Phytoplankton

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Chesapeake Bay Program Indicator Framework

Reporting Level Indicators

Indicator and Data Survey

For each indicator for which you are responsible, please provide the following information.  This information will be made available to the developers of the reports, the reviewers of the reports and by members of the public who may request detailed information about the data used in the reports.  Please refer to the sample for examples of the level of detail that should be provided.

A.  Category/Name/Source/Contact

(1) Category of Indicator

___ Factors Impacting Bay and Watershed Health

___ Restoration and Protection Efforts

___ Watershed Health

_x_ Bay Health

(2) Name of Indicator: Chesapeake Bay Phytoplankton Index of Biotic Integrity (PIBI)

(3) Data Set Description: A PIBI score is calculated for each station-date sampling event in the index period, which is currently spring (March-May) and summer (July-September).  There are 31 stations in the CBP phytoplankton monitoring program, and all are monitored at least once a month.  The Living Resources Data Manager/Analyst uses data drawn from the phytoplankton and water quality monitoring databases to produce a PIBI score for each station-date sampling event.  Multiple parameters (metrics) in the databases are individually scored and then averaged.  PIBI scores range from 1.0 (very degraded communities) to 5.0 (desirable, least-impaired communities).  For area-weighting purposes, a station’s PIBI scores are assumed to represent the segment where the station is located.  Areas of the biomonitoring station segments are taken from U. S. Environmental Protection Agency, Chesapeake Bay Program (2004).  Individual PIBI scores can be grouped spatially by station, tributary, salinity zone, or the entire bay, and/or temporally by season (spring, summer), year, 3-5 year period, or the entire period of record.  Analysis results are presented as the frequency of PIBI scores meeting a minimum restoration target score of PIBI>=3. This is a change in reporting threshold from 2005. This change was made so that phytoplankton reporting thresholds better aligned with those used for SAV and Benthos. Individual PIBI scores can be grouped spatially by station, tributary, salinity zone, or the entire bay, and/or temporally by season (spring, summer), year, 3-5 year period, or the entire period of record.  Analysis results are typically presented as: a) a median or average PIBI score, or b) the frequency of PIBI scores in a given rank.  PIBI ranks are “Good” if the PIBI score is 4.0-5.0, “Fair-Good” if PIBI is 3.33-4.0, “Fair” if PIBI is 2.67-3.33, “Fair-Poor” if PIBI is 2.0-2.67 and “Poor” if PIBI is 1.0-2.0. 

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.) Primarily long-term monitoring, but the program benefits research and can be used to track phytoplankton community health indicators. This indicator will be unavailable after the 2009 Health and Restoration report due to the termination of all phytoplankton monitoring as of 30 September 2009.

Which parameters were measured directly? Abundances of individual species and the phytoplankton taxonomic groups, chlorophyll a, pheophytin, and dissolved organic carbon (DOC).  

Which were obtained by calculation? Biomasses of the phytoplankton taxonomic groups and the total micro-nano- phytoplankton size fraction.

(4) Source(s) of Data: Morgan State University Estuarine Research Laboratory (Richard Lacouture, rlacouture@moac.morgan.edu) and Old Dominion University (Harold Marshall, hmarshal@odu.edu) collect and count the phytoplankton samples.  

Is the complete data set accessible, including metadata, data-dictionaries and embedded definitions?  If yes, please indicate where complete dataset can be obtained. The underlying phytoplankton and water quality monitoring databases and documentation are available athttp://www.chesapeakebay.net/data/index.htm.  Field and laboratory methods are described in the Quality Assurance Project Plans (QAPP) on file at CBPO (http://www.chesapeakebay.net/data/index.htm, or contact Mary Ellen Ley, Quality Assurance Officer).  The complete PIBI data set is presently available from Jacqueline Johnson, Living Resources Data Manager/Analyst, and will shortly be available on www.chesapeakebay.net.  Analysis methods are currently outlined in this document, three publications, and a white paper: 

Buchanan, C., R. V. Lacouture, H. G. Marshall, M. Olson, J. Johnson.  2005.  Phytoplankton reference communities for Chesapeake Bay and its tidal tributaries.  Estuaries 28(1):138-159.

