Parasitol Res DOI 10.1007/s00436-014-3781-4

Gastrointestinal parasites of free-living Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Northern Red Sea, Egypt S. Kleinertz & C. Hermosilla & A. Ziltener & S. Kreicker & J. Hirzmann & F. Abdel-Ghaffar & A. Taubert

Received: 27 November 2013 / Accepted: 10 January 2014 # Springer-Verlag Berlin Heidelberg 2014

Abstract The present study represents the first report on the gastrointestinal parasite fauna infecting the free-living and alive Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting waters of the Red Sea at Hurghada, Egypt. A total of 94 individual faecal samples of the examined bottlenose dolphins were collected during several diving expeditions within their natural habitats. Using classical parasitological techniques, such as sodium acetate acetic acid formalin method, carbol fuchsin-stained faecal smears, coproantigen ELISA, PCR and macroscopical analyses, the study revealed infections with 21 different parasite species belonging to protozoans and metazoans with some of them bearing zoonotic and/or pathogenic potential. Four identified parasite species are potential zoonotic species (Giardia spp., Cryptosporidium spp., Diphyllobothrium spp., Ascaridida indet.); three of them are known to have high pathogenic potential for the examined dolphin species (Nasitrema attenuata, Zalophotrema spp. and Pholeter gastrophilus) and some appear to be directly associated with stranding events. In detail, the study indicates stages of ten protozoan species (Giardia spp., Sarcocystis spp., Isospora (like) spp., Cystoisospora (like) spp., Ciliata indet. I and II, Holotricha

indet., Dinoflagellata indet., Hexamita (like) spp., Cryptosporidium spp.), seven trematode species (N. attenuata, Nasitrema spp. I and II, Zalophotrema curilensis, Zalophotrema spp., Pholeter gastrophilus, Trematoda indet.), one cestode species (Diphyllobothrium spp.), two nematode species (Ascaridida indet, Capillaria spp.) and one crustacean parasite (Cymothoidae indet.). Additionally, we molecularly identified adult worms of Anisakis typica in individual dolphin vomitus samples by molecular analyses. A. typica is a common parasite of various dolphin species of warmer temperate and tropical waters and has not been attributed as food-borne parasitic zoonoses so far. Overall, these parasitological findings include ten new host records for T. aduncus (i.e. in case of Giardia spp., Sarcocystis spp., Cryptosporidium spp., Nasitrema spp., Zalophotrema spp., Pholeter gastrophilus, A. typica, Capillaria spp., Diphyllobothrium spp. and Cymothoidae indet.). The present results may be used as a baseline for future monitoring studies targeting the impact of climate or other environmental changes on dolphin’s health conditions and therefore contribute to the protection of these fascinating marine mammals.

S. Kleinertz (*) : C. Hermosilla : J. Hirzmann : A. Taubert Institute of Parasitology, Justus Liebig University Giessen, Rudolf-Buchheim-Str. 2, 35392 Giessen, Germany e-mail: [email protected]

Introduction

A. Ziltener : S. Kreicker Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland A. Ziltener : S. Kreicker Dolphin Watch Alliance (DWA), Gossau, Switzerland F. Abdel-Ghaffar Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt

To date, very little is known on parasitic infections of freeliving marine mammal populations (Raga et al. 1997). In general, cetaceans have been reported as hosts of a variety of parasites belonging to the groups of protozoa, nematoda, cestoda, trematoda, acanthocephala and crustacea (Aznar et al. 1994; Cerioni and Mariniello 1996; MignucciGiannoni et al. 1998; Dailey 2001; Fertl 2002; Fernández et al. 2004; Colón-Llavina et al. 2009; Quiñones et al. 2013). However, the gastrointestinal parasite fauna of freeliving and alive Indo-Pacific bottlenose dolphins (Tursiops aduncus) from the Red Sea has not been investigated so far.

