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Unit IV Notes- Marine Ecology I. Energy A. Matter and Energy Life requires both matter and energy to exist. –Matter that makes up living organisms consists of about 13 of 118 known elements. • Carbon, Hydrogen, Nitrogen, and Phosphorous are four major elements. Law of conservation Energy/Mass cannot be created nor destroyed; it can only be changed from one form to another. B. Autotrophy and Heterotrophy Most marine organisms get their energy directly or indirectly from the sun. Autotrophy- process of self-feeding by creating rich compounds called carbohydrates (i.e. plants, algae, phytoplankton). Heterotrophy- process of getting energy and matter by consuming other organisms (i.e. zooplankton, fish, etc.) C. Respiration Both autotrophs and heterotrophs must convert carbohydrates into useable energy. Done through cellular respiration: C6H12O6 + 6O2 → 6CO2 + 6H20 + ENERGY D. Photosynthesis Process of using light energy to create carbohydrates from inorganic compounds. 6CO2 + 6H20 + LIGHT ENERGY → C6H12O6 + 6O2 D. Photosynthesis cont. Organisms that perform this are called autotrophs, which are also known as primary producers. Carbohydrates are the basic building block of all larger molecules characteristic of life on earth. Even producers use cellular respiration. E. Aerobic and Anaerobic respiration Aerobic respiration- uses oxygen Anaerobic respiration- used by organisms in environment without oxygen. F. Chemosynthesis Process of using chemicals to create energy-rich organic compounds. – Similar to photosynthesis because it produces carbohydrates. – Differs because it does not use sunlight as energy source, but chemical energy in inorganic compounds. – Not as efficient as photosynthesis. – Used by bacteria that live on the ocean floor. END OF NOTES PART 1!! II. Primary Production This is the base of an ecosystem. In the ocean there are several producers, including: –Plants –Algae –Plankton The land is only slightly more productive than the ocean. Marine plants and algae are responsible for producing a fair amount of dissolved oxygen in the ocean. However, a very important group of primary producers are the plankton. Plankton A wide variety of organisms that share a habitat and lifestyle Not one species, but include many species from virtually every major group of organisms found in the sea. They can be autotrophic or heterotrophic. Types of Plankton Phytoplankton Account for 92-96% of oceans primary productivity These are the only plankton that are producers (they can undergo photosynthesis). Examples: Diatoms and Dinoflagellates Zooplankton Primary and Secondary consumers that feed on phytoplankton and other heterotrophic plankton. Largest Plankton in the sea is the Mola Mola or Ocean Sunfish (it is also the largest bony fish). Limiting Factors Physical or Biological necessities that restrict survival of primary producers. Too much or too little will reduce population of an organism. 1. Eutrophication Pollution that results from excess nutrients in the ocean. Algae and plants overgrow due to presence of fertilizers and reduce the amount of nutrients available to plankton. 2. Plankton bloom Can deplete nutrients available for plants, algae and other plankton. 3. Sunlight All primary producers require sunlight to undergo photosynthesis. The amount of sunlight in the ocean varies due to depth, season and/or water clarity. End of Notes Part 2!!! III. Food Webs/Chains Trophic Levels Representation of how energy transfers from one level to the next. Primary Producers Base Autotrophs Examples: Algae, Plants and Plankton Primary Consumers Heterotrophs Herbivores Most important primary consumer- Zooplankton Secondary Consumers Feed Primarily on Zooplankton Carnivores Decomposers Lastlevel Bacteria and Fungi Energy Flow Only about 10% of energy passes from one level to the next. Other 90% is used for work (repair, reproduction, etc). Food Webs Represents the flow of energy through consumption in nature. Shows organisms have different choices of prey and eat across a trophic pyramids theoretical levels (a primary consumer can also be a secondary consumer). Biological Magnification (Biomagnification) Small concentrations are increased as they go up a food chain. DDT – Remember the lab! Biogeochemical Cycles Carbon-Oxygen Cycle – Photosynthesis & Cellular Respiration Water Cycle – Evaporation, Precipitation & Run-Off Nitrogen Cycle – Ammonia, Nitrosomonans, Nitrite, Nitrobacter & Nitrate IV. Marine Lifestyles Plankton – Group of plants (phytoplankton) and animal (zooplankton) that exist adrift in ocean currents – Neuston • Plankton that float at the surface (i.e.: Portuguese man-of-war) Nekton – What you visualize when you think of marine organisms – Swim- small invertebrates to large whales Benthos – Live on or in the bottom – Motile or sessile 3 groups – Eipfauna • Animals that live on the sea floor (crabs) – Epiflora • Plants that live on the sea floor (sea grasses) – Infauna • Partially or completely buried in the sea floor (clams, sand dollars, tubeworms) Deposit or Suspension Feeders – Deposit- Feed off detritus (loose organic and inorganic matter) drifting down from above – Suspension- Filter particles (mostly plankton) suspended in water for food. End of Notes Part 3!! V. Ocean Zones Based on Light and Location Division by Light Photic Layer (sunlight layer) – 2 areas • 1. Euphotic Zone (eu= good) – Goes to about 660’. – Enough light for photosynthesis – Home to a variety of marine species – Relatively warm temperatures • 2. Dysphotic Zone (dys= difficult) – Nicknamed “Twilight Zone” – Goes to about 3300’ – Insufficient light for photosynthesis – Animals here must be able to handle cold temperatures, higher pressures, and darkness Aphotic Layer (midnight zone) – No sunlight therefore no plants – Can reach depths of close to 20,000’ – Very cold and completely dark – Life isn’t easy here; fewer organisms than other zones – Some animals do not have eyes Division by Location 