Marine Algae

• Scientists who study seaweeds are called phycologists

What is algae? • Commonly known as seaweed • Plantlike aquatic organisms that vary in size from microscopic to macroscopic • Although multicellular- they are classified in the kingdom Protista • Live in sunlight waters

Not the same as land plants!! Why? - Algae do not have true stems, roots, or leaves How similar to land plants? - Produce food and oxygen though photosynthesis

Why are they important to the sea? Important to the sea: both directly and indirectly • All animal life in the ocean is in some way linked to marine plants and seaweeds are essential to ocean health - Chloroplasts are food factories- the place where sugar is manufactured - Some marine animals eat algae for this benefit - When algae dies, it decomposes and the sugar (glucose) and other nutrients are released into the water where microscopic algae and filter feeders take in the nutrients - Oxygen producers

Why are they important to humans? • Some 400 different species around the world are used by people for food, stock feed, medicines, and fertilizers • You probably have eaten some seaweeds today –extracts from seaweeds are used in toothpaste, ice cream, and many other foods

5.1 Marine Algae cont. • Agar: chemical found in other red algae used to make – Food – medicinal product – medium for growing bacteria in labs.

What are the 3 types of Algae? • Brown Algae- The Phaeophyta • Red Algae- The Rhodophyta • Green Algae- The Chlorophyta

5.1 Marine Algae cont. Green Algae • Classified in phylum Chlorophyta, – most closely related to plant, due to pigments – lack typical roots, stems, and leaves – nonvascular plants water passes directly into algae’s cells from their surroundings. – 3 types Enteromorpha, Codium, Acetabularie

Green: Chlorophyta Ulva (sea lettuce)- thin, leafy, bright green, shallow water EnteromorphaFilamentous, on rocks, intertidal zone Codium- spongy, bracnching, subtidal zone

5.1 Marine Algae cont. Brown Algae • Classified in phylum Phaeophyta, – color brown or olive-green due pigments in cell, chlorophyll and yellow pigment zanthophyll. – Important member of ecosystems – providing shelter or nutrients for other organisms. – People eat algae raw or cooked.

• 3 types Sargassum, Laminaria, Fucus

Brown: Phaeophyta Laminaria (kelp)- long fronds, holdfast on rocks, subtidal zone Sargassum – floats, branching, provides cover, open sea

Fucus (rockweed)- air bladders, branching, intertidal zone

• Kelp: the brown algae – Largest seaweed in the ocean. – Grows rapidly from the seafloor to the surface. – One species of kelp, Laminaria, thrives in the colder waters. – Giant kelp Nereocystis and Marcrocystie reach 60 meters and more. – used in different industries, • • • •

ingredient in prepared foods, Medicines Paints paper product.

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Holdfast: keeps the kelp tightly anchored to the ground, so it won’t be pushed away by the waves; must glue on to a rock or hard substrate, not soft, sifting sand; different from roots because it doesn’t actually grab nutrients from the ground -instead, nutrients can enter any part of the plant, all of which can photosynthesize.

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Stipe: long like a stem, with room for many “branches”, but doesn’t have tubes and “sap”.

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Blades: analogous to leaves; long and broad in order to collect as much sunlight as possible for photosynthesis.

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Bladders: air sacs to hold the plant up; the stipe isn’t a strong support, and the blades need to reach the water’s surface to get sunlight, so these air bubbles make the top

of the plant float.

• http://www.youtube.com/watch?v=GcbU4b fkDA4

Red Algae • Most abundant and commercially valuable. phylum Rhodophyta. • 3 types of red algae – Coralline algae (Corrallina) – Irish moss (Chondrus crispus) – Porphyra.

• Found on rocky shores from the in intertidal to the subtidal zones, also found at much greater depths than either brown or green algae. • Red pigment phycoerythrin and the blue pigment phycocyanin enable red algae to use limited light at deep depths to carry out photosynthesis.

Red Rhodophyta • Chondrus (irish moss)short, bushy, covers rocks, subtidal zone • Porphyra- thin leaves, attaches to rocks, intertidial zone • Corallina- hard, brittle, branching, intertidal zone

Effects of temperature on seaweed distribution • The greatest diversity of algal species is in tropical waters • Marine algae in colder waters are PERENNIALS meaning it completes its life cycle in more than two growing seasons • During the colder seasons only part of the alga remains alive, sometimes as a mass of stem-like structures. When the temp warms up in the spring, this body part initiates the new growth

• http://www.youtube.com/watch?v=QP_Hb Q5cWSk