Benthic Scores Final

Everything you ever wanted to know
about StreamWatch stream scores:
Why do we use indexes and metrics?
What is the ASCI index?
What metrics are used to calculate an ASCI score?
What is the VASOS index?
What metrics are used to calculate a VASOS score?
What do the scores mean?
What is an assessment?

Why do we use indexes and metrics?

Why do we use indexes and metrics? (cont…)
Aquatic bugs respond to many variables.
A few examples of these variables are:

water quality stream habitat conditions

temperature habitat complexity
dissolved oxygen food availability
dissolved constituents light
toxins flow

Ecological responses are highly complex
• “The ecosystem is not more complex than we think,
it is more complex than we can think” - Frank Egler
• To understand ecological responses, we need
meaningful simplification.
• Applied science tries to narrow the responses down
to a few indicators (in this case, key metrics).
• Metrics must be defensible AND the final expression
must be understandable.
• Thus, an index is born. An index is composed of
various metrics. The metrics are then used to
produce a score.


StreamWatch uses 2 indexes to produce 2 scores:

Adapted Stream Virginia Save Our
Conditions Index - Streams Index -
allows us share our data allows us to share our
with the Virginia data with VASOS and
Department of make comparisons with
Environmental Quality the rest of state

What is the ASCI index? (cont…)
• To evaluate water quality, the VA Department of
Environmental Quality (DEQ) uses the Stream
Conditions Index (SCI), developed by the
Environmental Protection Agency (EPA)
• StreamWatch uses the Adapted Stream Condition
Index (ASCI) because our sampling protocol is
slightly different than VA DEQ:
StreamWatch DEQ

2 or more nets/sample 6 nets/sample

all collected bugs are identified a subset of collected bugs are ID’d

200 bugs/sample 100 bugs/sample

What metrics are used to calculate an ASCI score?

What metrics are used to calculate an ASCI score? (cont…)

The Adapted Stream Conditions Index use 8 metrics:

Metric Best Value
Total Taxa 22
EPT Taxa 11
% Ephemeroptera 61.3%
% [Plecop. + (Trich. - Hydr.)] 35.6%
% Scrapers 51.6%
% Chironomidae 0
% Top 2 dominant 30.8%
HBI 3.2



Metric Best Value
Total Taxa 22
EPT Taxa 11
% Ephemeroptera refers to each of the measurements
61.3%
The Metric column
% [Plecop. + (Trich.this index.
(or metrics) used in - Hydr.)] 35.6%
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



Metric Best Value
Total Taxa 22
EPT Taxa 11
The Best Value column lists the best possible number
% [Plecop. + (Trich. - Hydr.)] if there are 22 Total Taxa
35.6%
for each metric. For example,
% Scrapers your sample, the score for this metric
(families) in 51.6%
would be 100.
% Chironomidae 0
HBI 3.2



Metric Best Value
Total Taxa 22
Metrics written in red refer to negative response metrics.
EPT Taxa that higher values produce lower scores.
11
This means
% Ephemeroptera sample has no Chironomidae
61.3%
For example, if your
(midges), the score for that metric will be 100. If your
sample is 40% midges, the metric score will drop to 60.
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



Metric Best Value
Total Taxa 22
EPT Taxa 11
% [Plecop. +means total number of families in the
Total Taxa (Trich. - Hydr.)] 35.6%
% Scrapersyou have 22 different families in your
sample. If 51.6%
% Chironomidae for this metric will be 100.
sample, the score 0
HBI 3.2



Metric Best Value
Total Taxa 22
EPT Taxa 11
EPT Taxa means total number of families in the orders
% Scrapers 51.6%
of Ephemeroptera, Plecoptera and Trichoptera (Mayfly,
% Chironomidae 0
Stonefly and Caddisfly). If you have 11 different EPT
% Top 2 in your sample, the score for this metric will be
families dominant 30.8%
100.
HBI 3.2



Metric Best Value
Total Taxa 22
EPT Taxa 11
% Scrapers 51.6%
% Chironomidae means percent of the sample made
0
% Ephemeroptera
% Top 2 dominant61.3% of your bugs are mayflies, the
30.8%
up of mayflies. If
HBI for this metric will be 100. 3.2
score


% [Plecoptera + (Trichoptera - Hydropsychidae)]
Metric percent of the sample made up Stoneflies(X95)
Best Value +
means
Total Taxa - Netspinners). If 35.6% of your bugs are
(Caddisflies 22
EPT Taxa + (caddisflies - netspinners), the score for this
stoneflies 11
metric will be 100.
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2


% Scrapers means percent of the Index use 8 metrics:
The Adapted Stream Conditions sample made up of
bugs that scrape their food (periphyton) from
Metric Best Value (X95)
underwater surfaces. Examples of scrapers are snails,
Total Taxa 22
flathead mayflies and water pennies. If 51.6% of your
bugs are scrapers, the score for this metric will be 100.
EPT Taxa 11
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



Total Taxa
% Chironomidae means percent of22 sample made
the
EPT Taxa 11
up of midges. If you have no midges in your sample,
% Ephemeropterametric will be 100.61.3%
the score for this
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



Total Taxa 22
% Top 2 dominant refers to the 2 dominant families, or
EPT Taxa 11
families with the most number of bugs in your sample.
% the two most dominant families make up 30.8% of
If Ephemeroptera 61.3%
% [Plecop. + (Trich. - score for this metric will be 100.
your sample, then the Hydr.)] 35.6%
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



