Abstract

The objective of the study was to describe the abundance, distribution and diversity of macro benthic assemblages in Azuabie creek, upper Bonny estuary of the Niger Delta, Nigeria. Benthic samples were collected from ten sampling stations, seven (St. 1, 2, 6, 7, 8, 9 and 10, respectively) along the main creek and three (St. 3, 4 and 5, respectively) along a creeklet that empties into the main creek between April, 2006 and March, 2007. This ensured a total coverage of the entire creek along its salinity gradient. Polychaetes constitute 96% of the macrobenthos and were observed in more than 90% of the stations examined while fish were the least making up less than 1% of the organisms; other taxawere oligochaetes (2%), crustaceans (1%) and bivalvia (1%). In all, 37 species constituting 34 genera were observed, with the polychaetes having 29 species in 26 genera. Streblospio sp., and Boccardia sp., had higher densities at station 6 and 5, respectively during the dry season but Nephtys spp. and Nereis spp. had higher densities at station 1and lower densities at Sts. 5 and 6. Although, minimal variation was observed across periods, mean species richness was highest (3.92) in the month of October but species were most evenly distributed at station 10 across all sites studied. Species diversity also showed minimal variations (1.27-1.64) across periods but remarkable variation (0.00-2.12) between stations. Cluster analysis of the organisms separated station 3 from others due to its azoic nature; St 7, 8 and 10, respectively fell in the same group, while the others showed no clear pattern. The observed distribution/pattern of macro-invertebrate assemblage are strongly related to salinity gradient, sediment composition/characteristics and anthropogenic influence in the study area.

Keywords:

Azuabie creek, density, distribution, diversity, infauna, invertebrates, upper bonny estuary,

References

Competing interests

The authors have no competing interests.

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