I will be examining how chlorophyll relates to exceedences in the following water quality

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I will be examining how chlorophyll relates to exceedences in the following water qualityparameters (criteria/thresholds in parentheses):

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1) Dissolved oxygen (5.5 mg/l or 5.0 mg/l)

Designated Use Criteria Concentration/Duration Protection Provided Temporal Application

Migratory fish spawning

and nursery use

7-day mean > 6 mg liter-1 (tidal habitats with 0-0.5 ppt salinity)

Survival/growth of larval/juvenile tidal-fresh resident fish; protective of threatened/endangered species.

February 1 - May 31

Instantaneous minimum > 5 mg liter-1 Survival and growth of larval/juvenile migratory fish;

protective of threatened/endangered species.

Open-water fish and shellfish designated use criteria apply June 1 - January 31

Shallow-Water bay grass use

Open-water fish and shellfish designated use criteria apply Year-round

Open-water fish and shellfish use1

30-day mean > 5.5 mg liter-1 (tidal habitats with 0-0.5 ppt salinity)

Growth of tidal-fresh juvenile and adult fish; protective of threatened/endangered species.

Year-round 30-day mean > 5 mg liter-1 (tidal habitats with >0.5 ppt salinity)

Growth of larval, juvenile and adult fish and shellfish; protective of threatened/endangered species.

7-day mean > 4 mg liter-1 Survival of open-water fish larvae.

Instantaneous minimum > 3.2 mg liter-1 Survival of threatened/endangered sturgeon species.2

Deep-water seasonal fish and

shellfish use

30-day mean > 3 mg liter-1 Survival and recruitment of bay anchovy eggs and larvae.

June 1 - September 30

1-day mean > 2.3 mg liter-1 Survival of open-water juvenile and adult fish.

Instantaneous minimum > 1.7 mg liter-1 Survival of bay anchovy eggs and larvae.

Open-water fish and shellfish designated-use criteria apply October 1 - May 31

Deep-channel seasonal refuge

use

Instantaneous minimum > 1 mg liter-1 Survival of bottom-dwelling worms and clams. June 1 - September 30

Open-water fish and shellfish designated use criteria apply October 1 - May 31

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1) Dissolved oxygen (5.5 mg/l or 5.0 mg/l)2) pH (6-9)

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I will be examining how chlorophyll relates to exceedences in the following water qualityparameters:

1) Dissolved oxygen (5.5 mg/l or 5.0 mg/l)2) pH (6-9)3) Percent-Light-Through-Water (22% or 13%)

From EPA-CPB’s “Chesapeake Bay Submerged Aquatic Vegetation Water Quality and Habitat-Based Requirements andRestoration Targets: A Second Technical Synthesis” (2000)

http://archive.chesapeakebay.net/pubs/sav/07.pdf









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1) Dissolved oxygen (5.5 mg/l or 5.0 mg/l)2) pH (6-9)3) Percent-Light-Through-Water (22% or 13%)4) DO Saturation (125%)

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Excessive dissolved gas super-saturation is associated with:

· Bubble formation in the cardiovascular system, causing blockage of blood flow and death (Jensen 1980, Weitkamp and Katz 1980, Fidler 1988).

· Overinflation and possible rupture of the swim bladder in young (or small) fish, leading to death or problems of overbuoyancy (Shirahata 1966, Jensen 1980, Fidler 1988, Shrimpton et al. 1990a and b).

· Extracorporeal bubble formation in gill lamella of large fish or in the buccal cavity of small fish, leading to blockage of respiratory water flow and death by asphyxiation (Fidler 1988, Jensen 1988).

· Sub-dermal emphysema on body surfaces, including the lining of the mouth. Blistering of the skin of the mouth may also contribute to the blockage of respiratory water flow and death by asphyxiation (Fidler 1988, White et al. 1991).

Source: British Columbia Water Quality Guidelines of Dissolved Gas Supersaturation (1994)

Gas bubble trauma in a juvenile rainbow trout

http://www.env.gov.bc.ca/wat/wq/BCguidelines/tgp/




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In addition to being linked to harmful impacts on aquatic life, DO super-saturation is alsoan excellent indicator of algal blooms.

USA EPA (1986) recommends a dissolved gas criterion of 110% to protect aquatic life. Other sources suggest 125% for DO saturation. This is the number I’ve chosen to use as athreshold.

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1) Dissolved oxygen (5.5 mg/l or 5.0 mg/l)2) pH (6-9)3) Percent-Light-Through-Water (22% or 13%)4) DO Saturation (125%)

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I’m analyzing three types of monitoring data:

1) DATAFLOW (HRSDS and VIMS)2) Long-term, mid-channel fixed stations (DEQ)3) Continuous (VIMS)

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DATAFLOW provides a precise estimation of chlorophyll in space.When run frequently (as it is in the lower James), it also capturestemporal variability. These two qualities make DATAFLOW the idealdataset for assessing chlorophyll.

So if there are relationships between chlorophyll and water qualityexceedences, I would expect to find evidence in theDATAFLOW data.

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Step 1. Plot DATAFLOW cruisetrackpoints…

Case study: JMSMH

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…over Bay Interpolator cells

JMSMH

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Step 2. Generate descriptive statistics for each cell that intersectsa cruise point

• mean chlorophyll• mean DO concentration• mean Kd

• mean pH• mean DO Saturation %

JMSMH

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From EPA’s 2008 Technical Support for Criteria Assessment Protocols Addendum

percent-light-through-water

http://www.chesapeakebay.net/channel_files/20963/2008_addendum_ambient_water_quality_criteria.pdf

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Step 3. Repeat for each cruise.

