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Chapter 50

Unit 9 - Chapter 50 Bio 1M03 .docx
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Department
Biology
Course
BIOLOGY 1M03
Professor
James S Quinn
Semester
Winter

Description
Bio 1M03 Unit Nine: Ecology Chapter 50: Introduction to Ecology  Ecology – the study of how organisms interact with their environment 50.1 Areas of Ecological Study  Four main levels of analysis – to understand why organisms live where they do and in what numbers o Organisms o Populations o Communities o Ecosystems Organismal Ecology  How individuals interact with their environment  Explore the morphological, physiological and behavioural adaptations that allow individuals to live successfully in a particular area o Behaviour – focuses on how organisms respond to a particular stimuli from environment  Stimuli such as changes in temperature or moisture, an escape response from pray, or rival challenging for a mate o Physiological adaptations that allow individuals to thrive in heat, drought cold or other demanding physical conditions  Eg/ Sockeye Salmon o After spending four or five years feeding and growing in the ocean (salt water), they travel hundreds or thousands of km to return to the stream where they hatched (fresh water) o Females create nests in the gravel stream bottom and lay eggs o Males compete for the chance to fertilize eggs as they are laid o When breeding is finished, adults die Population Ecology  Population – group of individuals of the same species that live in the same area at the same time  Focus on the change in number of individuals in a population over time  Focus on endangered species – mathematical models can assess the impact of proposed dams, changes in weather patterns, altered harvest levels or specific types of protection efforts  Eg/ Each female salmon produces thousands of eggs – few survive to adulthood; only 2 return to the stream of their birth to breed o Populations have declines o Habitats have become dammed or polluted Community Ecology  Community – consists of the species that interact with each other within a particular area  Nature of interactions between species and consequences of interactions o Predation, parasitism, competition o How groups of species respond to disturbances (fires, floods, volcanic eruptions)  Eg/ Salmon are eaten by predators and eat smaller fish; disturbances such as over-fishing reduce food supply Ecosystem Ecology  Ecosystem – all the organisms in a particular region along with non-living components o Abiotic components – air, water, soil  How nutrients an energy move among organisms and between organisms and the surrounding atmosphere and soil or water  Eg/ Salmon form a link between marine and freshwater ecosystems – transport chemical energy from one habitat to another o Harvest nutrients in the ocean o When they die, they decompose, transport molecules to streams Bio 1M03 How Do Ecology and Conservation Efforts Interact  Conservation Biology – the effort to study, preserve and restore threatened populations, communities and ecosystems o Ecologists study how interactions between organisms and their environments result in a particular species being found in a particular area at a particular population size o Conservation biologists apply these data to preserve species and restore environments 50.2 Types of Aquatic Ecosystems  An organisms environments is composed to physical an \d biological components o Abiotic (physical) components – temperature, precipitation, sunlight and wind o Biotic components – other members of the organisms own species as well as other species What Physical Factors Play a Key Role in Aquatic Ecosystems?  Key physical factors that shape aquatic ecosystems – water depth and the rate of water movement o Water depth – dictates how much light reaches the organisms that live in a particular region o Water movement – presents a physical challenge; can carry organisms away  Water Depth and light o Water absorbs and scatters light – the amount and types of wavelengths available to organisms change dramatically as water depth increases  Ocean water removes light in the blue and red regions of the visible spectrum – blue and red wavelengths are required for photosynthesis in many species o In pure seawater – total amount of light at 10m is less than 40% of what it is at the surface  Virtually no light at depths > 40m o In seawater with organisms or debris – light penetration is less than in pure seawater o Productivity is affected by light  Productivity – the total amount of carbon fixed by photosynthesis per unit area per year Freshwater Environments > Lakes and Ponds  Ponds are small  Lakes are large enough that the water in them can be mixed by wind and wave action  Water Depth o Littoral (seashore) zone – consists of the shallow waters along the shore, where flowering plants are rooted o Limnetic (lake) zone – offshore and comprises water that receives enough light to support photosynthesis o