GASTROINTESTINAL HELMINTH PARASITES OF SOME COMMERCIALLY IMPORTANT FISH SPECIES OF ANAMBRA RIVER, NIGERIA.

SOURCE:

Faculty: Biosences
Department: Zoology

CONTRIBUTORS:

Nwadike, C.C;
Ilozumba, P. C. O;

ABSTRACT:

The increase in demand for protein especially to combat the incidence of protein deficiency disease (kwashiorkor) in Nigeria has led to studies aimed at tapping of all avenues of protein production of which fisheries is an important one. An investigation was conducted on the gastrointestinal helminth parasites of some commercially important fish species of Anambra River, Nigeria, between August, 2012 and August, 2014. The sample comprised one thousand and twenty five fishes belonging to 20 families and 43 species. The fishes were purchased from fishermen and fish mongers at Otuocha, Nsugbe and Enugwu-otu, transported to the laboratory and identified based on morphological structures/features. Routine body measurements for fish such as standard length, total length, weight, and sex were determined, after which the fishes were carefully and thoroughly examined for helminth parasites by opening the alimentary canal from the cloacal end to the anterior limit of the oesophagus. Parasites seen were picked with a small paint brush and placed in normal saline. Nematodes were fixed in 70 % alcohol while cestodes and acanthocephalans were fixed in 4 % formaldehyde. Parasite abundance and their preferred sites, seasonal variation and physico-chemical parameters of the river were recorded. Thirteen fish species were found to be infected by helminth parasites namely Clarias gariepinus (9.67 %), C. anguillaris (26.67 %), C. lazera (16.67 %), Heterobranchus longifilis (16.67 %) (Family; Clariidae); Synodontis eupterus (30.23 %), S. batensoda (23.33 %) (Family; Mochokidae); Channa obscura (28.77 %) (Family: Channidae); Auchinoglannis occidentalis (25.00 %) (Family: Bagridae); Chrysichtys nigrodigitatus (5.13 %) (Family: Claroteidae); Protopterus annectens (4.55 %) (Family: Protopteridae); Schilbe mystus (5.26 %) (Family: Schilbeidae); Heterotis niloticus (53.06 %) (Family: Osteoglossidae/Arapaimidae) and Malapterurus electricus (56.25 %) (Family: Malapteruridae). Nineteen species of helminth parasites were isolated comprising nine cestodes, Unidentified Weyonia species, Weyonia youdeoweii, W. synodontis, Plerocercoid larva, Polyonchobothrium clarias, Sandonella sandoni, Electrotaenia malapteruri and 2 unidentified; trematode, Emoleptalea species, three nematodes, Procamallanus laeviconchus, Dujardinascaris species and Spirocamallanus species and six acanthocephalans, Neoechinorhynchus species, Tenuisentis niloticus and 4 unidentified acanthocephalans. Unidentified Weyonia species were recovered from S. eupterus (4.65 %), W. youdeoweii from S. eupterus (9.30 %) and S. batensoda (6.67 %), W. synodontis from S. batensoda (3.33 %), Plerocercoid larva from C. anguillaris (13.33 %), P. clarias from C. anguillaris (13.33 %) and C. lazera (16.67 %), S. sandoni from H. niloticus (37.41 %) and E. malapteruri from M. electricus (50.00 %). Emoleptalea species were recovered from C. gariepinus (6.45 %). Procamallanus laeviconchus was recovered from C. obscura (28.77 %) and H. niloticus (2.72 %), Dujardinascaris species from H. niloticus (1.36 %) and Spirocamallanus species from S. batensoda (1.67 %) and C. gariepinus (3.22 %). Neoechinorhynchus species were recovered from S. eupterus (16.28 %) and S. batensoda (8.33 %), T.niloticus from H. niloticus (31.29 %), S. batensoda (3.33 %) and M. electricus (6.30 %). Synodontis batensoda is reported as a new host record for T. niloticus. Heterotis niloticus is reported as a new host record for P. laeviconchus. Emoleptalea species is reported as a new geographical record/ new parasite record in Nigeria. Correlation analysis revealed that there was a significant relationship between the weight of A. occidentalis, C. anguillaris and C. obscura at P<0.05 while S. batensoda, H. longifilis and C. gariepinus had an inverse significant relationship. For the fish length, correlation analysis revealed that there was a significant relationship between the length of S.eupterus,M. electricus and C. obscura and helminth infection at P<0.05 while an inverse significant relationship was seen in S. batensoda, C. anguillaris, H. longifilis and C. gariepinus. All cestodes were recovered from the intestine of their host, likewise the trematode, Emoleptalea species. Procamallanus laeviconchus, Dujardinascaris species and Spirocamallanus species were recovered from intestine, rectum of their host. Neoechinorhynchus species were recovered from intestine and rectum while Tenuisentis niloticus were recovered from intestine. Mixed infections involving different species of helminth parasites occurred in H. niloticus and S. batensoda. The mochokids infection by cestode parasites recorded a higher prevalence in the dry season than in the rainy season. On the contrary, all three species of nematode parasites, P. laeviconchus, Dujardinascaris species and Spirocamallanus species recorded a higher prevalence in the rainy season than in the dry season in all their respective fish hosts. The values of water parameters determined in the dry season, pH (6.63), temperature (28.60) and dissolved oxygen (5.35) were slightly higher than in the wet season [pH (6.36), temperature (26.40) and dissolved oxygen (4.0)], although they were all within the stipulated limit. Additional studies will be required before the component community of helminths infecting the fishes of Anambra river can be ascertained especially as it relates to zoonotic infections.