1. Marine Science Chapter 5 Marine Algae & Plants

2. 5.1 Marine Algae  Algae  Algae is a plantlike aquatic organisms that vary in size from microscopic to macroscopic (multicellular), with some species more than 60 meters long. multicellular  Organisms that are multicellular are made up of more than one cell.  Seaweeds  Seaweeds are multicellular algae that live in the sunlit waters of the ocean.

3. 5.1 Marine Algae  You can find seaweeds deposited along the strandline.  Ulva  Ulva is tissue-thin sea lettuce, bright green in color of due to the chloroplasts in its cells.  More than 500 species of macroscopic algae live in the ocean.  These algae are classified according to the color of the pigments in their cells, green, brown, & red.

4. 5.1 Marine Algae Reproductive Cycle of Algae thallus  The leafy part of a seaweed is called the thallus. sporophyte thallus  Specialized cells at the edge of the thallus produce spores. The thallus that produces spores is called the sporophyte thallus, which is diploid.  Diploid  Diploid refers to the normal number of chromosomes, found in the body cells of an organism.  Haploid  Haploid refers to one-half the normal number of chromosomes, found in the reproductive cells

5. 5.1 Marine Algae Reproductive Cycle of Algae spore  The spore is a reproductive cell that contains the organism’s haploid number of chromosomes.  Spores have flagella that beat back and forth, thus moving them along. gametes gametophyte thallus  Each spore develops into a leafy thallus that produces gametes. This thallus is called the gametophyte thallus, and it is haploid.

6. 5.1 Marine Algae Reproductive Cycle of Algae  The gametes it produces are reproductive cells that contain the haploid number of chromosomes necessary for sexual reproduction. fertilization  The union of a sperm cell with an egg cell is called fertilization. zygote  The two gametes fuse to produce a zygote, a fertilized egg cell that contains the species’ normal diploid number of chromosomes.

7. 5.1 Marine Algae Reproductive Cycle of Algae sporophyte (diploid) thallus  The zygote divides and develops into the next leafy sporophyte (diploid) thallus. alternation of generations.  This succession of two types of generations (sporophyte/asexual and gametophyte/sexual) is called alternation of generations.

8. 5.1 Marine AlgaeGreen Algae The green algae are classified in the phylum Chlorophyta. Many species of green algae grow attached to rocky substrates on or near the ocean’s surface. Green algae lack the typical roots, stems, and leaves that are found in most land plants. Land plants that have water-conducting cells are called vascular plants. Plants that do not have special water-conducting cells are called nonvascular plants. Water passes directly into the algae’s cells from their surroundings.

9. 5.1 Marine AlgaeGreen Algae Enteromorpha, a filamentous alga, thrives under environmental conditions that are unsuitable for most kinds of algae and plants. Enteromorpha can tolerate temperatures that vary widely from summer to winter as well as alternating periods of wetness and dryness. When it rains heavily, Enteromorpha is even able to adapt to a temporary freshwater environment.

10. 5.1 Marine AlgaeBrown Algae The brown algae are classified in the phylum Phaeophyta. This color results from the mixture of the green pigment chlorophyll and the yellow pigment xanthophyll within the cells. Brown algae provide shelter or nutrients for other organisms and a variety of products for humans.

11. 5.1 Marine AlgaeBrown Algae The largest seaweeds in the ocean are the brown algae known as kelp. One species of kelp, Laminaria, thrives in the colder waters along the coasts of Maine and California. Kelp lives in the subtidal zone, where it attaches to rocks with a large and very sturdy holdfast providing habitat for other marine organisms. A chemical in kelp called algin is used in many different industries. Algin is an important binding ingredient in various prepared foods, medicines, paints, and paper products.

12. 5.1 Marine AlgaeBrown Algae Sargassum, floats on the water’s surface in the Atlantic Ocean and in some seas off the coasts of Asia. The algae forms floating mats where both water and weather are calm. The middle of the Atlantic is known as the Sargasso Sea. The Sargasso Sea supports a rich community of organisms, including fish, shellfish, and young sea turtles that live within the protective covering of the seaweed.

13. 5.1 Marine AlgaeRed Algae Red algae are classified in the phylum Rhodophyta. They are the most abundant, and commercially valuable, of the marine algae. Red algae are found on rocky shores from the intertidal to the subtidal zones. Some species are found at much greater depths than either brown or green algae.

14. 5.1 Marine AlgaeRed Algae The red pigment phycoerythrin and the blue pigment phycocyanin enable red algae to use the limited light that penetrates deeper water to carry out photosynthesis. Phycoerythrin masks the green pigment chlorophyll, which is also present in red algae.

15. 5.1 Marine AlgaeRed Algae Irish moss (Chondrus crispus) is a short, bushy seaweed found in the lower intertidal and subtidal zones. Irish moss carpets rocks with a dense, spongy growth. This seaweed is harvested for use as a food item called carrageenan. Carrageenan is a binding agent in ice cream, puddings, deli turkey, and toothpaste.

16. 5.1 Marine AlgaeRed Algae A soft red algae supplies a chemical called agar, which is also used to make food and medicinal products, and as a medium for growing bacteria. A few species of red algae are hard and brittle. The coralline seaweeds (Corallina) have calcium carbonate in their cell walls.

