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Transcript
Primary Productivity in the Marine Environment Fig. 13.5 Primary productivity Energy is converted into organic matter to be used by cells Photosynthesis using solar radiation ○ 99.9% of marine life relies directly or indirectly on photosynthesis for food Chemosynthesis using chemical reactions Happens in hydrothermal vents at bottom of ocean with no light Remember, energy cannot be created or destroyed – it only changes form Let’s talk about energy Biological organisms need biochemical processes to happen in an orderly fashion in order to maintain life ○ Needs constant input of energy to maintain that order ○ Our cells need energy in form of ATP ATP formed during cellular respiration Need input of carbon (i.e. glucose) and oxygen for cellular respiration That carbon source and oxygen comes from photosynthesis (primary productivity) Photosynthetic productivity Chemical reaction that stores solar energy in organic molecules ○ Photosynthetic organisms fix carbon and energy from atmosphere - Also incorporate other elements and molecules necessary for life (nitrogen, phosphorus, etc) - What do we need these for? For making proteins, lipids, DNA, etc. - Use some of that for their own energy source for life - Excess moves it’s way up the food chain Now we are going to revisit photosynthesis and cellular respiration Remember, we are following electrons and protons OIL RIG – Oxidize it loses, reduced it gains Photosynthesis – process of fixing carbon from the atmosphere into organic material that now has energy from the sun trapped in the bonds of the molecule What is the chemical formula for photosynthesis? Review this Prezi: http://prezi.com/2byn9gmriian/photosynthesis/?utm_campaign=s hare&utm_medium=copy Cellular Respiration Review this Prezi: http://prezi.com/8_qehzkw- vuk/cellularrespiration/?utm_campaign=share&utm_medium=c opy Is glucose the only molecule that can be broken down and oxidized during cellular respiration to gain energy? Measuring primary productivity Capture plankton Plankton nets Ocean color Chlorophyll colors seawater SeaWiFs on satellite Factors affecting primary productivity Nutrients Nitrate, phosphorous, iron, silica Needed for bacteria and phytoplankton to make more DNA, proteins, etc to make more of themselves Most from river runoff Productivity high along continental margins because of nutrient runoff Solar radiation Uppermost surface seawater and shallow seafloor are most productive, need light! Euphotic zone surface to about 100 m (330 ft) Upwelling and nutrient supply Cooler, deeper seawater nutrient-rich Areas of coastal upwelling sites of high productivity Fig. 13.6a http://cordellbank.noaa.gov/images/environment/upwelling_470.jp Light transmission Visible light of the electromagnetic spectrum Blue wavelengths penetrate deepest Longer wavelengths (red, orange) absorbed first Light transmission in ocean Color of ocean ranges from deep blue to yellow-green Factors Water depth Turbidity from runoff Photosynthetic pigment (chlorophyll) ○ “dirty” water in coastal areas, lagoons, etc. are areas of high productivity, lots of plankton (preventing that “blue” color) http://upload.wikimedia.org/wikipedia/commons/a/a5/LightningVolt_Deep_Blue_Sea.jpg Types of photosynthetic marine organisms Angiosperms Seed-bearing flowering plants, example is mangroves Macroscopic (large) algae Larger seaweeds, like kelp Microscopic (small) algae phytoplankton Photosynthetic bacteria Macroscopic algae – “Seaweeds” Brown algae http://www.starfish.ch/photos/plants-Pflanzen/Sargassum.jpg Macroscopic algae – “Seaweeds” Green algae Codium Caulerpa brachypus, an invasive species in the Indian River Lagoon http://www.sms.si.edu/IRLspec/images/cbrachypus2.jpg http://192.107.66.195/Buoy/System_Description_Codium_Fragile.jpg Macroscopic algae – “Seaweeds” Red algae Most abundant and most widespread of “seaweeds” Varied colors http://www.dnrec.state.de.us/MacroAlgae/information/Indentifying.shtml http://www.agen.ufl.edu/~chyn/age2062/lect/lect_15/22_14B.GIF Microscopic algae Produce food for 99% of marine animals Most are planktonic phytoplankton http://biologi.uio.no/akv/forskning/mbot/images Golden algae Diatoms (tests of silica) ○ ○ ○ Most abundant single-celled algae – 5600+ spp. Silicate skeletons – pillbox or rod-shaped ooze Some w/ sticky threads, spines slows sinking www.bren.ucsb.edu/ facilities/MEIAF Microscopic algae Coccolithophores (plates of ate) ○ Flagellated ○ calcium carbon plates possibly sunshades ○ Coccolithid ooze fossilized in white cliffs of Dover http://www.esa.int/images Microscopic algae Dinoflagellates Mostly autotrophic; some heterotrophic or both Flagella in grooves for locomotion Many bioluminescent Often toxic when toxin is concentrated due to bloom ○ Red tides (algal blooms) fish kills (increase nutrients, runoff) http://oceanworld.tamu.edu/students/fisheries/images/red_tide_bloom_1.jpg http://www.hku.hk/ecology/porcupine/por24gif/Karenia-digitata.jpg Microscopic algae Dinoflagellates Pfiesteria found in temperate coastal waters Ciguatera - illness caused from eating fish coated with Gambierdiscus toxicus Paralytic, diarhetic, amnesic shellfish poisoning Pfiesteria