Used to form jellies, thicken mixtures • Preserves, pharmaceutical applications Other Fertilizers, additives in animal feeds

II. Flowering Plants (Angiosperms) • Flowering plants have true leaves, stems and roots (unlike multicellular algae) • • • Contain specialized tissues that transport water, minerals and nutrients Dominant sporophyte Few truly marine species • • Seagrasses entirely submerged most of the time, but other marine angiosperms intolerant of prolonged immersion Marine angiosperms expend considerable energy coping with effects of salt water Seagrasses (50 -60 species) A. • • • Not true grasses (related to lilies) Roots, stems and shoots grow from horizontal rhizome Flowers typically small and inconspicuous (Why? ) • Pollen carried by water currents; No need to attract pollinators

II. Flowering Plants (Angiosperms) A. Seagrasses Eelgrass (Zostera) – Temperate Atl, Pac; Tropical Pac 1. • • • Most widely distributed; in shallow, protected coastal waters Common in oxygen-poor sediments Highly productive; provides shelter for many animals Surf grass (Phyllospadix) – Temperate Pac 2. • • Lives on rocky shores; experience wave action May be exposed at low tide Turtle grass (Thalassia) – Tropical 3. • • Lives on muddy and sandy bottoms in calm waters to 10 m Stabilize sediments on landward sides of Caribbean reefs

Fig. 6. 13

Eelgrass (Zostera marina)

II. Flowering Plants (Angiosperms) A. Seagrasses Eelgrass (Zostera) – Temperate Atl, Pac; Tropical Pac 1. • • • Most widely distributed; in shallow, protected coastal waters Common in oxygen-poor sediments Highly productive; provides shelter for many animals Surf grass (Phyllospadix) – Temperate Pac 2. • • Lives on rocky shores; experience wave action May be exposed at low tide Turtle grass (Thalassia) – Tropical 3. • • Lives on muddy and sandy bottoms in calm waters to 10 m Stabilize sediments on landward sides of Caribbean reefs

Fig. 6. 13

Surf Grass (Phyllospadix scouleri)

II. Flowering Plants (Angiosperms) A. Seagrasses Eelgrass (Zostera) – Temperate Atl, Pac; Tropical Pac 1. • • • Most widely distributed; in shallow, protected coastal waters Common in oxygen-poor sediments Highly productive; provides shelter for many animals Surf grass (Phyllospadix) – Temperate Pac 2. • • Lives on rocky shores; experience wave action May be exposed at low tide Turtle grass (Thalassia) – Tropical 3. • • Lives on muddy and sandy bottoms in calm waters to 10 m Stabilize sediments on landward sides of Caribbean reefs

Fig. 6. 13

Turtle Grass (Thalassia species)