Fish Biodiversity Index Calculator

Calculate Shannon-Wiener diversity (H'), Simpson's index, Pielou's evenness, and Margalef's richness from species abundance data.

Inputs

Species 1 count

Species 2 count

Species 3 count

Species 4 count

Species 5 count

Species 6 count

Species 7 count

Species 8 count

Tab to move between fields

Results

Shannon-Wiener H'

1.72

Simpson's diversity (1-D)0.78

Simpson's D (dominance)0.22

Pielou's evenness (J')0.83

Species richness (S)8

Total individuals (N)130

Margalef's index1.44

1

Your Inputs

Values entered

= Species 1 count = 45, Species 2 count = 30, Species 3 count = 20, Species 4 count = 15, Species 5 count = 10, Species 6 count = 5, Species 7 count = 3, Species 8 count = 2

= 8 inputs provided

2

Shannon-Wiener H'

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 1.72

Shannon-Wiener diversity index using natural log. Higher values = more diverse. Typical range 0-4.

3

Simpson's diversity (1-D)

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 0.78

Simpson's diversity index. Ranges 0-1; closer to 1 means higher diversity.

4

Simpson's D (dominance)

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 0.22

Simpson's dominance index. Probability that two random individuals belong to the same species.

5

Pielou's evenness (J')

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 0.83

Ratio of observed to maximum possible diversity (0-1). 1.0 = perfectly even distribution.

6

Species richness (S)

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 8

Total number of species with at least one individual.

7

Total individuals (N)

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 130

Sum of all individual counts across species.

8

Margalef's index

Calculated from your inputs

= Based on Species 1 count (45), Species 2 count (30), Species 3 count (20), Species 4 count (15), Species 5 count (10), Species 6 count (5), Species 7 count (3), and Species 8 count (2)

= 1.44

Margalef's species richness index: (S-1)/ln(N). Accounts for sample size.

How to Use This Calculator

Enter the number of species observed in the survey transect or station.
Input the abundance (individual count) for each species.
Review the Shannon diversity index (H'), Simpson's index (D), and species evenness (J').
Compare indices across sites or time periods to assess biodiversity change.
A Shannon H' above 3 indicates high diversity; below 1.5 indicates low diversity or dominance.

How the result changes with Species 1 count

Species 1 count	Shannon-Wiener H'
10,000	0.06
35,000	0.02
65,000	0.01
90,000	0.01

What each input means

Species 1 count: Number of individuals of the first species in the sample.
Species 2 count: Number of individuals of the second species.
Species 3 count: Number of individuals of the third species.
Species 4 count: Number of individuals of the fourth species.
Species 5 count: Number of individuals of the fifth species. Enter 0 if fewer species.
Species 6 count: Number of individuals of the sixth species. Enter 0 if fewer species.
Species 7 count: Number of individuals of the seventh species. Enter 0 if fewer species.
Species 8 count: Number of individuals of the eighth species. Enter 0 if fewer species.

What each result means

Shannon-Wiener H': Shannon-Wiener diversity index using natural log. Higher values = more diverse. Typical range 0-4.
Simpson's diversity (1-D): Simpson's diversity index. Ranges 0-1; closer to 1 means higher diversity.
Simpson's D (dominance): Simpson's dominance index. Probability that two random individuals belong to the same species.
Pielou's evenness (J'): Ratio of observed to maximum possible diversity (0-1). 1.0 = perfectly even distribution.
Species richness (S): Total number of species with at least one individual.
Total individuals (N): Sum of all individual counts across species.
Margalef's index: Margalef's species richness index: (S-1)/ln(N). Accounts for sample size.

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