Marine Bio Week 6 Lecture Notes
Marine Bio Week 6 Lecture Notes EBIO 2100
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This 7 page Class Notes was uploaded by Cara Macdonald on Sunday October 9, 2016. The Class Notes belongs to EBIO 2100 at Tulane University taught by Timothy Mclean in Fall 2016. Since its upload, it has received 6 views. For similar materials see Marine Biology in Environmental Biology at Tulane University.
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Date Created: 10/09/16
Multicellular primary producers: 10/4/16 • Multicellular algae: o Macrophytes/ Macroalgae § No true leaves, stems, roots -- entire body is thallus § Holdfast: similar to a root system • Instead of working into soil, attach directly to surface of a hard substrate o Secrete substance like glue to hold fast to surface • Do not function to absorb nutrients § Single, stem-like structure called stipe: • Extension allowing for one or multiple large blades o Like leaves but much thinner o Every cell is exposed to the outside; can take in what it needs/release what it doesn’t without relying on veins • Pneumatocysts: gas-filled bubbles on leaves to maximize photosynthesis § Diversity of shape: small, filamentous blades; tubes combined into lea fy structure (sea lettuce); multi -bladed o Green algae: most actually terrestrial and freshwater algae § Most microalgae § Multicellular green algal species: • Different genera from poles to tropics • Some are common and can dominate in harmful algal blooms o Ex. green tide • Have same chloroplasts as land plants, so typically appear green o Enteromorpha: unbranched thin, hollow filaments o Ulva: thin sheets o Valonia: spheres or clusters of spheres o Caulerpa: highly invasive tropical species, multi -nucleated cells creating tubes § Thought by 2050-2060 it will cover entire floor of Mediterranean Sea o Codium: spongy stipes “dead man’s fingers” o Halimeda: can produce calcium carbonate; segmented, calcareous green algae o Brown algae: exclusively marine, primarily along temperate/polar rocky coasts § Prefer cold water because colder water has higher concentration of nutrients § Actually vary in color from deep green to dark brown • Chlorophylls mixed with yellow -brown pigments, mainly fucoxantin § Ectocarpus § Padina: thick, spongy blades § Sargassum: very important in mid -atlantic region; pneumatocysts to keep that at surface in warm waters • Doesn’t need to be attached to anything, can just sort of float • Particularly bad problem in past couple years: huge blooms of sargassum with dead matter piling up on the beach o Impacts tourism industry o Brings in sea urchins/other organisms which use as a habitat § Sulfur compounds release terrible odor § Kelps: in temperate/sub -polar regions living below low -tide level; valuable habitat for various animals • Laminaria: large blades up to 3m • Nereocystis: up to 30m stipes and 4m blades w large pneumatocysts • Macrocystis: giant kelp up to 100m long (largest bottom -dwelling organism on sea floor) can form kelp beds/ forests o Red algae: large taxa united by presence of phycobilis (red phytopigments) § Exclusively marine and virtually cosmpolitan § Similar variations of filaments and flattened branches but more variation at cellular/micro-structure level § Some species have simplified to being small parasites of other algae • Some have even lost chlorophyll (heterotrophs relying on hosts) • To what phylum do algae belong? (this information changes all the time) o Not all related, so we cannot classify into a single, taxonomic entity § Green algae/red algae placed into plant kingdom (but not real plants) § Phaeophytes, dinoflagellates, diatoms grouped together in kingdom Chromista § Euglenoids are kingdom Protista § Cyanobacteria are in kingdom Bacteria • Reproduction: o Asexual: sometimes a thallus just gets fragmented, leading to a new individual § Also called vegetative reproduction o Alternation of generations: some species release spores or zoospores; some produce gametes § Environmental conditions can influence whether spores or gametes are produced and/or when they are released o Microalgae have a third generation: carposporophyte § Diploid stage arising from fertilization § Produce carpospores (diploid) --> sporophytes o Macroalgae have NO alternation of generation: § Just one stage that, after a period of time, becomes sexually mature and repeats process § Some green algae exist only as haploid organisms going through a very brief diploid stage Algae does a body good! • Good source of: o Fiber o Vitamins o Essential oils/lipids (fatty acids) o Minerals (contain all trace elements) o Very high protein content (complete protein) o Low in fat • Nori: looks like green seaweed, actually red algae o Porphyra genus grown in huge complexes off coast of Japan o Cultivation began in 17th century in Japan and China § Bundled branches anchored in intertidal o Dr. Kathleen Mary Drew -Baker: English phycologist § Showed that filamentous shell -boring alga, Conchocelis, is additional diploid phase in life cycle of Porphera § Development of