Simulation labs for Biology 4263

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Simulation labs for Biology 4263

  • I gave an introductory lab talk on Keystone Predators and Barnacles and Tides on Thursday , April 16th. These labs are due to me by May 4, 2009.
  • Tonight, I will discuss Limiting Nutrients and Competition, Go Fish, and Oil spills. These labs are due by May 20th.
  • Background material covered tonight
    • Limiting Nutrients and Competition
    • Go Fish
    • Oil spills

Limiting Nutrients and Competition

  • Algal growth is dependent on the availability of sunlight and essential nutrients including nitrogen, phosphorous, and iron
  • This lab considers the availability of sunlight to the growth rate of hypothetical green algae and the three nutrients to green, blue, and red algae by themselves and in combinations
  • The objective of the laboratory exercise is to explore how nutrient availability can influence competition between species of algae

Background Information

Are phytoplankton adapted to light intensity?

  • Pmax is the intensity of light at which photosynthesis is maximal
  • Pmax - light intensity relationship for different types of phytoplankton suggests adaptation
    • diatoms versus dinoflagellates
    • Diatoms reach Pmax at low light levels
    • Dinoflagellate photosynthesis maximal under high light intensities


  • Various nutrients can be limiting and the kinetics of nutrient uptake is important
  • Limiting nutrients include N, P, Fe, Si
  • Nutrients enter phytoplankton cells by active transport
    • surface area/volume is important to phyto body size


  • Required for amino acids
  • Soils on land are 0.5% N
  • Seawater averages 0.00005% N
  • Nitrogen frequently limits phytoplankton in coastal oceans

More on nitrogen

  • Massive amounts of N from fertilizers reach coastal oceans today and is the most important cause of eutrophication
  • Ammonium (NH4), nitrate (NO3) and nitrite (NO2) are possible forms

More on nitrogen

  • Most phytos prefer ammonium but can use nitrate
  • N fixation (from N2) important in some locations like estuaries
  • Inputs from many sources and nitrogen cycle is complex with many bacterial transformations

Other nutrients:

  • Phosphorus (PO4)
    • Animal excretion is a source of P
  • Iron (Fe)
    • In vast areas of the open ocean (Pacific), Fe is limiting
    • Why iron?
    • The Geritol Hypothesis
  • Silicon (Si02)
    • silicate limiting only in diatoms

Nutrient kinetics

  • Rate of uptake depends on nutrient concentration (to a point)
  • V (uptake rate) = Vmax * S / (ks + S) where S = concentration of a limiting nutrient, Vmax = maximum uptake rate and ks = half saturation constant (the nutrient concentration at Vmax/2)
  • Vmax

Go Fish: Fisheries Management Techniques

  • Collapse of fisheries stocks :
      • NMFS – 45% of the fish stocks whose status is known are being overfished
  • Why do fisheries collapse ?
    • Overfishing
    • Environmental factors – climate change, change in salinity, pollution
    • Ecological factors – changes in predators or prey – fishing down the food web (Essay to accompany this report)
      • Pauly
      • Worms et al.
      • de Musert et al. 2008
  • Sustainable strategies
    • Maximal sustainable yield (MSY) – popular but often unsuccessful
    • Constant effort
    • Adaptive methods
  • Squonkfishery

Oil Spills : Population Growth

  • Oil eating bacteria –PWS, Dr. Ralph Portier
  • Logistic equation – simulations of population growth
    • Bacterial division rates
    • Oil (food) availability

Incomplete Applications

  • Must be completed by tomorrow at 4:30 PM or can’t be registered
  • Two people – notarized participant agreement
    • Millie Dave
    • Sumit Patel

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