'Lungs of the sea' defies odds by making comeback at former US nuclear submarine base

Yet in the space of a century, more than 90 per cent of Britain’s seagrass has vanished due to pollution, dredging and coastal development.

One area affected has been Holy Loch off Dunoon, Argyll, which feeds into the Firth of Clyde.

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Once rich in marine life, its seagrass beds were badly damaged in the mid to late 20th century, when the loch became home to a United States Navy nuclear submarine base.

Dredging, chemical contamination — notably copper and zinc — and run-off from agriculture and forestry are thought to have driven the habitat to local disappearance.

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But according to a new report in the scientific journal The Glasgow Naturalist, seagrass has made a spectacular and spontaneous comeback.

The findings are based on a detailed field survey carried out in mid-2025, covering about 20 hectares of shoreline at low tide.

Dr Neil Hammatt, warden of the Holy Loch Nature Reserve and a co-author of the study, said the first tentative signs of recovery were noticed in 2022.

“Since then the area has expanded and the beds have become denser,” he said.

“What makes this remarkable is that, unlike most recent UK examples, there has been no planting. This appears to be a natural regeneration.”

The species identified, Zostera noltii, plays a vital ecological role, acting as nurseries for fish and invertebrates, recycling nutrients and locking away carbon in sediments, making them a powerful ally in mitigating climate change.

The report suggests that seeds or fragments may have been carried into Holy Loch by tidal currents from neighbouring waters such as Loch Long or the Gare Loch.

The recovery follows decades of gradual ecological improvement since the American base closed in 1992. Given the loch’s industrial past, the authors describe the findings as “ecologically significant” and a rare insight into the conditions under which passive recovery can occur. Protecting such areas, the report argues, may be as important as actively restoring them.

More than six decades on, with the Cold War hardware gone, Dr Hammatt said: “Ultimately, this is evidence of nature’s ability, when left to its own devices, to bounce back from environmental degradation and is good news when it comes to tackling climate change.”

Holy Loch was no stranger to naval influence.

During the Second World War, the Royal Navy had based vessels there, sending them out on Atlantic operations.

By the early 1960s, however, the strategic stakes had risen sharply as the United States and the Soviet Union accelerated the expansion of their nuclear arsenals.

The Americans had developed the Polaris submarine-launched nuclear missile but needed a European base. An agreement with Britain brought the missiles to the Clyde. On 3 March 1961 the submarine tender USS Proteus — a vast veteran of the Pacific war — sailed into Holy Loch to establish the base. She carried 980 officers and men, along with up to 500 dependants, and acted as a floating support ship for the ballistic missile submarines. While crews rotated in and out by air, families settled along the loch.

The arrival of Polaris submarines in British waters was controversial from the start. The day after the Proteus docked, about 1,000 protesters marched along the shore, according to reports at the time.

The impact was felt not only in strategic terms but also brought a culture shock to the area, albeit some economic benefit. Nearby Dunoon, whose heyday as a seaside resort was already fading by 1961, was transformed by the sudden influx of American sailors and their families.