In the fall of 2013, Dr. H. Bruce Rinker led a team of field researchers into México’s southwestern coastal region to investigate the impacts of three common environmental pollutants on biodiversity and human populations in the aftermath of Tropical Storm Manuel.
Highlights of the project included:
- A first-time-ever pilot study on marine plastics pollution conducted in Guerrero, México.
- Tropical Storm Manuel in September 2013 likely confounded the reported marine debris in the region.
- The study also evaluated mercury and petroleum contamination as common urban pollutants.
- An integrated and long-term drainage-basin approach is necessary to counter the effects of such pollutants.
- As a consequence of this pilot study, and general field observations, the researchers provided a number of policy recommendations to the State of Guerrero about pollutants, fish and wildlife, and conservation in the region.
In the fall of 2013, Biodiversity Research Institute (Portland, ME, USA) partnered with Sustenta Soluciones S.A. de C.V. (México City, México) to conduct a three-week pilot environmental study along a 200-km stretch of coastline in the State of Guerrero. The focus was on three common pollutants often used as reliable predictors of ecological toxicity: plastics, mercury, and petroleum (PAHs). The pilot was a component of a much larger conservation campaign called Limpia Guerrero 2013 funded by the State of Guerrero.
Marine Plastics Pollution. Beach debris abundance was estimated from one-meter-wide belt surveys along 100-m stretches of beach on seven beaches between Acapulco to Zihuatenejo/Ixtapa, sorted and categorized by 10 types, and weighed. Nearly 9,700 pieces of litter were collected from a total sample area of 1.5 hectares. Litter density varied from 0.42 to 44.26 pieces per m2. As a category of debris, plastics pollution varied from 0.05 to 4.44 pieces per m2 of beach. The average proportion of plastics among total marine debris collected from the seven beaches of Guerrero was 24.81% (ranging from 1.10% to 69.72%), a low value when compared to the proportion globally among marine debris (60% to 80%) but high when compared to other recent surveys around the Pacific Ocean. Not surprisingly, beaches located in more public or lower income areas showed the highest density of marine debris and the highest density of plastics pollution. Tropical Storm Manuel in September likely confounded, even aggravated, the standing surface litter detected along the coastline of Guerrero.
Mercury (Hg) Pollution. Of 25 fish sampled during the study, four exceeded the U.S. EPA fish advisory concentration of 0.3 ppm. Based on the results of our pilot survey, we urge residents to abstain from eating Swordfish and sharks and limit their consumption of Horse-eye Jack (Caranx latus) and Manta Ray (Manta birostris). Some wading birds, songbirds, and other invertivorous birds sampled had blood mercury concentrations high enough to indicate concern about overall ecological health; however, the sample size was too small to make meaningful conclusions. From our limited number (13 individuals) of piscivorous birds sampled, two (Black Skimmer, Rynchops niger, and Royal Tern, Thalasseus maximus) exceeded the effect level established for fish-eating birds and wildlife. Over 70% of women of reproductive age sampled during our study exceeded the lowest observed adverse effect level of 0.3 ppm.
Petroleum (PAHs) Pollution. The use of FTA cards to detect PAHs in the blood of wildlife is a new approach for analyzing petroleum. We found detectable levels of PAHs ranging from 5.1 to 20.2 ng/mL in 11 samples out of a possible 26. Acenaphthene, one type of PAH cited as a hazardous substance by the U.S. EPA, was found in nine of those 11 samples. Preliminary results suggest invertivorous birds may be more susceptible to the biological intake of PAHs than fish-eating species. Further investigation is merited, especially given the potential of the FTA cards for long-term storage under field conditions for environmental emergencies.
Thus, based on the results of our three-week pilot study in Guerrero, we found unequivocal environmental signals for plastics, mercury, and petroleum pollution along the coastline and urge the state authorities to support long-term ecological research on these common contaminants to determine their causes and their potential solutions.
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