Citation:

Cicchetti, G., E. Shumchenia, AND K. Ruddock. Changes to habitats over time in Narragansett Bay and setting management targets using BCG approaches. Coastal & Estuarine Research Federation 24th Biennial Conference, Providence, RI, November 05 - 09, 2017.

Impact/Purpose:

This work supports EPA goals (SSWR 6.1A) to document habitat changes over time in Narragansett Bay as related to previous management decisions, and uses this information to help National Estuary Programs and other management groups develop environmental targets that appeal to public sentiment. The presentation describes changes in the distributions of seagrass, benthic, macroalgal, saltmarsh, and shellfish habitat in Narragansett Bay (RI) since the 1700s, and compares this to changes in stressors and management decisions over the same time period. This comparison, together with the historic habitat loss information, is used as the basis for a Biological Condition Gradient (BCG) approach to support non-regulatory decision-making. The BCG is a U.S. EPA method for bioassessment, and provides a framework that National Estuary Programs and other groups have used to engage the public, prioritize habitat types, set numeric targets for habitat management, then track and report progress towards these targets. This work illustrates and clarifies application of this tool using the dramatic recent reductions of nutrient inputs to Narragansett Bay as an example. There are no known policy ramifications or political implications of the presentation.

Description:

We compare changes in the distributions of seagrass, benthic, macroalgal, saltmarsh, and shellfish habitat in Narragansett Bay (U.S.A.) since the 1700s to changes in stressors and management decisions over the same time period, and describe a method that management programs can use to set non-regulatory targets for habitat protection and restoration. The city of Providence at the northern head of Narragansett Bay is the population center of Rhode Island, and the largest source of nutrient pollution to the Bay is the output of three large Wastewater Treatment Facilities that discharge into the Providence River. These facilities have dramatically reduced their nutrient loads in recent years. We report on changes to the mosaic of habitats in Narragansett Bay over historic time and over different spatial areas from north to south, east to west, and mainstem to side embayments. We relate these changes to gradients in a number of stressors and physical factors, with attention to the spatial effects of recent reductions in nutrient and stormwater inputs. Our analyses show recent improvements in nutrient-sensitive seagrass and benthic habitats in the northern Bay, coincident with reductions in nutrient input. Different habitats respond to different stressors, and the historical data remind us that, despite recent improvements, we have lost vast acres of many valued habitats over the last centuries. Further, new stressors including sea level rise are now presenting new threats to estuarine habitats. In particular, current and future saltmarsh loss is a significant issue. Finally, we describe how National Estuary Programs and other groups have used long-term habitat mosaic data with the EPA Biological Condition Gradient (BCG) approach to engage the public, prioritize habitat types, set numeric targets for habitat management, then track and report progress towards these targets.

Record Details: