When the small ones tease the largest: Microplastic and phthalate ester occurrence in cetaceans occasionally found in the German North Sea and Baltic Sea.

Living in potentially burdened waters and prey on loaded species, marine mammals are sentinels for microplastic (MP) pollution. Here, seven different species of cetaceans were investigated covering baleen (Mysticeti) and toothed (Odontoceti) whales stranded along the German coast between 2016 and 2021. Intestinal and faecal samples of 12 sperm whales, three minke whales, two dolphin species, one long-finned pilot whale, one fin whale and one neonate orca were analysed. The concentrations of 11 phthalates were assessed in blubber and muscle samples. MPs were detected with Nile Red staining, polymer identification was conducted using μFTIR spectroscopy. Four individuals showed no MP burden. An average of 4.6 MPs (Odontocetes) and 3.25 MPs (Mysticetes) were found. A share of 0 and 19 MPs was found per 10 g of faeces. Polyamide, polyolefin and polyester were detected. No significant differences between baleen or toothed whales were identified. In individuals which revealed macro debris inside their stomach also showed MPs in their faeces. Individuals with an empty stomach (N = 3) still showed MP presence. Nine compounds of PAEs were quantified in both muscle and blubber of seven species in different concentrations. DEHP was the most abundant compound. The results cannot be linked to the burden in the North - or Baltic Sea, since not all investigated specimens are regularly occurring here. Evidence is given that both baleen and toothed whales from the northern hemisphere are similarly burdened with MPs, and that not only ingested macro-debris can be assumed as a source for MP.