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The Red Sea is a seawater inlet of the Indian Ocean and the world’s northernmost tropical sea. It is a rich and diverse ecosystem characterized by a high degree of endemism (6 % corals, 17 % fishes) and contains extensive coral reefs, as well as seagrass beds, mangroves and salt marshes (Goren and Dor 1994; De Vantier et al. 2000). Still very little is known about cetaceans residing in this marine area. Eight cetacean species are considered regular: Indo-Pacific bottlenose dolphin (T. aduncus), common bottlenose dolphin (T. truncatus), spinner dolphin (Stenella longirostris), pantropical spotted dolphin (S. attenuata), humpback dolphin (Sousa chinensis), longbeaked common dolphin (Delphinus capensis), Risso’s dolphin (Grampus griseus) and Bryde’s whale (Balaenoptera edeni). Other eight species are considered rare (Notarbartolodi-Sciara et al. 2007). The Indo-Pacific bottlenose dolphin is the smallest and the most common of eight cetacean species in the Northern Egyptian Red Sea and occurs in coastal and reef habitats. Its coastal distribution makes this species particularly vulnerable to anthropogenic threats, such as coastal development, overfishing, bycatch and water and noise pollution. Additionally, a ‘swim-with-dolphins’ tourism, which is entirely unregulated by Egyptian authorities, is increasingly offered around Hurghada. This poses a high degree of stress to the animals living in complex fission–fusion societies and might have a strong impact on their health condition on both the individual and population level (Bejder et al. 2006; Christiansen et al. 2010). Bottlenose dolphins are apex predators and feed on a variety of prey types, such as numerous species of fish, as well as cephalopods, and occasionally small sharks, rays and crustaceans (Wells 1998; Amir et al. 2005). Thus, they represent the near terminal links of food webs in marine ecosystems. Up to date, investigations on the dolphin gastrointestinal parasite fauna have been exclusively carried out on stranded dolphins, dolphins from by-catch or on animals in captivity. Consequently, parasitological examinations were generally performed post mortem by necropsy, occasionally providing information on the animal’s death (Dailey and Walker 1978; Raga et al. 1997; Gibson et al. 1998; Jaber et al. 2006). So far, research on cetacean parasites worldwide mainly focused on the following cetacean species: Balaenoptera acutorostrata, B. physalus, Delphinus delphis, Globicephala macrorhynchus, G. melas, G. griseus, Kogia breviceps, K. sima, Lagenorhynchus acutus, L. albirostris, Lagenodelphis hosei, Megaptera novaeangliae, M. bidens, M. densirostris, Orcinus orca, Peponocephala electra, Phocoena phocoena, Physeter macrocephalus, Sotalia guianensis, S. attenuata, S. clymene, S. frontalis, Sotalia coeruleoalba, Sotalia longirostris, Stenella sp., Steno bredanensis, T. truncatus and Ziphius cavirostris (Kumar et al. 1975; Abril et al. 1991; O’Shea et al. 1991; Slob et al.

1996; Gibson et al. 1998; Lehnert et al. 2005; Aznar et al. 2006; Carvalho et al. 2010; Loizaga de Casto et al. 2011; Mateu et al. 2011; Oliveira et al. 2011; Aytemiz et al. 2012; Quiñones et al. 2013), with the majority of these studies being performed on D. delphis, P. phocoena, Stenella spp. and T. truncatus. However, only little data is available on parasites in Indo-Pacific bottlenose dolphins. Tomo et al. (2010) investigated 167 stranded or by-caught individuals of T. aduncus and 15 of T. truncatus, post mortem for lungworm infections. They found 11 % of the Indo-Pacific bottlenose dolphins and 20 % of the common bottlenose dolphins being infected with lung nematodes (Halocercus lagenorhynchi, Stenurus ovatus and Pharurus alatus). Two other studies focused on Toxoplasma gondii infections in T. aduncus (Jardine and Dubey 2002; Omata et al. 2005). Omata et al. (2005) proved an exposition of the Indo-Pacific bottlenose dolphins from Solomon Island to T. gondii via analyses of serum samples of 58 specimens. Van Wormer et al. (2013) stated that infections of humans and animals occur by contaminated terrestrial and aquatic sources, emphasizing the need for joint examination of human, domestic animal and wildlife populations. The present study aimed to identify the gastrointestinal parasite fauna occurring in freeliving and alive Indo-Pacific bottlenose dolphin (T. aduncus) populations, within their natural habitats, from the Northern Red Sea, Egypt.

