Family Level Taxonomic Identification
for the Puget Sound Lowlands B-IBI

Family Level 5 Metric B-IBI Descriptions

Taxon means a single taxonomic group such as family, genus, or species. Taxa is plural. For family-level scoring, all taxa are identified to the family level.

Total Taxa Richness
The total number of unique taxa identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Ephemeroptera Taxa Richness
The total number of unique mayfly (Ephemeroptera) taxa identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Plecoptera Taxa Richness
The total number of unique stonefly (Plecoptera) taxa identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Trichoptera Taxa Richness
The total number of unique caddisfly (Tricoptera) taxa identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Percent Dominance
The sum of individuals in the single most abundant taxa in each replicate, divided by the total number of individuals in that replicate, multiplied by 100. The numbers from the three replicates are then averaged for this metric.

Percent Dominance Example

Step 1

Calculate taxa totals

Step 2

Single most numerous taxa

Step 3

Calculate Percentage

Taxon 1 = 10 organisms
Taxon 2 = 8 organisms
Taxon 3 = 3 organisms
Taxon 4 = 1 organism

Pick Top 1:
Taxa 1 = 10

(# organisms in dominant taxa / Total # individuals) X 100

(10 / 22) X 100

Total = 22 organisms

Total = 10 organisms

Percent Dominance = 45%

5 Metric Family Level Scoring Criteria

5 Metric Family Level Scoring Criteria

Criteria are for family-level identification of all taxa. The 5-metric B-IBI will not give you as much qualitative information as a 10-metric B-IBI, but it will provide you with a relative integrity score. Researchers continue to evaluate the effectiveness of the 5 metric B-IBI. Square braces indicate the value next to the brace is included in the range; rounded parentheses indicate the value is not included.



Scoring Criteria

Metric

1

2

3

4

5


Total number of taxa

[0, 7]

(7, 13]

(13, 19]

(19, 25]

>25

Number of Ephemeroptera taxa

[0, 1]

(1, 2]

(2, 4]

(4, 6]

>6

Number of Plecoptera taxa

0

(0, 1]

(1, 2]

(2, 3]

>3

Number of Tricoptera taxa

0

(0, 2]

(2, 4]

(4, 6]

>6

% dominance (1 taxon)*

>85

[70, 85]

[55, 70)

[40, 55)

<40


* The higher the number of taxa within this metric, the lower the final score.

5 Metric Family Level B-IBI Worksheet

METRIC Rep 1 Rep 2 Rep 3 Replicate Average Metric IBI Score
(1,2,3,4 or 5)

Total number of taxa

         

Number of Ephemeroptera (mayfly) taxa

         

Number of Plecoptera (stonefly) taxa

         

Number of Tricoptera (caddisfly) taxa

         

% dominance (1 taxon)

         
Total B-IBI Score
(Add Metric B-IBI scores for Total B-IBI score)
 
For the percentage metrics, remember to multiply the final computation by 100 for each replicate, e.g., % dominance = (total number predator individuals / total number individuals) X 100