Genus Level (pre 1999) Taxonomic Identification
for the Puget Sound Lowlands B-IBI

Genus Level (pre 1999) 10 Metric B-IBI Descriptions

Taxon means a single taxonomic group such as family, genus, or species. Taxa is plural. For genus-level scoring, aquatic insects are identified to the genus level, with the exception of chironomids, which are identified to the family level. Non-insects are identified to the order or family level.

Total Taxa Richness
The total number of unique taxa is 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 is 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 is 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 is identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Number of Long-Lived Taxa
The cumulative number of unique long-lived taxa identified across all three replicates.
 
Number of Intolerant Taxa
The cumulative number of unique intolerant taxa identified across all three replicates.
 
Percent Tolerant Individuals
The total number of tolerant individuals counted in each replicate, divided by the total number of individuals in that replicate, multiplied by 100. The percentages from the three replicates are then averaged for this metric.
 
Number of Clinger Taxa
The total number of unique clinger taxa is identified in each replicate. The numbers from the three replicates are then averaged for this metric.
 
Percent Predator Individuals
The total number of predator individuals counted in each replicate, divided by the total number of individuals in that replicate, multiplied by 100. The percentages from the three replicates are then averaged for this metric.
 
Percent Dominance
The sum of individuals in the three (3) most abundant taxa in each replicate, divided by the total number of individuals in that replicate, multiplied by 100. The percentages from the three replicates are then averaged for this metric.
Percent Dominance Example

Percent Dominance Example

Step 1

Calculate taxa totals

Step 2

Sum 3 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 3:
Taxa 1 = 10
Taxa 2 = 8
Taxa 3 = 3

(# organisms in 3 dominant taxa / Total # individuals) X 100

(21 / 22) X 100

Total = 22 organisms

Total = 21 organisms

Percent Dominance = 95%
10 Metric Genus Level (pre 1999) Scoring Criteria

10 Metric Genus Level (pre 1999) Scoring Criteria

Criteria are for genus-level identification of most insects and chironomids to family. 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

3

5

Taxa richness and composition


Total number of taxa

[0, 10)

[10, 20)

> 20


Number of Ephemeroptera (mayfly) taxa

[0, 3)

[3, 5.5)

> 5.5


Number of Plecoptera (stonefly) taxa

[0, 3)

[3, 5.5)

> 5.5


Number of Trichoptera (caddisfly) taxa

[0, 2)

[2, 4.5)

>4.5


Number of long-lived taxa

[0, 0.5)

[0.5, 2)

> 2

Tolerance


Number of intolerant taxa

[0, 0.5)

[0.5, 2)

> 2


% of individuals in tolerant taxa

> 50

[50, 20)

< 20

Feeding ecology


% of predator individuals

[0, 5)

[5, 10)

> 10


Number of clinger taxa

[0, 8)

[8, 15)

> 15

Population attributes


% dominance (top 3 taxa)

> 75

[75, 50)

< 50

10 Metric Genus Level (pre 1999) B-IBI Worksheet

METRICS (averaged) Rep 1 Rep 2 Rep 3 Replicate Average Metric IBI Score
(1, 3, or 5)

Total number of taxa

          

Number of Ephemeroptera (mayfly) taxa

          

Number of Plecoptera (stonefly) taxa

          

Number of Tricoptera (caddisfly) taxa

          

% of individuals in tolerant taxa

          

Number of clinger taxa

          

% of predator individuals

          

% dominance (3 taxa)

          
METRICS (cumulative) Rep 1 Rep 2 Rep 3 Cumulative Unique Metric IBI Score
(1, 3, or 5)

Number of long-lived taxa

          

Number of intolerant taxa

          
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., % predator individuals = (total number predator individuals / total number individuals) X 100