Long-Term Ecological Change in the Niger Delta Estuarine Fisheries System: A Paleoecological and Contemporary Analysis

This research examined long-term ecological change in the Niger Delta estuarine fisheries system using an innovative integration of paleoecological archive analysis and contemporary ecological monitoring, spanning a 200-year reconstructed timeline and a two-year field study period. Understanding pre-industrial baseline conditions and the trajectory of ecological change in this heavily impacted system is essential for setting meaningful restoration targets and informing fisheries recovery projections. Sediment cores were extracted from five estuarine sites in Bayelsa, Delta, and Rivers states, and analysed for fish scale deposits, diatom assemblages, heavy metal profiles, and hydrocarbon geochemistry at decadal resolution. Contemporary ecological data encompassing fish community composition, habitat condition, water quality, and fishing pressure were collected from 12 estuarine stations over two annual cycles. Integration of paleoecological and contemporary datasets was achieved through principal component analysis and breakpoint analysis to identify ecological regime shifts. Results revealed two major historical regime shifts: the first coinciding with the onset of commercial petroleum production in the late 1950s, marked by sharp increases in sediment hydrocarbons and declines in sensitive diatom taxa, and the second in the 1990s, associated with the combined effects of intensified oil production, population growth, and fishing pressure escalation. Contemporary fish diversity is estimated to be approximately 40 percent below reconstructed pre-petroleum reference levels. The study provides original long-term baselines for the Niger Delta fisheries ecosystem and recommends the integration of paleoecological evidence into national restoration benchmarking for Niger Delta ecological recovery programmes. Keywords: paleoecology, ecological change, Niger Delta, estuarine fisheries, regime shift