Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Ocean acidification wikipedia , lookup
Deep sea fish wikipedia , lookup
Abyssal plain wikipedia , lookup
Arctic Ocean wikipedia , lookup
Marine biology wikipedia , lookup
Marine pollution wikipedia , lookup
Ecosystem of the North Pacific Subtropical Gyre wikipedia , lookup
Effects of global warming on oceans wikipedia , lookup
PROPERTIES OF SEAWATER 2016-2017 WATER 80 to 90 % of the volume of most organisms Buoyancy and support Pure water 3 forms: Liquid Gas – atmosphere Solid – snow and ice •Molecules •1 atom of oxygen 2 atoms of hydrogen •H2O •Bent •Polar •Bond is shared •Hydrogen bond – one end of a molecule attracts the oppositely charged end of another molecule . VISCOSITY •The resistance of water molecules to external forces that would separate them. •Floating and swimming •Reduces sinking tendency of some organisms •Magnifies problems with drag SURFACE TENSION The mutual attraction of water molecules at the surface of a water mass that creates a flexible molecular “skin” over the water surface. DENSITY – TEMPERATURE RELATIONSHIP Water at 4 degrees Celsius or above – density increases with decreasing temp. Below 4 degrees the pattern reverses. Ice is 8% less dense than water. HEAT CAPACITY Heat – form of energy. In water, heat is transferred from place to place by convection and conduction. Heat energy measured in Calories CALORIE Amount of heat needed to raise the temperature of 1 gram of water 1 degree Celsius. HEAT CAPACITY The measure of heat energy required to change the temperature of 1 gram of a substance 1 degree Celsius. Water has the highest heat capacity. LATENT HEAT OF FUSION The heat that must be extracted from a liquid to freeze it to a solid at the same temperature. Water = 80 cal/g. LATENT HEAT OF VAPORIZATION The heat energy required to convert a liquid to a gas at the same temperature. Water = 540 cal/g. The high heat capacity and the large amount of heat required to evaporate enables large bodies of water to resist extreme temp. fluctuations. Provides a temp. moderating effect for the marine environment and adjacent land areas. SOLVENT ACTION Water – being small and having polar charges allows it to interact with and dissolve most naturally occurring substances, especially ions. DISSOLVED SALTS Account for the majority of dissolved substances in seawater. SALINITY Total amount of dissolved salts Measured in parts per thousand Average ~ 35 ~ Range from 0 at river mouths to ~ 40 at Red Sea Primary mechanism of salt and water addition or removal are: Evaporation Precipitation River run off Freezing and thawing of sea ice Salts dissolve and produce ions: Major and minor ions Major accounts for 98% of total salt conc. LIGHT AND TEMPERATURE IN THE SEA Organisms in upper portion use light for: Vision photosynthesis Amount of energy reaching surface depends on: Dust - clouds -gases Organisms that are photosynthetic must live in the Photic Zone. Things that diminish photosynthetic activity- decrease depth are: --dissolved substances --suspended sediments --plankton population Seawater rapidly absorbs the violet and orange-red portions of spectrum. blue and green penetrate deeper Red usually absorbed in top 10 m. 10% of blue penetrates to 100 m. When sunlight is absorbed by water molecules – it is converted to heat energy – motion of water molecules increases. Temperature is used to measure the change in molecular motion. SALINITY – TEMP. – DENSITY RELATIONSHIPS Density increases when temp. decreases or salinity increases. Temp. fluctuates more than salinity so it has a greater influence. THERMOCLINE A subsurface zone to rapid temp. decrease with depth. (~1 degree Celsius / meter) PYCNOCLINE •Ocean layer, usually near the bottom of the photic zone, marked by a sharp change in density. •Large density difference on either side of the thermocline separates ocean into 2 layers. •This inhibits mixing and exchange of gases, nutrients, and organisms. PRESSURE At sea level 1 atm. In sea pressure increases 1 atm/ 10 m depth. DISSOLVED GASES Dissolved gases and acid/base buffering: Solubility of gases in sea water is a function of temp. Greater solubility at lower temp. MOST ABUNDANT GASES IN SEAWATER Nitrogen Carbon dioxide Oxygen ACIDITY OF THE OCEAN Abundance of hydrogen ion controls acidity and alkalinity of the solution. - carbonic acid – bicarbonate- carbonate system in seawater acts as a buffer – limit changes in pH. Open ocean pH 7.5 to 8.4 OXYGEN Oxygen concentration influences distribution of organisms. Oxygen introduced into seawater two ways: 1. transfer of oxygen from atmosphere to seawater. 