Transcript Green algae
Chapter 6 Multicellular Primary Producers: seaweeds and plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Non-plant photosynthetic organisms Photosynthetic bacteria, unicellular algae and seaweeds Multicellular algae: the seaweeds Also called macrophytes, macroalgae, macrobenthic algae Classification of seaweeds and marine plants Characters all eukaryotes all multicellular lack highly specialized structures and reproductive mechanisms characteristics of land plants 5 Figure 6.01 General structure General structure Thallus(葉狀體) Blades(葉片); 2 characters (no vein, identical on both sides) Pneumatocyst (氣泡) Stipe (莖片) Holdfast (固著器) -- lack of transport abilities 7 Three types of seaweed Green algae Brown algae Red algae -- Differences depends on the proportion of different pigments 8 Green algae 9 Green algae Phylum Chlorophyta Most restricted to freshwater and terrestrial environments 7000 species; 10% is marine; many are unicellular Distributed mainly in the bays, estuaries and isolated tidal pools land plants may evolved directly from green algae chlorophyll pigment 10 Figure 6.02 bottom sea lettuce Ulva(海萵苣) Dead man’s finger -- extend from tropical to temperate waters Calcareous green algae Figure 6.04 Brown algae Brown algae Phylum Heterokontophyta, Class Phacophyta Fucoxanthin(褐藻素) dominate over chlorophyll primary producers on temperate and polar rocky coasts Almost 1500 species are marines Include the largest and most complex seaweeds 15 Figure 6.05 rockweeds or wrack Figure 6.06 rockweeds or wrack Floating algae; Sargasso Sea, Kelps: great abundance in temperate and sub-polar latitudes. -- form kelp beds or forest 18 kelp Kelp forest Kelps • Found in deeper water below the lowest tide level • Can grow at least 50 cm per day in optimal condition, reaches 100 m • Among the richest, most productive environment in marine realm 20 Figure 6.09 Red algae Red algae Phylum Rhodophyta red pigments; phycobilins mask chlorophyll The largest group of seaweeds, about 4000 species; most exclusively marine Found in most shallow water marine environment Filamentous red algae and flatter branches 22 Coralline red algae 23 Coralline red algae Smooth or rough encrusting growth on rocks Warm-water coralline red algae actively involve in formation and development of coral reefs. 24 Life history (reproduction) Asexual reproduction and sexual reproduction Asexual reproduction vegetative reproduction -- (1) fragments of thallus, (2) produce spores zoospore (游動孢子) 26 Sexual reproduction create gametes and form zygotes Four basic patterns (types) of reproduction 28 Figure 6.11a Type A: most common among all groups of seaweeds Figure 6.11b Type B: unique to red algae -- 3 generations Figure 6.11c Type C: some green and brown algaes -- similar to the sexual reproduction Figure 6.11d Type D: in some green algaes Gamete development can be influenced by: (1) amount of nutrients, (2) temperature, (3) length of day light Trigger factors : splashing of incoming tide, or by chemical messagers of opposite sex. -- Some male and female gametes timed to release at the same time 33 Figure 6.12 Economic importance Farming or mariculture of seaweeds Economic importance -- Phycocollids -- Algin -- carrageenan -- Agar; -- Seaweeds 35 Economic importance Phycocollids: food processing; form suspension and gel Algin: stabilizer and emulsifier, baking, chemical industries, pharmaceutical, texture, etc. Carrageenan: emulsifier, diaery products Agar: foods, canning, cosmetics, medicine Seaweeds: fertilizer, hospitals, nutritional supplements, reduce soil acidity 36 Flowering plants • about 250000 species, or angiosperms • Divison Magnoliophyta -- Kingdom Plantae • True roots, leaves, stem; specialized tissue for transport materials • Reporduction by sporophyte (flower) 37 Seagrass Truly marine plants Characters; (1) rhizomes, (2) pollens are long and thread-like ; transported by water column of animal feces 38 Figure 6.13a Seagrass Figure 6.13b Eelgrass -- about 60 species -- in many temperate and tropical regions -- inhabits shallow, well-protected coastal waters -- distinctively flat, ribbon-like leaves -- in oxygen-poor sediment Salt marsh plants 41 Salt marsh plants Cordgrass, land-plants tolerant of salt Live in salt marshes and other temperate soft-bottom coastal areas Submerged by seawater only at high tide halophytes 42 Functions of Salt marsh Highly productive, provide habitat and breeding grounds for many commercial species Protection against erosion and provide natural water purification system 43 Figure 6.14 Mangrove Mangrove Shrubs and trees adapted to live along tropical and subtropical shores Essentially land plants that can tolerate salt About 80 mostly unrelated species of flowering plants 45 Adaptations prop roots Viviparous seed Waxed leaves