Isolation of Parasites from Black Tiger Prawn; Peneaus monodon from Isaka River, Okirika Local Government Area, Rivers State, Nigeria

Aims: To determine the parasitic fauna, site-specificity of the parasites in the host and the parasite load in relation to length, weight and sex of P. mondon.

Study Design: The study is a survey using prawns from Isaka River as a case study.

Place and Duration of Study: The study area is an armlet of the Nigerian Ports Authority highway-sea and samples were collected between December 2014 and January 2015.

Methodology: Cast and spread technique was adopted in the study. Fishing-net was used to collect samples from the River. The stratified random sampling method was used in selecting the 103 prawns examined in the study. The hemolymph of the prawn was extracted using a 2 ml syringe at the site of collection to maintain the integrity of the specimen and preserved in EDTA bottle. Samples were then preserved in an ice chest and transported to the laboratory for morphometric and growth parameters evaluation. Exo-secretions, gills, appendages and gastrointestinal contents of the prawns were evaluated using standard parasitological techniques. Identification of parasites was achieved using the compound light microscope and standard guides. Physiochemical parameters of the River were determined using standard techniques and equipment. Data was analyzed with Measures of Central tendencies and Analysis of Variance.

Results: The data revealed an overall prevalence of 97.09% in the study. However, females harbored (58%) more parasites than males (42%). Parasites belonging to four phyla; Nematoda 111(17.03%), Platyhelminthes 32(4.08%), Arthropoda 73(10.63%) and Protozoa 469(68.27%) were recovered from the study. Phylum Protozoa had the highest abundance of 475(68.27%) and had the highest parasite diversity of up to eight species. Faunal specificity revealed a total of 742 parasites comprising of (11.05%), Trichuris spp. (4.16%), Ascaris spp. (2.15%), Spirocamallanus spp. (2.82%), Hysterothylacium spp. (1.62%), Capillaria spp. (0.80%), Enterobius spp. (4.17%), Lernaea (3.23%), Trematode (5.64%), Nematopsis spp. (9.7%), Porospora spp. (11.96%), Haplosporidium spp. (11.29%), Blastodinium spp. (11.02), Vahlkampfia spp. (3.36%), Colacium spp. (5.64%), Paramoeba spp. (6.04%), Pekinsus spp. (3.62%), Tapeworm (1.21%), Diatoms (4.56%) and Myzomolgus spp. (6.61%) were recovered. There were significant differences (P>0.05) in parasite loads in the examined animals in relation to the sex, body length, and weight. Site specific parasitism showed that the hemolymph had the highest parasite load of (80.58%) while the gastrointestinal tract had the highest diversity of parasites in the study. The physiochemical parameters of the water body varied from standards permissible in brackish water ecosystem.

Conclusion: The study revealed that P. monodon was highly susceptible to a wide range of parasites, attributable to the compromised ambient environmental status of the habitat and trophic affiliation of the prawns. The study states that the lipoproteins enriched hemolymph of P. monodon may have predisposed it to heavy parasitism.