W elcome
to the Coalition for Buzzards Bay's Baywatchers water quality data site. The
Baywatchers
program
is Massachusetts’ largest volunteer-based monitoring effort and the primary
source of long-term data used to assess the health of more than 30 harbors
and coves from the Westport Rivers to Woods Hole and the Elizabeth Islands. This extension of our main website was created to inform visitors of the
state of water quality of the Bay’s harbors, coves, and rivers. To
begin learning about the water quality health of any area of Buzzards Bay,
simply choose a location from the animated map on the left hand side of
this screen.
WHAT IS IT? The Bay Health Index measures the nutrient-related health or level of nitrogen fertilization (eutrophication) of each of the Bay's major harbors and coves and provides an "at a glance" picture of conditions throughout Buzzards Bay. The index is the sum of five individual health scores: oxygen, nitrogen, chlorophyll a pigments, water clarity, and salinity. It does not include bacteria monitoring and is not an index of swimmability or shellfish bed status. The results of these criteria are combined and reported as a color-coded chart that indicates the overall health of the sampling location. Click here for more information on the Bay Health Index
WHAT'S MEASURED? Dissolved Oxygen Dissolved oxygen (DO) is one of the most important parameters for determining the health of an embayment and is required for the survival of plants and animals. DO concentration represents the balance between inputs from photosynthesis and the atmosphere and outputs due to plant and animal respiration and decaying organic matter. Low oxygen levels clearly indicate a disruption of the balance due to an overabundance of respiration and decay relative to the amount of oxygen input that the system receives. Nitrogen Nitrogen is the primary nutrient controlling plant production in Buzzards
Bay embayments. Some nitrogen input is essential for growth of phytoplankton
(microscopic plants) and the animals they support. But too much nitrogen
creates an overabundance of plant matter causing reduced water clarity and
low oxygen conditions. For our calculations, total nitrogen is divided into
inorganic (DIN - Dissolved Inorganic Nitrogen) and organic forms (DON -
Dissolved Organic Nitrogen or PON - Particulate Organic Nitrogen). Knowing
the amount and form of nitrogen helps to identify its source, its potential
impact to an embayment, and where management decisions are needed. Chlorophyll Chlorophyll a is the primary photosynthetic green plant pigment found in
algae and most phytoplankton. Measuring the abundance of chlorophyll
a and its immediate breakdown product, pheophytin a, indicates the amount
of living algae in a body of water and is used to determine if a bloom has
occurred. High levels often indicate nutrient enriched conditions, and result
in reduced water clarity, greenish coloration and the potential for low
dissolved oxygen levels. Water Clarity Water clarity is affected by the amount of suspended particles in the water
column. Typically, the higher the level of eutrophication, the
less light penetrates into the water column. Light penetration is important
for photosynthesis and plant growth. Reduced water clarity can shade bottom
dwelling plants, clog fish gills and shellfish, and hinder prey fish from
finding food. Baywatchers measure water clarity using a device known as
a Secchi Disk, a black and white circle that is lowered into the water.
The depth that the disk disappears to the eye is known as the Secchi depth. Salinity Salinity is the measurement of the amount of dissolved salts in a volume of water and is expressed in parts per thousand (ppt). Salinity levels can range from 35 ppt in offshore waters to 0 ppt for freshwater from groundwater or stream inputs. Buzzards Bay and its sub-embayments contain a mixture of seawater and freshwater. Water column stratification can occur when dense, higher salinity water forms a wedge under lighter freshwater. Since plants and animals are adapted to a specific range of salinity, data can be used to delimit the range and habitat of various organisms within an embayment.
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