Fatal aspergillosis and evidence of unrelated hearing loss in a harbor porpoise (Phocoena phocoena) from the German Baltic Sea

Abstract

Detailed post-mortem investigations including the auditory pathway are needed to advance our understanding of how underwater noise and other stressors affect hearing in cetaceans. A 12-year-old female porpoise (Phocoena phocoena) stranded alive in June 2021 at the German Baltic Sea coast and died some hours later. The most significant pathological findings were lesions caused by a severe aspergillosis that spread from the lung and pulmonary lymph node to the cerebellum. Based on molecular sequencing, the fungus was identified as Aspergillus fumigatus. Severe pyogranulomatous and necrotizing inflammation was diagnosed in the lung and the associated lymph node. In the left part of the cerebellum, focal, severe purulent and necrotizing meningoencephalitis with intralesional fungal structures was confirmed histologically. In addition, multifocal, severe, chronic, granulomatous, and eosinophilic gastritis with intralesional parasite structures was found in the stomach. Parallel stripes (linear skin markings) were detected along the caudal part of both body sides, which have not been previously described for harbor porpoises. Inner ear analysis revealed evidence of focal loss of outer hair cells in several regions from 120 to 580 µm from the apex of the right cochlea using immunofluorescence. The evidence of low-frequency hearing impairment was compatible with noise-induced hearing loss. This is the first case of concurrent presumptive noise-induced hearing loss and unrelated aspergillosis in a free-ranging harbor porpoise.

Characterizing the marine mammal exposome by iceberg modeling, linking chemical analysis and in vitro bioassays

“…33 Besides the high contaminant burden of marine mammals demonstrated in this study, other reports from the literature show that these animals are under severe health stress and at high risk of dying from infectious diseases. 3,11,29,[86][87][88][89] In addition to adult males, which do not transfer part of their HOCs body burden to their offspring, especially young marine mammals (most of the individuals analyzed in this study fall into this category) are exposed to high concentrations of HOCs due to maternal transfer of HOCs during pregnancy and lactation, potentially causing physiological effects such as immunosuppression. 11 The measurement and monitoring of the chemical burden by quantication of legacy compounds as well as emerging compounds with similar properties helps to strengthen the link between exposure and adverse health outcomes for the organisms and the ecosystem.…”

Ultrastructure of the organ of Corti in harbor seals (Phoca vitulina)

“…For marine mammals, studies of hearing, sound production, and auditory anatomy contribute to understanding the potential harm of intense sounds (e.g., Southall et al, 2005). In particular, understanding the morphology of the inner ear of different species provides insight into auditory adaptations (Ketten, 2012;Martins et al, 2020) and enables the identification of tissue damage that may be associated with exposure sound sources (Morell et al, 2015;Morell et al, 2017;Morell et al, 2021;Morell et al, 2022a;Rohner et al, 2022). The organ of Corti, which contains the sensory cells, allows for the transduction of sound vibrations into neural signals.…”