Tails and fins: Subtle changes in growth following chronic embryonic exposure to AC electromagnetic fields in elasmobranchs

Abstract

Tails and fins: Subtle changes in growth following chronic embryonic exposure to AC electromagnetic fields in elasmobranchs Annemiek Hermans 1, Jeroen Hubert 2, Antonio P Chiovaro 2, Eva Witsen 2, Tom Spanings 2, Hendrik V Winter 3, Edwin M Foekema 4 Affiliations Expand PMID: 42247836 DOI: 10.1016/j.marpolbul.2026.119937 Abstract Subsea power cables used to transport offshore wind-generated energy emit electromagnetic fields (EMFs) into the marine environment. These anthropogenic fields overlap with naturally occurring biotic and abiotic EMFs that elasmobranchs can detect and use for navigation, prey detection and predator avoidance. When egg-laying sites overlap with subsea cables, embryos may be chronically exposed to EMFs throughout development, yet the effects remain largely unknown. We compared the morphology and behaviour of thornback skate (Raja clavata) and small-spotted catshark (Scyliorhinus canicula) juveniles exposed to alternating current EMFs (1.8 and 4.6 μT) throughout embryogenesis, with an unexposed control group. In skates, tail length was significantly shorter (5.3%) in exposed individuals at both one and three months post-hatching, while in exposed sharks, the pectoral fins were 11.2% larger at birth, a transient effect that disappeared after one month. These results may indicate subtle changes in growth of EMF exposure. As tail/fin-to-body ratios were unchanged, the extremities could be proxy for overall differences in length, possibly obscured by postural variation. Activity levels and ventilation rates did not differ between treatments, nor were startle or avoidance responses observed following acute EMF exposure. However, sharks showed a significant difference in ventilation rate between 0.1 μT (background) and 10 μT, indicating EMF detection. We conclude that chronic exposure during embryogenesis causes subtle, species-specific growth effects without behavioural impairment. Although ecological relevance of these findings is unclear, it highlights the need for caution when extrapolating EMF sensitivity across elasmobranch species.

AI evidence extraction

Main findings

Chronic embryonic exposure to AC EMFs (1.8 and 4.6 μT) caused subtle, species-specific growth changes: shorter tail length in skates and larger pectoral fins at birth in sharks, with no behavioral impairments observed. Sharks detected EMF at higher intensities but activity and ventilation rates were otherwise unaffected.

Outcomes measured

• tail length
• pectoral fin size
• activity levels
• ventilation rates
• startle responses
• avoidance responses

Limitations

• sample size not reported
• ecological relevance unclear
• only two species studied
• postural variation may obscure length measurements

Suggested hubs

• occupational-exposure (0.3)
  Study of EMF exposure effects, though in marine animals rather than humans.
• environmental-exposure (0.9)
  Exposure to EMF from subsea power cables in marine environment affecting wildlife.

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    "study_type": "randomized_trial",
    "exposure": {
        "band": "extremely low frequency",
        "source": "subsea power cables",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "chronic embryonic exposure throughout development"
    },
    "population": "thornback skate (Raja clavata) and small-spotted catshark (Scyliorhinus canicula) juveniles",
    "sample_size": null,
    "outcomes": [
        "tail length",
        "pectoral fin size",
        "activity levels",
        "ventilation rates",
        "startle responses",
        "avoidance responses"
    ],
    "main_findings": "Chronic embryonic exposure to AC EMFs (1.8 and 4.6 μT) caused subtle, species-specific growth changes: shorter tail length in skates and larger pectoral fins at birth in sharks, with no behavioral impairments observed. Sharks detected EMF at higher intensities but activity and ventilation rates were otherwise unaffected.",
    "effect_direction": "mixed",
    "limitations": [
        "sample size not reported",
        "ecological relevance unclear",
        "only two species studied",
        "postural variation may obscure length measurements"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.6999999999999999555910790149937383830547332763671875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "elasmobranchs",
        "embryonic exposure",
        "alternating current electromagnetic fields",
        "growth effects",
        "behavioral effects",
        "subsea power cables",
        "marine environment"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.299999999999999988897769753748434595763683319091796875,
            "reason": "Study of EMF exposure effects, though in marine animals rather than humans."
        },
        {
            "slug": "environmental-exposure",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Exposure to EMF from subsea power cables in marine environment affecting wildlife."
        }
    ]
}

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