Molecular characterization and prevalence of Halarachne halichoeri in threatened southern sea otters (Enhydra lutris nereis).

Risa Pesapane,Erin Dodd,Janet Foley,Nadia Javeed,Melissa Miller

doi:10.1016/j.ijppaw.2018.09.009

Abstract

Parasitism, particularly in concert with other sublethal stressors, may play an important, yet underappreciated role in morbidity and mortality of threatened species. During necropsy of southern sea otters (Enhydra lutra nereis) from California submitted to the Marine Wildlife Veterinary Care and Research Center's Sea Otter Necropsy Program between 1999 and 2017, pathologists occasionally observed nasopulmonary mites infesting the respiratory tracts. Infestation was sometimes accompanied by lesions reflective of mite-associated host tissue damage and respiratory illness. Our objectives were to estimate prevalence of nasopulmonary mites, determine the taxonomic identity of the observed mites, and create a DNA reference for these organisms in southern sea otters as an aid in population management. Using unique morphological characteristics discerned via light and scanning electron microscopy (SEM), we identified the mites as Halarachne halichoeri, a species typically associated with harbor seals (Phoca vitiluna). The 18S, 16S, 28S and ITS1-2 genetic regions were sequenced and submitted to GenBank. We observed H. halichoeri mites in 25.6% (95% CI 19.9–33.4%). of southern sea otters from a subset of necropsies performed between 2012 and 2017. This is the first documentation of H. halichoeri in southern sea otters and is suggestive of parasite exchange between sea otters and harbor seals.

Highlights

The southern sea otter (Enhydra lutris nereis) is a federally protected species (USFWS, 1977) that is found only in California, USA
Mites known to parasitize the respiratory tracts of marine mammals encompass two genera of the family Halarachnidae (Acari: Mesostigmata) (Mullen and O'Connor, 2002): Orthohalarachne mites are commonly associated with fur seals (Otariidae) and walrus (Odobenidae), whereas Halarachne mites are typically found in earless seals (Phocidae) but have been reported in non-pinnipeds, including northern sea otters (Enhydra lutris kenyoni) (Domrow, 1962; Kenyon et al, 1965)
Necropsy records at the Marine Wildlife Veterinary Care and Research Center (MWVCRC) document southern sea otters infested with nasopulmonary mites at least as far back as 1999, the identity, prevalence, pathology, and ecology of these mites remained unstudied over the past two decades

Summary

Introduction

The southern sea otter (Enhydra lutris nereis) is a federally protected species (USFWS, 1977) that is found only in California, USA. Mites known to parasitize the respiratory tracts of marine mammals encompass two genera of the family Halarachnidae (Acari: Mesostigmata) (Mullen and O'Connor, 2002): Orthohalarachne mites are commonly associated with fur seals (Otariidae) and walrus (Odobenidae), whereas Halarachne mites are typically found in earless seals (Phocidae) but have been reported in non-pinnipeds, including northern sea otters (Enhydra lutris kenyoni) (Domrow, 1962; Kenyon et al, 1965) Mites of both genera can cause respiratory illness, including sinusitis, sneezing, coughing, facial pruritus, head shaking, pneumonia, edema, and lung congestion (Dunlap et al, 1976; Baker, 1987; Alonso-Farré et al, 2012). This same manuscript provides insight into associations among common respiratory findings and nasopulmonary acariasis in necropsied southern sea otters

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