Lacouture, R. V., J. M. Johnson, C. Buchanan, and H. G. Marshall.  2006. Phytoplankton Index of Biotic Integrity for Chesapeake Bay and its Tidal Tributaries.  Estuaries 29(4):598-616.  

Lacouture, R. V., J. M. Johnson, C. Buchanan, and H. G. Marshall. (Submitted, J. Plank. Res.) The procedure for estimating carbon content of phytoplankton and its application to phytoplankton taxonomic data in Chesapeake Bay Estuary.

Buchanan, C.  January 2006.  A restoration goal for Chesapeake Bay phytoplankton communities.  White paper prepared for the Chesapeake Bay Program Living Resources Subcommittee.  12p.

(5) Custodian of Source Data (and Indicator, if different): Jacqueline Johnson, Living Resources Data Manager/Analyst

(6) CBPO Contact:  

Jacqueline Johnson jjohnson@chesapeakebay.net (Living Resources Data Manager/Analyst) 

B.  Communication Questions

(complete either part 1, 2, or 3)

1.  Restoration and Protection Efforts indicators only

(7a) How much has been completed since 1985 (or baseline year)?  How much has been completed since 2000?

(8a) How much was done last year?

(9a) What is the current status in relation to a goal?

(10a) What is the key story told by this indicator?

(11a) Why is it important to report this information?

(12a) What detail and/or diagnostic indicators are related to this reporting level indicator? (Detail and diagnostic indicators can be spatially-specific, parameter-specific, temporally-specific information, etc.)

2.  Bay Health or Watershed Health indicators only

(7b) What is the long-term trend?  (since start of data collection)  The annual, bay-wide, area-weighted frequency of PIBI > 3.0 the final choice for a reporting level indicator.  Between 1986 and 2009, this indicator has averaged 49.88% and has ranged from 36.3% 73.9% (Figure 1 and Figure 4). This indicator is area-weighted and thus heavily influenced by conditions in the larger mesohaline and polyhaline segments (MH/PH) (Figure 4), which tend to be better than those in low salinity segments of the tidal tributaries and upper Bay (TF/OH).  

Figure 1. Bay-wide PIBI

PhytoplanktonFigure1.gif

Figure 2. Maryland Tributaries

PhytoplanktonFigure2.gif

Figure 3. Virginia Tributaries

PhytoplanktonFigure3.gif

Figure 4. Mainstem

PhytoplanktonFigure4.jpg

Maryland tributaries tend to show long-term declines in the annual average PIBI scores in most area (Figure2). In 2009, only three tributary showed improvement over 2008. The Potomac River has achieved a 43.1% pass rate, the upper Eastern Rivers achieved a 15.6% pass rate and the Choptank achieved a 21.7% pass rate. Most of  these improvements are being driven by improvement in the Oligohaline and Tidal Fresh regions of the rivers. Virginia tributaries continue show a mixed long-term picture (figure 3). However only the York River showed a slight improvement from 2008 .

(8b) What is the short-term trend? (10-year trend) There is no discernable trend.  Too many extreme wet and extreme dry years together.

(9b) What is the current status in relation to a goal? 

Based on all data from 2009, 53.9% percent of phytoplankton communities in bay surface waters attained a PIBI >= 3.0 or meet current Benchmark or Threshold status. 

Initially numeric phytoplankton restoration goal of PIBI > 4.0 on the index’s 1 - 5 scale was recommended by the Living Resources Subcommittee (1/26/06).  Attainment of this goal is expected to coincide with attainment of Chesapeake Bay water quality standards (Buchanan 2006).  The goal can be interpreted two ways, with the first being more stringent and difficult to attain: 

(a)Some high percent (e.g. 100%) of all Chesapeake tidal surface water have PIBI scores greater than or equal to 4.0 in the index period. 

(b)The average or median PIBI value weighted by segment area is greater than or equal to 4.0 in the index period.

The frequency of IBI values equal to or greater than 3 is calculated for each segment by year. For the reporting regions: area weight frequency by segment area and then sum for the reporting area. When 90% or more pass “Benchmark” or “Threshold” of 3.0 the goal of the reference community distribution is achieved

 (10b) What does this indicator tell us?  

