3 IntroductionNonplant photosynthetic organisms include photosynthetic bacteria and unicellular algae and the seaweeds.The seaweeds are “plant-like” because they are multicellular primary producers. A few seaweeds are actually not primary producers but instead parasite other seaweeds.
6 Introduction to Multicellular Algae Seaweeds= macrophytes =macroalgaeAll multicellular (unicellular green and brown algae are not seaweeds)EukaryoticThere is a large variety of seaweeds
7 General Structure Seaweeds Lack true leaves, stem, and roots of plants Have the following structures:Thallus – complete body of seaweedBlade – leaf-like flattened portion of thallus. This provides a large surface area for photosynthesis. They have no veins.Pneumatocysts – gas-filled blades used for floatationStipe – stem (with no vascular tissue)Holdfast – attaches the thallus to the bottom (not roots). No water/nutrient transport system.
12 Types of Seaweeds Green Algae Phylum Chlorophyta Only about 10% of 7,000 species are marine (most of them are unicellular).They are very common in some marine environments.Typically they are bright green because the chlorophyll is not masked by other pigments.
14 Types of Seaweeds Some types of green algae: Filamentous – filaments may be branched or notEnteromorpha – have a thin thallus form a hollow tube and are found in areas of high pollution.Sea lettuce (Ulva) – paper-thin sheetsValonia – forms large spheres in the tropics and subtropicsCaulerpa – single tube with multiple nucleiDead man’s fingers – (Codium) – multinucleated filaments woven into a spongy branching thallus.Halimeda – calcareous green algae – thallus contains filaments that contain calcium carbonate, when it dies, it plays a role in the formation of coral reefs.
17 Green AlgaeHalimeda…a calcareous reef building alga
18 Phylum: Heterokontophyta, Class: Phaeophyta Types of SeaweedBrown AlgaePhylum: Heterokontophyta, Class: PhaeophytaAnatomy:Brown color comes from more fucoxanthin (yellow-brown pigment) than chlorophyll.Almost all species are marine
19 Phylum Heterokontophyta: Class Phaeophyta – Brown Algae
20 Types of Seaweed Brown Algae Some examples of Phaeophyta Kelps (Laminaria, Agarum, Alaria, Egregia, Eisenia, Nereocystis, Macrocystis)EctocarpusDictyotaPadinaDesmaresFucus – Rockweed or wracks (exposed at low tide)Sargassum – spherical air bladders that keep it afloat
26 Types of Seaweeds Red Algae Phylum: Rhodophyta Most common of the three.Have red pigments called phycobilins which mask chlorophyll.Mostly marineNot as complex as brown algae, some are parasites, others have lost their chlorophyll and become heterotrophsMost are filamentous
28 Types of Seaweed Red Algae Examples: Gelidium and Gracilaria are found worldwideEndocladia forms wiry clumps on rocksGigartina – one of the most massive red algae (blades up to 2m long)Porophyta – found on rocky shoresRhodymenia – found in the Atlantic – blades can reach 1m longChondrus – Iris mossCorallina – red algae that deposit calcium carbonate – involved in the creation of coral reefs.
33 Life HistoryAsexual reproduction is more important than sexual reproduction.Some seaweeds produce spores (that can live dormant in unfavorable conditions)Some have a thick wallZoospores have a flagellaSexual reproduction (with the production of gametes) is common in seaweeds. This ensures genetic variation.Turn your textbooks the page 107.
37 Economic ImportanceFarming or mariculture of seaweed occurs all over the world.Seaweeds produce several types of gelatinous chemicals called phycocolloids.Algin (an important phycocolloid) has many uses (frosting, dairy products, shampoo, shaving cream, plastics, pesticides, etc.) It is found in kelp (Macrocystis).
38 Economic ImportanceCarrageenan (another important phycocolloid) found in red algae, it is used in dairy products as well as a variety of processed foods.Agar (another important phycocolloid) protects ham, fish, and meats during canning, in low calorie foods, and as a thickener. It is also used in research.Some other uses for seaweeds includes fertilizers, food additives, and wound dressing in hospitals.
45 Introduction to Flowering Plants There are 250,000 species of flowering plants (common name: angiosperms)/(phylum or division: Magnoliophyta)Few live in the oceanThey have true leaves, stems, and roots (that transport nutrients and water).They belong to the kingdom plantaeReproduction involves an elaborate reproductive organ, the flower.Most of these species are not truly marine (only the seagrasses are). The others spend some time (at high tide submersed or just their roots are submersed).
47 SeagrassesSeem to resemble grass but are not grasses. They are most closely related to the lily family.Horizontal stems called rhizomes.Flowers are small and inconspicuousPollen is carried by water currentsEelgrass or Zostera (50-60 species known), it is found in oxygen poor bedsSurf grass inhabits areas on rocky coasts exposed to wave action.
55 Seagrasses are flowering plants Reproductive plantsflowerFruit with seeds
56 Salt MarshMedcalfe Marsh, near Charleston, Oregon
57 Salt-Marsh PlantsCordgrasses are true members of the grass family – they are not really marine. They just tolerate the salt air and spray.Tolerant plants called halophyles live in salt marshes but keep their leaves above water. Many of them have leaves that contain salt glands.
61 MangrovesTrees and shrubs adapted to living along tropical and subtropical shores around the world.More than 80 different species of plants share the common name “mangrove”.Red mangroves are found in areas without frost. Some adaptations of red mangrove are: thick leaves, seeds germinate while still attached to the parent tree. (Like a pencil, once mature, it falls and sticks into the mud)
62 MangrovesMangroves thrive in salty environments and are able to obtain freshwater from saltwater.Some spp. secrete excess salt through their leaves while other block absorption of salt at their roots.
63 Mangrove ImpactsAt one time, nearly 0.5 million acres of mangroves surrounded Florida’s coastal zone contributing to ecosystem health in a variety of ways.-Trap and cycle organics, chemical elements, sediment and minerals.-Provide shelter for marine organisms.