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Sal engg college 067 by 140670106005 Environments and Life What is your current classification? A. B. C. D. Freshman Sophomore Junior Senior Guiding Questions • What factors determine the ecological niches of species, and by what means do species obtain nutrition? • What factors govern the geographic distribution of species? • What factors govern the distribution of aquatic life? Environmental Differences • Tropical vs Polar - Terrestrial and Marine • Low vs High Elevation • Shallow vs Deep • Wet vs Dry Hypsometric Curve • Curve showing the proportions of the Earth’s surface above and below sea level Hypsometric Curve QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Climate • Climate – Controls distribution of species globally – Has changed through time • Plate tectonics and other changes affect climate Ecology • Ecology – Study of the factors that govern the distribution and abundance of organisms in natural environments • Habitats – Environments on or close to Earth’s surface inhabited by life • Terrestrial • Aquatic – Marine – Freshwater Ecology • Ecologic niche – The way a species relates to its environment, including food, nutrients, physical and chemical conditions • Life habit – The way a species lives within its niche • Limiting factors – Naturally occurring, restricting condition (physical and chemical) – Competition • Shared drive for limited resources – Predation Competition Arises because organisms share space Predation also comes in here by possibly limiting or preventing another species from inhabiting a particular environment. Ecosystem • Ecosystem – Organisms of a community and the physical environment they occupy • Population – Group of individuals that belong to a single species and live together in a particular area Ecosystem • Ecologic community – Populations of several species living in a habitat • Producers – Photosynthesizing organisms; foundation of community • Consumers – Herbivores: feed on producers – Carnivores: feed on other consumers Ecosystem • Biota – Fauna: animals and protozoans of an ecosystem – Flora: plants and plantlike protists • Food chain – Sequence of consumption for producers to consumers Food Web • Food web – More complex than simple food chain • More common – Several species occupy each level Ecosystem • Parasites – Feed on living organisms • Scavengers – Feed on organisms that are already dead Ecology The movement of materials through an ecosystem. Components within ovals are consumers. Figure 4-35 (p. 134) Interdependence of photosynthesis and respiration. Figure 4-38 (p. 136) Simple pyramid of ocean life. Biogeography The distribution and abundance of organisms on a broad geographic scale. Biogeography • Temperature • Moisture • Nutrients Ecosystem • Diversity – The variety of species that live together within a community • Lower in more difficult habitats • Predation influences diversity – Heavy can reduce diversity – Moderate can increase diversity by reducing competition • Opportunistic species – Species that specialize in invading newly vacated habitats Biogeography • Distribution and abundance of organisms on a broad geographic scale • Limiting factors – Diversity increases toward equator – Barriers can affect dispersal Life Habitats The mode by which an organism lives, feeds in an environment 1. Tropical vs. Polar 2. Low vs high altitude 3. Shallow vs deep 4. Benthic vs. Planktonic Atmosphere • Regulates Earth’s temperature (-18°C w/o atmosphere) • Composition – N2, O2, CO2 • Tilt of the Earth affects solar insulation, temperature, and climate In our present atmosphere, concentrations of O2 and CO2 are: A. O2 > CO2 B. O2 < CO2 C. O2 = CO2 The Atmosphere • Nitrogen -78% • Oxygen - 21% • Carbon dioxide (CO2 ) - 0.037% or 370 ppm • Methane (CH4) - 0.00018% or 1800 ppb Solar Radiation Daylight Which receives more hours of daylight? Equator vs Poles The amount of daylight (# of hours) averaged over a year is the same at the poles as at the equator Solar Radiation Solar Radiation • Temperature difference is due to the angle of the sunlight and the albedo • In the high latitudes, the sun hits at a low angle and therefore the unit energy of sunlight is spread over a large crosssectional area of the earth’s surface. In the tropics, the sun hits directly and therefore is much more concentrated Solar Radiation Solar Radiation Albedo refers to the reflectivity of the Earth’s surface 1. Snow and ice is very reflective - much of the solar radiation is reflected by to the solar system 2. Water has a low albedo and absorbs a lot of the solar radiation QuickTi me™ and a TIFF (U ncompressed) decompressor are needed to see this picture. Solar Radiation Quick Time™ and a TIFF (Uncompressed) decompress or are needed to see this picture. Solar Radiation Solar Radiation • When do we have summers? • True or False • Summers on Earth occur when it passes closest to the Sun Solar Radiation • Obliquity or Tilt (23.5°) of the to Earth’s rotational axis • This tilt gives us seasons. Summer is when the northern or southern hemisphere is point towards the Sun Atmosphere • Regulates Earth’s temperature • Composition – N2, O2, CO2 • Tilt of the Earth affects solar insulation, temperature, and climate Solar Radiation Heat Capacity Movement of Air mass • Rises at Eq. and sinks near Poles • The high solar radiation at the equator heats the air masses, causing them to rise (buoyant). • As the air rises, the temperature of the air mass decreases Atmospheric Circulation • Net transport – Air sinks at the poles, rises at the equator – Simplified model • No tilt • No Coriolis effect Rising Air QuickTime™ and a TI FF (Uncompressed) decompressor are needed to see this pict ure. As the air rises, the temperature of the air mass decreases (adiabatic lapse rate 5°C/km) Cold air holds less water vapor. Voila, rain and the tropical rainforest. Low pressure systems usually have rain because the rising air drop water as the air ascends and cools Rising Air QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Atmospheric Circulation • Coriolis effect • Earth’s rotation causes air and water masses to be defected to the right (clockwise) in the northern hemisphere – Counterclockwise for southern hemisphere Atmospheric Circulation • If we reverse the direction and launch a rocket from Panama towards Washington DC, which way will it curve? • A = Right • B = Left • C = Not at all because Panama is close to the Eq. Coriolis force • Deflection of moving objects to the right in the No. Hemisphere and left in the So. Hemisphere Coriolis Force Atmospheric Circulation • Actual pattern is more complex – Three circulation cells – Trade winds, westerlies, easterlies • Intertropical convergence zone – Northern, southern trade winds converge near equator • Changes seasonally Temperature Variations • Atmosphere retains heat • Solar radiation – Absorbed and turned into heat energy – Reflected • 6-10% ocean • 5-30% forest • 45-95% ice and snow Trade winds • As the dry air descending around 30° begins to flow back towards the Eq. it is deflected to the right. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Trade winds As the dry air descending around 30° begins to flow back towards the Eq. it is deflected to the right. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Trade winds The NE and SE trades converge on the latitude where the maximum in convection (rising air) is occurring. This is the warmest location. Today, this is between 4 and 10°N and is termed the Inter-Tropical Convergence Zone (ITCZ) The Terrestrial Realm • • • • • • • Latitudinal Zones and Vegetation Rain forests Deserts Savannah Grasslands Temperate Forest Conifer or Evergreen Forest Tundra Terrestrial Realm • Vegetation follows climatic zone – – – – Tropical rain forest Desert savannahs Temperate forests Polar tundra Terrestrial Realm • Tropical Climates – 18–20° C (64–68° F) – 0–30° latitude • Tropical Rain Forest – Dense vegetation Rain forests • develop under the tropical low pressure systems. Rising air dumps lots of rain. Found within a few degrees near the equator QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Terrestrial Realm • Deserts – Dry trade winds remove moisture – 20–30° north and south of the equator – < 25 cm rain/year – Little vegetation • Savannah, grasslands – Too dry to support forests • (<10 inches of water per year) develop under the sinking dry air masses and under the dry Trade Winds. Usually found around 30° latitude. Deserts QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Savannah Grasslands • found between Rain forest and Desert and receive seasonal rain falls. Not enough rain throughout the year to support woodland QuickTi me™ and a T IFF (Uncom pressed) decom pressor are needed to see t his pic ture. QuickTi me™ and a T IFF (Uncom pressed) decom pressor are needed to see t his pic ture. Tundra - Arctic ecosystem where layer beneath soil remains frozen throughout the year. QuickTi me™ and a TIFF (U ncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncomp resse d) de com press or are nee ded to s ee this picture. Terrestrial Realm • Poles – Defined by ice sheets and glaciers today – Absent or reduced at times in the past Terrestrial Realm • Glaciers – Ice in motion – Glide and spread – Present at high latitudes and high elevations near equator Terrestrial Realm • Tundra – Limited water – Grasses, sedges, lichens, shrubs dominate – Cannot support tall trees • Evergreen coniferous forests – South of tundra – Spruce, pine, fir Terrestrial Realm • Temperate forests – Longer summers, slightly warmer – Deciduous trees • Maples, oaks, beeches • Mediterranean climate – Dry summers, wet winters – Common 40° N and S of equator • Californian, Mediterranean region Climate • Altitude – Similar to latitudinal gradient – At base • Deciduous forest – On slopes • Evergreen forest • Tundra above tree-line – At top • Glaciers Climate • Mountains • Rain shadow – Prevailing winds bring moisture • Precipitation on windward side • Aridity on leeward side – Rain shadows common on east side of North American mountain chains Climate • Seasonal Change – High heat capacity of water • Less change in ocean temperatures than on land • Monsoon Circulation – Summer winds flow onshore; bring rain – Winter winds offshore Plants as Climate Indicators • Sensitive indicators of change – Cycads • Tropics and subtropics today • Fossil distribution allows reconstruction of climate patterns Plants as Climate Indicators • Leaf Margins – Tropics • Smooth, waxy margins – Temperate climates • Jagged margins Marine Realm • Ocean currents – Wind driven – Follow atmospheric patterns • Trade winds – Push waters west; form equatorial currents – Equatorial countercurrents • Return flow • Gyres – Clockwise in Northern Hemisphere – Gulf Stream Marine Realm • Circumpolar current – Circles Antarctica – Very cold Marine Realm • Polar circulation – Sea ice leads to more saline water – Cold, dense waters sink – Antarctic waters • Flow north at depth – Arctic waters • Flow south at depth Marine Realm • Ocean circulation – Waves • Surface waves – Wind driven – Break when seafloor interacts at shallow depths – Tides • Cause major movement of water in oceans • Due to rotation of solid Earth beneath bulges of water produced by gravitational attraction of the moon Marine Realm • Continental Shelf – Submarine extension of continental landmass • Shelf break – Edge of shelf • ~200 m w.d. • Continental Slope • Continental Rise • Abyssal Plain Figure 4-31 (p. 131) Classification of marine environments. (After Hedgspeth, UJ. W., ed. 1957. Treatise of Marine Ecology and Paleoecology. Geological Society of America Memoirs 67(1): 18.) The Marine Realm • The depth of the Sea • Moving from the beach seaward, one crosses a consistent pattern of water depth changes. The continental shelf extends from the shoreline to the continental shelf break. Water depths over the shelf vary from 0 to ~200 m. This environment is very important for benthic communities because the photic zone in the ocean extends only down to 200m. Consider the implications for primary production The Marine Realm • The Shelf break marks the distal edge of the shelf where seaward of this point, water depths increase at a greater rate (3 to 5°slope) compared with the shelf (1 to 2°slope). The Marine Realm • Continental Slope. • Typically, the slope extends down to 3000 to 3500 m. Near the base of the slope is the transition from continental to oceanic crust. The Marine Realm • The Slope gives way to the Continental Rise. This is a less steep surface that segways to the Abyssal Plain (the ocean floor). The Rise is created as sediments are transported down the slope in turbidity currents. The Marine Realm • At the base of the slope and out on the abyssal plain, the slope decreases significantly and the sediments are dropped, forming the Rise Figure 4-31 (p. 131) Classification of marine environments. (After Hedgspeth, UJ. W., ed. 1957. Treatise of Marine Ecology and Paleoecology. Geological Society of America Memoirs 67(1): 18.) Marine Realm • Near shore – Barrier islands – Marshes – Epicontinental seas Marine Realm • Photic Zone – Region of ocean where enough light penetrates to permit photosynthesis • Pelagic life – Plankton • Phytoplankton • Zooplankton – Nekton • Benthic life – Suspension feeders – Deposit feeders Marine Realm • Marine Biogeography – – – – Tropical Subtropical Transitional Subarctic Figure 4-36 (p. 135) Major ocean surface currents. Marine Realm • Corals – Most require warm water – Common in tropics • Reef builders – Coral polyp – Builds coral cup – Connected to other polyps • Symbiotic relationship with algae Marine Realm • Salinity – Limiting factor near shore – Oceanic • 35 ppt – Brackish • Lower than marine • Bays, lagoons – Hypersaline • Higher than marine • Hot arid climates The portion of the temperature-depth curve in the ocean that shows maximum change is the thermocline. Deep Water Circulation Atmospheric Circulation • If we reverse the direction and launch a rocket from Panama towards Washington DC, which way will it curve? • A = Right • B = Left • C = Not at all because Panama is close to the Eq.
