Environmental safety level of lead (Pb) pertaining to toxic effects on grey mullet (Mugil cephalus) and Tiger perch (Terapon jarbua)

Abstract

Acute and chronic bioassay toxicity test of Lead (Pb) in Grey Mullet (Mugil cephalus), and Tiger perch (Terapon jarbua) was conducted. LC50 values (Lethal Concentration) from acute tests and chronic values were calculated by the geometric mean of the No-Observed-Effect Concentration (NOEC) and the Lowest-Observed-Effect Concentration (LOEC) in a study period of 30 days. This research was conducted to evaluate the quantitative relationship between toxicity test statistics and correlation between toxicant and the organisms exposed. Three test average LC50 was analyzed for 24, 48, 72, and 96 h and the 96 h average LC50 of M. cephalus and T. jarbua is 2.57 ± 0.47 and 2.99 ± 0.23 mg/L of Pb, respectively. Significant correlation is observed with the increased time duration and exposure concentration. The NOEC and LOEC values were calculated based on survival of test organisms for M. cephalus and T. jarbua and the values are 0.014 and 0.029 and 0.011 and 0.022 mg/L, respectively. The chronic value is found to be 0.011 mg/L for M. cephalus and 0.021 mg/L for T. jarbua. The intensity of biochemical and histological alterations increased gradually with increased Pb concentration and the exposure time. Toxicity testing is the primary step to determine the water quality safe limit on marine organisms. The outcome of the study indicates that the sensitivity of juvenile organisms to Pb, persistence of toxic effects and biomarkers as a tool capable of revealing the toxic effects of heavy metals on the environment and aquatic biota.

A protocol for identifying suitable biomarkers to assess fish health: A systematic review

“…In laboratory toxicity tests, GSH/GSSH in gills and in whole fish (including M . cephalus ) increased following Pb exposures [69], while GSH/GSSG levels varied with tissue and life stage following Cd exposure [109, 110]. Specifically, results from the latter two studies indicate GSH/GSSG is biphasic, with increasing activity occurring up until a certain concentration after which levels decline [109, 110].…”

“…Similar to field studies the responses to Cu and to Cd, respectively, varied with tissue type and showed a biphasic response meaning it could not be used to confirm exposure to higher metal concentrations [109, 110, 116]. In contrast, Pb exposure resulted in a negative response in GST levels in gills and whole juveniles of two different fish species under all concentrations [69]. The absence of a biphasic response to Pb may be due to the metal concentrations not reaching threshold levels for this protein.…”

“…Notwithstanding, differences in CAT activity were identified between M . cephalus and Terapon jarbua following controlled Pb exposure [69]. Results from these toxicity tests show that CAT activity can be species, tissue, metal and concentration dependent [49, 69, 110, 116, 117].…”

“…Laboratory toxicity tests showed that LPOX activity in gills, liver or spleen significantly increased when fish were exposed to Pb, Cu or Cd [69, 116, 117]. LPOX activity, however, can vary with tissue, with an increase in gill and liver tissue following exposure to Cd or mixed metals in sediment, but not in kidneys [110, 113].…”

“…The relatively consistent changes in LPOX activity in response to metal exposures in a number of studies, including for M . cephalus [69, 72, 114], suggest this enzyme is a potential biomarker for assessing fish health in Gladstone. However, its suitability will depend on whether species-specific and seasonal responses can be differentiated from those resulting from metal contamination.…”