Species diversity and population size of earthworms after oil spillage in a pipeline vandalized area in Lagos State, Nigeria

This study investigated the impact of repeated oil spill on the population of earthworm in an oil pipeline vandalized area in Lagos state, Nigeria after oil spillage. The study area was divided into two study sites; I (100 m within the epicenter of spill) and II (500 m away from spill) based on the impact of the spill; samples were collected every month for two years using standard methods. Data collected were subjected to Mann Whithney (U- test), Shannon-Weiner Diversity Index analyses and Pearson correlation. In the first year, only Lybiodrilus violaceous, was encountered in site I while site II had L. violaceous and Dichogaster Modigliani (H = 0.28). In the second year, Sites I and II had four species; L. violaceous, D. modiglanin, Ephyriodrilus afroccidentalis and Heliodrilus lagosensis (H = 0.73). Abundance of earthworm in Site II was significantly higher than in Site I for the first year but no significant difference in the two sites for the second year. There was also significant difference in Site I between the first and second year but not for Site II. There was negative impact on the abundance and diversity of earthworms in Site I compared to Site II during the first year with slight recovery recorded during the second year. L. violaceous was identified to be the most abundant; the increase in number and species of earthworm in the second year suggests possible remediation of the environment. [PUBLICATION ABSTRACT]