Let's Calculate Biodiversity
Biodiversity & Depth

Teacher/Student Information

Objective

Students should be able to describe some abiotic factors that influence the diversity of biofilm organisms in a vertical (stratified) profile of Inner Harbor water from 1-5 meters. The key abiotic factors for discussion are depth, pH, light penetration, salinity, dissolved oxygen and temperature.

Scenario/Prompt

Biofilm discs from the Baltimore Inner Harbor were sampled from 1 meter, 3 meters, and 5 meters. Each disc was accompanied by a water sample from each depth. The rack design shown on left (learn how to make your own biofilm rack). In the lab, a research team analyzed the biodiversity of each disc and the water quality samples from each depth. The biodiversity measures computed included richness (S), Simpson's index (D), Simpson's index of diversity (1 - D), Simpson's reciprocal index (1/D), Shannon-Wiener index (H), and evenness (E). Water quality analysis included tests for salinity, dissolved oxygen, temperature and pH.

Assignment

Look closely at the data and write a hypothesis that describes your prediction about how biodiversity and depth are related. (A hypothesis can be written as an "if ... then" statement like, "If the depth ___________ then the biodiversity will ____________.").

• Level 1 Data
  
  

  Diversity	Water Quality
  Species Name # Pi Pi2 Piln[Pi] Measure Value Whip Mud Worms 5 0.125 0.016 -0.113 S 6 Mussels 12 0.300 0.090 -0.157 D 0.201 Barnacles 7 0.175 0.031 -0.132 1 - D 0.799 White Anemones 8 0.200 0.040 -0.140 1/D 4.969 Dusky Sea Slugs 2 0.050 0.003 -0.065 H 0.731 Hydras 6 0.150 0.023 -0.124 E 0.939 Totals 40 1.000	Salinity 9 ppt Dissolved Oxygen 8 ppm pH 7.4 Temperature 23° C

   
  
  
  
• Level 2 Data
  
  

  Diversity	Water Quality
  Species Name # Pi Pi2 Piln[Pi] Measure Value Whip Mud Worms 4 0.190 0.036 -0.137 S 4 Mussels 8 0.381 0.145 -0.160 D 0.283 Barnacles 3 0.143 0.020 -0.121 1 - D 0.717 White Anemones 0 0.000 0.000 0.000 1/D 3.528 Dusky Sea Slugs 0 0.000 0.000 0.000 H 0.573 Hydras 6 0.286 0.082 -0.155 E 0.952 Totals 21 1.000	Salinity 12 ppt Dissolved Oxygen 5 ppm pH 7.6 Temperature 20° C

   
  
  
  
• Level 3 Data
  
  

  Diversity	Water Quality
  Species Name # Pi Pi2 Piln[Pi] Measure Value Whip Mud Worms 2 0.400 0.160 -0.159 S 3 Mussels 1 0.200 0.040 -0.140 D 0.360 Barnacles 2 0.400 0.160 -0.159 1 - D 0.640 White Anemones 0 0.089 0.008 0.000 1/D 2.778 Dusky Sea Slugs 0 0.000 0.000 0.000 H 0.458 Hydras 0 0.000 0.000 0.000 E 0.960 Totals 5 1.000	Salinity 17 ppt Dissolved Oxygen 2.5 ppm pH 7.8 Temperature 18° C

Next, answer the following questions:

1. What is the trend in diversity as depth increases?
   
   
2. How do the water quality results relate to the trend identified in question 1?
   
   a). In your description be sure to clearly discuss the influence of at least 2 water quality factors that impact the diversity of the biofilm samples.
   
   b). In addition, identify and describe one water quality factor that has the greatest influence on the diversity.
   
   

Good luck.