For the results I’m going to show,I used 71 summertime cruises from2007-2012. This resulted in 8748samples (cell averages).

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Probability of Exceeding Selected Water Quality Parameter Thresholds

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Based on cell-averaged DATAFLOW measurementsJMSMH, July-September 2007-2012 (n=8748)

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DO < 5.0 mg/l

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pH>9.0

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DO Saturation >125%

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PLW <22%

criterion=10 ug/l

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Based on cell-averaged DATAFLOW measurementsJMSMH, summer months 2007-2012 (n=8748)

• DO and pH exceedences are very rare in the daytime surface waters monitored by DATAFLOW.

• Exceedence rates in DO Sat and PLW appear to increase with chlorophyll.

• This analysis would seem to suggest that the current criterion (10 ug/l) is protective of water quality.

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PLW <22% ProbabilityBy binCumulativeProbability

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DO Saturation >125%

ProbabilityBy binCumulativeProbability

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JMSMH Summer

Based on semi-monthly/monthly fixed station monitoring conducted by DEQ and VIMS, 1985-2013 (n=29).

BUT…

There doesn’t seem to be arelationship between seasonal chlorophyll averages and water quality exceedence rates.

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seasonal average chlorophyll (ug/l)

30-Day Mean DO (5.0 mg/l)Instantaneous Min DO (3.2 mg/l)

Dissolved Oxygen

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seasonal average chlorophyll (ug/l)

PLW 22% (secchi)

Water Clarity

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Summer chlorophyll averages and 90th percentiles based on DATAFLOW, plotted against the exceedence rate of the 30-Day Mean DO criterion (5.0 mg/l) observed at DEQ/VIMS fixed stations

JMSMH

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summer mean chl (ug/l)<---DATAFLOW--->

<--F

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2011

20082009

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<--F

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CONMON data allow us to answer these important questions:

1) Over what time period(s) do we see relationships between chlorophyll and water quality exceedences?

2) How do these relationships change with increasing duration?

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Four durations examined:

1) Instantaneous chlorophyll (15-minute observations)

2) 24-hour average chlorophyll3) 7-day average chlorophyll rolling averages4) 30-day average chlorophyll

Following results are for JMSOH Summer

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15-min chlorophyll (ug/l)

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cumulative probability

pH >9.0

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DO <5.0 mg/l

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DO SAT >125%

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PLW <13%

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15-minute chlorophyll (ug/l)

JMSOH CONMON Summer 2006-2008 Instantaneous Chlorophyll

n=23,115

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24-hour chlorophyll average (ug/l)

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90th percentile pH >9.0

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24-hour average chlorophyll (ug/l)

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10th Percentile DO < 5.0 mg/l

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90th Percentile DO SAT >125%

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Mean PLW <13%

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JMSOH CONMON Summer 2006-2008 24-hour Average Chlorophyll

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7-day average chl (ug/l)

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90th Percentile pH >9.0

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bin probabilitycumulative probability

90th Percentile DO SAT>125%

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7-day average chlorophyll (ug/l)


Mean PLW <13%

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JMSOH CONMON Summer 2006-2008 7-Day Average Chlorophyll

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90th Percentile pH >9.0

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10th Percentile DO <5.0 mg/l

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Mean PLW<13%

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JMSOH CONMON Summer 2006-2008 30-Day Average Chlorophyll

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Three things jump out at me…

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1. The chlorophyll bin where we see a jump in exceedences shifts to lower values with increasing duration.

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DO SAT >125%

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The chlorophyll bin where we see a jump in exceedences shifts to lowervalues with increasing duration.

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1. The chlorophyll bin where we see a jump in exceedence rate shifts to lower values with increasing duration.

2. The strength of a relationship is dependent on the duration.

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PLW <13%

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Mean PLW<13%

“If we can keep the chlorophyll at less than 10 ug/l,water clarity will still be poor. But at least we won’t make it worse!”

“There isn’t a relationship between chlorophyll and water clarity.”

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1. The chlorophyll bin where we see a jump in exceedence rate shifts to lower values with increasing duration.

2. Exceedences can be obscured by increasing duration.

3. The duration affects how we talk about exceedences.

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“DO saturation was excessive in JMSOH 6% ofthe time during the summer months.”

“JMSOH experienced excessive DO saturation levels during26% of the 24-hour periods monitored during this study.”

“22% of the 7-day periods sampled in JMSOH werecharacterized by at least 16 hours of excessive DOsaturation levels.”

“12% of the 30-day periods sampled in JMSOH werefound to have at least 72 hours of excessive DOsaturation levels.”

All the statements below describe the same dataset, just parsed in different ways. But which statement is more meaningful to aquatic life?

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DO SAT >125%

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ns

ns ns

ns

ns= no significant difference, Wilcoxon-Rank Sum test

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ns

a a b

a b c

ns= no significant differenceKruskal-Wallis ANOVAPairwise Wilcoxon Rank Sum

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Based on summertime DEQ/VIMS fixed station monitoring in JMSOH, 1985-2013. Redline indicates the chlorophyll criterion for this segment-season. (n = 29)

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season average chlorophyll (ug/l)

30-Day Mean DO (5.0 mg/l)

Instantaneous Minimum DO (3.2 mg/l)

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June 27, 2006 July 17, 2006 August 6, 2006 August 26, 2006 September 15, 2006

CHO

ROPH

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(UG

/L)

DO

% S

ATU

RATI

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DO % Saturation

chlorophyll

Spearman r=.56

I will be examining how chlorophyll relates to exceedences in the following water quality

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Transcript of I will be examining how chlorophyll relates to exceedences in the following water quality