Comparative analysis of growth performance and survival of the West African mangrove oyster, Crassostrea tulipa (Lamarck, 1819) cultivated by suspension and bottom culture methods in the Densu Estuary, Ghana

Abstract

AbstractThis study compares the efficacy of suspension and bottom culture methods of the West African mangrove oyster, Crassostrea tulipa on recycled oyster shell cultch in the Densu Estuary, Ghana, which is geared towards its mass cultivation. It further assessed the relationship between selected environmental factors and growth performance as well as survival of C. tulipa. Oyster spat grew up to 5.56 ± 0.10 cm shell height (SH) in suspension culture and 4.60 ± 0.14 cm SH in bottom culture on the convex surface of the oyster shell cultch, whereas oysters cultured by suspension and on the bottom measured 5.59 ± 0.14 cm SH and 4.68 ± 0.14 cm SH on the concave surface of the cultch, respectively. There was a significant difference (p < 0.001) between the growth rate of oysters cultured by suspension (1.02 ± 0.24 cm/month for oysters in the convex surface of the cultch, 1.00 ± 0.24 cm/month for those grown on the concave surface) and on the bottom (0.80 ± 0.23 cm/month and 0.81 ± 0.23 cm/month for oysters on convex and concave sides of the cultch, respectively). There was no significant difference in the survival of oysters cultured by suspension and bottom methods on both surfaces of the cultch between January and June 2018 (χ2 = 0.06, p = 0.99; χ2 = 0.19, p = 0.99, respectively). Oysters cultured by the suspension method on the convex surface had a survival of 47.45% and that of the concave surface was 46.73% in July 2018, whereas oysters grown on the bottom showed 100% mortality. Oyster growth and survival showed a significant relationship with dissolved oxygen (p = 0.004; 0.039) and salinity (p = 0.027; 0.012), respectively. Based on the findings, the suspension culture method is recommended over the bottom approach.