EVE 12: Life in the Sea
EVE 12: Life in the Sea EVE 012
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This 10 page Class Notes was uploaded by AlexandraRita Notetaker on Monday April 18, 2016. The Class Notes belongs to EVE 012 at University of California - Davis taught by Susan Williams in Spring 2016. Since its upload, it has received 31 views. For similar materials see Life in The Sea in Business at University of California - Davis.
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Date Created: 04/18/16
th Day 5 (April 12 ) – Kelp Forests New species of kelp discovered in Aleutian Islands in 2007 • Def. Kelp: a type of large brown seaweed -‐‘Golden V kelp’ -‐ Length = 10’ Very isolated distribution • volcanic activity, warm sands in cold seas • Shallow (15‘ or 3 m) • Aleutian Islands Kelp Morphology How do large kelp survive in the sea? 1. Stay upright in photic zone plenty of light for photosynthesis tosupport large size • gas bladders (pneumatocysts) 2. Adaptations for drag large holdfasts anchor kelp 3. Streamlining minimize surface area exposed to drag Kelp-‐based Food Web Effect of a top predator in marine ecosystems • Kelp – sea urchin – sea otter • Sea otters are top predators. • Sea otters control sea urchins. • Sea urchins eat kelp. • Sea otters present-‐ fewer sea urchins • more kelp • higher biodiversity 2 Sea otter -‐ sea urchin -‐ kelp interaction ‘top-‐down’ control of marine biodiversity • Predators can keep dominant organisms ‘in check’, from outcompeting other species. • ‘Top down’-‐ control of marine biodiversity by predators, which sit at the top of the food web. -‐Also referred to as a trophic cascade The loss of top predators, such as the sea otter, can result in loss of marine biodiversity. Economic Benefits of Seaweeds • Estimated 6 billion dollars in US • Kelp as food-‐ -‐Value of kelp ‘wakame’ (Undaria): $149 million US The kelp ‘wakame’ (Undaria pinnatifida) • Non-‐native in CA • Invasive marine species: a non-‐native species that can harm native sea life and marine natural resources Sabellid Worm Infestation of Abalone • Non-‐native sabellid worm was imported to abalone farms. – Caused bankruptcy of 2 abalone farms Eradication efforts were unsuccessful. • Invasive species 3 Summary: Kelp & Kelp Forests • Kelp is an example of a benthic primary producer. • ‘Kelp’ describes a type of brown seaweeds that are large and grow in cool waters on rocky shores. • Kelp have complex life histories with microscopic phases that produce gametes. The female produces a pheromone that attracts the male g amete, which swims. • Giant kelps (Macrocystis, Nereocystis (bull kelp)) form large forests. They are seaweed ecosystem engineers because of the structure they provide for other organisms and because they modify the water flow environment. • Top-‐down control of an ecosystem (trophic cascade) means that an organism higher in the food web has an important effect on the lower levels in the food web, e.g., the primary producers, or on the diversity and abundance of animals. The sea otter exerts top-‐down control on the primary producers in a kelp forest through eating sea urchins. Sea urchins in high numbers can decimate kelp, leaving primarily crustose coralline red algae (resistant to grazing). The loss of an apex predator can result in decreased biodiversity. End of Day 5 Notes 4 th Notes Day 6 (April 14 ) – Marine Flowering Plants Marine Flowering Plants • Closely related to terrestrial flowering plants, esp ecially freshwater angiosperms • Angiosperms: Green plants that reproduce by flowering, producing pollen and seeds. • ‘vascular plants’ -‐ ‘veins’ transport water and sugars -‐ true roots, leaves, stems • Angiosperms evolved from green algae that colonized la nd from the ocean, adapted to freshwater lakes, then recolonized the sea, adapting to salinity and rigorous water motion. • Form coastal, often intertidal, ecosystems -‐Seagrass beds (‘meadows’) -‐ mangrove forests -‐salt marshes • Provide the important ecosystem functions and services -‐ high primary production and food web support -‐stabilization of soft coastal sediments -‐nursery habitat for economically valuable species • Vulnerable to human activities -‐coastal development -‐nutrient over fertilization (eutrophication) -‐aquaculture -‐ introductions of non-‐native species 5 Global Ocean Primary Production • 55% of total PP on earth occurs in ocean. • Distribution and rates of primary production in the ocean: -‐Seagrasses, algal beds, salt marshes, and mangroves highly productive and valuable ecosystems Sea Grasses 55 species of sea grass on earth. (One of the most productive