Environmental Parameters include: Currents and water turbulence . Temperature . Salinity . Nutrient element (productivity) . Dissolved oxygen levels . Depth and substrate type .
The circulation of sea water in the world’s oceans is driven by wind and contrasts in density due to variable temperature and salinity. There are two types of current A- Oceanic current ( global circulation ) B- Local currents ( generated by waves and tides 1- Currents
I- Global circulation ( horizontal and vertical ) Global current are very important in Paleoecology Indirect effect on organisms such as : - Temperature - Salinity - And concentration of nutrients Direct effect on organisms : Distribution of biota by : - Transporting pelagic species . - Transporting the pelagic larval stage of many benthonic forms . - Transporting shells after death of the organism .
I- Global circulation ( horizontal and vertical ) Types of Global circulation: Horizontal current: Wind is the driving force behind surface current. Vertical current: It is more important and controlled by density differences in the water.
Factors controlling the density of seawater are : - Temperature ( Most important ) - Salinity. - And suspended sediment content. Vertical current: Effect of temperature about vertical current: The temperature difference between the surface and bottom - Less dense water on top ( warmer ) - More dense water on the bottom ( Cooler )
Importance of vertical circulation: 1- Recycling nutrient Elements released by decay of organic matter, which sinks to the bottom . 2- Brings dissolved oxygen Brings dissolved oxygen from the surface to the depths where it can be utilized by organisms living there . 3- Occurrence of divergent and convergent current ( see Figure 2,3 ). Vertical current:
II- Local currents Local currents are generated by : 1- Wind 2- Tides 3- And local density differences ( e.g. turbidity currents ) 1- Wind : Wind-generated current are usually associated with wave , thus Wave-related currents are effective only in shallow water . 2- Tides : Tides also generated currents but effects are limited to shallow water . 3- Density differences : Density generated current, especially turbidity current, are very important in their effects on organisms. Also, effective in shallow as well as deep water . ( see Figure 5 ).
Biological effects of currents: Advantages of current 1- Bring food to the organism. 2- Remove waste products. 3- Bring dissolved oxygen. 4- Bring nutrient elements for plants.
- Disadvantages of strong currents : Organisms can’t hold themselves or maintain position . - Disadvantages of weak currents : The organisms must produce their own currents to bring in food and dissolved oxygen and to eliminate wastes . Other effects of current : - Hard or coarse substrates are more common in high currents, - Soft substrates in low currents .
<ul><li>Rang of temperature in the ocean is approximately –2 - 40ºC. </li></ul><ul><li>- The coldest waters (freezing. ) are found in the Polar Regions. </li></ul><ul><li>- Highest surface temperatures occur in lagoons or bay settings marginal to tropical oceans. </li></ul><ul><li>(Temperature may sometimes exceed 40ºC.) </li></ul>2- Temperature
Vertical Variation: - Temperature decreases with depth in the oceans except in Polar Regions. - The surface separates the warmer surface water from the colder deep water is called Thermocline layer . Geographic Variation: Surface temperature is controlled by solar energy. It varies inversely with latitudes. 2- Temperature
(animation 3) You can see temperature decreases with increasing depth. The Thermocline are layers of water where the temperature changes rapidly with depth. Figure 4
<ul><li>Biological Effect: </li></ul><ul><li>Temperature has a great effect on metabolic ( 1 ) rate, this rate increases with increasing temperature. </li></ul><ul><li>At higher temperatures, metabolic rate decreases and death ensue. However in some cases, organisms can change their metabolic rate with changing temperature. </li></ul>(1) Metabolic is the set of chemical reactions that happen in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. 2- Temperature
Salinity is a measure of the concentration of dissolved salts in seawater. It is defined as the weight in grams of dissolved solids in 1K of seawater. The most common cations in seawater are Na + , Mg 2+ , Ca 2+ , k + and Sr 2+ . The most common anions are Cl - , SO4 2- , Br - and F - . 3- Salinity Dissolved salts in sea water ( atoms ): 55.3 % Chlorine 30.8 % Sodium 3.7 % Magnesium 2.6 % Sulfur 1.2 % Calcium 1.1 % Potassium
Biological Effect: The concentrations of dissolved solids in seawater ( salinity ) are very important to organisms . Some organisms are very tolerant of Salinity variation , others have narrow tolerances . Salinity affects the osmotic pressure (1) across cell membranes within organism . marine invertebrates are in osmotic equilibrium with sea water, and if any organism is to survive in water more saline than sea water, its physicological functioning must include a mechanism for preventing desication by osmosis. 3- Salinity Osmosis: is the movement of solvent, such as water, through a barrier from a less concentrated solution into a more concentrated solution.
