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Six decades of change in pollution and benthic invertebrate biodiversity in a southern New England estuary
Citation:
Hale, S., H. Buffum, AND M. Hughes. Six decades of change in pollution and benthic invertebrate biodiversity in a southern New England estuary. MARINE POLLUTION BULLETIN. Elsevier Science Ltd, New York, NY, 133:77-87, (2018).
Impact/Purpose:
Benthic invertebrate biodiversity Narragansett Bay supports many ecosystem functions and services important to people using the bay and living on the surrounding shores. Changes in biodiversity over time can result in changes to ecosystem functions and services. To help understand biodiversity change and its drivers, we extracted data from three US EPA national monitoring programs to calculate changes in community composition and taxonomic distinctness (a measure of biodiversity) over the past six decades in the bay. We found that community composition of the entire bay changed, 1990–2015, but not at a reference station (North Jamestown, 1957–2010). In contrast, the community at a more impacted site, Spar Island, changed drastically, along with a severe loss of biodiversity, 1975–2015. This loss has serious implications for the ecosystem functions and services provided by benthic communities. We correlated these changes with several pollution variables. We compared the benthic community before and after recent reductions of around 50% in total nitrogen from wastewater treatment facilities at the head of the bay. Biodiversity is an important ecological indicator of what is happening in our environment and is being used by the Office of Water as a key indicator in the National Conditional Coastal Assessment. In managing a system as complex as Narragansett Bay, it is important to have an inventory of what species are present, to know how that inventory has changed over time, and to understand what factors forced those changes. Among other things, this information is needed to assess the impacts of permitting proposed activities and whether particular EPA and state programs are effective in what they are trying to achieve for water quality and ecosystem health in our bays and coastal areas.
Description:
Pollution has led to a decline of benthic invertebrate biodiversity of Narragansett Bay, raising questions about effects on ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. Changes in community composition and taxonomic distinctness (biodiversity) were calculated from the 1950s—when quantitative benthic invertebrate data first became available—to 2015. Change in community composition of the bay was correlated with changes in dissolved inorganic nitrogen, dissolved oxygen, and sediment contaminants. A mid-bay reference site showed moderate changes in community composition but no change in biodiversity. In contrast, a more impacted site in the upper bay showed substantial differences in community composition over time and a decline in taxonomic distinctness. Bay-wide, as inputs of some stressors such as nutrients and sediment contaminants have declined, there are signs of recovery of benthic biodiversity but other stressors such as temperature and watershed development are increasing.