commercial cultivation using floating bamboo mats and nets that were artificially seeded became possible § Revolutionized industry → over $2 milion/year megaindustry § Paper published in 1948, after 1946 massive typhoons in Japan almost completely obliterated species of red algae • Dr. Drew-Baker hailed as the Mother of the Sea in Japan; celebrated each year on April 14. Monument of her erected in 1963 in Uto, Japan o Other mariculture: § Dulse in Ireland or Atlantic Canada § Purple laver most widely used red alga for various traditional foods from around the world § Sea lettuce used in salads, soups § Kelps: ~12 species used with meat, fish, soups, pet food § Red alga “Irish moss” Chrondis crispus good source of carrageenan (polysaccharide that makes up 55% of alga) • Acts as emulsifier, gelling or stiffening agent, processed meats, sauces and ice cream, also used in brewing as a fining agent to produce a clearer beer § Many extractable molecules, i.e. Phycocolloids: • Kelps: cell wall is a source of heteropolysaccharide, algin • Mannuronic vs. guluronic acid: composition varies by species and thallus location o stabilizer/emulsifiers in dairy products, pharmaceutical/industrial applications, thickener in printing inks • Agar: gelling agent in icings, glazes, processed cheese, jelly sweets, marshmallow; to make clear, stable gel for microbiologists to grow cultures or molecular biologist to separate molecules § Many potential m edicinal uses: • Tuberculosis, arthritis, colds, influenza, anti -STDs, vermifungal agent, anti-cáncer, etc. • Natural fertilizer (harvested or as extract): o High salt content, water retention, plant -like hormones, trace elements, etc. § Development into biofue ls (biodiesel): • Can grow huge vats of algae and extract oil to run cars, engines, etc. o Currently many small startups and big oil are investing heavily • Reproductive strategies; o Alternation of generations: § Algae: two types of thalli involved • Diploid thalli (sporophyte generation) o meiosis→ haploid spores • Spores develop into haploid thalli (gametophyte generation) o Create haploid gametes • Seagrasses o Only group of plants that can tolerate being fully submerged in water all the time • Salt-marsh grasses • Mangroves § Last 3 have true tissues e.g. vascular tissues § Last 2 are plants adapted for a terrestrial existence in high saltwater conditions, cannot survive completely submerged § All eukaryotic, multicellular, photooautotrophic organisms with chloroplasts and cell walls Flowering Plants: angiosperms • True leaves, stems, roots and conductive tissues (xylem, phloem, etc.) • Reproduction involves dominant sporophyte that produces a flower • Came to dominate on land among all plants • Some may be salt-tolerant (coastal or along marshes) • Only seagrasses are truly marine (fully living submerged) Seagrasses: not really grasses, most closely related to the lily family • ~60 species in temperate and tropical locations • Most flowers are small /inconspicuous o Nothing pollinates them: must self -pollinate • Some long and skinny, some have broader leaves shooting off of rhizomes • Roots growing into a substrate • Named for organisms that eat them (ex. Turtle grass, manatee grass, etc.) Advanced Primary Producers 10/6/16 • Seagrasses: o Pollen carried by water currents o Tiny seeds carried by water currents or deposited in feces o Provide critical food source for a few species o Dead material becomes particulate detritus contributing to lower food chain organisms o Critical habitat for lots of organisms o Develop in intertidal and shallow subtidal areas on sands and muds (low to no wave action preferred o Stabilize sediment/reduce erosion o Prevent resuspesion of sediments in water (improves clarity for other plants t o photosynthesise) o Help slow water down and increase sedimentation o Food for some organisms → creates detrital pool as food source for many more o Refuge for many organisms o Threats to seagrasses: § Salinity § Water temperature § Turbidity: like high water clarity o Beds are particularly sensitive to degradation: § Agriculture pollution/ run -off (herbicides) § Industrial pollution § Domestic pollution • Salt-marsh plants: o Genus name: spartina o Cordgrasses are true members of the grass family o Terrestrial, salt tolerant species (halophytes) § Salt gland in leaves allow to excrete excess salt • Filter out salt, concentrate it and push it out of leaves o In soft-bottomed marshes/shallow bays/tidal creeks of temperate areas § (only exposed to salt during high tides) o Can tolerate salt and being underwater (at least to a degree) § Could not survive completely submerged, but tolerate some fluctuation along their stems o Flood and ebb currents transport saltwater, nutrients, plankton, sediments, etc. in/out of marsh o Highly productive especially when the plants have died and bacteria/fungi break it down § Also provide critical habitat for multiple organisms • Transient visitors and permanent inhabitants • Mangroves: shrubs and trees that grow right along the coastlines o ~80 unrelated, terrestrial, halophytic