Transcript Slide 1

Parameter
One of a set of measurable factors (e.g. temperature, pH), that define a
system and determine its behavior.
Indicator
A measurable feature that provides useful evidence of system quality
or reliable evidence of trends in quality
Metric
- a standard of measurement
- an attribute with empirical change in value along a gradient of
human disturbance.
- a measure of (a biological) attribute.
- data analysis summary
Types, examples of metrics
Biological
EPT
% Sensitive Diatoms
plant/animal condition
Physical
(river) channel length, sinuosity
(land use type) area, density
Chemical
pH
Temperature
DO PPM
DO %Sat
etc.
Index
an aggregated number used to judge condition (e.g. IBI, RBP)
A water quality index is a means to summarize large amounts of water
quality data into simple terms (e.g., good, fair, poor) for reporting to
management and the public in a consistent manner.
Indices
Can tell whether overall WQ poses threat to uses - e.g.
habitat for aquatic life
irrigation water for agriculture and livestock
recreation and aesthetics
drinking water supplies.
Multimetric Indices (EPA, Bio example)
numbers that integrate several biological metrics to indicate a site’s
condition.
designed to be sensitive to a range of factors (physical, chemical,
and biological) that stress biological systems,
are relatively easy to measure and interpret.
Indices - Multimetric approach
each metric is given a rating according to whether its value
approximates,
deviates somewhat from, or
deviates strongly from
values measured in least-disturbed ecosystems of a particular type within a
region.
These ratings (e.g., excellent, moderate, fair, and poor) can be used to
make decisions about whether the water body condition indicates that
aquatic life is being supported.
Advantages of an index include
ability to represent a variety of variables in a single number,
ability to combine various measurements in a variety of different
measurement units in a single metric
effectiveness as a communication tool.
can be used to convey relative differences in water quality between sites (or
@ one site) over time
Index examples
Air Quality Index
Levels of Health Concern
Numerical
Value
Meaning
0-50
Air quality is considered satisfactory, and air pollution
poses little or no risk.
Moderate
51-100
Air quality is acceptable; however, for some pollutants
there may be a moderate health concern for a very
small number of people who are unusually sensitive
to air pollution.
Unhealthy for
Sensitive Groups
101-150
Members of sensitive groups may experience health
effects. The general public is not likely to be affected.
Unhealthy
151-200
Everyone may begin to experience health effects;
members of sensitive groups may experience more
serious health effects.
Very Unhealthy
201-300
Health alert: everyone may experience more serious
health effects.
Hazardous
> 300
Health warnings of emergency conditions. The entire
population is more likely to be affected.
Good
Air Quality Index
Good:
simple
number and color easy to remember
succinct
underlying explanation pertaining to issue important to
audience (public health).
AQI Caveats:
How AQI Calculated:
monitors record concentrations of major pollutants at many locations
ground-level ozone
particle pollution
carbon monoxide
sulfur dioxide
nitrogen dioxide
formula used to convert raw values into numeric scale.
Highest – rated pollutant becomes AQI for that day.
E.g. ozone = 90, Sulfur dioxide = 88; AQI = 90.
Problems. If:
Sensitivity to one type of pollution.
OR: need to know where pollution types are coming from.
AQI alone not helpful. Underlying information useful
Indices - Good general rule
When presenting indices,
The overall “score” is valuable
but make supporting detailed information accessible.
AQI Presentation tip:
Print score/color on web site home page, familiar
icon/box (like weather info)
Clickable links to more detailed table, information.
Carlson’s Trophic State Index
Trophic State Indices (TSIs) are an attempt to provide a single
quantitative index for the purpose of classifying and ranking lakes, from
standpoint of nutrient influence on water quality .
Carlson TSI commonly used by Volunteer Monitors
Carlson TSI assumption:
major assumption is that suspended particulate material in the water
controls Secchi depth and that algal biomass is the major source of
particulates;
Increased nutrients (phosphorus):
Produce increased algal biomass (chlorophyll a)
Produce decreased water clarity (Secchi disk)
Carlson TSI quantifies this relationship.
