Abstract
Background: This study aimed to analyse levels of heavy metals (Pb, Hg and Cd) in the aquatic body, gills and stomach of the oysters Crassostrea cuculata and Crassostrea glomerata, the metallothionein (MT) level in the gills and stomach of both oysters, and relationships between heavy metals level (Pb, Hg and Cd) in the gills and stomach to MT level in both types of oysters. Methods: The research method utilized was a descriptive method. The oyster samples were taken from three stations: Sendang Biru, Popoh and Prigi beaches. MT values were assessed using confocal laser scanning microscopy. The heavy metal levels were assessed using atomic absorption spectrophotometry method. Results: Both oyster heavy metal content obtained in the southern coastal waters exceeded the safe limit set by the State Minister of Environment No. 51 of 2004. In general, the expression of MT was found to be higher in gastric tissue compared to gill tissue. Conclusions: The relationship between levels of the heavy metals Pb, Hg, and Cd in oyster gills and stomach has a strong relationship with MT levels in the gills and stomach in both types of oysters.
Highlights
Coastal areas are often under the pressure of ecological pollution originating from human activities
This study aims to analyze heavy metal level (Pb, Hg, and Cd) in the tissues of oysters (Crassostrea cuculata and Crassostrea glomerata) and the coastal waters of the South coast of East Java to determine their relationship to MT (MT) expression
Heavy metal analysis Heavy metals (Pb, Cd, and Hg) in oysters and the seawater at each sub-station were measured by atomic absorption spectrophotometry (AAS) following the measurement procedures in previous studies carried out by Hertika et al, 201817 A total of 50 ml seawater samples obtained from each substation were filtered with a 0.45-mm polycarbonate membrane to separate particles which caused contamination in heavy metal measurements
Summary
Coastal areas are often under the pressure of ecological pollution originating from human activities. Heavy metals settle on the bottom of the seabed by sedimentation. This can contaminate marine biota with heavy metals and threaten human health as consumers[3,4,5,6,7]. MT has been widely used as a specific biomarker because the expression of MT reflects the presence of heavy metals[13,14,15]. Previous research has revealed that the induction of MT expression increases after the organism is exposed to heavy metals[16]. Hertika et al.[17] found the existence of positive relationships between heavy metals and MT expression in North East coast oysters. Results: Both oyster heavy metal content obtained in the southern coastal waters exceeded the safe limit set by the State Minister of Environment No 51 of 2004. Conclusions: The relationship between levels of the heavy metals Pb, Hg, and Cd in oyster gills and stomach has a strong relationship with MT levels in the gills and stomach in both types of oysters
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