Water column transparency (clarity) is currently too poor and nutrient levels too high to support healthy phytoplankton communities in Chesapeake Bay.  Overall status of the phytoplankton community is Fair-Poor in low salinity waters and Fair in high salinity waters; status is highly variable at many bay stations.  Algal blooms are still frequent, abundances of harmful algal species are often high, phytoplankton biomass and species composition are highly variable, and algal cells exhibit signs of stress.  An earlier downward (degrading) trend in phytoplankton status in low salinity waters has leveled off.  

(11b) Why is it important to report this information?

Phytoplankton are important because they use dissolved nutrients and sunlight to produce oxygen and new biomass.  They are the base of most Chesapeake food webs, and moderate, stable levels are needed for healthy benthic invertebrates and zooplankton populations, and ultimately abundant fish and birds.  These desirable levels are an expected response to nutrient load reductions and improvements in water clarity through sediment load reductions.  Presently, algal blooms are a frequent, episodic problem in Chesapeake Bay, indicated by high chlorophyll a concentrations.  Blooms occur when growth fueled by high nutrient loadings outstrips losses to consumers.  Uneaten phytoplankton biomass sinks to the bottom and eventually decomposes, resulting in hypoxia and anoxia.  Phytoplankton are typically blamed for clouding the water, but recent evidence suggests suspended sediments are more often responsible.  Poor water clarity stresses phytoplankton photosynthesis and can favor undesirable species.

(12b) What detail and/or diagnostic indicators are related to this reporting level indicator?

Median or average values of the PIBI scores are used when characterizing the overall status of individual stations and their segments.  The status of a station or area can vary from Poor to Good depending on seasonal and annual fluctuations in water quality.  The frequency of each PIBI rank is another useful means of characterizing bay waters.  For example, an area-weighted analysis of the PIBI scores shows that an average 21.8% of Chesapeake tidal surface water ranked as Poor between 1986 and 2004; 20.0% ranked Fair-Poor, 25.0% ranked Fair, 18.4% ranked Fair-Good, and 14.8% ranked Good.

3.  Factors Impacting Bay and Watershed Health indicators only

(7c) What is the long-term trend?  (since start of data collection)

(8c) What is the short-term trend? (3 to 5 year trend)

(9c) What is the current status?

(10c) What is the key story told by this indicator?

(11c) Why is it important to report this information?

(12c) What detail and/or diagnostic indicators are related to this reporting level indicator?

C.  Temporal Considerations

(13) Data Collection Date(s):  this monitoring program was terminated as of 30 September 2009. Phytoplankton samples were collected monthly at twenty-seven (31) fixed stations in the Chesapeake mainstem and tidal tributaries.  The index period for the PIBI is currently spring (March-May) and summer (July-September), although IBIs for autumn and winter could be developed.  Monitoring began in 1984 (Maryland) and in 1985-1986 (Virginia).  Several stations were sampled for only 1-2 years (EE3.1, Chester River; ET4.2, Tangier Sound; RET4.1, Pamunkey River), 7 years (SBE2, Elizabeth River), or 12 years (CB1.1, mouth of the Susquehanna).  These stations are not included in the analysis because doing so temporarily biases the bay-wide status and trend results.  A data gap occurs at the mainstem station CB5.2 in 1996-1997 when biological sampling was temporarily stopped. In 2007, four additional stations were added in Maryland to improve data coverage ET3.1, Sassafras River, ET4.2, Chester River, WT6.1, Magothy River, and WT8.1, South River.  PIBI values estimated from other years are used for these two years because the CB5 segment is large and the data gap causes a noticeable bias in the bay-wide results.  Lesser data gaps occur at multiple Virginia stations in the earlier years due to mismatches in phytoplankton and water quality sampling dates that preclude PIBI calculations.  Estimated values are only used in the James TF5.5 station for 1995 and spring 1996.

(14) Planned Update Frequency (e.g. - annual, bi-annual):

(a) Source Data: Monitoring has ceased, no additional updates are planned for the near future

(b) Indicator: annual

(15) For annual reporting, month spatial data is available for reporting: This monitoring program was terminated as of 30 September 2009. All final data had been delivered as of 15 January 2010.

