General Principles of Aquatic Ecology
KAREN L. LANCOUR
National Rules Committee Chairman – Life Science
Part I: General Principles of Aquatic Ecology
Lotic ecosystems – flowing water
Lentic ecosystems – still water
o Coral Reef Ecology
Review of Ecology Principles:
Ecology = the systematic study of how organisms interact with one another and with their environment
Environment consists of both a living component, the biotic environment (other organisms) and a non-living component, the abiotic environment, e.g. physical factors such as soil, rainfall, sunlight, temperatures
Ecology is an extremely complex and very diverse subject and it includes a variety of disciplines in addition to biology, e.g. geology, chemistry, physics, meteorology, and mathematics
Four levels of ecological organization:
Population - group of individuals of the same species occupying a common geographical area Community - two or more populations of different species occupying the same geographical area Populations and communities include only biotic factors Ecosystem - a community plus its abiotic factors, e.g. soil, rain, temperatures, etc. Biosphere - the portion of the earth that contains living species. It includes the atmosphere, oceans, soils and the physical and biological cycles that affect them
A watershed or drainage basin is an area of land where water from rain and melting snow or ice drains downhill into a body of water, such as a river, lake, reservoir , wetland.
Watershed surface water management plans are implemented to reduce flooding, improve water quality, and enhance stream and wetland habitat.
Land usage and water treatment methods are important in maintaining water quality in the watershed.
Ecology of Populations
Population Ecology = the study of how populations interact with their environment Population = group of individuals of the same species occupying a common geographical area Habitat - where a species normally lives
Characteristics of populations - Each population has certain characteristics: Population size = number of individuals making up its gene pool Population density = number of individuals per unit of area or volume, e.g. persons/square mile
Population distribution = the general pattern in which the population members are dispersed through its habitat, may be: Clumped (most common), Uniformly dispersed (rare), or Randomly dispersed
Age structure defines the relative proportions of individuals of each age: Pre-reproductive, Reproductive, and Post-reproductive
Population size and growth
Population size is dependent on births, immigration, deaths, and emigration Zero population growth designates a near balance of births and deaths Exponential growth: If birth and death rates of a population remain constant they can be combined into one variable r = net reproduction per individual per unit time (rate of increase) Population growth may be represented mathematically as: G = rN Where G = population growth per unit time, r = rate of increase and N= the number of individuals. When plotted against time a graph in the shape of a J will be obtained denoting exponential growth, i.e. one variable increases much faster than the other
As long as per capita birth rates remain even slightly above per capita death rates, a population will grow exponentially - with ever-increasing rates and shorted "doubling times" It took 2 million years for the world's human population to reach 1 billion, yet it took only 12 years to reach the fifth billion
If a population lives under ideal conditions it may display its biotic potential - the maximum rate of increase under ideal conditions. Few populations live under ideal conditions because a number of factors limit...
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