Mercury bioaccumulation and biomagnification in Ozark stream ecosystems

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Isotope Geochemistry

Background:

• Mercury (Hg) contamination is a global environmental concern, impacting aquatic ecosystems and food webs.
• Understanding Hg transfer pathways is crucial for assessing ecological and human health risks.

Purpose of the Study:

• To investigate mercury (HgT) transfer pathways in Ozark stream food webs.
• To analyze the relationship between HgT concentrations, stable isotopes (δ¹³C, δ¹⁵N, δ³⁴S), and trophic position in various aquatic organisms.
• To evaluate HgT levels in crayfish, Asian clam, northern hog sucker, and smallmouth bass.

Main Methods:

• Analysis of total mercury (HgT) and stable isotopes (δ¹³C, δ¹⁵N, δ³⁴S) in crayfish, Asian clam, northern hog sucker, and smallmouth bass.
• Calculation of trophic position (TP) using δ¹⁵N values.
• Statistical modeling (ANCOVA, regression) to predict HgT concentrations based on TP and organism length.

Main Results:

• HgT concentrations were lowest in crayfish and highest in smallmouth bass.
• HgT levels were higher in biota from mining-influenced streams compared to forested watersheds.
• HgT concentrations in hog suckers and smallmouth bass were strongly correlated with HgT in crayfish, but not Asian clams.
• Trophic position and organism length were significant predictors of HgT concentrations in fish.

Conclusions:

• Crayfish play a significant role in HgT transfer to higher trophic levels in Ozark streams.
• HgT concentrations in fish are influenced by their diet, trophic position, and growth rates.
• Elevated HgT levels in smallmouth bass and hog suckers present a potential risk to human health and wildlife.