A METHODOLOGICAL FRAMEWORK FOR ASSESSING SEA LEVEL RISE EFFECTS ON A MARINE TURTLE NESTING BEACH: A CASE STUDY AT MAYTO, JALISCO, MEXICO

Climate change is a major threat to already endangered sea turtle populations. The effects that aspects of climate change, such as sea level rise and increased storm intensity and frequency, could have on currently undeveloped and not yet studied sea turtle nesting rookeries are unclear. Mayto Beach in Jalisco, Mexico is one such rookery, and this study aimed to provide data that will help beach managers understand potential climate change effects on this beach. We measured slope profiles on part of Mayto Beach at various time steps from 2014-2015 to quantify changes in beach slope. Six transects were established about 50 m apart, and slope angles were taken every 5 m, starting from permanent landmarks at the vegetation line going perpendicular to the low tide line. The study area underwent significant changes in slope over the year (t=2.72, P=.04) and lost about 21% of its area. The result was a steeper, thinner beach. Daily and weekly sampling time steps gave different results from annual readings, likely because of monthly tidal flux. Expanding the study area to include more transects along the 12 km beach and profiling slopes every three months is recommended. Construction setback regulations and community support to enforce those rules are needed. This study provides a baseline beach profile and natural erosion and accretion rates, and will help sea turtle conservationists and beach managers proactively plan to protect nesting habitat from the impacts of sea level rise before coastal development occurs. Further, the methods used here are low cost, simple, and replicable anywhere in the world.