Cooccurrence of Schistosoma Haematobium, Other Trematode Parasites, an Annelid (Chaetogaster limnaei limnaei), and a Nematode Parasite (Daubaylia potomaca) in Bulinus globosus.

* Correspondence: okeke.ogochukwucarol@gmail.com Multiple symbiotic interactions are the coexistence of three or more organisms of different taxonomic groups. Such symbioses are common in freshwater snails because they face a variety of biotic interactions (Hunter, 2006). The parasitic symbiotic relationship between freshwater snails and trematode parasites is well documented. There is evidence that trematodes affect growth, reproduction, and survival of their snail host. There are also records of symbiotic association between freshwater snails and an annelid worm, Chaetogaster (Buse, 1974; Rodgers et al., 2005; Agbolade et al., 2007; Fried et al., 2008; McKoy et al., 2011; Zimmermann et al., 2011; Stoll et al., 2013). Two subspecies of Chaetogaster limnaei are recognized: one subspecies, C. limnaei limnaei von Baer, 1827, lives as an ectosymbiont in the mantle cavity or outer surfaces of freshwater snails and occasionally mussels, whereas the other subspecies, C. limnaei vaghini Gruffydd, 1965, is parasitic in freshwater snails and feeds mainly on kidney cells (Buse, 1974; McKoy et al., 2011). Smythe et al. (2015) recorded both the ectosymbiotic and parasitic forms of C. limnaei in Physa gyrina collected from streams and ponds in central New York. Another symbiont is the parasitic nematode Daubaylia potomaca Chitwood & Chitwood, 1934. The nematode inhabits all tissue and blood spaces within the snail host and ultimately leads to death of the host. It is postulated that C. limnaei limnaei indirectly increases nematode presence by downregulating trematode parasites, which through competition are negatively associated with the nematode (McCaffrey, 2014). Other symbionts are bacteria, fungi, Ichthyosporea spp. , Microsporidia spp. , rotifers, and protozoans (Hertel et al., 2004). The aim of the present study was to investigate the symbiotic interactions within Bulinus globosus Morelet, 1866 collected from Nike Lake, southeastern Nigeria. Nike Lake is situated in the Enugu East Local Government Area (LGA) and lies between latitudes 6°31′N and 6°36′N and longitudes 7°36′E and 7°41′E. The lake is eutrophic with mean depth, pH, water temperature, dissolved oxygen, total hardness, calcium hardness, and Abstract: Cooccurrence of Schistosoma haematobium, other trematodes, Chaetogaster limnaei limnaei, and Daubaylia potomaca was investigated in Bulinus globosus collected at Nike Lake from October 2011 to September 2012. The snail sizes as well as the numbers of these organisms were recorded. Single infections of S. haematobium, other trematodes, C. limnaei limnaei, and D. potomaca were 0.3%, 46.38%, 1.03%, and 2.66%. Coinfection of S. haematobium-C. limnaei limnaei was 0.3% while that of S. haematobium-other trematodes was 0.15%. Coinfections of C. limnaei limnaei-other trematodes and D. potomaca-other trematodes were 2.16% each. There was no cooccurrence of C. limnaei limnaei-D. potomaca or S. haematobium-D. potomaca. The mean intensity of C. limnaei limnaei-S. haematobium was significantly higher than C. limnaei limnaei single infection. The mean intensity of single C. limnaei limnaei infection and C. limnaei limnaei-other trematodes coinfection was comparable. Mean intensity of D. potomaca-other trematodes coinfection and D. potomaca single infection was similar. In relation to snail size, significant variation was observed in other trematodes infection where the snails ≥8 mm had significantly higher infection rates than the snails <8 mm. The varying prevalence and mean intensities of the various symbionts in B. globosus suggest the existence of biotic interactions.