[MARMAM] Question concerning bottlenose dolphin behavior and its relationship to diurnal cycles

I currently attempting to locate papers discussing bottlenose dolphin behavioral variation according to diurnal cycle. This information will help me in discussing how my sampling methodology impacts the discussion of the data that I have collected for my master's thesis on bottlenose dolphin energetics differ between estuarine and oceanic dolphins. I sampled from dawn to dusk, but I need to find information on how dolphin activity during the dusk to dawn time period differs from my observation times and so I was wondering if anyone might have any suggestions for papers to read on that topic. Robert Clelland reclella@coastal.edu