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Aquatic GrassesAquatic grasses, or submerged aquatic vegetation, are one of the most important habitats in Chesapeake Bay. Bay grasses provide critical habitat to key species such as blue crab and striped bass, and can improve water clarity.
Chesapeake Bay - Indicator Details:
Threshold Map
High Resolution Raster Version (PNG)
Station DataEstimates of aquatic grasses cover are derived each year by VIMS using aerial surveys. The aquatic grasses score is determined as the area of aquatic grasses present in each of the 15 reporting regions as a percentage of the restoration goal. Each reporting region is assigned a score representing progress towards the goal.
Data Map
This map shows the preliminary aquatic grass (submerged aquatic vegetation) distribution in 2011. While aquatic grasses fringe long sections of the shoreline, there are many areas of the Bay in which they no longer occur or have experienced a significant reduction in area. For example, aquatic grasses are absent in the Back, West, and Nanticoke Rivers and have very low coverage in many other areas. During 2011, aquatic grasses decreased considerably in many regions such as the Rappahannock, York, Lower Bay, Upper Western Shore and across the Susquehanna Flats of the Upper Bay. Only one region showed an increase between 2010 and 2011, the Choptank River, which improved by ~20%. This assessment is based on aquatic grass survey data provided by VIMS. See http://www.vims.edu/bio/sav for more information.
Estimates of aquatic grasses cover are derived each year by VIMS using aerial surveys. Survey data was used to determine area of aquatic grass in each reporting region. Due to Hurricane Irene, aerial surveys were unable to be conducted of the Potomac, and Patapsco and Back regions. Estimates of aquatic grass extent was based on the observations from 2010. See the methods for aquatic grasses for more details.
Ranking
Comparison of Bay Health Index scores for 2011 (
) compared to (
)
| Score (%) | |
| 0 20 40 60 80 100 |
| Upper Bay | |
| Upper Western Shore | |
| James River | |
| Potomac River | |
| Rappahannock River | |
| Lower Bay | |
| Overall Bay | |
| Lower Eastern Shore (Tangier) | |
| Choptank River | |
| Upper Eastern Shore | |
| York River | |
| Patuxent River | |
| Mid Bay | |
| Lower Western Shore (MD) | |
| Patapsco and Back Rivers | |
| Elizabeth River | No Growth Zone |
This figure ranks each region from best to worst for aquatic grasses scores in 2011. The aquatic grasses score is determined as the area of aquatic grasses present as a percentage of the restoration goal. The Upper Bay and Upper Western Shore regions are closest to the restoration goal; though both took a considerable turn for the worse in 2011. The Rappahannock was also much lower in 2011 and has returned to 2008 levels of growth. The York, Patuxent, Mid Bay, Lower Western Shore (MD), Patapsco and Back, and the Elizabeth River regions all received failing grades for aquatic grass growth in 2011. Overall, most regions are far from achieving their restoration goals. This assessment is based on aquatic grass survey data provided by VIMS. See http://www.vims.edu/bio/sav for more information.
Excel SpreadsheetTrends Graph
This graph is dynamic, you can: a) show and hide items by clicking them in the legend, b) select year range (click and drag), and c) 
export as an image.
Excel SpreadsheetThreshold Levels
| Reporting Region | SAV restoration goal by reporting region (acres) |
| Upper Bay | 14,978 |
| Mid Bay | 18,436 |
| Lower Bay | 35,872 |
| Patuxent River | 1,954 |
| Potomac River | 21,203 |
| Rappahannock River | 2,534 |
| York River | 3,304 |
| James River | 2,629 |
| Elizabeth River | No Grow Zone |
| Upper Eastern Shore | 12,866 |
| Choptank River | 13,953 |
| Lower Eastern Shore (Tangier) | 57,651 |
| Patapsco-Back Rivers | 389 |
| Upper Western Shore | 3,661 |
| Lower Western Shore (MD) | 1,811 |
| Total | 191,241 |