Big Bend Seagrasses Aquatic Preserve - Water Quality

Water quality monitoring plays a major role in the Big Bend Seagrasses Aquatic Preserves' (BBSAP) understanding of natural and human impacts on coastal waters. Researchers use water quality data to document short- and long-term changes within the water column in an effort to quantify the spatial and temporal variability and trends. These are applied both seasonally and as a function of tidal forcing, of the selected abiotic parameters (e.g. establish baseline data) within BBSAP. Water quality affects humans and other parts of the environment; accordingly, it is essential to develop a proficient water quality monitoring program to recognize and prevent potential negative impacts to BBSAP.

A healthy water body contains a balanced amount of nutrients with normal fluctuations in salinity and temperature. It also has plenty of oxygen, which is a basic requirement for nearly all aquatic biota, and little suspended sediment, so that living aquatic resources can breathe or receive enough sunlight to grow. Nutrients, like nitrogen and phosphorus, occur naturally in water, soil and air. Just as nutrient fertilizers are used to promote plant growth on lawns and farm fields, nutrients in the water encourage the growth of aquatic plants and algae. Although nutrients are essential to all plant life within BBSAP, an excess of these nutrients can be harmful. This is called nutrient pollution. The two general sources of adverse impacts on water quality are point and nonpoint source pollution. Point source pollution can be traced to a single identifiable source, such as a discharge pipe. Nonpoint source pollution comes from diffuse sources such as stormwater runoff that collects sediment, nutrients, bacteria, pesticides, fertilizers, animal or human waste, heavy metals, oil and grease. When these nutrient sources are not controlled, excess nutrients find their way into the groundwater, creeks, rivers, and eventually the Gulf of America. Stormwater runoff is considered the primary water quality threat in most of the BBSAP watershed. It causes habitat degradation, fish kills and closure of shellfish beds and swimming areas.

BBSAP's current water quality monitoring project utilizes several methods to examine water column characteristics. Basic water quality parameters are monitored, and this data provides information to assess the condition of biological assemblages. To properly assess water quality conditions, long-term data sets are used to develop baseline data. While routine water quality monitoring detects effects of nutrient enrichment, it is not designed to detect trace levels of toxicants or contaminants. Biological assessments, coupled with habitat assessment, such as physical and chemical measurements, will aid in identifying probable causes of impairment not detected by physical and chemical water quality analyses alone, such as nonpoint source pollution and contamination, erosion, or poor land use practices. Current water quality trends throughout BBSAP indicate a slight increase in total nitrogen and phosphorous. Continued long-term water quality monitoring is therefore necessary and essential to protect the valuable natural resources in BBSAP.