Materials and methods Study area, sample collection and coprological analysis The Indo-Pacific bottlenose dolphins (T. aduncus) were studied in the Red Sea along the coastline of Hurghada, Egypt. The study area encompassed 600 km2 and ranged from the reefs of Umm Usk (27°35.001 N, 33°52.272 E) in the north to Abu Hashish reef (27°1.453 N, 33°55.644 E) in the south. The general topography of the research zone was comprised of islands and of a variety of exposed and unexposed reef types, such as patch, ridge and platform reefs; however, by far, the most dominant were mainland and island fringing reefs (Riegl and Velimirov 1994). The reef systems were shallow and the maximum depth between reefs and islands in the open water was about 300 m. Ad libitum boat- and underwater-based surveys during scuba dives were conducted since 2009. This worldwide unparalleled research methodology not only allows underwater behavioural observations which are impossible to monitor otherwise, but also provides comparatively uncomplicated access to dolphins’ faecal and vomitus material (Fig. 1). In this study, a total of 94 individual faecal samples were collected during underwater surveys. When defecation occurred, scat samples were immediately collected in 1.5-ml tubes (Eppendorf), which were held in a specially

Parasitol Res Fig. 1 Dolphin faecal sample collection. 1 Observation and diving with free-living IndoPacific bottlenose dolphins (Tursiops aduncus). 2 Specially designed wrist tube holder for free diving. 3 Collection of marine faecal samples by the use of Eppendorf tubes

designed ‘wrist tube holder’ (see Fig. 1), and the defecating individual dolphin was identified via photography. Thereafter, ethanol was added to the faecal sample and it was stored at 4 °C until further analysis. Additionally, two vomitus samples were collected and preserved in 70 % ethanol. Parasitological analyses were performed at the Zoology Department, Faculty of Science, Cairo University, Egypt. Coproscopical analyses were performed by using the standard sodium acetate acetic acid formalin (SAF) technique with ethyl acetate (Yang and Scholten 1977; Young et al. 1979). The SAF technique was used for the detection of parasite eggs, cysts, sporocysts and oocysts within faecal material. In addition, a carbol fuchsin-stained faecal smear (Heine 1982; Bauer 2006) was carried out for the detection of Cryptosporidium spp. oocysts. Furthermore, coproantigen ELISAs (ProSpecT®, Oxoid) were performed for the detection of Cryptosporidium and Giardia antigens in faecal samples. Taxonomic relationships as well as morphological identification of the isolated digenean taxa were exclusively based on adult morphological features (Fernández et al. 1998a, b). The parasitological identification of eggs was based on morphological characteristics referring to other reports (e.g. Kumar et al. 1975; Mehlhorn and Peters 1983; Dailey 1985; Abril et al. 1991; Eckert et al. 2008). All sample procedures were conducted in accordance to institutional and Egyptian national ethics.

Molecular analyses To characterize specimens of adult Anisakis found in vomitus content of Indo-Pacific bottlenose dolphins on species levels, we chose a molecular approach PCR amplifying and sequencing a partial region of the nuclear ribosomal RNA genes including internal transcribed spacers (ITS) and in addition a partial region of the mitochondrial cytochrome c oxidase subunit II gene (cox2). Genomic DNA was extracted from pieces of individual adult Anisakis using the QIAamp DNA Blood Tissue Mini Kit (QIAGEN, Hilden, Germany) according to the tissue protocol. In brief, 80 mg of tissue was lysed in ATL lysis buffer with 2 mg/ml proteinase K, and the DNA was purified over anion exchange columns and eluted in 100 μl of distilled water. The partial rDNA region was amplified using a combination of universal oligonucleotides: AnITS_F2 (5′GGATAAACAAGTTCGGA-3′; Skov et al. 2009), F2662 (5′-GGCAAAAGTCGTAACAAGGT-3′; Ishiwata et al. 2004), NC5 (5′-GTAGGTGAACCTGCGGAAGGATCATT3′; Gasser et al. 1996), NC2 (5′-TTAGTTTCTTTTCCTCCG CT-3′; Gasser et al. 1993) and D2A and D3B (5′-ACAAGT ACCGTGAGGGAAAGTTG-3′ and 5′-TCGGAAGGAACC AGCTACTA-3′; De Ley et al. 1999). The cox2 region was amplified using oligonucleotides 211 and 210 (5′-TTTTCT AGTTATATAGATTGRTTTYAT-3′and 5′-CACCAACTCT TAAAATTATC-3′; Nadler and Hudspeth 2000). The thermocycling profile used in 50 μl PCR reactions with 500 ng of sample DNA was initial denaturation of 94 °C for

