Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014) From the Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Austria Parasitological examination of common hippopotamus (Hippopotamus amphibius) faeces in the Gamba Complex of Protected Area in Gabon S. RIETMANN* and C. WALZER received August 5, 2013 accepted November 12, 2013 Keywors: Hippopotamus amphi- Schlüsselwörter: Hippopotamus bius; parasite, faeces, Gabon. amphibius, Parasiten, Kotproben, Gabun. Summary Zusammenfassung 1. Oktober 2011 wurden an 46 Tagen 77 Kotproben von Flusspferden ge- Effective conservation of Parasitologische Untersuchung sammelt. Die Proben wurden in eine species requires scientific von Flusspferdekot (Hippopota- Lösung aus 15 g Natriumacetat, 20 ml evidence upon which to base mus amphibius) in Gabun Eisessig, 40 ml Formalin (37 %) und decisions. Health threats to wild- 925 ml Leitungswasser xiert. Jede life must be considered when Einleitung Probe wurde gesondert mittels Se- devising conservation strategies. Die Gefährdung von Wildtierpo- dimentation (nach der modi zierten Reference data on diseases, their pulationen auf Grund von Krank- Methode von Benedek) und Flota- spread and their consequences heitsgeschehen stellt eine wach- tion (nach der McMaster Methode) for both hosts and people are key sende und ernstzunehmende untersucht. factors in the sustainable Bedrohung dar. Wissenschaftlich management of wildlife species. fundierte Kenntnisse über Krank- Ergebnisse In this study we investigated the heiten, Krankheitserreger sowie In 70 der 77 Proben wurden Pa- possibility of extracting parasites Krankheitsverläufe und daraus fol- rasiten gefunden. 61 Proben wa- and assessing parasite type from gende Konsequenzen fungieren ren positiv für Eier von Fasciola faeces of the common hippo- als nötige Grundlagen im Rahmen spp. und in 42 Proben wurde Ei- potamus (Hippopotamus am- eines evidenzbasierenden Ent- meria gefunden. Vier Proben wa- phibius) from the central African scheidungsprozesses für nachhal- ren positiv für Larven von Stron- country of Gabon. Faecal samp- tiges Arten-Management. Diese gyliden, eine Probe beinhaltete ein les were collected in the eld, Studie befasst sich mit der Unter- deformiertes Strongyliden-Ei. xed in a formalin solution and suchung gastrointestinaler Parasi- analysed using otation and sedi- ten von Flusspferden (Hippopota- Schlussfolgerungen mentation methods. We found mus amphibius) und evaluiert die Das Fixieren von Kotproben in parasites in 70 out of 77 samples; Nutzung der angewandten Metho- einer Lösung aus Formalin, Natri- mainly comprising the genera de als Basis zur Überwachung pa- umacetat und Eisessig ermöglicht Eimeria and Fasciola. The study rasitärer Geschehen in freileben- eine zuverlässige Evaluierung von suggests that our methods are den Flusspferdpopulationen. Parasiten. Die Ergebnisse weisen suitable for screening faecal auf eine geringe parasitäre Vielfalt parasites of free-ranging hippo- Material und Methode und eine geringe Belastung der potamuses. Das Untersuchungsgebiet dieser Flusspferde im Gamba-Komplex Studie war der Gamba-Komplex im hin. Die verwendete Methode lie- Südwesten Gabuns in Zentralafrika. fert zuverlässige Daten über pa- Abbreviations: CITES = Convention Er erstreckt sich über eine Fläche rasitäre Geschehen in freileben- on International Trade in Endangered von 11.320 km2 und besteht aus ei- den Flusspferden. Ein Vergleich Species; GCPA = Gamba Complex of nem Gefüge aus Schutzgebieten mit anderen Methoden bezüglich Protected Areas; IUCN = International mit einem weitläu gen Wassersys- Sensitivität und Spezi tät sollte in Union for Conservation of Nature; WWF = World Wildlife Fund tem. Zwischen dem 14. Juni und dem Betracht gezogen werden. 66 Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014) Introduction hippopotamus is fully protected throughout the country under Gabonese law (Law N° 1/82 of July The common hippopotamus (Hippopotamus 22nd 1982). Nevertheless, numbers seem to be de- amphibius L.) was once widespread across sub- clining and poaching for meat and tusks is today Saharan Africa. In the past, it occurred along the thought to constitute the biggest threat for this spe- length of the Nile River all the way to the delta and in cies in Gabon (WHITE et al., 1983; CHRISTY et al., South Africa to the Cape. The common hippo- 2008). potamus was extirpated from many of these areas in The Gamba Complex of Protected Areas (GCPA) is historic times (KINGDON, 1997). The species is reported to contain the highest density of common believed to have experienced an overall decline of hippopotamuses in Gabon (DALLMEIER et al., 2006). 