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| Browse History: Overview (2009) | Chlorophyll a (2009) | Coastal Bays Health Index (2009) | Dissolved Oxygen (2009)
Dissolved OxygenDissolved oxygen is critical to the survival of the Coastal Bay's aquatic life. The amount of dissolved oxygen needed before aquatic organisms are stressed, or even die, varies from species to species.
Maryland Coastal Bays - Indicator Details:
Threshold Map
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Station Data Download (Excel)
This map shows how often dissolved oxygen levels were within designated threshold categories in 2009. Good water quality is characterized by having dissolved oxygen concentrations that are frequently in the higher threshold levels (indicated by shades of green), while poor water quality tends to have dissolved oxygen concentrations that are frequently in the lower threshold categories (indicated by shades of yellow and orange). In 2009, regions of the Coastal Bays generally had dissolved oxygen levels that were frequently poor in concentration relative to the thresholds.
Creating this map
Dissolved oxygen was measured bi-monthly to monthly at 80 stations in 2009. The median dissolved oxygen concentration for each station was scored according to the threshold categories and represented.
Dissolved oxygen was measured bi-monthly to monthly at 80 stations in 2009. The median dissolved oxygen concentration for each station was scored according to the threshold categories and represented.
Data Map
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This map shows median bottom dissolved oxygen levels for the summer of 2009. The area with the lowest median dissolved oxygen concentration was the western tributary of St. Martin River, where runoff and groundwater high in nutrients has a direct effect on the water quality. Low dissolved oxygen concentrations is regulated primarily by the quantity of water and nutrients.
Understanding this map
Dissolved oxygen was measured bi-monthly to monthly at 80 stations in 2009. Median dissolved oxygen levels are represented at each station.
Dissolved oxygen was measured bi-monthly to monthly at 80 stations in 2009. Median dissolved oxygen levels are represented at each station.
Ranking
Comparison of Bay Health Index scores for 2009 (
) compared to (
)| Score (%) | |
| 0 20 40 60 80 100 |
| Isle of Wight Bay | |
| Chincoteague Bay | |
| Overall Coastal Bays | |
| Assawoman Bay | |
| Newport Bay | |
| St. Martin River | |
| Sinepuxent Bay |
This figure ranks each region from best to worst for dissolved oxygen. The highest-ranked regions in 2009 were the Isle of Wight and Chincoteague Bays, whereas the lowest-ranked regions were Sinepuxent Bay and St. Martin River.
Excel SpreadsheetThreshold Levels
| Score | Thresholds (mg L-1) |
| 100 | ≥7.0 |
| 80 | 6.0–<7.0 |
| 60 | 5.0–<6.0 |
| 40 | 3.0–<5.0 |
| 20 | 1.0–<3.0 |
| 0 | <1.0 |