17. 5.2 Beach Plants Beach plants are found in an area called the upper beach. High tides and heavy surf make it very difficult for plants to take root in the sand along the lower beach. Winds move the sand into small hills called dunes. The dunes are held in place by the roots of beach plants.

18. 5.2 Beach Plants Sand dunes are also very delicate. Salt spray and sea mist mix with the sand to form a protective crust. This crust allows for more sand to pile up over time making the dunes larger. Walking on dunes breaks this crust and can begin the process that leads to a dune’s destruction.

19. 5.2 Beach Plants The beach grass Ammophila has long underground stems and deep roots that help hold the sand in place and thus stabilize the dunes. Beach grasses are also widely spaced to minimize competition with one another. Sea oats (Uniola paniculata) are extremely salt tolerant. Sea oats are used in dune stabilization programs because its extensive system of underground stems and roots helps reduce erosion.

20. 5.2 Beach Plants The upper beach resembles the kinds of conditions you would find in a desert. Summer time temperatures can average 98 ° F or 37 ° C. A desert plant, the prickly pear cactus, Opuntia compressa, grows in this region of the beach. This plant has a thick waxy covering to minimize water loss from evaporation. Another common dune plant, the seaside goldenrod, stores water in its stem.

21. 5.2 Beach Plants At the summit of the dunes, woody shrubs and trees such as the beach plum and pitch pine are often found. Trees often grow as tall as the dunes, but no taller, due to the drying winds blowing off the ocean. This sea breeze acts like a pruning shear to keep the tree heights low. Most beach plants are vascular plants that produce flowers and seeds.

22. 5.3 Marine Grasses The tall reed grass called Phragmites is a marsh grass can be easily identified by its fluffy brown tassels. Along the water’s edge, in the intertidal zone, grows two species of cordgrass (Spartina) in the intertidal zone. (See Figure 5-8.) And a tall, coarse species of cordgrass, (Spartina alterniflora,) grows in the lower intertidal zone, where it is covered by water during periods of high tides; it can tolerate changes in salinity and temperature.

23. 5.3 Marsh Grasses Cordgrass is an important member of salt marsh communities; its survival is linked to that of the fiddler crabs and mussels that live on and around its roots. Cordgrass has the ability to break down industrial pollutants that flow into marshes, releasing the chemicals as harmless gases.

24. 5.3 Marsh Grasses Cordgrass species have adaptations that enable them to survive in water that is salty. Special glands located in the leaves are able to excrete excess salt. Animal life lick the marsh grasses to obtain this valuable nutrient. Marsh grasses have a short life cycle, dead and decaying grass makes up most of the marsh. This decay produces important nutrients to enrich the water.

25. 5.3 Marsh Grasses Plankton feed on these nutrients. Due to the high level of nutrients in the water, great numbers of plankton can thrive in marshes. The plankton are a major food source for other marine organisms. Marshes are among the most biologically productive ecosystems in the world.

26. 5.3 Sea Grasses In the cooler waters along the Atlantic and Pacific coasts, lives the eel grass, Zostera marina. Eel grass lives in the protected bays and inlets of the subtidal zone. The tufts of eel grass grow close together, forming beds that provide hiding places for mollusks, crabs, and fish.

27. 5.3 Sea Grasses In the bays and inlets of warmer waters, along the coasts of Florida and the Gulf of Mexico, large beds of the turtle grass, Thalassia, grow. Turtle grass has underground stems called rhizomes, which form an interlocking mat that helps stabilize the sandy seafloor. Fish hide in the grasses, and invertebrates attach to the blades of grass. Turtle grass is an important food source for sea turtles.

28. 5.3 Sea Grasses When sea grass egg cells are fertilized by pollen, seeds are produced and shed into the water. If they settle on a suitable substrate, the seeds will germinate.

29. 5.4 Mangrove Trees Along tropical shores around the world, including the bays and inlets of Florida, the mangrove trees grow so close together they form a thick jungle of vegetation, called a mangrove swamp. At low tide, the arching prop roots of the mangrove tree are visible. Prop roots anchor the mangrove trees into the muddy sand and acts as a net to trap organic debris brought in by the tides. Mangroves are classified by their color, red, white, or black.

30. 5.4 Mangrove Trees Red mangroves are called the walking trees. The prop roots make the trees look like they are walking on water. Black mangroves get their name from their black trunk with leaves that are dark green on top and silver on the bottom. White mangroves cannot live in the water and they have no special root structures.

31. 5.4 Mangrove Trees The mangrove roots are covered at high tide, while the stems and leaves remain above water. Seedpods dangle from the branches of the mangroves. These pods are 10 to 12 cm in length and look like small pencils. When they are ripe, the pods fall into the water. They float vertically and are carried by ocean currents to other locations. When a seedpod makes contact with a suitable muddy bottom, it begins to grow into a mangrove seedling. When several seedlings take root, a new mangrove community is established.

32. 5.4 Mangrove Trees Mangrove communities are biologically productive areas. Mangrove swamps are often considered to be the “nurseries” of the sea. Young fish and other small animals survive by hiding in the grasses or within the tangled network of mangrove roots, where larger animals cannot pursue them.

33. 5.4 Mangrove Trees In North America, birds such as rails, herons, egrets, and terns, and mammals such as raccoons, muskrats, deer, and foxes, may be found living in and around salt marshes. In South Asia, the unusual proboscis monkey lives almost exclusively in the trees of the mangrove swamp, relying on the leaves for food.