Seasonal patterns of mercury bioaccumulation in lobsters

Overview

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Key numbers

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total Hg levels in legal-sized lobsters (carapace length: 8.255–12.5 cm; n = 34) collected during
sizes were similar in early and late seasons. The average chelipod size was ~7% larger in male
consumption (<0.2 ppm). Compared to late-season lobsters, early-season lobsters had significantly
higher Hg levels in tail (~55% increase; 0.130 ppm vs. 0.084 ppm; p < 0.05) and hepatopancreas
tissues (~29% increase; 0.099 ppm vs. 0.077 ppm; p < 0.05), suggesting that seasonal factors
of meat (0.2 parts per million (ppm)) to be safe. The global increase in Hg pollution renders
lobsters at the mouth of the Penobscot River contained high levels of Hg (0.293 ppm),
sizes outside the legal collection range (8.255–12.5 cm) were immediately released along
per time point) for 34 lobsters (male: n = 22; female: n = 12). The requirement to release
spectrophotometry. This instrument has a detection range of 0.05–500 ng, a precision
of 0.25 ppb, and a readability of 0.1 ppb, as well as standard sample calibration and
sizes revealed that male lobsters, on average, had claws that were 7.4% larger than those
Because we did not observe overt sex-biased differences in external anatomy (e.g., >10%
0.05) (Figure 5a). Similarly, the mean carapace length was 8.64 cm in the early season and
eggs) contained significantly higher Hg levels (mean = 0.1088 ppm) than tomalley (mean =
0.088 ppm) (p < 0.05) and claw tissue (mean = 0.087 ppm) (p < 0.05) (Figure 6). There was
trend, indicating that larger lobsters (~800 g) may have about ~50% more Hg than smaller
g) exhibited disproportionately high Hg levels (>0.15 ppm) (Figure 7). Although our data
MeHg (1). They found that most of the radioactive Hg (68%) was retained in the
hepatopancreas (tomalley) and only 8% in tail tissue. However, if a lobster was exposed
to ambient water containing radiolabeled MeHg, 23% of the Hg was retained in tomalley,
while 50% was retained in tail muscle. Hence, the uptake of MeHg in tomalley and tail
Italy) was higher in the tail muscle of cooked lobsters (0.75 ppm) compared to raw tail
muscle (0.51 ppm) (22). The authors concluded that boiling likely increases the sensitivity
higher total Hg levels in their tails, with a 54% increase (0.130 ppm) compared with
late-season lobsters (0.0844 ppm; p < 0.05) (Figure 8a). The average total level of Hg in
tomalley of lobsters harvested in the early season was also significantly higher at 0.099 ppm
versus 0.0766 ppm in the late season (29% difference; p < 0.05) (Figure 8b). In contrast,
there was a nonsignificant difference (~14%) in the level of total Hg when comparing claws
of lobsters from early season (0.0925 ppm) versus late season (0.0812 ppm) (p > 0.05)
for the observed ~14% increase in early-season lobsters, particularly if catch-and-release
for more than 50 years, it is notable that the levels of MeHg detected in our study were
and lobster biology but also for the safety of seafood consumers worldwide. Only 8.8%
the European Union has a less stringent Hg threshold of 0.5 ppm for the consumption of
a food safety perspective, all lobster specimens (n = 34) examined in this study meet the
rigorous EU standards for Hg content in seafood (Hg < 0.5 ppm), with only three specimens
showing a slight elevation (~0.2 ppm) above the more stringent U.S. threshold (Hg < 0.2
lobsters collected in Casco Bay, ME (n = 34; Pearson’s r = 0.87; R2 = 0.76).
1. versus male American lobsters (n = 22). Middle horizontal lines in the gray boxes

Methods (brief)

total Hg levels in legal-sized lobsters (carapace length: 8.255–12.5 cm; n = 34) collected during
were analyzed using atomic absorption spectroscopy. Hg in ambient water was undetectable,
Lobsters were collected in the Casco Bay waters (43.68°N, 70.18°W) of the Gulf of
compliance with state regulations. Legal-sized lobsters were collected every 2–4 weeks (4–6
fertile female lobsters largely accounts for the resulting sex bias in the sample.
were collected as wet tissues from the crushing claws, tails, and tomalley. Specimens were
Lobster tissue specimens were tested for total Hg content by atomic absorption spectroscopy
using a Leco AMA254 Advanced Mercury Analyzer (St. Joseph, MI) at Exact Scientific
Services laboratories (Ferndale, WA). This equipment combusts samples in the presence
ash) using a catalytic device. Hg is collected by adsorption onto a gold amalgamator trap.
of 0.25 ppb, and a readability of 0.1 ppb, as well as standard sample calibration and
length (cm), claw length (cm), and total weight (g). Our sampled lobster cohort included
levels in lobster tissues from the Gulf of Maine, we analyzed samples using atomic
absorption spectroscopy. This method combusts the samples, collects the resulting Hg vapor,
and quantifies it. We assessed the mean total Hg levels in different body parts of all sampled
Hg levels in surface water samples collected throughout the year were below the level of
specimen weight. Linear regression analysis of the atomic absorption spectroscopy data
and tomalley may be influenced by technical factors in sample processing that affect

Implications

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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.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised