Week 4 Marine Bio Notes
Week 4 Marine Bio Notes EBIO 2100
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This 8 page Class Notes was uploaded by Cara Macdonald on Sunday September 25, 2016. The Class Notes belongs to EBIO 2100 at Tulane University taught by Timothy Mclean in Fall 2016. Since its upload, it has received 4 views. For similar materials see Marine Biology in Environmental Biology at Tulane University.
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Date Created: 09/25/16
Week 4: What fuels life? • Most organisms get energy from the Sun: o Directly: Autotrophs (producers) § Photoautotrophs use energy from sunlight to produce organic molecules (food) • Bottom of food chain: all energy in all ecosystems is ultimately derived from the sun • Include plants, (terrestrial and aquatic), algae (macro and micro), certain other protists and some prokaryotes o Harmful agal blooms made up of cyanobacteria (single- celled organisms) • All collectively produce at least half the gas in the atmosphere • Can assume photosynthesis o Solar energy trapped in pigments of chlorophyll o Creating ATP, generating Oxygen as a waste product o Bring in carbon dioxide as carbon source • Marine plants have huge amounts of water, CO2 and light (if clear water close to surf ace) o Requires sunlight, energy, CO2, water and other required nutrients (N, P, Si- usually as silica SiO2, Fe) o Indirectly: Heterotrophs (consumers) § Heterotrophs eat autotrophs (or other heterotrophs) § Rely on autotrophs for energy and/or oxygen § Tops of the food chain § Undergo process of respiration: • Glycolysis: series of reactions to break down glucose • Aerobic respiration: in the presence of Oxygen; much more efficient in making ATP • Anaerobic respiration: cells may utilize fermentation • Photosynthesis is to building as respiration is to breaking down o Everything respires (including plants) but only plants photosynthesise o Balancing of building stuff up (photosynthesis) and breaking stuff down (respiration) § Usually photosynthesis rates are faster than res piration rates, which results in a net increase in organic matter (primary production→ allows for growth ) • It all comes down to cells: o The basic structure of life o All cells have 4 characteristics: § Genetic material (DNA) § Cell membrane (semi -permeable membrane) § Cytoplasm § Ribosomes o Prokaryotic cells: evolved before the evolution of a nucleus § Most primitive/ancestral of all known forms of life § Most have cell wall • All have nucleic acid, cell membrane, ribosomes o Eukaryotic cells: § Struturally complex w mu ltiple organelles including nucleus § Extensive endomembrane system § Structural and content differences: plant cell versus animal cell • Plant cells have cell walls for extra support; animal cells lack § Lots of singe-celled eukaryotes in the world o All marine organisms, regardless of habitat or lifestyle § Planktonic: organisms either so small or so weak they are at the mercy of where the water takes theme • Could be plankton or could be jellyfish § Benthic: organisms associated with the benthos (the bottom of the ocean) § Nektonic: things that live in the water and can swim • Fish, shark, etc, o One big challenge: how to deal with all the dissolved stuff in the water? § Review of diffusion: particles move from areas of high concentration→ low concentration • Down the gradient • Small, uncharged polar molecules and hydrophobic molecules move across the membrane o Osmosis: diffusion of water across a selectively permeable barrier § Direction of osmosis: determined by a difference in total solute concentrations § Isotonic solution: osmolyte concentration is the same as that inside the ll • How do marine organisms cope with solute differnces between themselves and their saline, aqueous environment? o Osmoconformers: § No active control of osmolyte/water balance § No internal concentration varies with surrounding osmolarity § Most can only tolerate a very narrow range of salinity o Osomoregulators: § Active control of their internal osmolyte concentrations § Can generally tolerate a wider range of salinities than osmoconformers § Mechanisms of osmoregulation: • Actively matching the internal osmolyte concentration to the external concentration o Sharks, rays, skates are capable of this o Increase the osmolyte concentration of their blood by adding urea to it § Bullsharks are able to regulate themselves much better than other sharks § Dunaliella sp. Produces lots of glycerol in its cytoplasm, increases internal osmolyte concentration, thrives in salt ponds • In other fishes that aren’t cartilagenous (sharks/ rays) c an maintain an internal osmolyte concentration not equal to the eternal concentration o Water loss by osmosis through gills and skin o Make up for this by drinking lots of seawater - have a physiology that filters out ions in the water § OR they have a very conc entrated urine • Specialized salt accumulating glands or cells to get rid of excess salt o Tear ducts in turtles • Plants and some algae have celll walls to impede swelling o So even in a hypotonic solution, it can only absorb so much water • How have marine orga nisms adapted to the various (and possibly changing) temperatures throughout the ocean? o Temperatures very low at the bottom of the ocean o Some organisms are heat -tolerant § Bacteria living in hot springs/geysers o Also affects pressure o Two schemes categorize organisms by how they regulate (or don’t) body temperature § All organisms generate metabolic