trees and shrubs o Grow along protected, muddy/sandy shores where they can stabilize themselves o In tropical/subtropical areas (form mangrove forests- mangals) o Have a thick network of prop roots exposed at low tide o Leaves have a thick, waxy cuticle reduce water loss § Osmosis wants water to move from inside the plant (high concentration) to outside the plant (low concentration) § Wax helps prevent stomata from losing water o Seed germinates while still attached to the tree, seedling will fall and spear into sediment to become established § Can grow and established before water could rise and, potentially, drown the sapling o Sediments are anaerobic, contain very little oxygen; not enough to supply for respiratory needs of roots/whole tree o Prop roots and pneumatophores for increased interactions with oxygen (respiration) § Leaves handle photosynthesis and bring in plenty of CO2 • Roots need oxygen to expire, don’t get enough from leaves (cuticle blocks) • Specialized structures to increase ability to take up oxygen o Ecological role of Mangroves: § Stabilize sediment § Accumulate detrital or other foreign material § Habitat for epiphytes (organisms that live attached to outside of other organisms) § Fish and invertebrate nursery - not a lot of wave action, steady and protected environment § nesting/roosting site for birds § Limited role as a direct food source, but detritus materials feed bacteria/microbes § Major contributor to detrital food chain § Protect shoreline from erosion during tropical storms o How can humans take advantage of mangroves? § Fish and shrimp cultivation § Food for people→ convert into aquaculture facilities • Losing a lot of mangroves to this purpose!! § Firewood and boat building material § Tanning material- produce tannins § Considered the finest honey by some people • Important characteristics of seaweeds and marine plants: table 6.1 in book Marine animals without a backbone: distinguish each different phylum from other phyla; describe and distinguish morphological character • Most multicellular organisms on Earth are: • Animals: o Vertebrates and Invertebrates (MANY more invertebrates) § Invertebrates make up 97%, most are insects o All major animal taxa are represented in the marine environment, some taxa are exclusively marine o Generally: § Eukaryotic with no cell walls § Multicellular, diploid with specialized cells § Heterotrophic § Require oxygen (cellular respiration) § Reproduce sexually, asexually, or both o Basic body structure: § Body architecture: • Acoelmate: have muscle layer and gut • Pseudocoel: have epidermis, muslce layer, and gut within • Coelom: have gut anchored in place within coelom and muscle layer/epidermis § Symmetry: • Radial: round, equal parts radiate from center • Bilateral: organism can be divided into left and right halves o Our first phylum violates symmetry requirement • Porifera: pore-bearing animals o Mostly asymmetrical, no anterior or posterior ends o 5,000 different species - live everywhere in the ocean, even in really deep places o No true organs or tissues (no nerves or muscles) o Low, but unique level of cellular differentiation o Sessile- contradicts most of what we think about animals, but larvae is m otile o Mostly marine, but not exclusively o Variable size, shape and color o Sponge characteristics of phylum: § Body architecture constructed around a system of water canals • Numerous tiny pores (ostia) in the surface to move water o Outside → atrium (spongoco el) → osculum § Specialized cells: • Porocyte on outside receives water • Pinacocytes: cover entire outside surface of sponge • Amoebocytes: create matrix of secreted proteins, creating bulk of body wall o Some secrete spicules: silica spikes secreted/embedded in body wall for extra support o Spongin also acts for structural support • Choanocytes: collar cells with flagella that beat to drive water through the pores so that food can be filtered out through villi • Water movement is required for filtering food, gas exc hange § Reproduction: • Asexually: can regenerate o Could shred a sponge and each new piece would regenerate, possibly fuse with others o 2 different species of sponge will segregate themselves and reform into their 2 separate species • Sexually: can produce gametes o Gametes swim, penetrate cell wall of opposite sex, fertilize and grow into a motile larva o Predators of porifera: § Nudibranch § Turtles § Sea slugs § Few species of fish • Sponges can use toxins to ward off predators/prevent predatio n o Porifera as refuge: § Sponges provide habitat for a wide variety of animals § As many as 16,000 different species have been found in one loggerhead sponge o Some different morphologies: § Tube sponges: can be up to a meter high! § Encrusting sponges: instead of growing up, they grow along a substrate and precipitate calcium carbonate layer § Boring: some bore into rocks/corals § Glass sponges: spicules covered in a very thin layer of living tissue, look naked • Found very deep, highly valued in some cultures
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