Bay Grass Abundance

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Chesapeake Bay Program Indicator Framework

Reporting Level Indicators

Indicator and Data Survey

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: Bay Grass Abundance

(3) Description of Dataset used to calculate percent of goal achieved: Acres of Submerged Aquatic Vegetation in Chesapeake Bay

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.) All of the above

Which parameters were measured directly? Acreage measured in photographs during the aerial surveys (after photo-interpretation).  Which were obtained by calculation? Aggregations of photo-interpreted data to segment, zone and bay-wide levels.

(4) Source(s) of Data: Virginia Institute of Marine Science via EPA grant

oIs the complete data set accessible, including metadata, data-dictionaries and embedded definitions?  If yes, please indicate where complete dataset can be obtained. Yes. Please refer to http://web.vims.edu/bio/sav/sav09/index.html.  Methods are also described in the Quality Assurance Project Plan (QAPP) on file for the EPA grant (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov) and at the VIMS web site (http://www.vims.edu/bio/sav/). See Chesapeake Bay SAV special reports at http://www.vims.edu/bio/sav/savreports.html and bibliography at http://www.vims.edu/bio/sav/savchespub.html.  Metadata are included with the data set posted at the VIMS web site (http://www.vims.edu/bio/sav/metadata/recent.html).

(5) Custodian of Source Data (and Indicator, if different): Bob Orth, VIMS or David Wilcox, VIMS

(6) CBPO Contact:  Nita Sylvester

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) 

(Note: based on preliminary data provided 2/25/10).

From 1984-2009

Bay-wide: Increased from 20.7 percent to 46.4 percent of goal achieved (38,228 acres in 1984 to 85,899 acres in 2009). Acreage has averaged 64,927 and has ranged from 38,228 to 89,659 acres. 

Upper Bay:  Increased from 31.7 percent to 99.9 percent of goal achieved (7,498 acres in 1984 to 23,598 acres in 2009). Acreage has averaged 11,570 and has ranged from 5,333 to 23,598 acres.

Middle Bay: Increased from 13.6 percent to 34.4 percent of goal achieved (15,643 acres in 1984 to 39,604 acres in 2009). Acreage has averaged 33,586 and has ranged from 15,643 to 52,973 acres.

Lower Bay: Increased from 32.8 percent to 49.3 percent of goal achieved (15,086 acres in 1984 to 22,697 acres in 2009). Acreage has averaged 20,202 and has ranged from 12,969 to 25,642 acres.

(8b) What is the short-term trend? (10- year trend) 

(Note: based on preliminary data provided 2/25/10).

From 2000-2009:

•Bay-wide: Increased from 37.4 percent to 46.4 percent of goal achieved (69,156 acres in 2000 to 85,899 acres in 2009). 

•Upper Bay: Increased from 62.7 percent to 99.9 percent of goal achieved (14,821 acres in 2000 to 23,598 acres in 2009). 

•Middle Bay: Increased from 29.1 percent to 34.4 percent of goal achieved (33,480 acres in 2000 to 39,604 acres in 2009).  

•Lower Bay: Increased from 45.3 percent to 49.3 percent of goal achieved (20,856 acres in 2000 to 22,697 acres in 2009).

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

(Note: based on preliminary data provided 2/25/10).

In 2009, there were 85,899 acres of bay grasses throughout the Bay, which was 46 percent of the goal and an increase of 9,039 acres from 2008.

In 2009:

•Grasses in the upper Bay covered about 23,598 acres (nearly 100 percent of the area’s 23,630-acre goal)

•Middle Bay grasses covered 39,604 acres (34 percent of the 115,229-acre goal for the area)

•Grasses in the lower Bay covered 22,697 acres (49 percent of the area’s 46,030-acre goal) 

(10b) What does this indicator tell us?  

For 2009, 85,899 acres of SAV were mapped in Chesapeake Bay and its tributaries.  

Notable changes in SAV distribution were measured between 2008 and 2009. SAV increased 12% (from 76,860 in 2008 to 85,899 in 2009). SAV increased in all three (Upper, Middle, and Lower) geographic zones delineated for Chesapeake Bay for the second time since 2001. In 2009, SAV increased in 39, decreased in 19, and remained unvegetated in 35 of the 93 CBP segments.

