Evidence of Hearing Loss and Unrelated Toxoplasmosis in a Free-Ranging Harbour Porpoise (Phocoena phocoena)

IJsseldijk, Lonneke L.; Berends, Alinda J.; Gröne, Andrea; Siebert, Ursula; Raverty, Stephen; Shadwick, Robert E.; Kik, Marja

doi:10.3390/ani11113058

Cited by 4 publications

(7 citation statements)

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“…While the pattern of sensory cell loss in two cases suggested individual apical variability instead of lesions (Morell et al, 2022), the other two showed evidence of sensory cell loss that is compatible with noise exposure. More details on these cases have been published elsewhere (Morell et al, 2015;Morell et al, 2021).…”

Section: Pathological Findings Compatible With Noise-induced Hearing ...mentioning

confidence: 99%

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Pathological findings in stranded harbor porpoises (Phocoena phocoena) with special focus on anthropogenic causes

et al. 2022

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Humans impact natural systems at an unprecedented rate. The North Sea is one of the regions in the world with the highest levels of anthropogenic activity. Here, the harbor porpoise (Phocoena phocoena) is an abundant species and is often regarded as an ecosystem sentinel. A post-mortem surveillance program was established in the Netherlands aimed at increasing knowledge of the effects of human activities on harbor porpoises. In this study, we describe the pathological findings related to anthropogenic and natural causes of death categories in 612 harbor porpoises that stranded between 2008 and 2019, and assess their relations to age, sex, season, and location. The largest anthropogenic category was bycatch (17%), with mainly juveniles affected and peak periods in March and September–October. Other, infrequently diagnosed anthropogenic causes of death were trauma (4%), largely most likely due to ship collisions, and marine debris ingestion and entanglement (0.3%). The risk of dying from anthropogenic causes was highest for juveniles. Lesions compatible with noise-induced hearing loss were investigated in carcasses which were fresh enough to do so (n = 50), with lesions apparent in two porpoises. Non-direct human-induced threats included infectious diseases, which were by far the largest cause of death category (32%), and affected mainly adults. Also, gray seal (Halichoerus grypus) attacks were a frequently assigned cause of death category (24%). There were more acute predation cases in the earlier study years, while porpoises with lesions that suggested escape from gray seal attacks were diagnosed more recently, which could suggest that porpoises adapted to this threat. Our study contributes to understanding porpoise health in response to persisting, new, emerging, and cumulative threats. Building up such knowledge is crucial for conservation management of this protected species.

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Section: Pathological Findings Compatible With Noise-induced Hearing ...mentioning

confidence: 99%

“…Several infectious agents have, however, been targeted and published separately, including on the prevalence of Brucella spp. (Maio et al, 2014), mycoses, specifically Aspergillus fumigatus (Kapetanou et al, 2020), herpesvirus (van Beurden et al, 2015), and Toxoplasma gondii (van de Velde et al, 2016;Morell et al, 2021).…”

Section: Infectious Diseasesmentioning

confidence: 99%

Pathological findings in stranded harbor porpoises (Phocoena phocoena) with special focus on anthropogenic causes

et al. 2022

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“…In part, this is due to the difficulty to provide a large number of individuals whose ears can be fixed rapidly after their death. To date, 3 out of 21 (14.3%) harbor porpoise individuals that had the beginning of the apex in a good preservation status for diagnosis, showed evidences of lowfrequency hearing loss (Morell et al, 2015;Morell et al, 2021;Morell et al, 2022a;Ijsseldijk et al, 2022). However, this prevalence may be underestimated since not all 21 individuals had a complete information of the apex.…”

Section: Low-frequency Hearing Lossmentioning

confidence: 99%

“…Because hearing is fundamental to cetaceans, changes to their auditory capabilities may impact their ability to carry out vital activities, such as navigation, feeding, and communication. Previous studies have shown that the cochlea of the harbor porpoise, as in terrestrial mammals, contains two types of auditory sensory cells: the inner hair cells (IHCs) and the outer hair cells (OHCs) (Morell et al, 2015;Morell et al, 2020;Morell et al, 2021;Morell et al, 2022a). Within the organ of Corti (or hearing organ), the sensory cells are arranged in one single row of IHCs and three rows of OHCs.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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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.

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“…TTS assessments are therefore a perfect tool for estimating effects on hearing. Affected hearing can potentially affect the survival of an individual (Mann et al, 2010;Morell et al, 2017;Morell et al, 2021a;Morell et al, 2021b), decreasing fitness and possibly leading to long-term population consequences (King et al, 2015). Temporarily affected hearing thresholds have been found in harbor porpoises after the exposure to single noise exposures with high received levels (Lucke et al, 2009), but also after an exposure to multiple events with lower received levels (Kastelein et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

A Result of Accidental Noise Pollution: Acoustic Flowmeters Emit 28 kHz Pulses That May Affect Harbor Porpoise Hearing

et al. 2022

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Large rivers like the Elbe or the Weser are periodically entered by harbor porpoises of the North Sea. They may even move 97 km upstream to the port of Hamburg, where their presence is highest in spring. This migration is believed to be related to important anadromous prey species travelling upstream for spawning. An acoustic flowmeter in the port of Hamburg emits signals in the hearing range of harbor porpoises. The pulses have a duration of 0.2 ms, a peak frequency of 28 kHz, a source level of 210 dB re 1 µPa and an inter-pulse interval of 4.2 s. The signals are continuously emitted from both sides of the river at a location where the river is 400 m wide. We evaluated the potential of these signals to induce temporary threshold shift (TTS) in harbor porpoise hearing. Hearing tests with a harbor porpoise in human care were conducted to determine TTS onset. We modelled the acoustic field based on underwater noise measurements. The acoustic flowmeters emit pulses in a highly directional beam with a source level high enough for inducing TTS in harbor porpoises by a single exposure up to a distance of approximately 72 m. The received cumulative sound exposure levels for harbor porpoises travelling along the flowmeters are mainly dependent on the timing and distance to the sound source. Accordingly, a close approach to the flowmeter at the time of transmission should be prevented. This could be the case, if vessels force harbor porpoises to displace closer to the flowmeters. We therefore suggest to decrease acoustic flowmeter source levels. This case study emphasizes the need for a mandatory authorization process prior to the use of underwater sound for any purpose with potential effects on aquatic life. Such an authorization process should carefully consider potential effects for target and non-target species.

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Evidence of Hearing Loss and Unrelated Toxoplasmosis in a Free-Ranging Harbour Porpoise (Phocoena phocoena)

Cited by 4 publications

References 81 publications

Pathological findings in stranded harbor porpoises (Phocoena phocoena) with special focus on anthropogenic causes

Pathological findings in stranded harbor porpoises (Phocoena phocoena) with special focus on anthropogenic causes

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

A Result of Accidental Noise Pollution: Acoustic Flowmeters Emit 28 kHz Pulses That May Affect Harbor Porpoise Hearing

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