TROPICS Field Study (Panama), 32-Year Site Visit: Observations and Conclusions for Near Shore Dispersant Use NEBA and Tradeoffs

The Tropical Oil Pollution Investigations in Coastal Systems (TROPICS) experiment initiated in 1984 on the Caribbean coast of Panama has become one of the most comprehensive field experiments examining effects of oil exposure to a combination of tropical marine reef, seagrass, and mangrove communities. The experimental dosage was chosen to simulate a severe but realistic spill scenario so that results could be useful in decisions about the extent to which dispersants reduced or exacerbated the effects of an oil spill on tropical environments of mangroves, seagrasses, and corals. Research has been conducted in the area prior to and 30+ years following exposure to evaluate long term effects. In July 2016, an international research team revisited the TROPICS field sites. In previous data collection visits, visual observations and core samples of the mangrove substrate at the non-treated (Oil only) site revealed the presence of oil. This “trapped” oil also apparently resulted in lower recovery rates for mangroves in that site. Of particular interest in the 2016 revisit was to determine the presence/non-presence of oil in core samples via new petroleum biomarker triple quadrupole mass spectrometry technology. Additionally, data collection and observations of the extent, diversity, and health of the shallow coral reefs, seagrass, and mangroves were conducted at the three sites. The focus was on the initial disruption and recovery of the study ecosystem over 32 years from the original dosing with crude oil or dispersed crude oil. Analysis qualitatively compared the 2016 results to 1984 pre-spill and post-spill conditions of each site. This paper discusses the results of the 2016 TROPICS study site revisit and conclusions for oil spill preparedness and response, particularly as it applies to the trade-offs for the use of dispersants in near shore tropical marine ecosystems.