Ecology and control of Typha species in Hadejia-Nguru Wetlands, Nigeria

Abstract. Abdullahi YBY, Balarabe ML, Khan AU, Adamu AK. 2019. Ecology and control of Typha species in Hadejia-Nguru Wetlands, Nigeria. Bonorowo Wetlands 9: 71-91. Typha proliferation causes several ecological problems, including transforming aquatic environments into terrestrial ones, interfering with various methods of catching fish, blockading river channels, and impeding navigation. The Hadejia Nguru wetland in Nigeria has an area of about 58,100 hectares, of which Typha species infested 35,000 hectares. The wetlands were divided into three sections, i.e., Upper, Middle, and Lower. In these segments, Typha species, water, soil, and sediment samples were collected, and the impact of Typha species on fish catch and distribution was assessed by splitting each segment into two sections: Typha uninfested and Typha infested. Each segment was separated into four sections for the biological control, each containing 2000 individuals of Typha interplant with 50kg, 25kg, 10kg, and no Phragmites karka, respectively. Each segment was manually separated into six sections as cutting Typha 15 cm, 10 cm, 5 cm below and 15 cm, 10 cm, 5 cm above the water. Each segment was divided into four sections for physical control, i.e., single black tarpaulin, double, triple, and no black tarpaulin. Typha latifolia and Typha angustifolia made up 64-70% and 30% of Typha species of the wetlands, respectivelyPhysico-chemical physics-chemical characteristics of water and sediment exposed substantial fluctuations, with PO4-P, NO3-N, and Mg concentrations ranging from 3.5-13.5 mg/L, 3-13 mg/L, and 1-10 mg/L, respectively. phosphate-phosphorus concentrations in the sediment ranged from 6.5 to 16 mg/kg, nitrate-nitrogen concentrations from 6 to 14 mg/kg, and organic matter concentrations from 4 to 12 mg/kg. The results also showed that high PO4-P, NO3-N, and Mg concentrations in water promote Typha development and proliferation. Sediment phosphate-phosphorus, nitrate-nitrogen, and organic matter concentrations showed a similar trend. The concentrations of water PO4-P, NO3-N, Mg, and sediment PO4-P, NO3-N, and Organic matter throughout the three segments revealed that the upper channel had a higher concentration than the middle, and the middle course had a higher concentration than the lower course. The distribution of T. latifolia and T. angustifolia followed the same pattern. The influence on fish catches and distribution revealed that open water had the maximum quantity and weight of fish taken, ranging from 83,167 to 173,026 kg and 14,402 to 59,355 kg, respectively, compared to Typha infested areas. Biological, manual, and physical strategies were used to control the spread of Typha. Biological control with P. karka reduced Typha species proliferation by 25%, with manual cutting at 15 cm below water level accounting for 95% of overall control. Typha proliferation was reduced by 54% when a black tarpaulin provided shade. Cutting at 15cm below the water's surface provided the finest control. Farmers should be educated on proper farming practices, particularly those that include manure rather than inorganic fertilizer. The optimum time to control Typha is when their density is low during the wet season.