Antarctic octopod beaks as proxy for mercury concentrations in soft tissues

Area of Science:

• Marine Biology
• Ecotoxicology
• Biogeochemistry

Background:

• The role of mercury (Hg) in Southern Ocean biota remains poorly understood.
• Octopods are abundant in the Antarctic ecosystem, making them important indicators of environmental contamination.
• Assessing mercury burdens in marine invertebrates is crucial for understanding food web dynamics and potential risks.

Purpose of the Study:

• To evaluate total mercury (T-Hg) concentrations in key tissues of two abundant octopod species, Adelieledone polymorpha and Pareledone turqueti, around South Georgia.
• To investigate the potential of using octopod beaks as a non-lethal proxy for estimating total mercury body burden.

Main Methods:

• Collected Adelieledone polymorpha and Pareledone turqueti specimens from the South Georgia region.
• Quantified total mercury (T-Hg) concentrations in upper/lower beaks, digestive gland, gills, and mantle muscle using established analytical techniques.
• Analyzed relationships between T-Hg concentrations in different tissues, particularly between beaks and muscle.

Main Results:

• Beaks exhibited the lowest T-Hg concentrations across both species, significantly lower than digestive glands, gills, and muscle.
• Digestive glands showed the highest T-Hg concentrations in both Adelieledone polymorpha and Pareledone turqueti.
• A significant positive correlation was found between T-Hg concentrations in beaks and muscle for Adelieledone polymorpha, with muscle tissue containing approximately 10 times higher T-Hg than beaks.

Conclusions:

• Octopod beaks can serve as a reliable proxy for estimating total mercury concentrations in muscle tissue for certain species.
• This finding offers a valuable, potentially non-lethal method for assessing mercury body burden in octopods and other cephalopods.
• Further research is warranted to validate this proxy across a wider range of cephalopod species and geographic locations.