in the world) Sea grasses are NOT true grasses (Can grow up to 2cm a day.) 6 Sea Grass Morphology • Sea grass leaves are bundled into leaf shoots • Roots and Rhizomes (Underground stems) anchor seagrasses in sediments • Seagrass leaves can be cylinders, ovals, or straps. Seagrass on the US west coast 1. Eelgrass (Zostera) Grows in sediments in quiet bays 2. Surfgrass (Phyllospadix) Grows on rocks -‐Both species are important habitat for California lobsters. Seagrasses have a simple life history. They produce pollen, flowers, and seeds Surf grass (Phyllospadix) • Long flowering shoots • Currents carry pollen to female flower • male flowers release pollen Enhalus • One of the biggest seagrasses • Grows in the Indo-‐ Pacific region. Important ecological functions of seagrass • High primary production – Supports herbivore and detritivore food webs • Sediment stabilization, coastal protection • Refuge from predators • Nursery areas for shrimps, crabs, lobsters, fishes • Food and habitat for endangered species seahorses, green turtles, manatees, dugongs, fishes • Provide detritus food and shelter for deep-‐sea (abyssal) animals -‐Several seagrass species are endangered with extinction (Johnson’s seagrass in Florida) • Sea grass beds are high in biodiversity 7 The high primary production of marine flowering plants • provides trophic support through two pathways. 1. Herbivores-‐ Herbivores eat living plant tissue. 2. Detritivores-‐ Animals eat detritus (dead organic matter). Plants die and form detritus. • Trophic support: The provision of food for animals in the food web. Trophic support = food web support Herbivory on seagrasses • sea urchins • fishes • ducks & geese • green turtle’s dugongs & manatees Trophic support • Provided by the primary production of marine flowering plants 1. Herbivores eat plat tissue directly. 2. Detritivores eat dead organic matter. Secondary consumers (predators) eat detritivores and herbivore lower in the food web. Human use of seagrasses • Early US settlers insulated houses and barns with dried eelgrass • Compost for gardens-‐ Europe, USA • Upholstering and packing-‐ Europe, North America • Production of high grade Paper-‐Europe, USA • Food, roofing, woven into blankets and dolls, cure for diarrhea -‐ Seri Indians, Mexico • Substitute for straw; fuel; bedding; roof thatch; cigars -‐ Denmark • Sturdy, durable dikes-‐Holland • Mulchon potato fields–Europe • "Zosterin", a strong gelling agent-‐USSR • Used in making nitrocellulose during WWI when cotton was scarce– 8 Germany • Seeds used as an aphrodisiac in the Indo-‐Pacific Eelgrass-‐ an ocean grain. Seri tribe of Sonora, Mexico. • seeds are harvested and made into flour • used in basketry, used in roofing and shades, and toys -‐The month of harvest is named for eelgrass and is a time of happiness. Coastal benthic marine ecosystems exist close to humans. • Nutrients from land cause algae to bloom, smother, and kill seagrass. • Sediments erode, biodiversity declines • Eutrophication: nutrient over-‐enrichment Epiphytes • Organisms that live on larger plants • Algal epiphytes naturally live on seagrass add to the primary production in seagrass beds. • Eutrophication-‐ algal epiphytes bloom, blocking light and carbon dioxide from seagrass. Mangroves • Tropical Marine Trees • Form Intertidal Forests • Flowering Trees (angiosperms) Mangrove adaptations to the sea • Prop roots • Drop leaves to rid excess salt • Aerial roots provide oxygen in low-‐oxygen (‘anaerobic’, ‘anoxic’) sediments 9 Mangrove Prop Roots • support large trees • provide nursery areas for fishes • Aerial roots provide oxygen (pneumatophores) • Mangroves are good for fishing Salt Marshes • Intertidal habitats dominated by salt-‐tolerant angiosperms. 1. Pickleweed (Sarcocornia virginica) 2. California cordgrass (Spartina foliosa) • a true grass • grows along creek banks in the marsh Eastern cordgrass invasion • Spartina alterniflora • grows in tight clumps • fills in mudflat habitat important for shorebirds • traps sediment and fills in channels Summary: Marine Flowering Plants (Angiosperms) 1. Marine angiosperms form coastal ecosystems: seagrass beds, mangrove forests, salt marshes. 2. Marine angiosperms have high rates of primary production, stabilize sof t sediments along shorelines, create habitat structure, provide nursery areas, support economically valuable and endangered species, and are important to humans. 3. Due to their close proximity to land and humans, seagrass beds, mangrove forests, and salt marshes are strongly influenced by human activities. -‐ Eutrophication -‐ Non-‐native species -‐ Habitat destruction 10