Binomics, Culture Trial and DNA Barcoding of Caridean Species from Three Lagoons, South-West Nigeria
A Thesis Submitted to the School of Postgraduate Studies, University of Lagos
Macrobrachium species are crustaceans found in most inland water and low brackish areas and are of economic importance and possible recruitment into aquaculture. The binomics, culture trial and DNA barcoding of caridean species Brackish water prawn (Macrobrachium macrobrachion) and African River prawn (Macrobrachium vollenhovenii) from Badagry, Lagos and Epe Lagoons, Nigeria were carried out between June 2013 and May 2015. The physico-chemical parameters of the study sites (N 6º 29′ 24.9856″ latitude, E 2º 45′ 52.5347″ longitude – Badagry Lagoon, N 6º 31′ 31.7846″ latitude, E 3º 48′ 23.9768″ longitude – Lagos Lagoon, N 6º 34′ 26.0″ latitude, E 3º 58′ 35.3″ longitude – Epe Lagoon) were measured in-situ. M. macrobrachion and M. vollenhovenii collected for 24 months were analyzed to determine their morphometric characteristics. M. vollenhovenii was reared in triplicate glass tanks with different Crude Protein (CP) levels of purified feed (25%, 30%, 35%, 40% and 45%) and 40% local diet as a control. Molecular technique (DNA barcoding) was used to identify Macrobrachium species found in the study areas. The DNA of the species was extracted using the phenol-chloroform protocol and Norgen tissue kit. Amplification and sequencing of M. macrobrachion and M. vollenhovenii were carried out and further identification of the species was done by comparing with sequenced data in the Genbank. The water temperature for the three lagoons ranged between 21.00 and 32.30 ºC; Dissolved Oxygen ranged from 1.50 to 14.00 mg/L; pH ranged between 5.00 and 9.39; salinity values ranged from 0.00 to 25.00 ‰; water transparency ranged between 17.78 and 175.00 cm and the conductivity ranged between 65.40 and 39600.00 µS/cm. Out of the 4729 specimens collected during the study period, 1770 specimens were from Badagry Lagoon, 924 from Lagos Lagoon and 2035 from Epe Lagoon. The total length (total weight) of M. macrobrachion from the three lagoons ranged from 4.8 cm to 12.8 cm (1.1 – 40.1 g), while M. vollenhovenii ranged from 4.3 cm to 22.6 cm (1.1 – 140.0 g). The condition factor (K) for the combined sexes of M. macrobrachion ranged from 0.3 – 1.4, 0.3 – 1.4 and 0.3 – 1.9 while M. vollenhovenii ranged from 0.4 - 2.7, 0.4 – 3.1 and 0.1 – 2.1 for Badagry, Lagos and Epe Lagoons respectively. The edible parts of M. macrobrachion constituted 44.93 % - 92.04 % of the body weight while that of M. vollenhovenii constituted 40.32 % - 89.80 % in the three lagoons. The stomach contents of M. macrobrachion and M. vollenhovenii from the three lagoons were made up of Bacillariophyta, Chlorophyta, Cyanophyta, Bivalves, Crustaceans, Copepods and detrital materials. The results of the food and feeding habit showed that M. macrobrachion and M. vollenhovenii had preference for detritus. The sex ratio (male: female) for M. macrobrachion and M. vollenhovenii were 1:1.03 and 1:0.21 respectively from Badagry Lagoon, 1:2.60 and 1:1.65 from Lagos Lagoon and 1:0.67 and 1:0.3 from Epe Lagoon. There were significant difference (P < 0.05) in the sex ratio recorded in the three lagoons except for M. macrobrachion from Badagry Lagoon, which showed no significant difference (P > 0.05). At the end of the culture trial, the tank that received 40% CP, compounded from local ingredients performed significantly (P < 0.05) better than the other treatments in terms of average Weight Gain (1.18g), Specific Growth Rate (0.61 %/day), Food Conversion Ratio (5.50), Protein Efficiency Ratio (0.60), Food Efficiency Ratio (0.21) and the survival rate (70.83%). New species of M. asperulum and M. nipponense were observed in Badagry and Epe Lagoons respectively. This study established the occurrence and distribution of M. macrobrachion and M. vollenhovenii from three interconnecting lagoons with the culture potentials of M. vollenhovenii in the laboratory. The phenol-chloroform protocol gave better gel-images than the Norgen tissue kit. The DNA barcode identified that some other species of Macrobrachium were present in Badagry and Epe Lagoons.