Citation:

Oczkowski, A., E. Santos, C. Wigand, Alana Hanson, E. Huertas, AND R. Martin. How a clogged canal impacts ecological health in a tropical urban wetland ecosystem. Workshop on the Restoration, Sustainability, and Health of the Martin Peña, San Juan, Puerto Rico, June 09, 2017.

Impact/Purpose:

This presentation describes the nitrogen dynamics associated with the closure of the Cano Martin Pena in San Juan, Puerto Rico and the impact of these dynamics on the water quality of the San Juan Bay Estuary. I will be providing a progress report on ongoing research to the EPA Region 2 Caribbean Office as well as to stakeholder groups interested in the ecological and human health issues associated with the San Juan Bay Estuary. This presentation will lay the essential groundwork on our application of stable isotopes to this system and provide an opportunity for stakeholder feedback.

Description:

The coastal city of San Juan, Puerto Rico is a tropical urban ecosystem interwoven among a series of interconnected bays, lagoons, canals, and mangrove wetlands. As the city has expanded, infilling and urban encroachment on what was previously mangrove wetland and open estuarine water has severely reduced flushing of the San Juan Bay Estuary. One area in particular, the Martin Peña channel that was 200 feet wide in the last century, has essentially been dammed. As a result, the adjacent low lying urban communities and mangrove wetlands experience frequent flooding by a potent mixture of stormwater and raw sewage. Local monitoring efforts have counted fecal coliform levels >40,000 CFU per 100 ml in the channel and >4,500 CFU per 100 ml in the adjacent lagoons. The lagoon levels are more than two- fold greater than EPA recommendations for Class 2 waters (non-primary contact). We are attempting to document how reduced flushing and poor water quality are impacting the ecology of the mangrove and lagoonal ecosystems. We are using a combination of stable isotope measurements of the ecosystem components and retrospective analyses to identify how the urban wetlands and estuary function. Our stable isotope analyses suggest that, despite heavy nitrogen enrichment from urban runoff and sewage, the microbial community in the wetland portion of the ecosystem is actively fixing nitrogen. While these observations are preliminary, the potential influence of fixation on the ecosystem nitrogen budget is surprising.

Record Details: