Effects of Localized NAO, ONI (ENSO) and AMO Events on Reproductive Patterns in Loggerhead (Caretta caretta) Sea Turtles in Broward County, FL, USA

• Main Author: Hammill, Allison L.
• Format: Other/Unknown Material
• Language: unknown
• Published: NSUWorks 2013
• Subjects: Caretta caretta; loggerhead sea turtles; North Atlantic Oscillation; Oceanic Niño Index; El Niño Southern Oscillation; Atlantic Multidecadal Oscillation; reproduction; nutrition; Marine Biology; Oceanography and Atmospheric Sciences and Meteorology; North Atlantic; North Atlantic oscillation
• Online Access: https://nsuworks.nova.edu/occ_stuetd/135; https://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1267&context=occ_stuetd

A variety of anthropomorphic and environmental stresses are threatening the existence of all seven species of sea turtles. There is growing evidence that alterations in surface waters and sediment temperatures are negatively impacting reproductive success of loggerhead sea turtles (Caretta caretta). Fluctuations in water temperature associated with localized climate oscillations heavily alter the food web dynamics of the ocean. Feeding conditions are expected to be a critical factor in determining body mass and productivity for breeding seasons. An increase in regional temperatures could lead to prolonged reduction in food sources, as well as reduced nesting and recruitment. Loggerhead sea turtle nesting data from 1995-2011 werre compared with the average yearly North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) which are important climatic events impacting the SST in the Atlantic Ocean. Because El Niño Southern Oscillation (ENSO) is a global event, it was proposed that turtles in the Atlantic may follow a similar trend. ENSO was quantified using Oceanic Nino Index (ONI). Analysis of loggerhead sea turtle nest frequencies from the years 1995-2011 in comparison to seasonal climate changes showed a significant inverse relationship between the detrended loggerhead nests and average yearly NAO when lagged two years, suggesting loggerheads may spend years prior breeding obtaining optimum body mass to increase successful reproduction. The detrended nesting data showed a tendency toward higher occurrence of nests during La Niña years while nest frequencies decreased during El Niño year; when the yearly detrended loggerhead nesting data was compared with the average yearly ONI; showing a significant inverse relationship without a lag. This may also suggest a relationship between changes of productivity of the ocean influenced by smaller scale climate changes and loggerhead nest frequencies.