Benthic (depth) zone – made up of the substrate o Photic Zone – regions of the littoral, limnetic and benthic zone that receive sunlight o Aphotic Zone – regions of the littoral, limnetic and benthic zone that do not receive sunlight  Water Flow o Water movement in lakes and ponds is driven by wind and temperature o Littoral and limnetic zones are in contact with more solar radiation and oxygen from the atmosphere - typically warmer and better oxygenated than the benthic zone o Benthic zone is nutrient rich – contains dead and decomposing bodies o Water from different depths can mix – driven by wind and changes in temperature  Allows well-oxygenated water from the surface to sink, and nutrient rich water from the benthic zone to rise  Organisms o Plankton (cyanobacteria, algae and other microorganisms, collectively) and their predators live in the photic zone o Animals (invertebrates and fish that consume detritus (dead organic matter) are common in the benthic zone Freshwater Environments > Wetlands  Wetlands – shallow-water habitats where the soil is saturated with water for at least part of the year Bio 1M03  Water Depth o Distinct from lakes and ponds  Only have shallow water  Have emergent vegetation – plants grow above the surface of the water  Most of the water in wetlands receives sunlight, and emergent plants capture sunlight before it strikes the water  Water Flow o Freshwater marshes and swamps – characterized by a slow but steady flow of water o Bogs – develop depressions where water flow is low or nonexistent  oxygen poor  Stagnant water – oxygen is used up during the decomposition of dead organic matter faster than it enters via diffusion from the atmosphere; decomposition slows once oxygen is depleted  Acids build up – low pH; nitrogen becomes available to plants  Organisms o Bogs  Stagnant and acidic  Unproductive habitats due to acidity and lack of available nitrogen and anoxic condition o Marches  Offer ample supplies of oxygenated water and sunlight – productive habitat  Have non-woody plants (lack trees, feature grasses) o Swamps  Offer ample supplies of oxygenated water and sunlight – productive habitat  Have trees and shrubs o Little overlap in the types of species found in bogs, marches and swamps Freshwater Environments > Streams  Streams – bodies of water that move constantly in one direction  Creeks – small streams  Rivers – large streams  Water Depth o Availability of sunlight is not a limiting factor – shallow enough that sunlight reaches the bottom  Water Flow o Structure varies along its length o Source – fast, cold, nutrient poor, high in O 2  Tends to be cold, narrow and fast where it originates (mountain glacier, lake, spring)  Oxygen levels tend to be high in fast-moving streams – water droplets are exposed to the atmosphere when moving water splashed over obstacles; oxygen diffuses into water  Cold water holds more oxygen than warm water o Near end – slows down, warmer, more nutrient rich, lower i2 O  Accepts water from tributaries and becomes larger, warmer and slower as it descends toward a lake, ocean or larger river  Oxygen levels are low in slow moving streams  Organisms o Photosynthetic organisms are rare in small, fast-moving streams  Nutrient levels tend to be low and most of the organic matter present consists of leaves and other materials that fall into the water from outside the stream o Fish, insect larvae, mollusks and other animals have adaptations that allow them to maintain their positions in the fast-moving portions of streams o As streams slow down and widen – conditions become more favorable for the growth of algae and plants; amount of organic matter and nutrients increase o Same stream contains different types of organisms near its source and near its end Freshwater/Marine Environments > Estuaries  Estuaries – form where ricers meet the ocean; freshwater meets salt water Bio 1M03 o Includes slightly saline marshes as well as the body of water that moves in and out of these environments o Salinity  Varies with changes in river flows and with proximity to the ocean  Has dramatic effects on osmosis and water balance; species that live in estuaries have adaptations that allow them to cope with variations in salinity  Water Depth o Shallow enough to allow sunlight to reach substrate o May fluctuate in response to tides, storms and floods  Water Flow o Fluctuates daily and seasonally due to tides, storms and floods o Fluctuations are important – it alters salinity, which affects which types organisms are present  Organisms o Very productive – shallow water allows sunlight to enter and nutrients are constantly replenished by incoming river water o Packed with young fish, vegetation and plankton Marine Environments > The Ocean  Water Depth o Intertidal (between tides) zone – consists of a rocky, sandy or muddy beach that is exposed to the air at low tide but submerged at high tide o Neritic Zone – extends from the intertidal zone to the depths of about 200 m  Outer most edge is