D.  Spatial Considerations

(16) Type of Geography of Source Data (point, line polygon, other):

The water quality and phytoplankton data are station-specific.  Station locations are given as decimal degree latitudes and longitudes in the database (NAD83).

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC): PIBI scores for individual station-date sampling events can be grouped spatially by station, tributary, salinity zone, or the entire bay, and temporally by season (spring, summer), year, 3-5 year period, or the entire period of record.  James River stations LE5.5 (1984-1996) and LE5.5W (1997-present) are treated as one.  The two stations in segment CB6 (CB6.1, CB6.4) are divided into two equal sub-segments.  

(18) Are there geographic areas with missing data?  If so, where? Only 27 Chesapeake Bay segments have biomonitoring stations (Table 1).  These segments make up approximately 82.8% of the total surface area of Chesapeake Bay and its tidal tributaries.  It is assumed that each station is representative of the phytoplankton communities in its segment, and that the 27 sampled segments are representative of the remaining CBP segments.  The biomonitoring stations are found throughout the bay mainstem and in all of the major tributaries (Figure 2).   

(19) The spatial extent of the reporting level indicator is best described as: (a).

(a) Chesapeake Bay (estuary)

(b) Chesapeake Bay Watershed

(c) Other (please describe): _______________________

Please submit any appropriate examples of how this information has been mapped or otherwise portrayed geographically in the past. Refer to Buchanan (2006).

(20) Can appropriate diagnostic indicators be represented geographically?  Yes.  Refer Buchanan (2006) and Lacouture et al. (2006).

E.  Data Analysis and Interpretation

(Please provide appropriate references and location of documentation if hard to find.)

(21) Is the conceptual model used to transform these measurements into an indicator widely accepted as a scientifically sound representation of the phenomenon it indicates?  (i.e., how well do the data represent the phenomenon?)  The procedure for developing indexes of biotic integrity, or IBIs, is well documented and tested.  Guidance for developing estuarine IBIs is provided in Gibson et al. (2000).  The Chesapeake PIBI correctly identified degraded and reference water quality conditions in 70.0% - 84.4% of the samples in the calibration data set, which were grouped into four salinity zones and two seasons (spring, summer).  The component metrics and the overall index performed very well in two different validation efforts.  The PIBI correctly identified 77.3% of all samples in an independent validation data set and had mean errors of 3.12% - 12.59%, depending on salinity and season, in a jackknife validation procedure (Lacouture et al. 2006).

An interim numeric phytoplankton restoration goal of PIBI > 4.0 on the index’s 1 - 5 scale was approved by the Living Resources Subcommittee because attainment of this goal is expected to coincide with attainment of Chesapeake Bay water quality standards (Buchanan 2006).  The goal can be interpreted two ways, with the first being more stringent and difficult to attain: 

(a)some high percent (e.g. 100%) of all Chesapeake tidal surface water have PIBI scores greater than or equal to 4.0 in the index period. 

(b)the average or median PIBI value weighted by segment area is greater than or equal to 4.0 in the index period.

Table 1. Monitoring stations, their segment name, and the area of their segment. 

STATIONCBSEGAREA SEGMENT (SQ KM)

