TRASHING TURTLES: QUANTIFYING POLLUTION ON THREE SEA TURTLE NESTING BEACHES IN COSTA RICA Kari Gehrke Emily Kuzmick Lauren Piorkowski Katherine Comer Santos Chris Pincetich Catalina Gonzalez Manuel Sanchez Lotti Adams Emma Harrison Randall Arauz Beth Whitman The Science Exchange Sea Turtle Internship Program, San Diego, CA, USA Sea Turtle Restoration Project, Forest Knolls, CA, USA Osa Conservation, Pejeperro Beach, Costa Rica Sea Turtle Conservancy, Tortuguero, Costa Rica PRETOMA, San Miguel, Costa Rica Florida International University, North Miami, FL, USA
Background 6.4 million metric tons of trash per year enters the oceans (U.N. 2009) 100 million marine mammals die from being entangled in debris (Carr 1987; Laist 1997). A beach with an excess amount of debris will create obstacles for the turtle (National Research Council 1990). Deter nesting attempts Seaward journey of the hatchlings Ingestion, entanglement in open waters Incubation blog.iesve.com pifsc.noaa.gov
Purpose of the Study The study collected data on spatial and temporal occurrences of trash and turtle activity on nesting beaches
Costa Rica July and Aug 2012 Tortuguero San Miguel, Guanacaste Pejeperro, Osa Peninsula
Research Questions 1. What was the density of pollution observed during the study period? 2. What types of pollution were found? 3. Was pollution correlated with turtle activity? 4. How can managers use this information to improve turtle nesting habitat?
Methods NOAA Marine Debris Shoreline Survey Field Guide (Opfer et al. 2012) Modifications in this study: Instead of land use zones, turtle use zones Recorded turtle activity Micro debris surveys- potential incubation problems Weekly density surveys- more frequent
Materials Digital camera GPS unit (if available) Measuring tape Work gloves or latex gloves Sturdy 12 in. ruler Magnifying glass Small folding shovel 5 mm stainless steel sieve Clipboard and Trash bags
Pre-data Collection Mapped out 3 (100-m) zones Anticipated High, Low and Zero Density based on nests from prior seasons in order to get variability in nesting habitat
Measuring the Zones
Weekly Turtle Density Surveys Walk 4 random transects per zone Record total turtle activity that entails: False crawls False nests Successful nests Predated nests
Weekly Trash Density Surveys Micro, Macro and Large Pollution Micro (5 mm 2.5cm) Macro (2.5 cm-0.3 m) Large > 0.3 meters
Weekly Trash Density Surveys Cont. Recorded size category, type (Plastic, metal, glass, rubber, processed lumber, cloth/fabric, unclassified) and quantity of each Trash left in place to record natural rate of accumulation and dispersal
Accumulation Survey ONLY during the last week of the study ALL transects included (n=180) Count, measure, and pick up all trash Results pending
What was the density of pollution during the study period? The mean macro size trash density from all sites was 0.2436 items/m2 (range 0-1.71) Large density= 0.001 items/m2 Micro item density=0.40 items/liter
Global context Anthropogenic debris on beaches in the SE Pacific (Chile): Results from a national survey supported by volunteers (Bravo et al.2009)
What types of pollution were found? N=252 91% macro 97% plastics Other studies also report mostly plastics (Ramos et al 2012; de Sul et al. 2007; Moore et al. 2001) 4000 Types of Trash Found on the Three Beaches (macro) 3500 3000 Number of trash (pieces) 2500 2000 1500 1000 500 0 Plastic fragments hard Bottle caps Plastic fragments foam Cups straws Beverage Bottles Food wrappers Categories
Was pollution correlated with all turtle activity? 0.12 Trash vs. Turtle Activity Turtle (activity/m^2) 0.1 0.08 0.06 0.04 0.02 0 0 0.5 1 1.5 2 Trash (items/m^2) Moderately strong R=.449 p=.001
How can managers use this information to improve turtle nesting habitat? When people see and touch plastic pollution they are most open to behavioral changes (Wabnitz & Nichols 2010) Organize group beach cleanups More trashcans on the beaches with regular disposal (Ramos et al. 2012)
Limitations and Improvements Groups were cleaning our study areas! PRETOMA erases turtle tracks, thus the observations were from the night. Rain correlated with trash? Tides? Are weekly random transects or accumulation surveys a better use of resources?
Acknowledgments