The Massachusetts Estuaries Project (MEP)—a collaborative effort between the Massachusetts Department of Environmental Protection (MA DEP) and the University of Massachusetts Dartmouth’s School for Marine Science and Technology—is assessing the current conditions of 89 embayments in southeastern Massachusetts. The project will develop site-specific nitrogen thresholds that communities can use as a management tool to identify corrective and protective measures needed. The Massachusetts narrative nutrient criteria state that all surface waters “shall not exceed the site-specific limits necessary to control accelerated or cultural eutrophication.” Massachusetts’ Surface Water Regulation and Classifications (314 CMR 4.05[4]) designate embayment waters as one of the following:
- Class SA: These waters are designated as “excellent habitat for fish, other aquatic life and wildlife and for primary and secondary contact recreation;” for approved areas, the embayment “shall be suitable for shellfish harvesting without depuration” and shall have “excellent aesthetic value.”
- Class SB: These waters are designated as “habitat for fish, other aquatic life and wildlife and for primary and secondary contact recreation;” for approved areas, the embayment “shall be suitable for shellfish harvesting without depuration” and shall have “consistently good aesthetic value.”
- Class SC: These waters are designated as “habitat for fish, other aquatic life and wildlife and for secondary contact recreation;” and shall have “good aesthetic value.”
MEP identified habitat indicators of primary concern in gaging embayment health and nitrogen assimilative capacity:
- Plant presence and diversity (e.g., eelgrass, macroalgae)
- Animal species presence and diversity (e.g., finfish, shellfish, infauna)
- Nutrient concentrations (nitrogen species)
- Chlorophyll concentration
- DO levels in the embayment water column
MEP focused on two major habitat quality indicators: eelgrass vs. macroalgal distribution and benthic communities (presence and diversity).
Eelgrass is a sentinel species for indicating nitrogen enrichment (as supported in the literature) and a fundamentally important species in the ecology of shallow coastal systems that provides habitat structure and sediment stabilization. In nitrogen-rich systems, eelgrass distribution tends to be less widespread and, in general, increases in macroalgae can be seen. In areas that do not support eelgrass beds, benthic indicators can be used to assess the level of nutrient-related habitat health (i.e., the amount of organic matter and DO concentrations). Benthic communities associated with increased nitrogen shift in response to resultant increases in organic matter deposition to the sediment. Increased organic matter in the sediment increases sulfide concentrations. Sediment oxidation decreases with reducing (sulfidic) conditions as more organic matter accumulates (Howes et al. 2003).
Reference:
Howes, B.L., R. Samimy, and B. Dudley. 2003. DEP/SMAST Massachusetts Estuaries Project – Site-Specific Nitrogen Thresholds for Southeastern Massachusetts Embayments: Critical Indicators – Interim Report. Massachusetts Department of Environmental Protection and University of Massachusetts Dartmouth, School for Marine Science and Technology. Prepared for Massachusetts Department of Environmental Protection. Accessed October 2016. https://yosemite.epa.gov/OA/EAB_WEB_Docket.nsf/Verity%20View/DE93FF445FFADF1285257527005AD4A9/$File/Memorandum%20in%20Opposition%20…89.pdf EXIT.