The 9,039 acre increase in total SAV coverage was strongly driven by changes in the Middle (5,083 ac) and Lower (3,312 ac) bay zones. Total area in the Upper Bay Zone remains relatively unchanged from 2008 levels, although there were local offsetting shifts within the zone. The growth and persistence of the SAV bed in the Susquehanna Flats, one of the largest SAV beds in the Bay, continues to be a major success story for SAV recovery today. In the Middle Bay Zone 84% of the increase occurred in five segments, Lower Central Chesapeake Bay (CB5MH), Honga River (HNGMH), Tangier Sound (TANMH1), Pocomoke Sound (POCMH), and Eastern Bay (EASMH). These changes reflect a large increase in widgeongrass, the dominant species in this region, and the continued expansion of eelgrass in Tangier Sound, following the 2005 dieback. In the Lower Bay Zone 82% of the increase occurred in three segments, Eastern Lower

Chesapeake Bay (CB7PH), Lower Rappahannock River (RPPMH), and Mobjack Bay (MOBMH). Increases in the Rappahannock River can be attributed to widgeongrass which is locally abundant and has fluctuated in past years, while increases in the other two segments reflect continued expansion of eelgrass after the 2005 dieback. This is the third year of SAV increase in the Lower Bay Zone since the eelgrass dieback.

In the Upper Bay Zone (21 CBP segments extending south from the Susquehanna River to the Chester and Magothy rivers), SAV increased 3% from 22,953 ac in 2008 to 23,598 ac in 2009.

In the Middle Bay Zone (44 CBP segments extending south from the Bay Bridge to the

Rappahannock River and Pocomoke Sound, and including the Potomac River), SAV increased 15% from 34,521 ac in 2008 to 39,604 ac in 2009.

In the Lower Bay Zone (28 CBP segments covering the region south from the Rappahannock River and Pocomoke Sound regions to the mouth of the Bay), SAV increased 17% from 19,386 ac in 2008 to 22,697 ac in 2009.

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

• Bay grasses are important because they produce oxygen, are food for a variety of Submerged Aquatic Vegetation (SAV) is important to the Chesapeake Bay aquatic ecosystem.  SAV supports the Bay's health by: 

• generating food and habitat for waterfowl, fish, shellfish and invertebrates; 

• adding oxygen to the water column during photosynthesis; 

• filtering and trapping sediment that otherwise would bury benthic organisms and cloud the water column;

• inhibiting wave action that erodes shorelines; 

• absorbing excess nutrients (which they require for growth), such as nitrogen and phosphorus, that may fuel the growth of unwanted algae in surrounding waters.

Trends in the distribution and abundance of SAV over time are useful in understanding trends in water quality (Moore, et. al. 2004). Fewer SAV indicate poor water quality, whereas abundant SAV indicate better water quality.  Review of photographic evidence from a number of sites dating back to 1937 suggests that close to 200,000 acres of SAV may have historically grown along the shoreline of the Bay (Moore, et. al. 2004). However, by 1984, the SAV community had fallen to a low of about 38,000 acres (Virginia Institute of Marine Science).

The loss of SAV from shallow waters of Chesapeake Bay, which was first noted in the early 1960s, is a widespread, well-documented problem (Batiuk, et al., 2000).  Although other factors, such as climatic events and herbicide toxicity, may have contributed to the decline of SAV in the Bay, the primary causes are eutrophication and associated reductions in light availability (Batiuk, et. al., 2000).   Like any other plant, SAV needs sunlight to grow and survive. Two significant pressures that impact the growth of SAV are sediment and excess nutrient pollution. Sediment—loose particles of clay and silt that are suspended in the water—make the water dingy and block sunlight from the plants. Similarly, excess nutrients in the water fuel the growth of algae, which also block sunlight from the plants. When SAV lacks the sunlight it needs, it cannot survive.

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

Density and changes by zone

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):  Baywide: 1978-2009, excluding 1979-1983 and 1988 when no surveys were conducted.  By zones: 1984-2009, excluding 1988 when no survey was conducted. 

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

(a) Source Data:  annual

(b) Indicator: annual

(15) For annual reporting, month spatial data is available for reporting:  February of the following year.

D.  Spatial Considerations

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

USGS 7.5 minute quadrangle maps are used to organize the mapping process.  231 quadrangles in the study area include all regions with potential for SAV growth.

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC): Data are aggregated to 78 tidal water segments for the Chesapeake Bay (2003 revised Chesapeake Bay Program (CBP) segmentation and zonation scheme) and further aggregated into three zones and then aggregated to the bay-wide level.

(18) Are there geographic areas with missing data?  If so, where? Areas mapped include all regions with potential for SAV growth.  Areas that do not have the potential for SAV growth are not mapped.

