Mercury Concentrations in Whale Shark (Rhincodon typus) Embryo Muscle Tissue

Area of Science:

• Marine Biology
• Environmental Toxicology
• Conservation Science

Background:

• Mercury (Hg) is known to transfer from mother to embryo in sharks.
• Embryonic Hg concentrations in filter-feeding shark species remain largely unreported.
• Understanding Hg transfer is vital for assessing risks to marine predators and ecosystems.

Purpose of the Study:

• To quantify total mercury (THg) concentrations in whale shark (Rhincodon typus) embryos.
• To compare THg levels in whale shark embryos with those of other shark species.
• To investigate potential relationships between THg concentration, body length, and sex in whale shark embryos.

Main Methods:

• Muscle tissue samples were collected from 27 whale shark embryos.
• Total mercury (THg) concentrations were measured using established analytical techniques.
• THg data were statistically compared with existing literature values for other shark embryos and analyzed for correlations with embryo size and sex.

Main Results:

• Whale shark embryos exhibited a mean THg concentration of 0.0762 ± 0.0163 µg/g dry weight (0.0224 ± 0.0054 µg/g wet weight).
• No significant correlation was found between muscle THg concentration and embryo body length.
• No significant difference in THg concentration was observed between male and female embryos (p > 0.05).

Conclusions:

• Whale shark embryos possess the lowest reported muscle THg concentrations compared to other studied shark embryos.
• This finding suggests a potentially lower mercury burden in this filter-feeding species during embryonic development.
• Further research is warranted to understand the implications of these low THg levels for whale shark populations and marine food webs.