Lecture_2 - Aquatic Ecosystems Second 230 Ecology lecture...

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Aquatic Ecosystems Second 230 Ecology lecture 20 October 2009 th Ed. How many of U have gone fishing? Where can one fish around here? Water –the milieu of life A molecule whose properties help understand life from macromolecules inside cells to individual physiology to spatial arrangement of terrestrial biomes All metabolically active organisms are mostly water by weight! Preservation by water removal – jellies and jams What are the properties of water that you can think of? AND how does the property impact life? If you want to learn more about water, I recommend Fresh Water by E. C. Pielou (U Chicago Press, 1998). Solubility of oxygen in water limits life in water. 15 mg O 2 /liter H 2 O at 0° C -maximum declines dramatically with increased temperature (Fig 3.11). Where is the water on the earth? Fig. 3.2 The Global H 2 O cycle – Reservoirs / compartments versus fluxes Rates of movement between compartments will have units of amount per time, eg., g hr -1 . The water cycle is ‘driven’ (get the energy from) solar radiation but the great reduction of the solubility of water vapor as temperature decreases and gravity are all important ‘players’. Metabolically active cells have a lot of water in them, but they also have lots of other stuff. The structure is usually based on non-polar macromolecules. Cells are filled with ions and often use ion pumps as part of functioning, eg, nerve cells. The concentration of ions in cells is higher than their concentration in fresh water but lower than that is sea water. Hypotonic and hypertonic are words that describe the relation of the cellular concentration to the concentration in the environment. The major cations in cells are Na and K. Animals
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Lecture_2 - Aquatic Ecosystems Second 230 Ecology lecture...

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