(19) The spatial extent of this indicator best described as:

(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 tohttp://www.vims.edu/bio/sav/sav03/re...cess_page.html for methods and http://www.vims.edu/bio/sav/sav03/qu...i024_page.html for an example.

(20) Can appropriate diagnostic indicators be represented geographically?  Yes.  Refer tohttp://www.vims.edu/bio/sav/sav03/re...cess_page.html for methods and http://www.vims.edu/bio/sav/sav03/qu...i024_page.html for an example.

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?)  Yes. This indicator has undergone extensive technical and peer review by state, Federal and nongovernment organization partner members of the SAV workgroup and the Living Resources subcommittee. Data collection, data analysis and QA/QC are conducted by the principal investigators/scientists. The data are peer reviewed by scientists on the workgroup. Data selection and interpretation, the presentation of the indicator, along with all supporting information and conclusions, are arrived at via consensus by the scientists in collaboration with the resource manager members of the workgroup. The workgroup presents the indicator to the subcommittee where extensive peer review by Bay Program managers occurs. See Chesapeake Bay SAV special reports at http://www.vims.edu/bio/sav/savreports.html and bibliography at

http://www.vims.edu/bio/sav/savchespub.html.  The SAV distribution data files are located at

http://www.vims.edu/bio/sav/savdata.html.  The SAV indicator is published at www.chesapeakebay.net/status_baygrasses.aspx.

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   Please refer tohttp://www.vims.edu/bio/sav/sav03/re...area_page.html

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model) Refer tohttp://www.vims.edu/bio/sav/sav03/re...cess_page.html for tools used to develop Orthorectification and Mosaic Production, Photo Interpretation and Bed Delineation.

(24) Are the computations widely accepted as a scientifically sound? Yes.  Refer to http://www.vims.edu/bio/sav/sav03/re...area_page.html

(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)?  Yes. Values used in the analysis are aggregated data, aggregated by Chesapeake Bay segment. Quality assurance project plan for the EPA grant to the Virginia Institute of Marine Sciences describes data collection, analysis, and management methods. This is on file at the U. S. Environmental Protection Agency Chesapeake Bay Program Office (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov). The VIMS web site at http://www.vims.edu/bio/sav/ provides this information as well. Metadata are included with the data set posted at the VIMS web site (http://www.vims.edu/bio/sav/metadata/recent.html)

(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 Historical analysis of SAV in the Potomac River and Analysis of Bay-wide Historic SAV to establish a New Acreage Goal. K. A. Moore, D. J. Wilcox, B. Anderson, T. A. Parham, and M. D. Naylor. Report to EPA Chesapeake Bay Program. April 2004 at

http://www.vims.edu/bio/sav/Final_SA...eport_2004.pdf. Refer to page 12.

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 the Quality Assurance Project Plan (QAPP) on file for the EPA grant (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov) and at the VIMS web site (http://www.vims.edu/bio/sav/).  

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?  Yes. The SAV survey is a general monitoring program, conducted to optimize precision and accuracy in characterizing annually the status and trends of SAV in tidal portions of the Chesapeake Bay. The general plan is to follow fixed flight routes over shallow water areas of the Bay to comprehensively survey all tidal shallow water areas of the Bay and its tidal tributaries. Non-tidal areas are omitted from the survey. SAV beds less than 1 square meter are not included due to the limits of the photography and interpretation. Annual monitoring began in 1978 and is ongoing. Methods are described in the Quality Assurance Project Plan (QAPP) on file for the EPA grant (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov) and at the VIMS web site (http://www.vims.edu/bio/sav/).  See Chesapeake Bay SAV special reports at

http://www.vims.edu/bio/sav/savreports.html and bibliography at

http://www.vims.edu/bio/sav/savchespub.html.

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used?  Please refer tohttp://www.vims.edu/bio/sav/sav02/re...ndex_page.html.  Methods are also described in the Quality Assurance Project Plan (QAPP) on file for the EPA grant (contact:

EPA grant project officer, Mike Fritz (fritz.mike@epa.gov) and at the VIMS web site

(http://www.vims.edu/bio/sav/).  See Chesapeake Bay SAV special reports at

http://www.vims.edu/bio/sav/savreports.html and bibliography at

http://www.vims.edu/bio/sav/savchespub.html.

