Trends in water quality and assessment of vegetation community structure in association with declining mangroves: A condition assessment of American Memorial Park
Raikow DF, Gross J, McCutcheon A, Farahi A. 2023. Trends in water quality and assessment of vegetation community structure in association with declining mangroves: A condition assessment of American Memorial Park. Natural Resource Report. NPS/PACN/NRR—2023/2610. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2301598
American Memorial Park (AMME) in Saipan contains a rare mangrove wetland that is known to support several endangered species. Through monitoring water quality and vegetation characteristics of the wetland for >10 years we documented a declining mangrove population, an increase in invasive plant species, and declining surface water salinity. Comprehensive surveys conducted in 2014 and 2019 quantified declines in the plant community observed by park staff. Surface water salinity declined from 2009 to 2018 and no other trend in surface water quality was observed. Over the time period of the present study, AMME experienced shifts in annual rainfall conditions that could be associated with ENSO cycles. Dry conditions beginning in late 2016 and continuing through mid-2018 resulted in some surface water sampling sites completely drying. Several stressors may have contributed to declines in mangroves adapted to saturated soils directly and allowed competing plants to proliferate, including disruption of hydrologic connectivity with marine waters resulting in reduced surface water salinity, reduced rainfall causing dry soil conditions, and physical storm damage to canopies. Recommendations include study of groundwater salinity, maintaining or modifying a culvert subject to filling with sediment or other excavation work to improve saline water flow to the wetland at high tides, the establishment of a new groundwater monitoring well, adding a surface water monitoring station near the culvert, conducting a spatial assessment of the mangrove habitat suitability within the mangrove wetland, and developing or assisting with mangrove interpretive and outreach programs.
- Type
- Published Report
- Authors
- Raikow, David; Gross, Jacob; McCutcheon, Amanda; Farahi, Anne
- Date of Issue
- 2023-12
- Publisher
- National Park Service
- DOI
- 10.36967/2301598
- Units
- AMME , PACN
- Keywords
- Fresh and Brackish Water Quality Monitoring Report, Groundwater, Mangrove, Saipan, Salinity, Surface water, Vegetation community, Water quality, Water Quality Monitoring Report, Wetland
- Subjects
- Ecological Framework: Biological Integrity | Focal Species or Communities | Wetland Communities