2. production of excess oxygen by photosynthesis. Oxygen consumed near the bottom can only be replaced by oxygen at the surface. Oxygen replenished by: Very slow diffusion process from oxygen rich surface layers downward. Downward vertical water movement. OXYGEN MINIMUM ZONE At intermediate depths animal respiration and bacterial decomposition use oxygen as fast as it is replaced. DISSOLVED NUTRIENTS Nitrates Phosphates Used by photosynthetic organisms. OCEAN IN MOTION •Constantly in motion •Enhances mixing and minimizes variations in salinity and temp. •Also disperses swimming and floating organism, eggs, spores, and larvae. •Toxic body waste are carried away while food, nutrients, and essential elements are replenished. Heat from the sun is the driving force behind oceanic circulation. Circulation processes beneficial to all life forms: 1. wave action 2. tides 3. currents -4. vertical water motion WAVES •- up and down movements of ocean surface. •Heating of earth’s atmosphere produces winds. •Winds produce waves and surface currents. •Waves are periodic vertical disturbances of the sea surface. SIZE AND ENERGY OF WAVE DEPENDS ON: 1. wind velocity 2. duration 3. fetch – distance over which the wind blows in contact with the sea surface. WAVES ARE CHARACTERIZED BY: Height – Vertical distance between a wave crest & the adjacent trough Wavelength - horizontal distance between 2 successive wave crests or 2 successive wave troughs Period – time required for two successive wave crests or troughs to pass a fixed point. ROGUE WAVES •Huge lone wave with very high crests and low troughs. –Formed when 2 or more large waves unite. or –When waves meet opposing currents. SWELLS More rounded crests and longer periods and extend beyond area they were generated. TIDAL BORE Occur in river and estuaries Black Dragon Tidal Bore BREAKER When water depth is less than ½ the wavelength, top of wave moves faster than bottom --pitches forward, crashes. WHITE CAPS Wind produces steep waves with narrow crests – crest are easily blown off by wind. TSUNAMIS Created by sudden disturbance. Energy transferred to water when it reaches surface and creates high velocity waves. TIDES Very long period waves, periodic rise and fall of sea surface. Most coast lines have 2 high and 2 low tides each day. Time between 2 consecutive high and low tides is approx. 6 hrs. 20 min. TIDAL RANGE Vertical difference between consecutive high tides and low tides. • Moon has twice as much force on tides than sun. • Moon completes 1 orbit around the earth each lunar month (27.5 days) • Two equal high and 2 equal low tides every 24 hours and 50 min. (a lunar day) Solar tides half as big as lunar tides. SPRING TIDES Sun, earth and moon are in alignments (new and full moon) These are extra high-high tides, etc. NEAP TIDES Occur a week later, sun and moon at right angles. Moderate tides During a lunar month get 2 spring and 2 neap tides. SEMIDIURNAL TIDES Two high tides - two low tides each lunar day. DIURNAL TIDES One high and one low each day. MIXED SEMIDIURNAL TIDES 2 high and 2 low but the successive high tides are different from each other. SURFACE CURRENTS Occur in regions where winds blow over the ocean with a reasonable constancy of direction and velocity 3 MAJOR WIND BELTS IN N. HEMISPHERE 1. Trade winds 2. Westerlies 3. Polar easterlies OCEAN CURRENTS A current – large mass of continuously moving ocean water. GLOBAL OCEAN CURRENTS Largest currents that move across the ocean 1. S. Equatorial 2. Gulf Stream 3. California current GYRES Currents that move in giant circles Also called surface currents Wind driven COUNTER CURRENTS Deeper, slow move in opposite directions from wind driven currents. UNDERTOE Returning current or backwash Strong current caused by wave action. TIDAL CURRENTS Swift moving currents, runs parallel to the shore. WHIRLPOOL Rapid movement of surface water in a circle. Formed between islands or result of strong winds. LONGSHORE CURRENTS Waves break at an angle and produce current that moves parallel to the beach SANDBAR Long hill of sand that is deposited a short distance from the shore •Forms parallel to the beach and acts like a dam. •If pressure is great enough – ma break and create a rush of water seaward = called rip currents = fast narrow currents of water traveling seaward. CORIOLIS EFFECT Currents deflected to the (right) in N. hemisphere and west (left) in S. hemisphere. Deeper water layers sit into motion by water above them – experience the Coriolis effect and spiral downward. EL NINO Prominent warming of the equatorial Pacific surface waters. Occurs irregularly every few years…usually at Christmas time. Occurs when pressure difference across the tropical Pacific relaxes and both surface winds and ocean currents either cease or reverse. VERTICAL WATER MOVEMENT Produced by sinking and upwelling processes. Upwelling – rising water masses Brings deeper nutrient rich waters to the surface. Produces area of high biological productivity. CLASSIFICATION OF MARINE ENVIRONMENTS Photic zone Aphotic zone 50 – 100m. below 100 m Light no light CLASSIFICATION OF MARINE ENVIRONMENTS CONT. Benthic division: Environment on sea bottom Continental shelf Littoral system: Supralittoral Eulittoral Sublittoral CLASSIFICATION OF MARINE ENVIRONMENTS CONT. Deep Sea System: Bathyal zone = continental slope Abyssal zone = abyssal plains and other ocean bottom areas. Hadal zone = below 6,000 m. - trenches CLASSIFICATION OF MARINE ENVIRONMENT: CONT. •Pelagic division: –Includes the entire water mass. 2 provinces: 1. Neritic - water over continental shelf 2. Oceanic - water over deep ocean Know diagram.