Linking Jellyfish and Leatherback Sea Turtle Distributions in Atlantic Canada

Abstract

Every year, endangered leatherback sea turtles (Dermochelys coriacea) migrate to Atlantic Canadian waters to feed on gelatinous zooplankton (‘jellyfish’). This thesis examined spatio-temporal patterns, and environmental drivers of jellyfish occurrence, and how this dynamic prey field shapes leatherback distribution in Atlantic Canada. Citizen science and scientific trawl survey data were used to describe jellyfish phenology. Cyanea capillata was the most common species, with peak occurrence in July, and in the Gulf of St. Lawrence. Sea surface temperature and observer effort were significant predictors of C. capillata observations by citizen observers. When jellyfish and leatherback occurrence was compared regionally, the turtles lagged jellyfish presence by two weeks on the Scotian Shelf, while the Gulf of St. Lawrence showed a less clear pattern in timing. These findings suggest observations by the general public can help track jellyfish distribution, and provide useful information for defining dynamic habitat for endangered leatherbacks in Atlantic Canada.