A Systematic Health Assessment of Indian Ocean Bottlenose (Tursiops aduncus) and Indo-Pacific Humpback (Sousa plumbea) Dolphins Incidentally Caught in Shark Nets off the KwaZulu-Natal Coast, South Africa

Abstract

Coastal dolphins are regarded as indicators of changes in coastal marine ecosystem health that could impact humans utilizing the marine environment for food or recreation. Necropsy and histology examinations were performed on 35 Indian Ocean bottlenose dolphins (Tursiops aduncus) and five Indo-Pacific humpback dolphins (Sousa plumbea) incidentally caught in shark nets off the KwaZulu-Natal coast, South Africa, between 2010 and 2012. Parasitic lesions included pneumonia (85%), abdominal and thoracic serositis (75%), gastroenteritis (70%), hepatitis (62%), and endometritis (42%). Parasitic species identified were Halocercus sp. (lung), Crassicauda sp. (skeletal muscle) and Xenobalanus globicipitis (skin). Additional findings included bronchiolar epithelial mineralisation (83%), splenic filamentous tags (45%), non-suppurative meningoencephalitis (39%), and myocardial fibrosis (26%). No immunohistochemically positive reaction was present in lesions suggestive of dolphin morbillivirus, Toxoplasma gondii and Brucella spp. The first confirmed cases of lobomycosis and sarcocystosis in South African dolphins were documented. Most lesions were mild, and all animals were considered to be in good nutritional condition, based on blubber thickness and muscle mass. Apparent temporal changes in parasitic disease prevalence may indicate a change in the host/parasite interface. This study provided valuable baseline information on conditions affecting coastal dolphin populations in South Africa and, to our knowledge, constitutes the first reported systematic health assessment in incidentally caught dolphins in the Southern Hemisphere. Further research on temporal disease trends as well as disease pathophysiology and anthropogenic factors affecting these populations is needed.

Epidemiology of lobomycosis-like disease in bottlenose dolphins Tursiops spp. from South America and southern Africa

“…In South Africa, although images of regular quality were available since 2006 and opportunistic surveys were carried out since 1999, LLD was detected only in 1 T. aduncus in November 2008. A case of lobomycosis was documented in 1 of 5 S. plumbea by-caught along the coast of KwaZulu-Natal (about 1000 km east of Plettenberg Bay) in 2010 to 2011 but not in 35 T. aduncus accidentally captured in the same region during the same period (Lane et al 2014).…”

“…However, it is possible that different aetiological agents cause skin diseases resembling lobomycosis in dolphins (Tajima et al 2015), and further research is necessary. In the Southern Hemisphere, only 3 histological studies have demonstrated the presence of a fungus resembling Lacazia loboi in skin lesions sampled in 2 Tursiops truncatus from Laguna (Simões-Lopes et al 1993) and the Tramandaí Estuary ) and a third in a Sousa plumbea from South Africa (Lane et al 2014). Molecular analysis of the pathogenic agents causing LLD in dolphins from South America and southern Africa will be necessary to firmly establish their taxonomic identity, specifically their relationship to known species of the genus Paracoccidioides and its sister taxon L. loboi.…”

“…The disease has been observed in common bottlenose dolphins Tursiops truncatus from the USA, Brazil and Europe, in Guiana dolphins Sotalia guianensis from Surinam and in an Indian Ocean humpback dolphin Sousa plumbea from South Africa (Table 1; Caldwell et al 1975, Symmers 1983, Cowan 1993, Simões-Lopes et al 1993, Reif et al 2006, Van Bressem et al 2007, Rotstein et al 2009, Lane et al 2014. Microscopically, lemon-shaped, budding yeast-like organisms resembling Lacazia loboi (Taborda et al 1999) were detected in skin lesions sampled in T. truncatus (Caldwell et al 1975, Simões-Lopes et al 1993, Paniz-Mondolfi et al 2012, Van Bressem et al 2007) and a S. guianensis from the Americas (Symmers 1983), and in a S. plumbea from South Africa (Lane et al 2014; Table 1). However, recent molecular characterization of the 43 kDa glycoprotein coding gene and of ribosomal DNA from lesions sampled in T. truncatus from the USA and Cuba, and in Indo-Pacific bottlenose dolphins T. aduncus from Japan, indicated that the yeast-like organism infecting these dolphins is more closely related (94−97%) to Paracoccidioides brasiliensis than to L. loboi (Rotstein et al 2009, Esperón et al 2012, Ueda et al 2013.…”

Another dolphin in peril? Photo‐identification, occurrence, and distribution of the endangered Indian Ocean humpback dolphin (Sousa plumbea) in Algoa Bay

“…The Indian Ocean humpback dolphin ( Sousa plumbea ) has been well researched in South African waters. Several studies have been conducted on its abundance (Atkins & Atkins, ; James, Bester, Penry, Gennari, & Elwen, ; Jobson, ; Karczmarski, Cockcroft, & McLachlan, ; Keith, Peddemors, Bester, & Ferguson, ), distribution (Atkins, Pillay, & Peddemors, ; Durham, ; Karczmarski, Cockcroft et al, ; Karczmarski, Winter, Cockcroft, & McLachlan, ; Melly, McGregor, Hofmeyr, & Plön, ), diet (Barros & Cockcroft, ), genetics (Mendez et al, ), life history (Plön, Cockcroft, & Froneman, ), and health assessment (Cockcroft, ; Lane et al, ; Plön, Albrecht, Cliff, & Froneman, ). This species has recently been recognized as separate from the Indo‐Pacific humpback dolphin ( Sousa chinensis ), based on molecular and morphological studies (Jefferson & Rosenbaum, ; Mendez et al, ).…”

日本における水族館飼育下の雄のカマイルカにみられた クジラ型パラコクシジオイデス症（paracoccidioidomycosis ceti）を疑う一例

“…Based on the new concept of PCM-C, the confirmed hosts are BD [1,7,9,10] and PWSD [2], although the Indian Ocean bottlenose dolphin (T. aduncus) [11,14], costero estuarine dolphin (Sotalia guianensis) [8], and Indian Ocean humpback dolphin (Sousa plumbea), are suspected hosts [14]. Suspected cases have also been recorded in an Australian snubfin dolphin (Orcaella heinsohni) [15] and in Irrawaddy dolphins (Orcaella brevirostris) based on photographic images [16].…”