7–20% between 1998 and 2008 (LEWISON and The GCPA is situated in south-western Gabon at OLIVER, 2008). As a result, it was rst listed on the latitude 1°50’-3°10’S and longitude 9°15’-10°50’E IUCN Red list in 2006 (IUCN, 2006). Major threats for (see Maps 1 and 2). The GCPA includes two of the the hippopotamus are habitat loss, habitat fragmen- thirteen national parks of Gabon, Moukalaba- tation and poaching (ELTRINGHAM, 1999; LEWISON Doudou (4,500 km2) and Loango (1,550 km2), and an and OLIVER, 2008; KLINGEL, 2013). intervening corridor (3,585 km2). Wildlife in the GCPA Today, hippopotamuses still range over much of is afforded some degree of protection by law. sub-Saharan Africa: in the west from Senegal and Hunting regulations are well de ned inside national Gambia and in the east from Sudan, Ethiopia and parks. The area has a very high biodiversity and an Somalia as far south as the Okavango River delta in extremely low human population density (<1 person Botswana, the Kunene River in Namibia and per km2) (TREBAOL and CHAILLOL, 2002; ALONSO KwaZulu Natal in South Africa. The estimated total et al., 2006). The GCPA comprises a mosaic of very population is in the order of 125,000–148,000 indivi- diverse habitat types that span altitudes at sea level duals (LEWISON and OLIVER, 2008). The common along the 200 km long pristine coast, up to about hippopotamus is still categorized as ‘vulnerable’ on 820 m a.s.l. on Mount Doudou. The equatorial climate the IUCN Red List (2013). It is also listed in Appendix is hot and humid (up to 85 % relative humidity) II of the Convention on International Trade in En- (LEMOALLE and ALBARET, 1995). The hydrologic dangered Species (CITES) of Wild Fauna and Flora landscapes in which hippopotamuses occur are due to concerns about the appearance of hippo- divided into three large basins. Together with an potamus ivory in international trade (CITES, 2013). additional network of rivers, these form a complex Parasites from free-ranging hippopotamuses were water network with wide permanently submerged rst reported during the beginning of the 20th cen- woods and mangrove forests. tury (see Tab. 1). Most samples were collected fol- Parasitological examination lowing culling operations undertaken to control po- pulation numbers in Eastern Africa. An overview of Fieldwork to sample hippopotamus faeces was the parasites found to date in the common hippo- carried out over 46 days between June 14th and potamus is shown in Table 1. Records are noticeab- October 1st 2011. Depending on accessibility and ter- ly absent from many areas in which hippopotamuses rain, surveys were performed by motorized boat, occur, including West Africa. quad, kayak or by foot. In total, surveys covered The aims of this study were threefold: I) to assess 1,500 km in distance across 12 different regions of the feasibility of parasitological screening of free the GBPA. By changing the tracks left by hippo- ranging hippopotamuses; II) to assess methods for potami after every sampling we tried to avoid extracting parasites from faeces and xing them in a collecting faeces from the same individual twice. The solution of formalin; and III) to identify diversity of ages of faeces was estimated by local guides based parasite species in the faeces of hippopotamuses on humidity, colour, smell and the impression of living in the Gamba complex. tracks next to it. We often found tracks and faeces in locations that had been sampled the previous day, Material and Methods and this increased con dence in the estimates of the age of hippopotami faeces, which were classi ed as Study Area fresh faeces deposited the previous night <24 h prior to collection; and old faeces deposited >48 h The territory of Gabon is largely (80%) covered by earlier. Each faecal sample collected took different forest. Consequently, the spatial distribution of the parts from the scat and sought to avoid contamina- hippopotamus in Gabon is restricted (MAYAUX et al., tion by sampling from parts of the scat that had the 2004). The IUCN estimates the species to number least contact with the surrounding soil. around 250 individuals in Gabon (IUCN, 2013), A total of 77 faecal samples were collected. Six of although robust information on population size these were taken from old scats, seven were taken and distribution is lacking (WWF, 2006). The from scat assessed as being between 24 and 48 hours 67 Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014) Tab. 1: List of parasites of hippopotamuses described in the literature Phylum Plathelminthes Echinostomatidae Ogmocotyle spp. MCCULLY et al., 1967 Fasciolidae Fasciola nyanzae e.g. LEIPER, 1910; JACKSON, 1921 Paramphistomidae Paramphistomum spp. e.g. LEIPER, 1910; NÄSMARK, 1937 Nilocotyle spp. e.g. SWART,