PARENT SESSION
Contributed Oral Session 83: Human Impacts on Coastal Areas
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal

The role of dredging in the emergence of coastal invasive species in the Niger delta.

Ohimain, Elijah,

ABSTRACT- Typically, mangrove ecosystems are difficult to invade principally because of their unique environmental conditions such as prolonged hydroperiods, flooding, salinity and anoxic conditions. In the Niger delta, following the dredging of access canals for crude oil extraction and the abandonment of the resultant dredged spoils has led to the alteration of these conditions particularly topography, which inadvertently create suitable condition for invasive species. In most cases acidification starts at the spoil dumps and after several years of weathering, acid tolerate plants mostly grasses and sedges begin to emerge and several years after, shrubs such as Alchornia cordifolia, Chromolaena odorata and fresh water woody trees including Anthocleista vogelii and Musanga sp. follows. Later still because of the limited dry lands within the coastal areas, abandoned spoils become attractive to the local population as sites for houses, fishing camps and home gardens, which is nevertheless regarded as a positive impact, though such settlements are dangerously close to highly pressured oil and gas installations. Routine maintenance activities such as Oil spill clean up along dredged canals often cause conflicts between the oil companies and the dredged spoils inhabitants. The aim of the paper therefore is to highlight the role of dredging activities in the modification of coastal mangrove wetlands, which have led to plant invasion among other impacts.

Key words: mangrove wetlands/coastal invasives, biogeochemistry, disturbance/dredging, geomorphology/landscape