The toxicity of mercuric chloride and methylmercuric chloride to Fundulus heteroclitus embryos in relation to exposure conditions

Abstract

SynopsisEmbryos in specific stage of the estuarine teleost, Fundulus heteroclitus, were exposed to mercuric chloride (MC) and methylmercuric chloride (MMC) under several distinct treatment conditions. Four-eight cell stage eggs (O-day old) were exposed for 4 days (continuous), 2 days and one day to each mercury compound. Oneday old (mid-blastula), 2-day old (mid-neurula) and 5-day old (beating heart) embryos were exposed 4 days to MC and MMC. Mortality for the four days immediately following the initiation of exposure was the embryonic response measured. Under most exposure conditions to the 4-8 cell eggs, progressive and significant reductions in survival were observed at all concentrations above 40 and 30 pgHg++l-' as MC and MMC, respectively. Reducing the duration of exposure to 1 day most significantly increased the survival potential of the 4-8 cell eggs. For all exposure treatments to the 4-8 cell eggs, significant differences in survival, between eggs exposed to MC and MMC, were determined at 40,60 and 80 pgHg++l-', indicating the presence of compound-dependent response differences. In all cases demonstrating response differences between MC and MMC exposed embryos, survival was significantly lower following exposure to MMC. Survival of embryos was progressively increased when the initiation of continuous exposure (4 days) was delayed 1,2 and 5 days after fertilization. As a result, compound-dependent response differences were progressively shifted to higher Hg++ concentrations. For both MC and MMC, survival of l-day old embryos exposed for 4 days was greater than that of O-day old eggs exposed for 1 day. Of the embryonic stages examined, it appears that the earlier cleavage stages are the most sensitive to mercury intoxication.

Mercury distribution in different tissues and trophic levels of fish from a tropical reservoir, Brazil

“…Besides the fact that the earliest stages of cell division are the most sensitive to Hg toxicity in the fish embryonic period, methylmercury is more toxic than InorgHg in this situation (Sharp & Neff, 1982). In the present study, we found higher OrgHg concentrations than InorgHg in the gonads.…”

Mercury‐induced reproductive impairment in fish

“…Hatching success was decreased in embryos exposed to 15 μg/L, with no hatching occurring at higher concentrations. Short‐term (1‐ to 5‐d) exposure of mummichog embryos to higher concentrations of inorganic mercury (40 μg/L) and methylmercury (30 μg/L) decreased survival, whereas a subchronic (32‐d) exposure to 10 μg/L decreased hatching success [119,120]. Embryos of the mummichog exposed to 5 μg/L of methylmercury until 3 d posthatch demonstrated no change in their morphology yet exhibited impairment in the ability of larvae to capture prey [121].…”

Effects of Short Term Methylmercury Exposure on Growth and Development of the Large Yellow Croaker Embryos and Larvae

“…The present study showed that the 48-h LC 50 value of MeHg (28.39 µg L −1 ) to embryos of large yellow croaker was generally lower than fathead minnow (Pimephales promelas, 71 µg L −1 ; Devlin, 2006), killifish (Fundulus heteroclitus, 50 µg L −1 ; Sharp and Neff, 1982), zebrafish (Danio rerio, 90 µg L −1 ; Cambero and Calvo, 2010) and coho salmon (Oncorhynchus kisutch, 54-71 µg L −1 ; Devlin and Mottet, 1992), but higher than the Japanese flounder (Paralichthys olivaceus, 15.3 µg L −1 ; Ren et al, 2019). While the 48-h LC 50 (18.27 µg L −1 ) and 96-h LC 50 (9.28 µg L −1 ) values of MeHg to large yellow croaker larvae was much Frontiers in Marine Science | www.frontiersin.org ;Wobeser, 1975;Mozhdeganloo et al, 2015), blue gourami (Trichogaster trichopterus, 48-h LC 50 , 94 µg L −1 , 96h LC 50 , 89 µg L −1 ; Roales and Perlmutter, 1974) and Japanese flounder (48-h LC 50 , 20.7 µg L −1 , 96-h LC 50 , 16.3 µg L −1 ).…”

“…Additionally, the chorions during late embryogenesis will gradually break and thereby increase the susceptibility of the embryos to waterborne toxicants (Ren et al, 2019). Therefore, the sensitivity of embryos to toxicants could be related to the processes by which the chorions biologically function in response to the waterborne toxicants entering the embryos (Sharp and Neff, 1982).…”