Lab

In this lab, students will calculate a Shannon-Wiener Diversity Index to evaluate biological diversity of samples taken from Knox Pond and LaMancha Wetland (semi-natural wetland adjacent to the Rio Grande). Students will learn the difference between species richness and species evenness in contributing to this calculation.

Learning Objectives:

When you finish this lab you will:

· Understand what a Shannon-Wiener Diversity Index is and identify factors that contribute to this index, including species richness and species evenness.

· Understand what a Shannon-Wiener Diversity Index is used for and why it is valuable in ecological studies.

· Learn to identify some common minnow species.

Fish Communities

One important way to compare aquatic systems is to measure biological diversity in the different bodies of water by comparing diversity values for different groups of taxa. For example, comparing groups such as diversity of aquatic insects, comparing minnows, comparing predatory fish, etc. In order to do this, you must learn what the valuable components of a diversity index are, including species richness and species evenness, and how these two components combine to arrive at an estimate of diversity. Normally you would compare diversity among two or more sites (bodies of water). As a lab, we will be working in Knox Pond so you will compare diversity of minnows caught in traps in three different areas of the pond. We are doing it this way as many of you have not sampled fish before and because we have limited time for lab.

Important Definitions related to Fish Communities

Species Richness – the number of individual species that occur in a sample. The more species present the “richer” the sample.

Species Evenness – this is a measure of the relative abundance of each species in a sample. For example, you may have a sample with 3 species present but “Species One” may make up 90% of all species within the sample indicating although 3 species are present, 2 may be relatively rare. Alternatively, your sample could be more robust with each species represented close to equally in each sample.

Shannon Wiener Diversity Index – this is a measure of species diversity that takes into account both species richness and species evenness. The equation for this index is

H = the Shannon Wiener Diversity Index

Pi = the proportion (n/N) of individuals of one particular species found (n) divided by the total number of individuals found for all species

ln = the natural log

s = the number of species observed

= the sum from species 1 to s

Higher values of H represent more diverse communities (or samples). A value near 0 would indicate that only one species was present. If species are evenly distributed, then the H value would be high as H is indicative of not only the number of species but also how species are distributed in a sample.

Lab Procedure

1. Assessing fish community

In this lab we will use the Shannon-Wiener Diversity index to compare the fish species captured in 1) an artificial pond, Knox Pond, where people often release unwanted pets and 2) a natural setting, LaMancha Wetland, a semi-natural oxbow wetland adjacent to the Rio Grande River near Mesilla, NM.

Knox Pond

La Mancha Wetland

REMEMBER

Pi = the proportion (n/N) of individuals of one particular species found (n) divided by the total number of individuals found of all species

Week 2

Students review Shannon Wiener Diversity index in class and collectively calculate a diversity index for each sample (i.e., each wetland)

1. Create a table that illustrates the species caught & amount for each pond and the Shannon Wiener Diversity index at each pond (so 2 tables). Please also show in your text how you calculated this index.

2. Create a bar graph that shows the number of species caught for each pond(both wetlands can be displayed in same figure).

3. Create two pie charts that show the percentage of each species caught as a portion of the entire sample for each pond. These graphs should provide the reader with a summary of all the species caught and their respective proportions in each pond.

4. Create bar graphs presenting the mean water quality parameters in the Knox pond compared to the La Mancha Wetland (If parameters have different units they cannot be displayed in the same figure)

*Note: Some of the information needed to answer these questions is not readily available on the data sheet and will require you to make calculations using data found on several sheets.