Nature - 2019.08.29

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nature research | reporting summary

April 2018

Field-specific reporting

Please select the best fit for your research. If you are not sure, read the appropriate sections before making your selection.

Life sciences Behavioural & social sciences Ecological, evolutionary & environmental sciences

For a reference copy of the document with all sections, see nature.com/authors/policies/ReportingSummary-flat.pdf

Ecological, evolutionary & environmental sciences study design

All studies must disclose on these points even when the disclosure is negative.

Study description

Research sample

Sampling strategy

This study presents a new model for the influence of ecosystem change on methylmercury bioaccumulation in marine food webs of

the Northwestern Atlantic Ocean over the past 30 years. Empirical data were used to quantitatively evaluate a mechanistic

simulation model for methylmercury bioaccumulation and evaluate changes over time.

Data include concentrations of methymercury measured in a variety of marine species from the Northwestern Atlantic Ocean,

stomach contents data from government databases, previously published data on seawater temperature anomalies, and seawater

concentrations of dissolved organic carbon and methylmercury, and sediment concentrations of methylmercury.

This study was based on all available data/samples over the last 30 years. No new sampling was conducted.

Data collection Data were collected from diverse sources in the peer-reviewed literature and government databases.

Timing and spatial scale

Data exclusions

Study focuses on model evaluation for the 2000-2003 period and patterns in temperature and methylmercury accumulation

between the 1970s to present in the Northwestern Atlantic Ocean.

We present results for temporal changes in a single tuna age/length class of Atlantic bluefin tuna. Other ages/lengths

would require additional simulations and are not included in this study.

Reproducibility All results are reproducible with code provided in this study.

Randomization

Blinding

Did the study involve field work? Yes No

Reporting for specific materials, systems and methods

Materials & experimental systems

n/a Involved in the study

Unique biological materials

Antibodies

Eukaryotic cell lines

Palaeontology

Animals and other organisms

Human research participants

Methods

n/a Involved in the study

ChIP-seq

Flow cytometry

MRI-based neuroimaging

Blinding was not relevant to this study because it involved a synthesis of data on fish Hg concentrations and ecological shifts.

Data on fish Hg concentrations were selected for similar length/age categories to ensure comparability. No randomization was needed.

This study does not include new experimental results. Code has been validated.