Biology Lecture Organismal Ecology 9 13 Organismal Ecology the interaction of individuals with each other and their physical environment Physiology mechanical physical and biochemical functions of living organisms All functions require energy obtained from food by respiration cellular and physiological respiration Respiration Unlocks the energy stored in the chemical bonds of organic molecules and puts it to work physiologically light energy chemical energy work and heat Energy rich molecules such as glucose can t be directly used for life processes must be converted into a readily usable chemical form ATP molecules are converted by the process of cellular respiration Cellular respiration requires a steady supply of oxygen cells must have a constant uninterrupted supply of oxygen and be able to remove carbon dioxide Physiological respiration the process by which multicellular organisms capture and excrete the gaseous fuel oxygen and waste carbon dioxide of cellular respiration Gas exchange in a eukaryotic cell where cellular respiration takes place is solely driven by diffusion down concentration gradients to get the gas in there you must have a concentration gradient more of something on one side than the other no active transport Fick s law of diffusion the rate of diffusion of a gas depends on the solubility of the gas in water temperature surface area available for diffusion difference in partial pressures of gas across gas exchange surface and thickness of the barrier of diffusion maximize gas exchange large surface area thin respiratory surface and large partial pressure gradient of the gas across the surface partial pressure pressure of a particular gas partial pressure of oxygen falls with increasing elevation Microscopic single celled organisms have very high surface area to volume ratios so simple diffusion of respiratory gases fully meets their requirements Surface area volume ratios and diffusion rates mass of tissue fall as body size increases Sea slugs increase their surface areas using external gills which are in direct contact with the water fish larvae change their predominant respiration mechanisms as they grow Larger animals must have an enlarged gas exchange surface gills alveoli of lungs and a circulatory system to meet respiratory needs 1 ventilation 2 gas exchange 3 circulation 4 cellular respiration Atmosphere is 78 Nitrogen and 12 Oxygen In environment high oxygen PP low carbon dioxide In cells high co2 low oxygen PP Notes from 9 15 Reading Spring Turnover Steps occur in response to changes in air temperature 2 Winter Stratification occurs water at surface is 0C at bottom is 4C high oxygen concentration on surface high nutrient concentration on bottom 3 Spring turnover water on surface reaches 4C making it heavier than the water below it As a result the surface water sinks which carries the oxygen down and nutrients up water on bottom rises to top Summer Stratification dense 4C water at bottom becomes nutrient rich while warmer water near the surface becomes oxygenated 22C Fall Turnover surface water cools to 4C and sinks carrying oxygen down and 4 5 driving nutrients up allows aquatic ecosystems to be much more productive Water flow effects productivity and is a physical force that organisms have to contend with Productivity the total amount of carbon fixed by photosynthesis per unit area per year wavelengths in the blue ad red regions of the visible spectrum are required for photosynthesis Water depth as depth increases the quantity of light available to organisms decreases surface water is oxygen rich deep water is nutrient rich MARINE ECOSYSTEMS Lakes and Ponds Water depth zones littoral zone seashore shallow waters where flowering plants are rooted limnetic zone lake offshore and receives enough light for photosynthesis benthic zone depths substrate photic zone regions of the zones that receive sunlight aphotic zone regions of the zones that don t receive sunlight plankton and other producers live in the photic zones along with the fish and small crustaceans that eat them detritus consume dead organic matter animals live in the benthic zone invertebrates and fish Wetlands shallow water habitats where soil is saturated with water for at least part of the year Three types bogs little or no water flow so oxygen poor waters oxygen is used up during the decomposition of dead organic matter faster than it enters via diffusion from the atmosphere oxygen is used up decomposition slows and acid builds up lowering the pH of the water nutrient poor due to lack of nitrogen Marshes lack trees and feature grasses reeds or other nonwoody plants Swamps dominated by trees adn shrubs Water depth only have shallow water meaning that only emergent vegetation plants that grow above the surface of water and catch sunlight before it hits the water Streams move constantly in one direction small streams creeks large streams rivers variables speed of current and availability of oxygen and nutrients Water depth sunlight reaches the bottom fast cold water that s nutrient poor and high in oxygen warmer water more nutrient rich but lower in oxygen From closes to the source to farthest away 1 2 faster water has more oxygen because water droplets are exposed to teh air when they splash over rocks or other obstacles where oxygen is diffused into droplets cold water holds more oxygen nutrients are washed away quickly in fast moving water Estuaries form where rivers meet the ocean where freshwater and saltwater mix shallow and sunlit water most productive environments on Earth salinity salt levels varies with changes in river flows declines where river floods and increases where river ebbs and with proximity to the ocean salinity effects osmosis and water balance species have adapted to coping wtih variations in salinity Water depth sunlight reaches substrate fluctuates in response to tides storms and floods fluctuation alter salinity which effects the types of organisms present Nutrient rich because slow moving river water enters the ocean Organisms young fish that feed on abundant vegetation and plankton while hiding from predators The Ocean continuous body of salt water Water Depth intertidal zone between tides rocky sandy or muddy beach exposed to the air at low tide but submerged at high tide nutrient rich neritic zone extends from the intertidal zone outermost edge is defined by the end of the continental shelf gently sloping submerged portion of continental plate nutrient