http://www.odu.edu/sci/biology/pfiesteria Photosynthetic bacteria Cyanobacteria – many different species Extremely small May be responsible for half of total photosynthetic biomass in oceans Anabaena http://www.micrographia.com/specbiol/bacteri/bacter/bact0 200/anabae03.jpg Gleocapsa http://silicasecchidisk.conncoll.edu/Pics/Other%20Algae/Blue_Green%20 jpegs/Gloeocapsa_Key45.jpg Regional primary productivity Varies from very low to very high depending on Distribution of nutrients Seasonal changes in solar radiation About 90% of surface biomass decomposed in surface ocean About 10% sinks to deeper ocean Only 1% organic matter not decomposed in deep ocean reaches bottom Biological pump (CO2 and nutrients to sea floor sediments) Temperate ocean productivity Seasonal variation with temperature/light/nutrients Winter: ○ High winter winds mixing of sediments/plankton ○ Low light & few phytoplankton nutrients increase Spring: ○ Phytoplankton blooms with more light, nutrients ○ Bloom continues until… Nutrients run out Herbivores eat enough phytoplankton Summer: often low production due to lack of nutrients Fall: Often second bloom, as winds bring up nutrients Polar ocean productivity Winter darkness Summer sunlight (sometimes 24 hours/day) Phytoplankton (diatoms) bloom Zooplankton (mainly small crustaceans) productivity follows HIGH PRODUCTIVITY!! Example Arctic Ocean Tropical ocean productivity Permanent thermocline is barrier to vertical mixing Low rate of primary productivity (lack of nutrients) above thermocline ○ That’s why tropical waters tend to be clear and blue Tropical ocean productivity Productivity in tropical ocean is lower than that of polar oceans That’s why tropical oceans look clear Tropical oceans are deserts with some high areas of sporadic productivity (oasis). Examples of these areas are: Equatorial upwelling Coastal upwelling (river runoff, etc.) Coral reefs Energy flow in marine ecosystems Consumers eat other organisms Herbivores (primary consumers) Carnivores Omnivores Bacteriovores Decomposers breaking down dead organisms or waste products Nutrient flow in marine ecosystems Nutrients cycled from one chemical form to another Biogeochemical cycling Example, nutrients fixed by producers Passed onto consumers Some nutrients released to seawater through decomposers Nutrients can be recycled through upwelling Feeding strategies Suspension feeding or filter feeding Take in seawater and filter out usable organic matter Deposit feeding Take in detritus and sediment and extract usable organic matter Carnivorous feeding Organisms capture and eat other animals Trophic levels Feeding stage is trophic level Chemical energy is transferred from producers to consumers On average, about 10% of energy is transferred to next trophic level Much of the energy is lost as heat Food chain Primary producer Herbivore One or more carnivores Food web Branching network of many consumers Consumers more likely to survive with alternative food sources • Food webs are more complex & more realistic • Consumers often operate at two or more levels http://users.aber.ac.uk/pmm1 Marine fisheries Fig. 13.23 Commercial fishing Most tonnage from continental shelves and coastal fisheries, compared to open ocean fisheries Over 20% of catch from areas of upwelling that make up 0.1% of ocean surface area Overfishing Taking more fish than is sustainable over long periods Remaining fish younger, smaller About 30% of fish stocks depleted or overfished About 47% fished at biological limit Aquaculture becoming a more significant component of world fisheries Incidental catch or bycatch Bycatch - Non-commercial species (or juveniles of commercial species) taken incidentally by commercial fishers Bycatch may be 25% or 800% of commercial fish Birds, turtles, dolphins, sharks http://www.motherjones.com/news/featurex/2006/03/bycatch_265x181.jpg Incidental catch or bycatch Technology to help reduce bycatch Dolphin-safe tuna TEDs – turtle exclusion devices Driftnets or gill nets banned in 1989 Gill nets banned in Florida by constitutional amendment in 1994 http://www.st.nmfs.noaa.gov/st4/images/TurtTEDBlu_small.jpg http://www.cefas.co.uk/media/70062/fig10b.gif Fisheries management Plaice Regulate fishing Closings – Cod fisheries of New England Seasons Size limits ○ Minimum size limits – protects juveniles, less effective ○ Min/max size (slot) limits – preserves juvs and larger adults (contribute most reproductive effort) http://www.cefas.co.uk/media/70037/fig7b.gif Fisheries management Conflicting interests Conservation vs. economic – “tragedy of the commons” Self-sustaining marine ecosystems Human employment International waters Enforcement difficult “Tragedy of the commons” – All participants must agree to conserve the commons, but any one can force the destruction of the commons http://farm1.static.flickr.com/178/380993834_09864a282c.jpg Fisheries management Consumer choices in seafood Consume and purchase seafood from healthy, thriving fisheries Examples, farmed seafood, Alaska salmon Avoid overfished or depleted seafood Examples, bluefin tuna, shark, shrimp, swordfish Visit: ORCA's Blue Diet page http://marineresearch.ca/hawaii/wpcontent/uploads/tuna-auction-largeview.jpg Figure 13.28