heat. Some can retain and maintian the heat (like us), while some organisms cannot retain their heat and rely on an outside source (like lying in the sun) § Ectotherm: cold-blooded § Endotherm: warm-blooded § Poikilotherm: body temperature varies • All ectotherms are poikilotherms • Some endotherms: large sharks, tunas and billfishes o Allows them to swim faster when muscles are warm § Homeotherm: maintains a very stable body temperature • NO ectotherms • Some endotherms: mammals and birds • Living in an aqueous environment → all exposed cell membrans can and do directly exchange nutrients, gases, heat and wastes o The rate and efficiency of such exchanges is proportional to the surface -to- volume ratio of a cell/organism o Diffusion limits how big the cells can get: materials must travel across the whole cell to the center § As cells/organisms get bigger, both SA and V grow • But V grows by the c ube, and SA by the square • A lot more needs to get brought in to feed the volume o Small cells/organisms have high S/V ratio and diffusion is possible o Larger cells/organisms must have dedicated mechanisms and/or organ systems for transfer of materials • How do aquatic organisms make more of themselves? o Prokaryotes: binary fission § Reproduce asexually to make identical copies of self o Eukaryotes: asexually/ mitosis § fission/budding in eukaryotes § Plants: may clone themselves asexually through vegetative reproduction (same idea/mitotic mechanism) § Animals: sexually/meiosis • Ways to ensure fertilization: o Some don’t need to fertilize at all, can reproduce asexually o Copulation: male/female OR hermaphrodite/hermaphrodite § Hermaphrodite: • May be simultaneous, with both male and female organisms (usually do not self- fertilize) • May change sex at a point in life (oysters, clownfish can do this) o Protandry: starting as male→ female o Protogyny: starting as female→ male o Some organisms have 1 offspring at a time, some have many o Broadcast spawning: no physical contact between mating members, just releasing gametes in the water in hopes that they meet and fertilize o Each species is named using binomial nomenclature: § I.e. genus species epithet: can help show us how organisms are related to each other § If two organisms can reproduce with each other/are compatible, they are the same species 9/22/16 • Life and how to classify it: o Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species § We can quickly determine if a speci es is related to another by its classification § System was developed by Linnaeus in the 1700s, has been modified greatly ever since • Not everyone agrees with the classification of species -- none is set in stone § Example: Dolphins and Humans • Both Eukarya, Animalia, Chordata and Mammalia o Commonalities end there o Taxonomy: we are able to group species into different taxa based on common characters § Allows us to group into trees § If a species is related, they presumably share some common ancestor in evolutionary history ( phylogeny) § Know how to read a phylogenetic tree, understand degrees of relatedness § Allows us to ultimately come up with the tree of life: • Understanding how everything is related through common characters/ancestry • Diversity of microscopic life • Fundamentals of biology recap: o Biology is the study of living things: § Creating and/or using energy to build and organize organic matter • Autotrophs and heterotrophs • Prokaryotes vs eukaryotes • Unicellular versus multicellular • Hierarchy of biological organization § Challenges of an aqueous, saline environment: • Diffusion of solutes and osmosis of water o Osmoregulators versus osmoconformers • Variations in temperature (and pressure) • SA/V ratio and how it relates to movement of materials in/out of organism • The Microbial World: o Learning objectives: § Important characteristics and ecological significance of marine viruse § Explain important characteristics and ecological significance of marine prokaryotes, protists, and fungi § compare/contrast between autotrophic and heterotrophic microbes § Diagram the most important characters of diatoms, dinoflagellates, foraminiferans and radiolarians • What do we mean by microbes? o Organisms less than 100 microns (cannot usually be seen with the naked eye, requires use of a microscope) § Viruses/bacteriophage § Prokaryotes § Fungi § Protists § Multicellular eukaryotes o Why do we care about them? § Can live in all oceanic habitats -- they are literally everywhere § Are the most numerous group of organisms on the planet -- highly abundant § Are capable of many different types of metabolism • bio/geochemical • animal/plant/human health • Viruses: obligate, intracellular parasites o All forms of life are infected by viruses: exist a s discrete particles but can have HUGE impacts on all forms of life § Rely on living things in order to reproduce themselves § Infect a cell, use its machinery to create new copies of its own genome § We are discovering new viruses frequently • Hundreds and hundreds of different viruses that humans are susceptible to • 95% of particles found are viruses, but still only have a small biomass § Most widespread family of viruses: herpes virus • 8 human herpes viruses • Almost all organisms are susceptibl e to some form or another • Not fatal to humans, but may be in other organisms o Vary in size, shape, genetic content, genome, host range (specificity of infection), etc. § Some have very very small genomes with 4 -5 genes, some have 200 -300 § Every virus is specific to