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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
Editable Vector Version (SVG)
High Resolution Raster Version (JPG)
Station Data
Estimates of aquatic grasses cover are derived each year 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 color representing progress towards the goal.
Data Map
Editable Vector Version (SVG) High Resolution Raster Version (JPG) Station Data
This map shows the preliminary aquatic grasses (submerged aquatic vegetation) distribution in 2007. 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 cover in many other areas. During 2007, many areas of the Bay, such as the Upper Bay and Upper Western Shore regions, experienced a significant increase in aquatic grasses area compared to 2006. There were also many regions recording a decline in aquatic grasses area such as the Patapsco and Back Rivers, Patuxent River and Lower Western Shore (MD) regions.
Estimates of aquatic grasses cover are derived each year using aerial surveys. Survey data was used to determine area of aquatic grass in each reporting region for 2006 and 2007. Percent (%) difference in area between 2006 and 2007 was calculated.
Ranking
Comparison of Bay Health Index scores for 2007 (
) compared to (
)
| Score (%) | |
| 0 20 40 60 80 100 |
| Upper Bay | |
| Upper Western Shore | |
| Potomac River | |
| James River | |
| Overall Bay | |
| Rappahannock River | |
| Lower Bay | |
| Lower Eastern Shore (Tangier) | |
| Lower Western Shore (MD) | |
| Upper Eastern Shore | |
| York River | |
| Choptank River | |
| Mid Bay | |
| Patuxent River | |
| Patapsco and Back Rivers | |
| Elizabeth River | No Growth Zone No Growth Zone |
This figure ranks each region from best to worst for aquatic grasses scores in 2007. 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. The Upper Western Shore and Upper Bay regions are closest to the restoration goal. Aquatic grasses in the Upper Bay region have been expanding in recent years. The Patapsco and Back Rivers region had the lowest score in 2007, mostly due to loss of aquatic grasses in the upper reaches. Overall, most regions are far from achieving their restoration goals.
Excel SpreadsheetTrends Graph
This graph is dynamic, you can check and uncheck regions (
checkboxes in legend), select year range (
click and drag), and export as an image (right click).
Editable Vector Version (SVG) 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 |