Ranges along a scale from 0-100.
Carlson TSI useful for
comparing lakes within a region
assessing changes in trophic status over time.
Higher values correspond to increased trophic state.
An increase in TSI of 10 units corresponds to a halving of Secchi depth and
a doubling of phosphorus concentration.
Carlson TSI Formulae:
TSI = 60 - 14.41 Ln Secchi disk (meters)
TSI = 9.81 Ln Chlorophyll a (ug/L) + 30.6
TSI = 14.42 Ln Total phosphorus (ug/L) + 4.15
Because these are interrelated by linear regression models, any one of the
variables can be used to derive a TSI score.
A list of possible changes that might be expected in a north temperate lake as the amount of
algae changes along the trophic state gradient.
TSI
Chl
(ug/L)
SD
(m)
TP
(ug/L)
Attributes
Oligotrophy: Clear
water, oxygen
throughout the year in
the hypolimnion
<30
<0.95
>8
<6
30-40
0.952.6
8-4
6-12
40-50
50-60
60-70
70-80
>80
2.6-7.3
7.3-20
20-56
4-2
2-1
0.5-1
Water
Supply
Fisheries &
Recreation
Water may be
suitable for an Salmonid fisheries
unfiltered
dominate
water supply.
Hypolimnia of
shallower lakes may
become anoxic
Salmonid fisheries
in deep lakes only
12-24
Iron,
manganese,
Mesotrophy: Water taste, and
moderately clear;
odor
increasing probability problems
of hypolimnetic
worsen. Raw
anoxia during
water
summer
turbidity
requires
filtration.
Hypolimnetic
anoxia results in
loss of salmonids.
Walleye may
predominate
24-48
Eutrophy: Anoxic
hypolimnia,
macrophyte problems
possible
Warm-water
fisheries only.
Bass may
dominate.
48-96
Blue-green algae
dominate, algal
scums and
macrophyte problems
Nuisance
macrophytes, algal
scums, and low
transparency may
discourage
swimming and
boating.
Hypereutrophy:
(light limited
productivity). Dense
algae and
macrophytes
56-155
0.250.5
96-192
>155
<0.25
192-384
Algal scums, few
macrophytes
Episodes of
severe taste
and odor
possible.
Rough fish
dominate; summer
fish kills possible
Carlson TSI Caveats:
Chlorophyll best for classification: most accurate at predicting algal biomass.
Carlson states total phosphorus may be better than chlorophyll at predicting
summer trophic state from winter samples
Transparency should only be used if there are no better methods available.
Use Carlson TSI with lakes with few rooted aquatic plants and little non-algal
turbidity.
Not appropriate for other lakes.
River Network Macroinvertebrate metrics, index
From Living Waters Manual
http://www2.rivernetwork.org/index.cfm
Two levels of sampling, analysis.
Level 1: Order. 6 metrics
Level 2: Family 10 metrics.
Level 2 uses 7 of the metrics to calculate
Overall Percent Similarity Index (to reference)
River Network Level 2 metrics used in index
Metric
Units/Typical range
Total family richness
Integer 0-35
EPT family richness
Integer 0-20
Family Biotic index
Number 0-10
% Dominance
% 0-100
Community Similarity Index
Decimal 0-1
% Composition of shredders
% 0-100
Ratio Scrapers/Filtering Collectors
Number X.XX (e.g. 2.55)
Steps to calculate River Network % Similarity Index:
Step 1: Calculate each metric for reference and for target collection.