a certain cell type • Cannot just infect any cell it finds o Whether or not viruses are “living” is moot • Ecological roles in the Oceans: o 1. Part of a microbial loop (like a food chain) o Some of the particles that aren’t eaten get released into the wa ter, dissolve into organic matter § What happens to this? • Phytoplankton don’t eat • Grazers don’t eat • Heterotrophic bacteria are able to recognize and make energy by consuming these “dead cells” o Virus abundance is important for contributing to this loop o When viruses infect a cell, they cause it to lyse and release its material, which contributes new food to the microbial loop § Produces Dissolved Organic Matter (DOP) and Particulate Organic Matter (POM) o 2. Cause disease to marine organisms, water -borne and seafood-borne disease to humans • Prokaryotes: 2 domains, bacteria and archaea o Most ancient forms of life, single -celled, non-nucleated organisms o 3 shapes of bacteria: § Cocci (round- coccus, diplococcus, streptococci, staphylococci), bacilli (bacillus, diplobacilli, streptobacilli) (rod) or other shapes § Structurally simple, with few shapes § Few, if any organelles § Yet, most metabolically diverse organisms on earth § Most have cell walls made of peptidogly can (not cellulose) § Asexual reproduction (binary fission) o Virus particles: 10^7 viruses/ml; bacteria: 10^6 cells/ml § These numbers are pretty much uniform throughout the ocean § How diverse are these numbers? • Samples and sequencing experiments found at leas t 18,000 species-- highly abundant, highly diverse o How can there be so many? What are all of these bacteria doing? § If you win, you lose: if one species is more abundant than another, it’s more likely you will be infected with viruses • Helps to limit any o ne species from predominating § They are playing important roles in the earth’s biogeochemistry • Ex carbon and nitrogen cycles, symbiotic relationships, biotransformation and remineralization o Special group: cyanobacteria § Formerly known as blue -green algae, because of their green color due to photosynthesis • Don’t have a nucleus, so they are prokaryotes that are photosynthetic § Ancient- fossilized (sometimes still alive!) in stromatolites (up to 3 billion years old) • May still be actually photosynthetic • Responsible for creating the first oxygen in our atmosphere now § Highly abundant and can be found everywhere (freshwater, saline water, land, etc.) • Prochlorococcus is probably the most abundant type in the ocean § Thought to be the cells that ultimately became the chloroplasts in eukaryotic cells § Important nitrogen fixers, especially in the ocean § Can cause highly toxic harmful “algal” blooms and dermatitis • Archaea: ancient, single -celled, non-nucleated organisms o Originally found in only “extreme” environments, but later shown to be common in marine environment (symbionts with other marine organisms) § Hot springs- vibrant color is different species of archaea. thermoacidophiles § Great salt lake: extreme halophiles § Sewage: methanogens (a lot in our stomach, gets excreted and ends up in sewage facilities) o Are now known to be much more widespread, not just in extreme environments • Photoautotrophs: photosynthetic • Chemoautotrophs: can synthesize food by using the chemicals around them • Heterotrophs: bacteria which can’t make their own food, rely on others Marine Microbiology: unicellular eukaryotes • Microalgae and protozoa→ Protists: 10^3-10^4 cells/ml • Pure phototrophs: get all energy from photosynthesis • Pure heterotrophs: get all energy from consuming others • Mixotrophs: capacity for photosynthesis when convenient, otherwise heterotrophic • Photosynthetic Protists: o Very diverse group with many different photopigments: not just about chlorophyll, also exists in other forms /pigments § Ie red algae, brown algae, etc. o Structurally simple (relatively -- cannot be compared with other plants) § Single cells-- no roots, leaves, stems, but still diverse in form • All kinds of different shapes and organizations o First group: Diatoms: § Large(st usually) group with many diverse species § Cosmopolitan: can be found in all different types of habitats § Unicellular but some may occur as a colony § Cells encased with unique overlapping, 2 -part cell wall made of silica embedded in an organic matrix (frustrule) • Clear wall lets in lights, allows for photosynthesis • Require an environment where silica exists • May have spikes to deter predators § Photosynthetic- most are planktonic, others sessile § Two basic morphologies: centric and pennate o Second group: dinoflagellates § Large, highly diverse, cosmopolitan § Unicellular (some may occur as colony) § Thick cellulose-based walls (theca: provides structural support/ predation deterrent) § Have two perpendicular flagella • Traverse flagella goes around girdle (on the side) • Longitudinal flagella is perpendicular o **Diatoms can’t move, just float § Multiple morphologies (primary spherical) affect environment interaction § Can be photoautotrophs, heterotrophs, or mixotrophs § Primarily responsible for most harmful algal blooms and fish kills • Makes seabirds, marine animals, us sick • Whole different spectrum of illnesses can be caused § Can form symbiotic associations and bioluminescence • Ex coral polyp with dinoflagellates insid e: provides safe place to grow, dinoflagellate provides food to its host • Bioluminescence: send out flashes of lights when startled or disturbed
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