2 Major Divisions – 1. Pelagic Division • Pelagius= “of the sea” • Open water at any depth • 2 zones – 2. Benthic Division • Benthos=bottom (bottom of the sea floor) • Ocean bottom below neritic and pelagic zones • Nutrients get here by “raining” down from waters above (detritus) Pelagic Division 1. Nertic zone (neritos= shallow) Intertidal Zone – Shoreline between high and low tides – High levels of light, nutrients, and oxygen – Stressful environment (drying, wave action) Subtidal Zone – Open Ocean – From shoreline to 650’ – Organisms all floaters or swimmers – Large numbers of phytoplankton 2. Oceanic Zone 4 areas – Epipelagic zone (epi= atop) – Mesopleagic (mesos= middle) – Bathypelagic (bathos= depth) – Abyssopelagic (a= without, byssos= bottom) Benthic Division 6 Areas 1. Supralittoral zone (supra= upper, litus=shore) – Water splashes but does not stay submerged – Drying out and thermal stress are a challenge 2. Littoral zone (littoral= of shore) – The band of coast covered and uncovered by tidal action- the intertidal zone Benthic Division cont. 3. Sublittoral zone (sub= below) – Inner sublittoral- near shore – Outer sublittoral- ocean floor out to edge of continental shelf 4. Bathyal zone – Seabed on the slopes and down to great depths Benthic Division cont. 5. Abyssal zone – Deep waters of the ocean 6. Hadal zone (hades=underworld) – Deepest: trench walls and floors End of Notes Part 4!! VI. Marine Ecosystems Ecology- studies how organisms relate to each other and their environment Abiotic and Biotic Factors – Biotic- living (quantity and type of organism) – Abiotic- non-living (temperature, wind, pH, currents, minerals, sunlight, etc). Ecosystem distinct entity usually with clearly defined physical boundaries, distinct abiotic conditions, an energy source, and a community of interacting organisms through which energy is transferred. (No ecosystem exists in isolation- therefore the ocean is composed of interacting ecosystems) Ecosystem cont. Community- collection of different organisms living and interacting in an ecosystem. (Includes all species and types of organisms) Population- group of the same species living and interacting within a community Ecosystem cont. Habitat- includes the area and conditions in which you find an organism. Microhabitat-exists on a very small scale Niche- organisms role in its habitat Ecosystems in the Open Sea Neutson ecosystem (plankton that live afloat on the sea surface) – Very thin layer (few mm) – Receives maximum amount of sunlight – Largest floating ecosystem- Sargasso Sea • Sargassum- brown algae accumulates in the middle of the North Atlantic as floating mats. Ecosystems in the Open Sea cont. Continental Shelf – Rarely exceeds 656’; s nutrients are kept in the photic zone. – Highly productive ecosystem Ecosystems in the Open Sea cont. Upwelling –Significant to open sea ecosystems because they bring nutrients from deep water to shallow more productive depths Costal Ecosystems Estuaries – Exists where the tides meet rivers – Trap and accumulate runoff sediments, so they are rich with nutrients and biologically productive – Provide shallow sheltered water with a steady stream or nutrients – Serve as nurseries for 75% of commercial fish species Costal Ecosystems cont. Salt Marshes – Exist in estuaries and along the coast – Halophytes- plants with adaptations that allow them to survive in salt water. • Have stomata on leaves that allow it to draw in oxygen into its submerged parts. • Sacrificial leaves that serve as a storage area for excess salt and fall of when the slat load reaches a certain point • Salt glands on leaves and stem excrete excess salt. Costal Ecosystems cont. Mangrove Swamps – Various adaptations allow them to live in salt water • Grow above waterline on stilt-like roots, which allows oxygen to reach the roots – Provide habitats for juvenile fish and invertebrates because of strong, tangled roots. – Protect habitat and coasts from erosion Costal Ecosystems cont. Sea grasses – Provide shelter – Internal salinity is the same as the sea water – Reproduce by releasing pollen into currents Costal Ecosystems cont. Intertidal zones – May be above waterline a times – Adaptations help retain moisture Costal Ecosystems cont. Beaches – Rich and productive ecosystem – Acts a filter that processes compounds entering the sea – Sand protects coastline • Reduce sedimentation caused by costal erosion – Complex organisms live in submerged beach sand – Meiofauna • Benthic organisms that live in spaces between sand grains Costal Ecosystems cont. Kelp and Seaweed – Seaweed-red, green, and brown algae – Kelp forest- very productive Costal Ecosystems cont. Coral Reefs – Most productive ecosystem – Threats to coral reefs • Nutrients • Increased temperature is causing coral bleaching (Global Warming) • Competitive algae • Sedimentation • Coral Disease End of Notes Part 5!! Polar Ecosystems The Arctic – Species found here have special adaptations • Anti-freezing compounds in blood • Low metabolism – Upwellings: Increased productivity because of nutrients being brought to the top – Challenges to marine organisms: • Reduced sunlight • Near freezing water Polar Ecosystems cont. The Antarctic – Largest nutrient-rich area on Earth – Supports massive phytoplankton blooms Deep-sea Ecosystems The Abyssal Zone – Average temperature 2C – No primary productivity (nutrients come from marine snow) – Greatest diversity found in the meiofauna Deep-sea Ecosystems cont. Whale Falls – Place where dead whales come to rest on the deep ocean floor Deep-sea Ecosystems cont. Hydrothermal Vents and Cold Seeps – Home to chemosyntheitc organisms Deep-sea Ecosystems cont. Hadal Depths- Ocean Trenches – Makes up the deepest ocean depths – Scientists know little because of limits of technology • Few submersibles have been built that can descend safely into the zone • 1 manned trip has been made to the deepest known spot in the ocean. End of Notes Part 6!!
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