Abundance and Density of Acrostichum aureum L. in Coastal Ecosystems of Southern Nigeria

Abstract

Acrostichum aureum Linnaeus is a rhizomatous fern of the Pteridaceae Kirchner family, which is generally found in elevated areas of mangrove forests or around agricultural fields. Over the years, the mangrove ecosystems in Akwa Ibom State have been degraded due to anthropogenic activities and pollutants from oil mining activities that act as stressors to endemic mangrove vegetation. It acts as a natural sea wall against the incursion of sea water intrusion landward amongst several other important functions; thus necessitating explorative studies on the population status of plant species in the ecosystem. This study was carried out at three mangrove locations within Iko Town, Okoroutip and Uta Ewa in Eastern Obolo, Ibeno and Ikot Abasi Local Government Areas respectively. The abundance and density of the plant species was calculated by enumerating the total number of A. aureum individuals observed within each sample plot across two seasons. Iko Town mangrove recorded the highest abundance and density of A. aureum with 34.25±2.78 and 856.25±69.50 (st/ha) in the dry season and 42.00±2.86 and 1050.00±71.44 (st/ha) in the wet season respectively. While Okoroutip mangrove had the least abundance and density of 13.25±1.03 and 331.25±25.77 (st/ha) respectively for dry season and 21.50±1.19 and 537.50±29.76 (st/ha) respectively for wet season. Whereas, Uta Ewa had an abundance and density value of 27.75±1.11 and 693.75±27.72 (st/ha) and 36.00±1.29 and 900.00±32.28 (st/ha) for dry and wet seasons respectively. The variations in abundance and density values of A. aureum were significantly different (p < 0.05) across the mangrove locations in both seasons. However, the abundance of A. aureum was notably higher in the wet compared to the dry season. This signifies that increased precipitation positively influenced the abundance of this mangroves’ species.