The Limnological Status of an Old Intermitent Pond during the Wet Season in Ekpoma, Southern Nigeria

Abstract

The limnological status of an intermitent borrow pit pond in Ekpoma, Edo
State of Nigeria was studied between June and September 2005 (wet season). In situ measurements of temperature, pH, electrical conductivity,
transparency and total dissolved solids (TDS) were recorded together with
the dissolved oxygen (DO), biochemical oxygen demand (BOD5), total
suspended solids (TSS), primary productivity and the phytoplankton species composition for the pond water. The study revealed that the pond was slightly alkaline (pH 7.9 – 8.4) and fresh with low electrical conductivities of 91.8 – 114.1ìS/cm and TDS of 46.4 – 57.2mg/l. Water temperature ranged from 26.0 – 32.10C and the pond was well oxygenated (DO values = 6.0 – 9.23mg/l) but slightly polluted with high BOD5 values (4.33 – 7.43mg/l) and highly turbid (TSS = 13.4 – 20.0mg/l). The high TSS was associated with run-offs and allochthonous inputs from the surrounding environment. The Gross Primary Productivity was low and ranged from 2.47 – 6.60mgO2/m3/day while the respiratory activities ranged from 1.8 – 5.23mgO2/m3/day. The distribution of phytoplankton was irregular but characterized by high densities and species diversity. The phytoplankton population was dominated by the Bacillariophyceae. These attributes are typical of an intermitent pond.

Key words: Limnological status, intermittent pond, physicochemistry,
phytoplankton, productivity.