Parasitol Res Fig. 2 Protozoan parasite stages from faecal samples of Tursiops aduncus. 1 Giardia spp. cyst (scale bar 7.5 μm). 2 Sarcocystis spp. sporocyst (scale bar 4.5 μm). 3 Holotricha spp. ciliate (scale bar 20 μm). 4 Cystoisospora (like) spp. oocyst (scale bar 7.3 μm)

5 min and 35 cycles of 94 °C for 30 s, 50 °C for 30 s and 72 °C for 1.30 s followed by a final extension of 72 °C for 5 min and final hold at 20 °C. The sequences were obtained by direct sequencing of the PCR amplicons and identified by GenBank database search using blastn (Sequences were deposited in GenBank under accession numbers HF911524 and KF701409-KF701412).

Results Parasite infections Parasitological analyses of faecal samples of free-living IndoPacific bottlenose dolphins revealed 21 different protozoan (10) and metazoan (11) parasite species. The metazoan species consisted of trematodes (seven species), cestodes (one species), nematodes (two species) and crustacean parasites (one species). A complete list of the parasitic stages and their prevalence is given in Table 1. Illustrations of the parasitic stages are depicted in Figs. 2, 3, 4 and 5. No acantocephalan parasite eggs were found in the examined samples. The most prevalent parasites were Ascaridida indet. (25.5 %) followed by Nasitrema attenuata (18.1 %) (Table 1). Most prevalent protozoan parasites within dolphin samples were Cryptosporidium spp. (3.1 %), followed by Sarcocystis spp. sporocysts and Giardia spp. cysts with identical prevalence, namely 2.1 % (see Table 1). Within the metazoan parasites, the

trematodes were the most rich in species (seven species) followed by nematodes with two different species. Referring to parasite family level, these parasitological findings included ten new host records (Giardia spp., Sarcocystis spp., Cryptosporidium spp., Nasitrema spp., Zalophotrema spp., Pholeter gastrophilus, Anisakis typica, Capillaria spp., Diphyllobothrium spp. and Cymothoidae indet.) for T. aduncus (Table 1). Except for Capillaria spp., which has never been recorded for dolphins belonging to the genus Tursiops before, all other parasite species had already been reported for another dolphin species of the same genus, namely T. truncatus, but not yet in T. aduncus. Parasites assigned ‘like’ were excluded from these analyses. Some of the parasite species detected in T. aduncus faecal samples bear zoonotic potential such as Giardia spp., Cryptosporidium spp., Anisakis spp. and Diphyllobothrium spp. which can cause severe human infections. Molecular analysis of Anisakis sp. The four collected adult Anisakis sp. were identified as A. typica based on partial sequences of the rDNA region and the mitochondrial cox2 gene. The longest, amplified sequence of the rDNA region was 2,402 bp (without primer sequences) including 402 bp of the 18S rRNA gene, the internal transcribed spacer 1 (ITS1), the 5.8S rRNA gene, the internal transcribed spacer 2 and 1,162 bp of the 28S rRNA gene. Alignment of the four

Parasitol Res Table 1 Prevalence (in percent) of parasitic infections in Tursiops aduncus, technique and sample origin

Protozoan parasites

Metazoan parasites

Groups

Parasite

(%)

Technique

Material

Protozoa

Giardia sp. Sarcocystis sp. Isospora (like) sp. Cystoisospora (like) sp. Ciliata indet. I

2.13 2.13 3.19 8.51 3.19

SAF SAF SAF SAF SAF

Faeces Faeces Faeces Faeces Faeces

Ciliata indet. II Holotricha indet. Dinoflagellata indet. Hexamita (like) sp. Cryptosporidium sp. Nasitrema attenuata Nasitrema sp. I Nasitrema sp. II Zalophotrema curilensis Zalophotrema sp. Pholeter gastrophilus Trematoda indet. I Trematoda indet. II Anisakis typica Ascaridida indet. Capillaria sp. Diphyllobothrium sp. Cymothoidae indet.

