Ecological interactions and unique resource partitioning between dolphins in the ultraoligotrophic eastern Mediterranean Sea

This study delves into the eco-dynamics of three dolphin species in the ultra-oligotrophic waters off the southern Israeli Mediterranean coast - two neritic: the common bottlenose dolphin (Tursiops truncatus) and the common dolphin (Delphinus delphis) and one pelagic: the striped dolphin (Stenella coeruleoalba). It utilizes compound-specific stable isotope analysis of individual amino acids to investigate carbon and nitrogen source variability and trophic positioning among the three species. Muscle samples from stranded individuals were analyzed for carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic ratios of amino acids, with Δδ¹⁵N (Glutamate-Phenylalanine) acting as an indicator of relative trophic position. The findings reveal minor differences in carbon source signatures and trophic position among species, but distinct nitrogen source signatures. The latter indicate discrete foraging habitats for bottlenose and striped dolphins and suggest that common dolphins transition between shallow benthic and deep pelagic feeding areas during the day and night, respectively, as part of their survival strategy.