Open AccessInfluence of Environmental Factors on Growth, Survival, and Heavy Metal Accumulation in Oyster, Crassostrea madrasensis (Preston, 1916) Cultivated in Negombo Estuary, Sri Lanka
Author(s) -
M. Gammanpila
Publication year - 2021
Publication title -
asian fisheries science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.275
H-Index - 7
eISSN - 2073-3720
pISSN - 0116-6514
DOI - 10.33997/j.afs.2021.34.3.001
Subject(s) - oyster , estuary , salinity , zoology , turbidity , chlorophyll a , ammoniacal nitrogen , dry weight , biology , fishery , wastewater , environmental science , environmental engineering , ecology , horticulture , botany
The growth of marine bivalves is affected by the interactions of several environmental variables, particularly water salinity, temperature, and food supply. Influences of environmental parameters on daily weight gain (DWG), survival and heavy metal accumulation in 225 numbers of oysters, Crassostrea madrasensis (Preston, 1916), placed at five locations in the Negombo estuary, Sri Lanka, were investigated. One-way ANOVA indicated significantly higher (P < 0.05) DWGs (0.22 ± 0.01 and 0.16 ± 0.01 g.day-1) in Pitipana and Munnakaraya, where highest mean salinity (20.9 ± 0.34 ppt) and chlorophyll-a (5.41 ± 1.49 µg.L-1) were observed. Significantly lower growth rate (0.04 ± 0.02 g.day-1) recorded in Thaladuwa, where lowest salinity (13.29 ± 1.13 ppt), highest turbidity (19.26 ± 0.99 NTU) and ammoniacal nitrogen (0.368 ± 0.078 mg.L-1) were recorded. DWG showed a significant second-order polynomial relationships with chlorophyll-a (R² = 0.44, P < 0.05) and salinity (R² = 0.28, P < 0.05). Negative exponential relationships of DWG were evident with higher level of ammoniacal nitrogen (R² = 0.24, P < 0.05) and phosphate (R² = 0.25, P < 0.05). The high concentration of lead (1.883 mg.kg-1) exceeded the EU permissible limit of 1.5 mg.kg-1 (wet weight) in oysters’ tissue where urban wastewater is released to the lagoon. There appeared to be health concerns due to heavy metal accumulation in oyster tissues in polluted areas of the estuary. The findings of this study are useful for understanding the potential impacts of environmental changes on oyster resources and the long-term sustainability of oyster fisheries and aquaculture.