1.06 3.19 1.06 11.70 3.19 18.09 9.57 1.06 4.26 9.57 6.38 12.77 1.06 2.13 25.53 2.13 8.51 1.06

SAF SAF SAF SAF ELISA SAF SAF SAF SAF SAF SAF SAF SAF PCR SAF/PCR SAF SAF morphological

Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Faeces Vomitus Faeces Faeces Faeces Vomitus

Trematoda

Nematoda

Cestoda Crustacea

A. typica sequences indicated no genetic diversity within the amplified rDNA region. The rDNA sequence of the A. typica worms vomited by T. aduncus of the Red Sea exhibited 100 % identity with the sequences of an A. typica haplotype characterized by three conserved, associated single nucleotide positions in the ITS1 (200C, 248G, 251A, e.g. AB432909) obtained from marine fishes of the Indo-Pacific compared to a geographically more widespread haplotype (ITS1: 200T, 248T, 251G, e.g. JQ934866) which according to GenBank entries was also found in fishes from the Mediterranean Sea and the Atlantic Ocean. The amplified mitochondrial cox2 sequence was 582 bp (without primer sequences) coding for an amino acid sequence of 194 aa from approximately 232 aa of the complete COII protein. As reported by previous studies (Valentini et al. 2006; Koinari et al. 2013), the cox2 sequence of anisakid nematodes is more divergent than the internal transcribed spacer sequences. The alignment of the cox2 sequences from the four adult Anisakis worms exhibited 17 polymorphic nucleotide positions. However, the aligned deduced amino acid sequences resulted in a single polymorphic amino acid position only with a conserved substitution of aspartic acid to glutamic acid in one of the four sequences (not shown). Identities of the amplified cox2 nucleotide sequences were

93–99 % to A. typica sequences deposited in GenBank and 87–89 % to sequences of other Anisakis species.

Discussion Common collection methods for analyses of intestinal parasites of cetaceans usually rely on accidental stranding of single or few animals or on dead specimens obtained from marine zoos (Gibson et al. 1998). By obtaining faecal samples directly from swimming Indo-Pacific bottlenose dolphins, this survey has revealed unique insights into the actual gastrointestinal parasitic fauna of alive, free-ranging T. aduncus within their natural habitat. Overall, the knowledge on dolphin faecal parasitic stages in the marine environment is scarce. Although some parasitoses, such as nasitremosis, are discussed as major causes of dolphin stranding (Dailey and Stroud 1978; Dailey and Walker 1978), the parasite fauna of marine mammals has not obtained sufficient attention so far (Oliveira et al. 2011). In this study, 21 different parasite species were detected within 94 individual dolphin faecal samples covering a respectable range of parasitic taxa. The parasitological determination of metazoan parasite eggs and of protozoan stages based on morphological characteristics only revealed as quite

Parasitol Res Fig. 3 Metazoan parasite eggs from faecal samples of Tursiops aduncus: Trematoda. 1 Nasitrema attenuata egg (scale bar 19 μm). 2 Nasitrema spp. egg (scale bar 23 μm). 3 Zalophotrema curilensis egg (scale bar 24.2 μm). 4 Zalophotrema spp. egg (scale bar 17.5 μm). 5 Pholeter gastrophilus egg (scale bar 10.5 μm). 6 Trematoda indet. I egg (scale bar 12.5 μm)

a challenge. For future parasitological research, the here provided photo galleries may supply a supportive basic tool for analyses on dolphins and other marine mammals since many of the here described parasites infect a wide range of marine final host. The most frequent parasitic stages found in the current study were by far digenean trematode eggs. Digenean trematodes parasitize the gastrointestinal system of a wide range of marine mammals and also infect nasal and cranial sinuses of small cetaceans (see Geraci and St. Aubin 1987). These parasites exhibit little impact on the hosts when residing in the lumen of the gut or in nasal cavities, but if they are localized in the parenchyma of organs or if their eggs spread via the blood system, they may cause severe granuloma formation (Parker et al. 1977; Dailey and Walker 1978; Geraci and St. Aubin 1987; Lewis and Berry 1988). The two families Brachycladiidae (former Campulidae) and Nasitrematidae

