Potential of bloody cockles (<i>Anadara senilis</i>) shells as alternative buffer to calcium carbonate for aquaculture in the Niger Delta, Nigeria

Abstract

A study was carried out to assess buffering efficiency of bloody cockle shells (Anadara senilis) on acidic borehole water for fish farming. Eighteen (18), 100-litre shaded plastic tanks (3/4- filled, pH 4.0) of three replicates per treatment of 270 g buffer agent were used. There were four trials of six treatments (T) namely control (C) [T1], calcium carbonate (CA) [T2], crushed burnt bloody cockle shells (CBBS) [T3], uncrushed burnt bloody cockle shells (UBBS) [T4], crushed unburnt bloody cockle shells (CUBS) [T5] and uncrushed unburnt bloody cockle shells (UUBS) [T6]. Temperature and pH were monitored morning, afternoon and night while dissolved oxygen, calcium and alkalinity were measured once for the duration of study using standard methods. Data were subjected to analysis of variance and descriptive statistics using Microsoft Excel. pH progressively increased from 4.0 to the acceptable range of 6.5-9.0 in all treatments except T1 at the end of study. All shell types performed well as buffering agent. However, crushed burnt bloody cockle shells are preferable to others in terms of food safety. Dissolved oxygen calcium and alkalinity values were within acceptable standard. The study recommends at least 270 g of the different shell types as organic buffer for fish production.

Keywords: Fish production, pH, organic buffer, bloody cockle shells, Niger Delta