The Abiotic Ecology and Prevalence of Palaemonid Shrimps (Crustacea: Palaemonidae) of Osse River, Edo State, Nigeria

Aims: To assess the relationship between the abundance of palaemonid shrimps and variation of the abiotic ecology of the river.

Study Design: Factorial design.

Place and Duration of Study: Osse River, Ovia North East Local Government Area of Edo State, Nigeria. April to December, 2015.

Methodology: Samples were collected between April and December, 2015; at night and early morning periods. All samples were collected from all stations on monthly basis to cover some part of rainy and dry seasons i.e. from April to December, 2015. Sex distribution pattern amongst the shrimp species and the ratio of male to female distribution for each species was analyzed mathematically. The sex variations across the stations were further analyzed using the Student’s T-test followed by a test of homogeneity of variance using Bartlett’s F-test. The physical parameters of the water were assessed using standard methods while the chemical parameters were determined by using Hydro-lab water quality meter Electronic Probe, Hanna.

Results: A total of 397 individuals, comprising 138 M. macrobrachion, 168 M. vollenhovenii, 27 M. felicinium, 29 M. lux, 24 N. hastatus and 11 P. maculatus were observed in the study area. Availability of the shrimps was: M. vollenhovenii > M. macrobrachion > M. lux > M. fellicinium > N. hastatus > P. maculatus. This conforms to the observations of Adebola and Olaniyan [1] but at variance with the observations of Eniade and Bello-Olusoji [2]. Population of the female shrimps outnumbered the male in all the species captured. The depth of the aquatic environment had significant negative correlations with M. macrobrachion (-0.54), M. vollenhovenii (-0.67), M. felicinium (-0.77), M. lux (-0.86), N. hastatus (-0.92), and P. maculatus (-0.85). This implies that depth is a major factor which must have influenced the abundance of the shrimps in the river. There was a significant positive correlation between nitrate and numbers of M. vollenhovenii (0.69), N. hastatus (0.56), and P. maculatus (0.73). Results show that abiotic factors such as pH (6.7- 7.5), temperature (27.5 – 28.2°C), depth (24.5 - 121 cm), and primary productivity nutrients are the major determining factors to the survival of the palaemonid shrimps. Higher cultivability was observed in M. vollenhovenii; followed by M. macrobrachion due their higher resistance to variability in the abiotic factors, this might be due to their relatively higher adaptability to tough conditions. Simulation of the values obtained at Station 2 of the study area is quite feasible and may generate optimal results in shrimp aquaculture.

Conclusion: Results show that Palaemonid shrimps are littoral organisms which are quite cultivable; particularly M. vollenhovenii and M. macrobrachion. They thrive under abiotic characteristics that can be simulated in captivity. Husbandry of the identified species in an artificial culture environment is quite feasible by consciously simulating the abiotic factors obtained at the most suitable location (Station 2). We however recommend further research into biology and feeding habits of palaemons. Result of this study has provided some information to support artificial breeding of the palaemonid shrimps for biological control of schistosomiasis and shrimp entrepreneurship.