HBI means Hilsenhoff Biotic Index Best Valueby a guy
(invented (X95)
Metric
named Hilsenhoff!) HBI is a measure of a bug’s
Total Taxa 22
tolerance of organic pollutants. The less tolerant a bug
EPT Taxa pollutants, the lower it’s HBI score. Every
11
is of organic
% Ephemeroptera is given an HBI score, and the HBI
61.3%
bug in the sample
% [Plecop.averaged. -If the average HBI score for your
scores are + (Trich. Hydr.)] 35.6%
% Scrapers is 3.2, the score for this metric will be 100.
whole sample 51.6%
% Chironomidae 0
HBI 3.2

More about HBI…
some examples of HBI scores are listed below
HBI Score Invertebrates

10 Soldier fly, Aquatic worm (tubificidae)
9 Spreadwinged damselfly, Skimmer dragonfly
8 Sowbug, Asian clam, Aquatic worm (naididae)
7 Planorbid snail, Crawling water beetle
6 Midge, Black fly, Common netspinner caddisfly
5 Dryopid beetle, Crayfish, Hellgrammite
4 Riffle beetle, Flathead mayfly, Pleurocerid snail
3 Fingernet caddisfly, Crane fly, Darner dragonfly
2 Brushlegged mayfly, Trumpetnet caddisfly
1 Common stonefly, Ameletid mayfly, Clubtail dragonfly
0 Roll-winged stonefly, Freeliving caddisfly


Whew! We’re almost done with the ASCI index. But
VA DEQ SCI and StreamWatch ASCI uses 8 metrics:
before we move on, you should know how these 8
Metric are combined to make a final ASCI score…
metrics Best Value (X95)
Total Taxa 22
EPT Taxa 11
% Scrapers 51.6%
% Chironomidae 0
HBI 3.2



Total Taxa 22
EPT Taxa 11
No individual metric score can exceed 100. For
example, even if you have 25 Total Taxa, the score will
be 100.
% Scrapers scores are averaged. This produces a final
All 8 metric 51.6%
% Chironomidae as simple as that! 0
ASCI score. It’s
HBI 3.2

What is the VASOS index? (cont…)

To evaluate water quality, Virginia Save
Our Streams uses a multimetric index
originally developed by the Isaak Walton
League of America, and later modified by
Dr. Reese Voshell at Virginia Tech.

What metrics are used to calculate a VASOS score?

What metrics are used to calculate a VASOS score? (cont…)

The VASOS index use 6 metrics:

Metric
% Mayflies + Stoneflies + Most Caddisflies
% Common Netspinners
% Lunged Snails
% Beetles
% Tolerant
% Non-Insects



Metric
% Lunged Snails
% Beetles
Again, metrics written in red refer to negative
% Tolerant
response metrics. This means that higher values
% Non-Insects
produce lower scores. For example, the more
netspinners in your sample, the lower the score.



Metric
% Lunged Snails
% % Beetles+ Stoneflies + Most Caddisflies is
Mayflies
the% Tolerant your sample made up of the three
percent of
ordersNon-Insects sensitive to (or intolerant of)
% that are most
disturbance.



Metric
% Lunged Snails
% Beetles
% % Tolerant
Common Netspinners is the percent of your
% Non-Insects
sample made up of netspinners.



Metric
% Lunged Snails
% Beetles
% Tolerant
% Lunged Snails is the percent of your sample
% Non-Insects
made up of lunged snails.



Metric
%% Mayflies + Stoneflies + Most Caddisflies up
Beetles is the percent of your sample made
of % Common Netspinners
beetles.
% Lunged Snails
% Beetles
% Tolerant
% Non-Insects



% Tolerant is the percent of the sample made up
Metric
of these bugs: worms, flatworms, leeches,
sowbugs, scuds, dragonflies+ Most Caddisflies
% Mayflies + Stoneflies and damselflies,
midges, black flies, lunged snails and clams.
% Lunged Snails
% Beetles
% Tolerant
% Non-Insects



Metric of the sample made
% Non-Insects is the percent
up% Mayflies + Stoneflies + Mostleeches,
these bugs: worms, flatworms, Caddisflies
crayfish, sowbugs, scuds, gilled snails, lunged
snails, clams. Snails
% Lunged
% Beetles
% Tolerant
% Non-Insects


How are these 6 metrics turned into a score?

Metric
% Lunged Snails
% Beetles
% Tolerant
% Non-Insects


Metric Add 2 points to Add 1 point to Add 0 points to
score if your score if your score if your
value is… value is… value is…
% Mayflies + Stoneflies + Greater than 32.2 16.1 - 32.2 Less than 16.1
Most Caddisflies
% Common Netspinners Less than 19.7 19.7 - 34.5 Greater than
34.5
% Lunged Snails Less than 0.3 0.3 - 1.5 Greater than 1.5

% Beetles Greater than 6.4 3.2 - 6.4 Less than 3.2

% Tolerant Less than 46.7 46.7 - 61.5 Greater than
61.5
% Non-Insects Less than 5.4 5.4 - 20.8 Greater than
20.8

What do the scores mean? (cont…)

ASCI score VASOS score

A score of 60 is a passing A score of 7 is a passing
score (this means the score (however, in the
stream meets the VA Rivanna basin, a score of
standard, set by DEQ). 7 or greater does not
A score below 60 fails necessarily indicate a
the VA standard healthy stream)

What is an assessment? (cont…)
Health assessments are based on multiple
ASCI samples/scores

• 5-6 samples per site
• Median and
minimum scores are
considered
• Very good and good
meet VA standards
• Fair fails VA
standards but could
recover
• Poor and very poor
are probably
persistently impaired

FOR MORE INFORMATION:
Stream Condition Index (SCI)
http://www.deq.virginia.gov/watermonitoring/bio.html

VA Save our Streams
http://www.vasos.org

StreamWatch reports
http://streamwatch.org/reports

History of Hilsenhoff Biotic Index
http://www.uwsp.edu/cnr/research/gshepard/History/History.htm

Benthic Scores Final

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