Mercury Levels in the Red Lobster Panulirus penicillatus, Green Lobster Panulirus gracilis, and Octopus Octopus oculifer Across the Galápagos Archipelago

Mercury analysis was conducted on leg muscle from red lobster (Panulirus penicillatus, n = 77), green lobster (Panulirus gracilis, n = 14), and arm muscle from octopus (Octopus oculifer, n = 27) collected across the Galápagos Archipelago. Lobster mercury concentrations (dry weight, DW) showed differences between species and were associated with carapace length, sex and location within red lobsters. Mercury concentrations ranged from 0.16 to 1.12 mg kg−1 in red lobsters (mean = 0.42 ± 0.19 mg kg−1) and 0.12–1.26 mg kg−1 in green lobsters (mean = 0.35 ± 0.32 mg kg−1). After accounting for carapace length, red lobsters had higher model-adjusted mercury concentrations than green lobsters, although the difference was sensitive to heteroscedasticity. Among red lobsters, females had higher mercury concentrations than males. Model-adjusted mercury concentrations also varied among islands, with the highest estimates in Española and Isabela and the lowest in Santa Cruz. Mercury concentrations in octopus ranged from 0.11 to 1.71 mg kg−1 DW (mean = 0.30 ± 0.30 mg kg−1 DW) and the primary analysis including all observations provided little evidence of a difference in mercury concentrations between the two islands. Estimated wet-weight mercury concentrations for the three species were generally below relevant US and EU regulatory thresholds, with exceedances limited to one green lobster and one octopus. Future research should focus on larger sample sizes and analysis of tail muscle, which may contain higher mercury concentrations.