contain most of the trematode species occurring in marine mammals worldwide, particularly within cetaceans (Delyamure 1955). In this work, we identified seven different digenean trematode eggs in T. aduncus faeces, but only three of them could be identified on species level, namely N. attenuata, Z. curilensis and P. gastrophilus. N. attenuata was the most prevalent species (18 %) indicating a rather wide spread of this pathogenic parasite in T. aduncus populations of the Red Sea. N. attenuata commonly resides innocuously in the craneal sinuses of small cetaceans (O’Shea et al. 1991), but adult stages may invade the brain causing extensive necrosis and fatal meningoencephalitis (Ridgway and Dailey 1972; Geraci and St. Aubin 1987). Comparable features were reported for the Amazon River dolphin, in which Hunterotrema macrosoma infections are associated with both pulmonary and cerebral lesions (Woodard et al. 1969). Cerebral nasitremosis is a major factor of natural mortality of common dolphins

Parasitol Res Fig. 4 Metazoan parasite eggs from faecal samples of Tursiops aduncus: Cestoda and Nematoda. 1 + 2 Diphyllobothrium spp. eggs (scale bars 25 μm). 3 Ascaridida indet. egg (scale bar 22 μm). 4 Capillaria spp. egg (scale bar 19 μm)

along the Pacific coast of the USA (Dailey and Walker 1978) and appears directly associated with stranding (Geraci and St. Aubin 1987). In addition, the formation of inflammatory granuloma following the spread of Nasitrema spp. eggs into

Fig. 5 Metazoan parasite stages from Tursiops aduncus vomitus samples: Nematoda and Crustacea. 1 Adult Anisakis typica (genetically identified) (scale bars 4 cm). Cymothoidae indet. 2 Dorsal. 3 Ventral (scale bars 1.25 cm)

different organs, such as the lung, was suggested as a cause of death in small cetaceans (Kumar et al. 1975; Parker et al. 1977; Dailey and Walker 1978; Lewis and Berry 1988). Overall, 13.7 % of examined Indo-Pacific bottlenose dolphins were found to be infected with Zalophotrema spp. This may be of clinical relevance since members of the genus Zalophotrema were reported to induce severe necrosis of parenchymal tissue (particularly in pancreas and the hepatobiliary system) as well as chronic fibrosis and hyperplasia of ducts (Woodard et al. 1969; Fleischman and Squire 1970; Geraci and St. Aubin 1987; Fernández et al. 1998a, b; Gibson 2005). In addition, infections with the gastrointestinal trematode P. gastrophilus were diagnosed in our study (prevalence of 6.3 %). These parasites have been reported to exhibit detrimental effects on the dolphin’s gastric organ (Woodard et al. 1969; Geraci and St. Aubin 1987). Adult P. gastrophilus trematodes are known to reside in the submucosa of the stomach within fibrotic nodules, eliciting intense pro-inflammatory responses (Woodard et al. 1969), thereby causing parasitic gastritis in infected animals. The genus Pholeter is known to be highly diverse within cetaceans (35 of 42 described species, see Mateu et al. 2011) with additional species infecting pinnipeds (seals) and mustelids (sea otters) (Aznar et al. 2001; Dailey 2007). The parasitological findings of the current study also include ten new host reports for T. aduncus, thereby providing a broader insight into the panel of parasitoses of this species. However, in the case of Cymothoidae indet., it cannot be

