[organism]

 [biofilms & biodiversity]

Let's Calculate Biodiversity
Try These Data

Species Richness & Simpson's Index: 3 Species | 6 Species
Species Richness & Shannon-Wiener Index: 3 Species | 6 Species


Using the species counts, fill out the following tables to calculate values for species richness, the Shannon-Wiener index and Evenness.

Some Notation:
  • Species Richness: S - the number of different species found on plate.
  • Pi - the number of a given species divided by the total number of organisms observed. When you compute the probability for each species, please use decimal percent (e.g., use 0.25 and not 25% or 1/4).
  • Shannon-Weiner index: H = -sum(Pilog[Pi])
    (While you may use any base, the natural log is commonly used)
  • Evenness: E = H/log(S)



After you enter your answer(s) for each step, press the 'Check Answer' button. You can use the 'Clear Answer' button to clear the answer(s) for any part.

  1. Calculate the species richness (S).
    Fill in the box with your answer and press the 'check answer' button.

    Species Name
    		 # Found
    		 Pi
    		 Piln[Pi]
    		Measure
    		 Value
    Whip Mud Worm
    		 8
    		  
    		  
    		 S
    Mussels
    		 20
    		  
    		  
    		 H
    		  
    Barnacles
    		 15
    		  
    		  
    		 E
    		  
    Totals
    		 43
    		  
    		  


     


  2. Calculate the Shannon-Wiener index (H) value.

    First, calculate the percent of each species identified in the sample.
    Place your answers in the Pi column (up to 3 decimal places).
    Do not calculate the sum of the Pis (it will be done for you).

    Species Name
    		 # Found
    		 Pi
    		 Piln[Pi]
    		Measure
    		 Value
    Whip Mud Worm
    		 8
    		 
    		 S
    Mussels
    		 20
    		 
    		 H
    		  
    Barnacles
    		 15
    		 
    		 E
    		  
    Totals
    		 43
    		 


     


  3. Second, calculate Piln[Pi]for each species.
    Place your answers in the Piln[Pi] column (again, up to 3 decimal places).
    Do not calculate the sum of the Piln[Pi]s (it will be done for you).

    Species Name
    		 # Found
    		 Pi
    		 Piln[Pi]
    		Measure
    		 Value
    Whip Mud Worm
    		 8

    		S
    Mussels
    		 20

    		H
    		  
    Barnacles
    		 15

    		E
    		  
    Totals
    		 43




     


  4. The sum of the Piln[Pi] values muliplied by -1 is really the Shannon-Wiener index (H).
    All that is left is for you to calculate Evenness (E).
    Put your answer in the box for E (again, up to 3 decimal places).

    Species Name
    		 # Found
    		 Pi
    		 Piln[Pi]
    		Measure
    		 Value
    Whip Mud Worm
    		 8

    		S
    Mussels
    		 20

    		H
    Barnacles
    		 15

    		E
    Totals
    		 43






  5. The final results looks like this!