(Instructions in Living Waters manual)
Step 2. Convert each metric score to % similarity (*use Dominance, CSI directly)
Example
Metric
Reference Score
Target population
score
% Similarity
Total Family Richness
23
18
78%
EPT family richness
15
7
47%
Family Biotic index
3.19
4.53
71%
% Dominance *
23%
28%
28%
Community Similarity Index *
1
0.31
0.31
% Composition of shredders
5%
0%
0%
Ratio Scrapers/Filtering
Collectors
1.5
0.08
6%
Step 3: Score results as follows
Metric
Score 6
Score 3
Score 1
Total Family Richness
> 80%
40-80%
< 40%
EPT family richness
>90%
70-90%
<70%
Family Biotic index
>85%
50-85%
<50%
% Dominance
<30%
30-50%
>50%
Community Similarity Index
>0.75
0.25-0.75
<0.25
% Composition of shredders
>50%
25-50%
<25%
Ratio Scrapers/Filtering
Collectors
>50%
25-50%
<25%
Step 4: Sum the Scores
Metric
Reference Score
Target population
score
Total Family Richness
6
3
EPT family richness
6
1
Family Biotic index
6
3
% Dominance
6
6
Community Similarity Index
6
3
% Composition of shredders
6
1
Ratio Scrapers/Filtering Collectors
6
1
Total
42
18
River Network Macroinvertebrate Index
Step 5. Divide Total Score:
Target population / Reference
18 / 42 = 43% similarity between target and reference collections.
Step 6. Categorize results
> 79%:
Non-impaired.
29-72%:
Moderately impaired
< 21%
Severely impaired
Observations/caveats:
Use with different sites within similar geographic area, stream
order, etc.
Information in each metric may provide additional insight,
overall index: i.e. aid in data interpretation.
depth to
Selecting/Creating metrics and indices
Multimetric Indices to Prepare and Analyze Data
http://www.epa.gov/bioindicators/html/multimetric.html
Five activities are central to making multimetric biological indexes
effective:
Classifying environments to define homogeneous sets within or across
ecoregions (e.g., streams, lakes, or wetlands; large or small streams; warmwater or cold-water lakes; high- or low-gradient streams).
Selecting measurable attributes that provide reliable and relevant signals
about the biological effects of human activities.
Developing sampling protocols and designs that ensure that those biological
attributes are measured accurately and precisely.
Devising analytical procedures to extract and understand relevant patterns
in those data.
Communicating the results to citizens and policymakers so that all concerned
communities can contribute to environmental policy.
Selecting/Creating metrics and indices
Good Metrics:
Sensitive to change
Predictable, consistent
Metrics vary in their scale--they can be:
integers
percentages
dimensionless numbers
qualitative observations (e.g. grassland vs. forest).
Translation into unitless scores must address this.
Standardization assumes that each metric
has the same value and importance (i.e., they are weighted the
same),
and that a 50% change in one metric is of equal value to
assessment as a 50% change in another.
Most IBIs contain between 8 and 12 metrics.
Metrics must be tested to ensure their precision and accuracy. (see
discussion in Wisconsin DNR “Development of a Wetlands Biological Index…”
report)
Metrics to Indices: Attributes to consider:
Scope - How many? - The number of water quality variables that do not meet
objectives, relative to the total number of variables measured.
Frequency – How often? - The number of individual measurements that do
not meet objectives, relative to the total number of measurements made.
Amplitude – How much? – The amount by which measurements depart from
those objectives.
Presenting Indices
General tips:
Know your target audience
Expertise level
Particular interest
Use objective
Personal: resource use
Education
Resource management/regulation
Where to target resources
Impaired waters designation
TMDL development
Etc.
Make your own indices. Examples.
Trout comfort zone (Combine DO, temperature, volume of lake containing
suitable values. … add duration/frequency of excursions?
Boating recreation index (Number of days when water levels, water quality,
weather, etc. (absence of duckweed on lake surface, open channels) combine
for “pleasant” boating experiences… add economic impact?)
Fishing recreation index. (Similar to boating - # of days when water levels,
bug hatches, etc. afford quality fishing)
Beach closure days (see fishing, boating above… for added economic impact,
consider extra weight for scores on holiday / high traffic periods).
Water clarity / home value index (Combine Secchi disk data with real estate
prices).
Haikus as water quality indices?
Shattering the stillness
Of an ancient pond
A frog jumps into water
-
- Basho