CB2.2CB2OH275.24

CB3.3CCB3MH361.59

CB4.3CCB4MH908.85

CB5.2CB5MH1474.62

CB6.4CB6PH743.35

CB6.1CB6PH743.35

CB7.3ECB7PH1520.78

CB7.4CB8PH412.43

ET5.2CHOMH274.20

ET5.1CHOOH15.04

ET4.2CHSMH 119.29

RET5.2JMSOH127.75

LE5.5-WJMSPH76.56

LE5.5JMSPH76.56

TF5.5JMSTF95.30

WT6.1MAGMH 26.53

WE4.2MOBPH342.70

WT5.1PATMH93.60

LE1.1PAXMH107.54

TF1.7PAXOH14.24

TF1.5PAXTF4.41

TF4.2PMKTF16.23

LE2.2POTMH887.86

RET2.2POTOH214.96

TF2.3POTTF150.44

LE3.6RPPMH323.83

RET3.1RPPMH323.83

TF3.3RPPOH19.54

ET3.1SASOH 33.09

SBE2SBEMH8.39

SBE5SBEMH8.39

WT8.1SOUMH 23.98

RET4.3YRKMH94.59

TOTAL_AREA9719.05

Figure 4.  Map of the phytoplankton monitoring stations and salinity regimes

PhytoplanktonFigure4A.gif

Maryland and 6 in Virginia for the index period.  A 3-year index period would reduce the uncertainty caused by low n sizes, but would not reflect the most recent changes.

The Living Resources Data Analysis Workgroup (LivRAW) and Living Resources Subcommittee (LRSC) have reviewed the PIBI.  The Monitoring and Assessment Subcommittee (MASC) and Science and Technical Advisory Subcommittee (STAC) were asked to review the PIBI and the interim numeric phytoplankton restoration goal in 2006. 

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   Please refer to Lacouture et al. (2006) for details regarding metric scoring procedures and thresholds.  The yearly average PIBI at each station and the yearly frequency of PIBI scores greater than or equal to 3.0 at each station are calculated for the index period (Mar-May and July-Sept).  Station-year averages and frequencies are area-weighted by the station’s fraction of the total Bay surface area, and finally summed to obtain the average PIBI and frequency of PIBI > 3.0.

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model)   In house computer programs have been written to generate values directly from CBP plankton and water quality databases.

(24) Are the computations widely accepted as a scientifically sound? The general approach of computing station-date specific IBI scores from multiple metrics is widely accepted and used. 

(25) Have appropriate statistical methods been used to generalize or portray data beyond the time or spatial locations where measurements were made (e.g., statistical survey inference, no generalization is possible)?  

Given the inherent limitations in the data, yes.  The underlying assumptions are:

PIBI scores obtained from fixed station data are representative of the station’s entire segment.  (This assumption is supported by the US EPA CBP (2003) description of segments as “regions having similar natural characteristics” that can be used to “define a range of water quality and resource objectives, target specific actions and monitor response.”)

PIBI scores obtained 6 – 10 times during the index period each year are representative of that year-period. 

(26) Are there established reference points, thresholds or ranges of values for this indicator that unambiguously reflect the desired state of the environment? (health/stressors only) 

Yes. Please refer to Buchanan (2006), Lacouture et al. (2006), and Buchanan et al. (2005).  

F.  Data Quality

(Please provide appropriate references and location of documentation if hard to find.)

(27) Were the data collected according to an EPA-approved Quality Assurance Plan?  Yes. Methods are described in Quality Assurance Project Plans (QAPP) on file at the Chesapeake Bay Program Office (contact: EPA Quality Assurance Officer Mary Ellen Ley)

If no, complete questions 28a – 28d:

(28a) Is the sampling design and/or monitoring plan and/or tracking system used to collect the data over time and space based on sound scientific principles?  

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used?  

(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid? 

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible? 

(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced?  Yes. 

(30) Were the sampling and analysis methods performed consistently throughout the data record?  

Some technical improvements were made in recent years (i.e., counting protocol, taxonomic identifications).  See EPA QA/QC Officer Mary Ellen Ley for details.  The effect of these improvements is being documented in a series of split sample studies comparing Maryland and Virginia results.

(31) If datasets from two or more agencies are merged, are their sampling designs and methods comparable?  

Sampling designs and field collection methods are very comparable.  See (30) above re laboratory method comparability.  

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set? Yes. 

(33) Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator? 

Uncertainty and variability in PIBI scores were tested in the calibration data set (Lacouture et al. 2006).  Uncertainty and variability in the reporting level indicators has not been investigated yet, however the data are available to do so.

(34) Are there noteworthy limitations or gaps in the data record?  Please explain. See (13) above. 

G.  Additional Information

(optional)

(35) Please provide any other information about this indicator you believe is necessary to aid communication and any prevent potential miss-representation. 

