Growth and survival performance of the West African mangrove oyster, Crassostrea tulipa cultivated by suspension and bottom culture methods in the Densu Estuary, Ghana

Abstract This study compares the efficacy of suspension and bottom culture methods of the West African mangrove oyster, Crassostrea tulipa, on recycled oyster shell cultches in connection with some environmental factors in the Densu Estuary, Ghana, from December 2017 to July 2018. Oyster spat grew up to 5.56 ± 0.10 cm SH for suspension and 4.60 ± 0.14 cm SH for bottom culture on the convex surfaces of oyster shell cultches, whereas oysters cultured on the concave surfaces by suspension and bottom cultured measured 5.59 ± 0.14 cm SH and 4.68 ± 0.14 cm SH, respectively. There was a significant difference (F = 36.26, p = 0.001) between the growth rate of oysters cultured on convex surfaces of cultches by suspension (0.80 ± 0.23 cm/month) and bottom culture (1.02 ± 0.24 cm/month). The growth rate of cultured oysters on concave surfaces of cultches by suspension (1.00 ± 0.24 cm/month) was significantly better (F = 22.32, p < 0.001) than the bottom approach (0.81 ± 0.23 cm/month). Before the extermination of oysters cultured on the bottom in July 2018, there was no significant difference in the survival of oysters cultured by suspension and bottom methods on the convex (χ2 = 0.06, p = 0.99) and concave surfaces (χ2 = 0.19, p = 0.99). Of the physico-chemical factors monitored, oyster growth and survival were significantly influenced by DO (p = 0.004; 0.039) and salinity (p = 0.027; 0.012), respectively. Suspension culture approach should be preferred over the bottom culture, especially for water bodies with low bulk density.