Low mercury content in Seychelles

Overview

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Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

• duce mercury into the marine ecosystem. Previous reaching up to 0.1 mg/kg (Squadrone et al., 2018). Even
• marily focused on fish, with results indicating similar nia radiata, reaching 0.17 mg/kg (Smith et al., 2010),
• mercury content to be below 0.5 mg/kg for most food ing the influence of species, collection site, and water
• of particular interest for their applications in food, (Table 1). Certain locations were classified as polluted
• Table 1. Description and co-ordinates of seaweed collection sites around Mahé Island, Seychelles, with details on habitat characteristics, anthro-
• ured on site using a Hach HQ1130 portable water qual- samples without requiring any pre-treatment. Sam-
• condition the seawater prior to using AP152 tablet rea- centrated in a gold amalgamator, then released into
• method was approximately 0.00001 mg/kg. (Fernán
• Figure 1. Boxplot illustrating mercury content (mg/kg) across different seaweed species. The x-axis represents the seaweed
• had the highest observed mercury content of 0.0055 mg/kg (Fig. 1). The species of seaweed had a significant
• mg/kg in Asparagopsis taxiformis from Anse Forbans, influence on mercury content ( H = 10.686, df = 4, p =
• Correlation analysis was performed to assess the rela- highest median mercury content (0.0019 mg/kg).
• ammonia nitrogen, nitrate, phosphate, and nitrite, to 0.0004 mg/kg), indicating high variability within the
• iro-Wilk test confirmed that the data for polluted it had a smaller sample size (n = 3) compared to the
• compare mean mercury contents between the two cant (H = 6.962, df = 5, p = 0.224; Fig. 2). This suggests
• all seaweed species and sites was 0.0017mg/kg (wet relationships between mercury content in seaweed
• Figure 2. Boxplot illustrating mercury content (mg/kg) in seaweed samples collected from various sites. The x-axis
• represents the different collection sites which are described in more detail in Table 1.
• Figure 4. Boxplot comparing mercury content (mg/kg) between seaweed samples of various species collected from
• pogenic activities in the area (as described in Table 1).
• = 27, p = 0.9284). The mean mercury contents were in other studies, where species differences significantly
• mg/kg, unpolluted: 0.00158 mg/kg, Fig. 4). Similarly, Smith et al., 2010). This interspecies variation suggests
• Gracilaria salicornia at 0.0038 mg/kg (wet weight), seaweeds. Even the sample with the highest mercury
• ards of 0.5 mg/kg set by the World Health Organi- ‘unpolluted’ due to low anthropogenic influence. This
• of 0.3 mg/kg (The European Commission, 2022). indicating high variability within the same location.

Methods (brief)

• September 9, 2025 when derived products are used. Samples were collected from different sites in Seychelles,
• option for development. High mercury levels could important seaweed species collected from areas con-
• species is targeted for its unique properties and appli- Seaweeds were collected on the 22nd of August 2024
• Caulerpa racemosa, commonly known as sea grapes, is were. Samples were collected by snorkelling or wading.
• ing opportunity for local consumption in Seychelles’ contamination. At each site, samples were taken from
• their use in fertilizers and animal feed, while Aspara- rate from each other. At least 10 g of each sample was
• gopsis taxiformis has gained attention for its potential collected. Each seaweed sample was kept in 1 L sample
• pogenic influence, pollution classification, and seaweed species collected. Sites were categorized as polluted or unpolluted based on proximity to
• Site Description Anthropogenic influence Considered Seaweeds collected
• box at approximately 20 °C. The bottles with the sam- solid samples. Each seaweed and site sample had
• samples was observed between collection and analysis. tion was conducted using a Milestone DMA-80 mer-
• ured on site using a Hach HQ1130 portable water qual- samples without requiring any pre-treatment. Sam-
• ples at each site were collected in 1 L sample bottles that were loaded into the instrument’s autosampler. The
• sample collection. The bottles were kept in a cooler box decomposition furnace, where samples were dried
• lection, the water samples were tested for total ammo- tion products were carried through a heated catalyst,
• The mercury content of the seaweed samples was Statistical analysis
• y-axis shows the mercury content observed in the samples, with each boxplot representing the range of contents for each
• was used to evaluate differences in mercury content sample of G. salicornia from Port Glaud, at 0.0038 mg/

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Seaweed/kelp foods (nori, wakame, kombu, dulse — as food products)
• Mercury
• Mercury
• Arsenic
• Nickel

Verification notes

• Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
• Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
• Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
• Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
• HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.