(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid? Yes. Methods developed for this survey are described in "2002 Distribution of submerged aquatic vegetation in the Chesapeake Bay and coastal bays. R. J. Orth, D. J. Wilcox, L. S. Nagey, A. L. Owens, J. R. Whiting, and A. Serio. VIMS Special Scientific Report Number 139. Final report to U.S. EPA, Chesapeake Bay Program, Annapolis, MD. Grant No.CB983649-01-0, 2003." available at http://www.vims.edu/bio/sav/sav02/.  This indicator has undergone extensive technical and peer review by state, Federal and non-government organization partner members of the SAV workgroup and the Living Resources subcommittee. Data collection, data analysis and QA/QC is conducted by the principal investigators/scientists. The data are peer reviewed by scientists on the workgroup. Data selection and interpretation, the presentation of the indicator, along with all supporting information and conclusions, are arrived at via consensus by the scientists in collaboration with the resource manager members of the workgroup. The workgroup presents the indicator to the subcommittee where extensive peer review by Bay Program managers occurs. See Chesapeake Bay SAV special reports at http://www.vims.edu/bio/sav/savreports.html and bibliography athttp://www.vims.edu/bio/sav/savchespub.html.  The SAV distribution data files are located at http://www.vims.edu/bio/sav/savdata.html.  The SAV indicator is published at www.chesapeakebay.net/status_baygrasses.aspx. 

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible? Quality assurance project plan for the EPA grant to the Virginia Institute of Marine Sciences describes data collection, analysis, and management methods. This is on file at the U. S. Environmental Protection Agency Chesapeake Bay Program Office (contact: EPA grant project officer, Mike Fritz(fritz.mike@epa.gov). The VIMS web site at http://www.vims.edu/bio/sav/ provides this information as well. Metadata are included with the data set posted at the VIMS web site (http://www.vims.edu/bio/sav/metadata/recent.html)

(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced?  Yes. Please refer to http://www.vims.edu/bio/sav/sav02/re...ndex_page.html.  Methods are also described in the Quality Assurance Project Plan (QAPP) on file for the EPA grant (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov) and at the VIMS web site

(http://www.vims.edu/bio/sav/).  See Chesapeake Bay SAV special reports at

http://www.vims.edu/bio/sav/savreports.html and bibliography at

http://www.vims.edu/bio/sav/savchespub.html.

(30) Were the sampling and analysis methods performed consistently throughout the data record?  Some technical improvements (e.g., photo-interpretation tools) were made over the 16 years of the annual SAV survey in Chesapeake Bay. Surveyors and analysts have carefully evaluated the effect of methodological changes along the way and made corrections to adjust for any known effects. Quality assurance project plan for the EPA grant to the Virginia Institute of Marine Sciences describes data collection, analysis, and management methods. This is on file at the U. S. Environmental Protection Agency Chesapeake Bay Program Office (contact: EPA grant project officer, Mike Fritz(fritz.mike@epa.gov). The VIMS web site at http://www.vims.edu/bio/sav/ provides this information as well. Metadata are included with the data set posted at the VIMS web site (http://www.vims.edu/bio/sav/metadata/recent.html)

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

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set? Yes. Quality assurance project plan for the EPA grant to the Virginia Institute of Marine Sciences describes data collection, analysis, and management methods. This is on file at the U. S. Environmental Protection Agency Chesapeake Bay Program Office (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov). The VIMS web site at http://www.vims.edu/bio/sav/ provides this information as well. Metadata are included with the data set posted at the VIMS web site (http://www.vims.edu/bio/sav/metadata/recent.html)

(33) Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator? No. Some technical improvements (e.g., photo-interpretation tools) were made over the 16 years of the annual SAV survey in Chesapeake Bay. Surveyors and analysts have carefully evaluated the effect of methodological changes along the way and made corrections to adjust for any known effects. Quality assurance project plan for the EPA grant to the Virginia Institute of Marine Sciences describes data collection, analysis, and management methods. This is on file at the U. S. Environmental Protection Agency Chesapeake Bay Program Office (contact: EPA grant project officer, Mike Fritz (fritz.mike@epa.gov). The VIMS web site at http://www.vims.edu/bio/sav/ provides this information as well. Metadata are included with the data set posted at the VIMS web site

(http://www.vims.edu/bio/sav/metadata/recent.html)

(34) Are there noteworthy limitations or gaps in the data record?  Please explain. Due to funding constraints, there were no surveys in the years 1979-1983 and 1988. Spatial gaps in 1999 occurred due to hurricane disturbance and subsequent inability to reliably photograph

SAV. Spatial gaps in 2001 occurred due to post-nine-eleven flight restrictions near Washington

D.C. Spatial gaps in 2003 occurred due to adverse weather in the spring and summer and Hurricane Isabel in the fall. Estimates of acreage in the non-surveyed areas, based on prior year surveys, were developed for those years (1999, 2001, 2003).

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.

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