Ch. 14

1. Ch. 14 Marine Ecosystems

2. What is ecology? • It is the science that studies how organisms relate to each other and their environment. • Considers both biotic (living) and abiotic (nonliving) aspects. • Examples of abiotic factors: temperature, wind, pH, currents, minerals, and sunlight • Examples of biotic factors: quantity and type of organisms in an environment • Studies the relationships and interactions of the abiotic and biotic aspects of the environment

3. Ecology Terminology • Ecosystem: a distinct entity usually with clearly defined physical boundaries, distinct abiotic conditions, an energy source, and a community of interacting organisms • Community: collection of different organisms living and interacting in an ecosystem • Population: a group of the same species living and interacting within a community • Habitat: includes the area and conditions in which you find an organism; organism’s address • Microhabitat: exists on a very small scale; • Niche: an organisms role in the habitat; it’s job

4. Energy Flow and Nutrient Cycles • Energy flow through a food web affects an ecosystem by determining how much energy is available for organisms at higher trophic levels • Carbon Cycle is the basis for most ecosystems • Nitrogen Cycle thought to be more limited in marine ecosystems than on land ecosystems • Temperate ecosystems get less sunlight but get far more nutrients • Most productive marine ecosystem found in cold temperate regions

5. ECOSYSTEMS IN THE Open sea

6. Neuston Ecosystems • Neuston: plankton that live afloat on the surface; only few millimeters thick • Thin ecosystem, but makes up a major ecosystem that receives the max amount of sunlight and covers 71% of Earth’s surface • In some areas, photosynthesis and primary productivity may be higher below this ecosystem; this is due to 2 factors • Photoinhibition: UV light may account for this; ozone depletion could make this worse; too much light overwhelms an autotroph to photosynthesize • Pollutants: may be reducing global warming by absorbing carbon dioxide; but oil-based pollutants stop this carbon dioxide from being absorbed at the surface • The Sargasso Sea is the world’s largest floating ecosystem

7. Upwellings • Important to open-ocean ecosystems • HOW?? • Bring nutrients from deep colder waters to surface • High upwelling activity= high nutrient activity

8. Coastal ecosystems

9. Estuaries • Exist where tides meet rivers; common where tidal range is high • Can be large complex deltas or simple wide stretches of river entering the sea • Rich with nutrients and biologically productive • Contain halophytes: saltwater plants which also support a large community of primary and secondary consumers • Organisms must tolerate wide salinity ranges • Provide shallow sheltered water so larvae and juveniles of other species can avoid predation and grow until they venture out to sea

10. Salt Marshes • Can exist in estuaries and along the coasts • Grow where its relatively flat land with nutrient rich sediment washed by the tides • Conditions vary within a salt marsh: upper marsh: rarely flooded by the tides lower marsh: areas flooded by salt water as a regular part of the tidal cycle • Halophytes in lower marsh deal with constant osmotic stress; Spartina: contain stomata- pores in the leaves through which it breathes (adaptation for survival) • Plants in upper marsh have a reduced osmotic stress; Pickleweed handles excess salt accumulation by storing it in the leaves; once reaches a certain point, leaf drops off

11. Mangrove Swamps • Contain mangrove trees that have a very similar niche as halophytes in salt marshes • Mangroves have adaptations that allow them to live in salt water and anaerobic mud • For example: red mangroves grow above the water line allowing oxygen to reach the roots • Use reverse osmosis (process of transporting water through a semipermeable membrane against the natural osmotic gradient) to obtain fresh water by filtering seawater through its roots • Other mangroves grow below the waterline; aerate their roots with tubes called pneumatophores which carry air from above the surface to roots • Mangroves in this ecosystem: have strong, tangled roots that provide habitats for juvenile fish and invertebrates; they also trap nutrients that help to protect coral reefs

12. Seagrass Ecosystem • Similar to the other ecosystems in that they stabilize sediments and provide shelter and habitats for other organisms • Seagrasses (plants that inhabit this ecosystem) live entirely under water except during unusually low low tides • They do not need a freshwater source • These ecosystems do not need a freshwater source and can exist in deep water • These ecosystems are heavily grazed by microbes, invertebrates, fish, turtles, and manatees

13. Beaches • Rich and productive ecosystems • Organisms live on the organic material in the sand mix • Worms, mollusks etc. live submerged in the sand • Meiofauna- benthic organisms that live in the spaces between sand grains- also very diverse in this ecosystem • Algae also live among the sand grains • The physical and organic processes that occur here aid in making the beach a giant filter; provides organic and inorganic material for certain organisms; run-off and material that has been washed up

14. Kelp and Seaweed Ecosystems • One organism that eats kelp is the sea urchin. • The sea urchin is also one of the primary foods of a sea otter • Killing the sea otters disrupts the kelp’s ecological balance by removing the sea urchin’s main predator. • With no sea otter’s to feed on sea urchins, the sea urchin population will rise, which means more grazing on kelp • Eventually sea urchin eats the kelp faster than it can grow. • Example of the interdependence that exists within an ecosystem.

15. Coral Reefs • Most diverse ecosystems in the ocean; however, also very fragile • Located in clear waters which make photosynthesis easier • Also require water that is relatively free of nutrients WHY?? • Pass on and preserve organic material; lack of nutrients protects coral from competitive organisms • Eutrophication (nutrient build up) and global warming (increase temp) both pose threats to coral ecosystems • Loss of coral will have a major affect on the global ecosystem

16. Polar ecosystems

17. The Arctic • Marine ecosystems in the arctic face challenges such as reduced sunlight under the ice and water; life is scarce under these ice caps • Animals that do live here have special adaptations: antifreezing compounds in blood, low metabolisms • However, when ice melts during warmer months, productivity increases; occurs mainly from April to August along the North Pacific and North Atlantic • This supports massive fisheries, marine mammals, and other organisms • Ecosystem flourishes from nutrients churned up from bottom

18. The Antarctic • More extreme climate than Arctic • During winter: sea ice doubles the area around the continent; adds area about the size of NA • Antarctic Divergence: largest nutrient rich area on Earth; supports massive phytoplankton blooms, copepod populations, and krill populations • Organisms have special adaptations (as in Arctic): some fish have anti freezing characteristics, slowed metabolisms • Most species here are specialized and found only here

19. Deep sea ecosystems

20. The Abyssal Zone and Whale Falls • No sunlight; no photosynthesis; No primary productivity in most of the deep ocean • Gets nutrients from marine snow: fall of sediment, dead organisms, fecal pellets and other nutrients from waters above • Most of deep ocean= abyssal zone. Covers about 30% of Earths surface; smoothest and flattest area; lacks dense life concentrations, but diverse species live here • Organisms that survive here: echinoderms, sea cucumbers, sea lilies, brittle stars, etc. • Whale fall: a place where a dead whale comes to rest on the deep-ocean floor; carcass brings massive concentration of nutrients

21. Hydrothermal Vents and Cold Seeps • Hydrothermal vents: source of primary productivity; bacteria at these vents are the base of this productivity • Cold Seeps: sulfide-rich fluids seep from rock on the ocean floor; called “cold” seeps because they are cold compared to hydrothermal vents • Cold seeps also contain the sulfide consuming bacteria found in hydrothermal vents

22. Hadal Zone- Ocean Trenches • Scientists know little about ecosystems within the hadal zone….. • WHY?? • Limits in technology: extreme pressure makes it expensive and difficult to make instruments capable of observing these depths • There have been brief observations made that found organisms in the Mariana Trench (deepest place on Earth); however, character and extent of these ecosystems remain largely unknown