Multidisciplinary studies on a sick-leader syndrome-associated mass stranding of sperm whales (Physeter macrocephalus) along the Adriatic coast of Italy

Sandro Mazzariol,Yara Beraldo De Quiros,Silva Rubini,Sergio Guccione,Michela Podestà,Letizia Marsili,Pasquale Troiano,Maria Morell,Cristiano Cocumelli,Vincenzo Olivieri,Simonetta Mattiucci,Bruno Cozzi,Di Francesco G ,Cristina Casalone,Fulvio Garibaldi,Annalisa Zaccaroni,Paolo Cipriani,Federica Giorda,Cinzia Centelleghe,A Fernandez ,Pietro Badagliacca,Michele Povinelli,Daniele De Nurra,Matteo Beverelli,Federica Marcer,María Cristina Fossi ,Giuliana Terracciano,Paola Modesto,Francesca Profeta,Nicola Ferri,Daniela Berto,Alessandra Pautasso,Giovanni Di Guardo

doi:10.1038/s41598-018-29966-7

Abstract

Mass strandings of sperm whales (Physeter macrocephalus) are rare in the Mediterranean Sea. Nevertheless, in 2014 a pod of 7 specimens stranded alive along the Italian coast of the Central Adriatic Sea: 3 individuals died on the beach after a few hours due to internal damages induced by prolonged recumbency; the remaining 4 whales were refloated after great efforts. All the dead animals were genetically related females; one was pregnant. All the animals were infected by dolphin morbillivirus (DMV) and the pregnant whale was also affected by a severe nephropathy due to a large kidney stone. Other analyses ruled out other possible relevant factors related to weather conditions or human activities. The results of multidisciplinary post-mortem analyses revealed that the 7 sperm whales entered the Adriatic Sea encountering adverse weather conditions and then kept heading northward following the pregnant but sick leader of the pod, thereby reaching the stranding site. DMV infection most likely played a crucial role in impairing the health condition and orientation abilities of the whales. They did not steer back towards deeper waters, but eventually stranded along the Central Adriatic Sea coastline, a real trap for sperm whales.

Highlights

Age was estimated on teeth analyses on examined animals or estimated on total length. *Data reported for these animals were estimated during refloation. n.e. means not evaluated
Cetacean mass strandings have attracted a growing attention from the media: these dramatic events induced an increase of the public concern towards the role of human activities and their effects on marine mammal conservation, with special emphasis on those related to anthropogenic sound sources
The sperm whale mass stranding described in the present report is only the 7th that was recorded along the Adriatic coastline since 155514

Summary

Introduction

Age was estimated on teeth analyses on examined animals or estimated on total length. *Data reported for these animals were estimated during refloation. n.e. means not evaluated. Cetacean mass strandings have attracted a growing attention from the media: these dramatic events induced an increase of the public concern towards the role of human activities and their effects on marine mammal conservation, with special emphasis on those related to anthropogenic sound sources. Sonar is not the only known, anthropogenic sound-related factor in the oceans associated to these dramatic events: other military and industrial activities like seismic surveys (Madagascar, 2008) have been linked to the phenomenon[4]. A study conducted by Madsen and colleagues[5] has suggested that acoustic disturbance due to the presence of wind turbines in the underwater environment could affect the behavior of marine mammals, to naval sonar. The present work reports the post-mortem findings obtained from the sperm whales involved in this last stranding episode, thereby proposing a reasonable hypothesis based on our multidisciplinary studies, literature and previous experience[12,15]

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Conclusion