Both options for reporting indicator are area-weighted and thus biased towards larger mesohaline and polyhaline segments (MH/PH).  MH/PH segment areas comprise approximately 87% of the total Bay surface area, or 94% of the Bay mainstem (all CB segments plus MOBPH and TANMH) and 77% of all the tidal tributary areas (all remaining PH and MH segments).  Tidal fresh and oligohaline segments (TF/OH) comprise only 13% of the total Bay surface area.  They are typically the most impacted by nutrients and sediments loads, and experience the lowest residence times and the greatest freshwater flow impacts.  

Several misconceptions about chlorophyll a and phytoplankton (algae) are common in management and public perceptions of bay restoration.  Correcting these misconceptions will encourage managers to use the PIBI as a functional tool, and will improve the general public’s expectations for a restored bay. 

• “Chlorophyll a is a measure of algal biomass”

False. Chlorophyll a is a measure of photosynthetic capability.  It is a photosensitive chemical used by most primary producers to capture sunlight energy, and it comprises about 0.1 - 5 % of an algal cell’s organic matter.  It correlates well with algal biomass when water clarity is good.  It over-estimates algal biomass when water clarity is poor because cells adapt to low light.

• “Reducing nutrients will starve the fish” (or “More is Better”)

False.  Data analysis suggests that lower nutrient concentrations–if coupled with better water clarity–will result in the same, or more, phytoplankton biomass for the food web (Buchanan et al. 2005).  There will be fewer and less severe algal blooms and food quality may improve.  It is worth noting that present-day “reference communities” for phytoplankton and zooplankton resemble the plankton communities of the 1950’s, when the bay ecosystem was considered “healthy enough” and supported much larger grazer populations. 

• “Oysters are one of the most important filter-feeders in Chesapeake Bay”

False. They once were…they no longer are.  Neither are menhaden.  Zooplankton and soft-bottom benthos presently graze most of the phytoplankton in Chesapeake Bay.

• “We can’t manage the zooplankton and benthos”

False.  We can indirectly manage their communities and improve their capacity to support fish, crabs, and birds to a significant degree by reducing nutrients and improving water clarity and dissolved oxygen.

• “We don’t need to monitor phytoplankton (or zooplankton) if we are monitoring–and attaining–the water quality criteria.”

False.  Chesapeake Bay has been changing physically, chemically, and biologically for a long time.  Simply reversing nutrient and sediment trends, and eventually attaining the water quality criteria, does not guarantee restoration of the bay food web described in CBP agreements.  Phytoplankton monitoring tracks the presence of non-native and harmful species, measures the quality and quantity of phytoplankton food for grazers, and verifies CBP water quality and ecosystem model predictions.

Citations:

Buchanan, C.  January 2006.  A restoration goal for Chesapeake Bay phytoplankton communities.  White paper prepared for the Chesapeake Bay Program Living Resources Subcommittee.  12p.

Buchanan, C., R. V. Lacouture, H. G. Marshall, M. Olson, J. Johnson.  2005.  Phytoplankton reference communities for Chesapeake Bay and its tidal tributaries.  Estuaries 28(1):138-159.

Gibson, G. R., M. L. Bowman, J. Gerritsen, and B. D. Snyder.  2000.  Estuarine and coastal marine waters: Bioassessment and biocriteria technical guidance.  EPA 822-B-00-024. U.S. Environmental Protection Agency, Office of Water, Washington, DC.  Available on-line athttp://www.epa.gov/ost/biocriteria...ries/Estuaries final.pdf.

Lacouture, R. V., J. M. Johnson, C. Buchanan, and H. G. Marshall. (Submitted, J. Plank. Res.) The procedure for estimating carbon content of phytoplankton and its application to phytoplankton taxonomic data in Chesapeake Bay Estuary.

Lacouture, R. V., J. M. Johnson, C. Buchanan, and H. G. Marshall.  2006. Phytoplankton Index of Biotic Integrity for Chesapeake Bay and its Tidal Tributaries.  Estuaries 29(4):598-616

U. S. Environmental Protection Agency, Chesapeake Bay Program.  2004. Chesapeake Bay Program Analytical Segmentation Scheme: Revisions, Decisions and Rationales 1983–2003. EPA 903-R-04-008, CBP/TRS 268/04.

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