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excluded that this typical fish parasitic isopod (Trilles 1991; Bunkley-Williams and Williams 1998) was accidentally ingested by sampled dolphins as fish prey. Several zoonotic pathogens were identified in T. aduncus faecal samples. Marine mammals are known as important hosts being inflicted in life cycles of metazoan parasites with zoonotic potential, such as Anisakis spp. (see Klimpel et al. 2004; Kleinertz et al. 2012), and were in the focus of several studies on these cetacean anisakid nematodes in the past (see Ugland et al. 2004; Cavallero et al. 2011) and Diphyllobothrium spp. (see Chai et al. 2005; Arizono et al. 2009; Jenkins et al. 2011), as well as of protozoan parasites (e.g. Cryptosporidium spp. and Giardia spp.; Mehlhorn and Piekarski 1998; Deng et al. 2000; Thompson et al. 2008). Especially T. aduncus may function as reservoir hosts of the latter parasites since it resides near to the highly populated coastline of Hurghada. In addition, this tourist-rich area raises further problems as the danger of zoonotic diseases appears enhanced by bringing dolphins and humans into close contact via swimming-with-dolphins tours. Consequently, water-borne zoonoses such as cryptosporidiosis and giardiosis have to be considered in this context (Coklin et al. 2007; Tzipori and Widmer 2008; McDowall et al. 2011; Salyer et al. 2012). In this study, we also detected Diphyllobothrium eggs in T. aduncus faecal samples. Accordingly, these cestodes were also recently found in stranded common bottlenose dolphins (Quiñones et al. 2013). Dolphin infections with mature Diphyllobothrium tapeworms are commonly innocuous (Arundel 1978; Geraci and St. Aubin 1987), but in cases of high parasitic burdens, debilitation and even death of parasitized host may result. Diphyllobothrium spp. cestodes can also encyst in the intestinal wall or form aggregates of adult worms (weighing >1 kg) inducing serious obstruction of the intestinal lumen (Cordes and O’Hara 1979). Overall, infections with Diphyllobothrium spp. represent important fish-borne zoonoses worldwide (Curtis and Bylund 1991; Chai et al. 2005; Scholz et al. 2009; Jenkins et al. 2011). It is known that neritic or near-shore cetacean species, such as T. truncatus, harbour higher numbers of helminth parasites than oceanic species such as common dolphins (Quiñones et al. 2013). It is worth noting that, especially in heavily infected animals, some parasites debilitate their hosts (e.g. Campula spp.) or exhibit pathogenic effects (e.g. Anisakis spp., Pholeter spp., Halocercus spp.) (Raga et al. 1997; Gibson et al. 1998; Oliveira et al. 2011). Within the current study, Ascaridida indet. infections were detected at moderate prevalence (25.5 %). Owing to undistinguishable morphologies, characterization on species level was not possible. However, the genera Anisakis and Pseudoterranova both were already reported in the genus Tursiops (Nadler et al. 2005; Mattiucci and Nascetti 2006; Colón-Llavina et al. 2009) and Contracaecum spp. are known to infect various dolphin species (Nadler et al. 2005). The fact

that all adult anisakids originating from vomitus samples were genetically identified as A. typica may render this species as the most likely one. A. typica is a common parasite of various dolphin species of warmer temperate and tropical waters (see Mattiucci et al. 2002, 2005; Mattiucci and Nascetti 2006) and has not been attributed as food-borne parasitic zoonoses so far (Koinari et al. 2013). Some data on the spectrum of intermediate fish hosts being scavenged of A. typica are available (e.g. Nadler et al. 2005; Farjallah et al. 2008; Palm et al. 2008; Klimpel and Palm 2011; Kuhn et al. 2011; Kleinertz et al. 2012), but in prey fish species of this particular geographic area, only A. simplex was found (Abdou et al. 2007; Arafa et al. 2009). In conclusion, this study adds to the current knowledge on intestinal parasite infections of free-ranging T. aduncus and calls for more research to be performed in this field especially for monitoring reasons. Acknowledgments We greatly acknowledge Michael Stadermann and his team at the SWDF Diving Center (Hurghada, Egypt), the Dolphin Watch Alliance (Gossau, Switzerland) for providing study samples, boat equipment and field support and Marquardt Media Production on behalf of the television company ZDF/Arte. We also thank Natalia Pryanishnikova for providing underwater photographs and Dr. Kernt Köhler (Institute for Veterinary Pathology, Giessen, Germany) for his support in taking pictures of adult A. typica and Cymothoidae indet. specimens.

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