Spatial variability of macrozoobenthic diversity on tidal flats of the Niger Delta, Nigeria: the role of substratum

Abstract

Baseline community assemblages and diversity of macrozoobenthic infauna in soft-bottomed intertidal flats at Bodo Creek on the upper reaches of the Andoni–Bonny estuarine system were determined spatially and in relation to sediment particle characteristics for two years from May 2006 to April 2008. Interstitial water temperature, pH, dissolved oxygen and conductivity varied, while biological oxygen demand at the sites was similar. A total of 7 742 specimens belonging to 47 genera and 29 families of macrofauna were recovered from the samples. Density ranged between 8 and 1 583 m⁻², while Shannon–Wiener diversity varied from 0.102 to 1.052. A Hutcheson t-test revealed significant inter-site diversity differences, except for Station 2 vs Station 5 and Station 4 vs Station 5. Canonical correspondence analysis (CCA) revealed that the nature of substratum accounted for 34% of the taxa distribution and abundance in the study area; variances for the first and second axes were 77.8% and 21.2%, respectively. The CCA ordination showed that Callianassa sp., Upogebia furcata and Keletistes rhizoecus were uniquely associated with Station 1 and were greatly influenced by the amount of silt and clay. Complementary roles of other physico-chemical parameters, as well as biological interactions in structuring the zoobenthic communities, were detected. The data are a potential baseline for measuring the degree of recovery following two recent oil spills.

Keywords:

• assemblages
• ecological linkages
• macrozoobenthos
• ordination