defined by the end of the continental shelf  Continental Shelf – gently sloping, submerged portion of a continental plate o Oceanic Zone – “open ocean” – deep-water regions beyond the continental shelf o Benthic Zone – bottom of the ocean o Photic Zone – the intertidal and sunlit regions of the neritic, oceanic and benthic zone o Aphotic Zone – areas that do not receive sunlight  Water Flow o Dominated by different processes at different depths o Intertidal zone – tides and wave action o Neritic Zone – currents that bring nutrient rich water from the benthic zone of the deep ocean toward shore  Nutrient rich water is carried toward the surface when it hits the steep slope of the continental plate o Oceanic Zone – large-scale currents circulate water in the ocean in response to prevailing winds and the Earths rotation  Organisms o Intertidal Zone  Organisms must be able to withstand physical pounding from waves and desiccation at low tide  High productivity due to availability of sunlight and nutrients by estuaries as well as currents that bring nutrients0aden sediments from offshore areas o Neritic Zone  High productivity on outer ridges due to nutrients contributed by upwellings at the edge of the continental plate  Major marine fisheries exploit organisms in neritic zone  Coral reefs (in the tropics; shallow regions) – very productive; warm and sunlit o Oceanic Zone  Photic zone – abundant sunlight, scare nutrients  When photosynthetic organisms and animals that feed on them die – bodies drift downward to aphotic zone – no mechanism to bring nutrients up  Aphotic – scarce sunlight, abundant nutrients  Species survive on dead bodies from photic zone Bio 1M03 50.3 Types of Terrestrial Ecosystems  Biomes – major groupings of plant and animal communities defined by a dominant vegetation type o Eg/ Broad-leaved, evergreen forests, deserts, grasslands  Many distinct communities exist within each biome  Each of the biomes found around the world is associated with a distinctive set of abiotic factors o Climate – the prevailing, long-term weather conditions found in an area  Weather – consists of the specific short-term atmospheric conditions of temperature, moisture, sunlight and wind o Temperature  Enzymes can only work at optimal efficiency in a narrow range of temperatures  Availability of moisture – water freezes at low temperature and evaporates at high temperatures o Moisture  Required for life and terrestrial organisms must replenish the water they lose to evaporation or transpiration o Sunlight  Required for photosynthesis o Wind  Exacerbates the effects of temperature and moisture  Increases heat loss due to evaporation an convection  Increases water loss due to evaporation and transpiration  Direct impact on organisms such as birds, flying insects and plants  That nature of the biome that develops in a particular region is governed by o Average annual temperature and precipitation o Annual variation in temperature and precipitation  Net Primary Productivity (NPP) – total amount of carbon that is fixed per year minus the amount of fixed carbon oxidized during cellular respiration o Fixed carbon that is consumed in cellular respiration provides energy for the organism but is not used for growth (production of biomass) o NPP represents the organic matter that Is available as food for other organisms o Estimated in terrestrial environments by measuring aboveground biomass (the total mass of living plants, excluding roots) Terrestrial Biomes > Tropical Wet Forest  Tropical Rain Forests  Found in equatorial regions  Plants have broad leaves and are evergreen  Older leads are shed throughout the year but there is no complete seasonal loss of leaves  Temperature o High o Low Variation – no seasonal variation  Precipitation Bio 1M03 o High amount – lots of rainfall o High variation  Vegetation o Favorable year-round growing conditions o Riotous growth o High productivity o Above ground biomass o High species diversity  Can find over 200 tree species in 10m x 100 m  May hold up to 30 million species of anthropods  Canopy – upper layer of large tree branches  From canopy to ground – complex assortment of vines, epiphytes (plants that grow entirely on other plants), small trees, shrubs, herbs Terrestrial Biomes > Subtropical Deserts  Found in two distinctive locations o 30 degrees latitude (distance from the equator) north and south  Temperature o High temperatures o Moderate Variation  Precipitation o Low precipitation o Low variation  Vegetation o Conditions rarely adequate for photosynthesis o Low productivity o Individual plants are widely spaced – may reflect intense competition for water o Desert species adapt to extreme temperatures and aridity  Grow at a low rate year-round  Eg/ Cacti – possess adaptations to cope with hot, dry conditions (small leaves or no leaves, thick waxy coating, CAM pathway for photosynthesis)  Break dormancy and grow rapidly in response to any rainfall
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