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Ocean Environment Thursday April 30 2015 3 07 PM There are three main components of this course The ocean environment Marine organisms Marine ecosystems 1 Geology of oceans 2 Physics of oceans 3 Chemistry of oceans A Ocean basins B Change over time C Plate tectonics D Geographical features of oceans 1 Continental Margins Continental shelf From shore outward Extensions of continent Vary in width 8 of ocean bottom Dynamic productive habitat rich in diversity of organisms Continental slope Usually start at shelf break Begin between 100 200 m deep Slope steeply rapidly reach 3000 4000 m Boundary between continents and ocean basins May also have Submarine canyons 2 Ocean basins Abyssal plains Large of deep ocean Extend from continent Basaltic rock covered with sediment Ridges rises Volcanic mountain ranges in every ocean Separate basins into sub basins 40 000 miles of ocean ridges Trenches About 2 of ocean floor Deep up to 11 000 m More common in Pacific Seamounts Found near island chains and continental slopes plate boundaries Formed by volcanic action Steep sided rising sharply from bottom More common in Pacific 2 Physics of oceans A Waves B Tides C Currents D Vertical water movements A Waves Waves influence distribution of many nearshore marine organisms Not flow of water but flow of energy Result of forces acting on water surface Formed by generating force usually wind o Wind drag lifts water away from surface o Wave magnitude factor of Wind speed wind duration distance over the water that the wind blows fetch Types of waves Progressive formed by wind progress away Swells long period uniform waves Breakers Water depth less than 1 2 of wavelength Bottom of wave slows but crest continues at faster speed o o o o Tsunamis B Tides Periodic changes in water level along coastlines Play huge role in life of many marine organisms Result of gravitational pull on oceans by moon and sun Water on side of earth facing moon pulled toward moon Bulges on moon Bulge also forms on opposite side of earth Areas of low water between bulges Area under bulges high tide Earth rotates over 24 hr period Most places experience two tidal cycles in 24 hours B Tides Over Time 24 hrs Daily Tide Cycle Greatly influenced by geographical factors Contours of shorelines Water depth Different areas have different patterns Diurnal tides one high and low tide per day Semidiurnal two high and two low per day Mixed semidiurnal highs and lows differ B Tides Over Time 28 Days Moon orbiting earth in 28 days also influences tides tidal cycle on approximately monthly basis In accordance with lunar cycle Spring tides Twice a month full and new moon Gravitational pull of moon and sun in straight line Time of highest and lowest tides Neap Tides Also twice a month 1st and last quarter of moon Sun and moon at right angles Smallest change between high and low tide TWICE A MONTH FULL AND NEW MOON GRAVITATIONAL PULL OF MOON AND SUN IN STRAIGHT LINE C Currents About 10 of ocean water involve in surface currents Driven by winds Move water in upper 400 m of ocean Move water horizontally in predictable patterns in ocean basins Major ocean gyres circular pattern around edge of ocean basin Influence dispersal of plankton and animals that follow plankton Dramatic impact on marine bio Produced by surface wind patterns Deflected by Coriolis effect Gyres formed of interconnected currents Influence biology on both local and large scale Western boundary currents nutrient poor Eastern boundary currents more productive D Vertical water movements Exchange of water between surface and deep water Deep water nutrient rich Surface water oxygen rich Examples Equatorial upwelling driven by currents Coastal upwelling driven by wind Seasonal vertical mixing cooling and sinking of surface water 50 of world fish catch from upwelling areas Only 0 1 of ocean surface 3 Chemistry of Oceans A Properties of water B Dissolved salts C Dissolves gases D Light E Temperature A Properties of water Sea water is obviously mostly water Water has a variety of properties that are critical for all living things Thermal properties Solvent properties pH and ionization Density properties B Dissolved Salts Na and Cl most abundant salts Salinity of ocean is variable Varies with evaporative precipitation FW runoff and ice formation C Dissolves gases Oxygen Carbon dioxide D Light Light attenuates quickly with depth At depth there is not as much light At depth there is light of different wavelengths E Temperature Temp declines rapidly at specific depth thermocline Thermocline depth varies with time and location Influences mixing of water and nutrients Influences movement of organisms all of these characteristics of sea water that very depending on where you are in the ocean temp salinity density Fundamentals of Marine Life 1 Organisms 2 Populations 3 Communities 4 Ecosystems 1 Organisms The life of marine organisms which is mostly what we will be studying in this class are related to three major phenomena A Homeostasis maintenance of constant internal environment B Biogeography range distribution of population where they are found C Habitat environmental conditions occupied A Homeostasis One of greatest challenges faced by marine organisms is maintaining stable internal environment water ions pH energy and gases Even more challenging when environment fluctuates greatly high low tide winter summer Day night Much energy required to maintain homeostasis Different types of organisms tolerate different levels of environmental fluctuations B Biogeography Each marine organisms has its own unique distribution geographical location found and habitats occupied within that geographical distribution both of which are related to the evolutionary history of the organism Within their broad geographical distribution marine organisms occupy specific types of habitats Each spp has an optimal range of conditions For each characteristic temp salinity etc Where organism thrives grows reproduces Zones of stress Above or below optimal range of conditions Greater energy expended for homeostasis Less energy for growth and reproduction Zones of intolerance cannot survive Related to fundamental versus realized niche C Habitat Habitat Specific place in the environment where an organism lives Marine habitats characterized by certain physical features Rocky shore Sandy beach coral reef etc all of these are major marine ecosystems Microhabitats Subdivisions within larger habitats subtidal intertidal supratidal


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URI BIO 360 - Ocean Environment

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