- Nutrient elements together with light are very important in determining the quantity of organisms living in a given environment (marine). - In nonmarine (terrestrial) environment, temperature and availability of water are additional factors. Productivity: Productivity is the rate of production of organic material by biological processes ( Physiological, Reproduction, Digestion, Interaction between organisms and Photosynthesis processes ) 4- Nutrient element
Productivity is divided into: primary productivity : The production of organic material by photosynthesis . Secondary productivity The production of organic material by animals utilizing preexisting plant and animal organic matter . 4- Nutrient element
4- Nutrient element Geographic variation: Geographic variation in nutrient element concentration and productivity is strongly influenced by global circulation patterns . Areas of divergent current are usually areas of high nutrient element concentration and of high productivity. This is because water enriched in nutrient element from below the compensation depth upwells in these areas.
Vertical Variation: Light is the energy source for the formation of organic material by photosynthesis. It is always available in shallow water, but its distribution may be seasonal . 4- Nutrient element
4- Nutrient element <ul><li>Biomass (Standing Crop): </li></ul><ul><li>It is the amount of living organic material present in a given </li></ul><ul><li>area at any one time. </li></ul><ul><li>How can we measure productivity or Biomass in the geologic record? </li></ul><ul><li>Fossil Biomass is difficult to measure for two reasons: </li></ul><ul><li>Very little of the original Biomass is preserved in the geologic </li></ul><ul><li>record. </li></ul><ul><li>2. The concentration of fossils is controlled not only by the rate </li></ul><ul><li>of their production but also by sedimentation rate . </li></ul>
4- Nutrient element Productivity is on average higher near continent than in the centers of oceans due to three factors: 1- Upwelling often occurs near coasts where surface water move away from the continent. 2- Increase of nutrient element concentration brought by rivers. 3- Organic material produced by photosynthesis accumulates on the shallow continental shelf.
5-Depth <ul><li>Important of Water depth is : </li></ul><ul><li>Interpreting paleogeography and geologic history. </li></ul><ul><li>Studying sedimentary basins and the occurrence of </li></ul><ul><li>hydrocarbons or other economic resources within these basins. </li></ul><ul><li>Influences sedimentary processes and properties. </li></ul>
Depth <ul><li>Water depth affects about many other factors: </li></ul><ul><li>Hydrostatic pressure. </li></ul><ul><li>Light. </li></ul><ul><li>Temperature. </li></ul><ul><li>Salinity. </li></ul><ul><li>Concentration of nutrient elements. </li></ul><ul><li>And quantity of dissolved gases. </li></ul><ul><li>Therefore, we can conclude that depth affect distribution </li></ul><ul><li>and morphology of plants as well as invertebrate animals. </li></ul>
<ul><li>Some factors play a particularly important role in determining the </li></ul><ul><li>Limits to niche. These are referred to as limiting factors. </li></ul><ul><li>Light is a limiting factor for all photosynthetic organisms, </li></ul><ul><li>Confining Most to the photic zone. </li></ul><ul><li>Nutrients are limiting in that they affect the structure of </li></ul><ul><li>an ecosystem and determine whether it is oligotrophic or </li></ul><ul><li>eutrophic. </li></ul><ul><li>Oxygen becomes limiting where the loss of oxygen </li></ul><ul><li>through oxidation of organic material exceeds the oxygen </li></ul><ul><li>dissolved in the seawater. </li></ul>Summary
Summary <ul><li>- Temperature is pervasive control on faunal distribution, </li></ul><ul><li>but it cannot generally be demonstrated in the fossil record </li></ul><ul><li>to latitude. </li></ul><ul><li>particularly important in shallow water generally. </li></ul><ul><li>Salinity can be an important limiting facor in nearshore </li></ul><ul><li>brakish and hypersaline environments. </li></ul><ul><li>Salinity, Substrate, substrate mobility and turbidity are </li></ul><ul><li>important factors in nearshore environments. </li></ul><ul><li>Light, Oxygen and food are commonly limiting in </li></ul><ul><li>deeper water. </li></ul>