This Week in The Jungle: Clearing the Second Pond
Morning light filtered through the canopy last week, glinting off the still waters of the Second Pond in Heligan’s Jungle. The air was warm, heavy with the scent of ferns, and the only movement came from a moorhen rippling the shallows. Then, from the shadows, Henry and Jungle Pete appeared at the water’s edge, untying the small boat that waits quietly under the shelter of overhanging foliage. Nets in hand, they pushed out into the green silence with the steady calm of men who know every inch of this place.
Their task was simple in theory, demanding in practice: clearing the summer surge of Net Weed, a catch-all term for mats of filamentous algae and invasive floating aquatic plants that thrive in warm, nutrient-rich water. In high summer, fed by long days and bright sunlight, the weed can spread with startling speed, turning open water into a dense green raft.
They worked slowly across the pond, dipping long-handled nets deep below the surface to haul up dripping, heavy armfuls of weed. Each netful teemed with tiny pond invertebrates, a reminder of the care needed for such work. Henry explained that this is not a battle to remove the weed entirely, but to keep it in balance as part of the Jungle’s new pond management plan. Left unchecked, the dense mats block sunlight from reaching the submerged plants below. These plants are more than decoration — they produce oxygen, stabilise sediment, and form the first tier of the pond’s food web. Without light, photosynthesis slows, oxygen drops, and fish, amphibians, and insects can become stressed. On warm, still nights, this can lead to sudden and sometimes fatal oxygen crashes.
From now on, the ponds will be cared for under a rolling management plan. Each year, one pond will be drained and de-silted, beginning at the top of the valley and moving gradually down to the bottom before the cycle starts again. Net Weed clearance will remain a summer-only task, lighter and more targeted, designed to prevent oxygen crashes and keep the habitat in balance.
In a pocket of sunlight between the tree ferns, Pete spotted a flicker of movement — a Great Diving Beetle, one of Britain’s largest and most striking water beetles. These swift predators hunt tadpoles, insect larvae, and even small fish, making them vital to the pond’s ecology. Their presence signals a healthy, functioning system.
Henry also spoke about another species the ponds are supporting: the water vole. Once a common sight across Britain, their population has been devastated by habitat loss, pollution, and invasive American mink. Last year, water voles were introduced to several spots in the Lost Valley, at the Jungle’s foot. Since then, they have been seen in the top pond, which offers the dense vegetation they need for food, nesting, and cover from predators. With careful management of plant diversity and weed growth, Henry hopes the voles will gradually travel down through the chain of ponds, making the Second Pond part of their range.
Well-vegetated pond edges are key to this vision. Marginal plants — reeds, sedges, and native flowering species — form a living fringe that protects against predators, shelters young wildlife, and provides food throughout the year. Around the Second Pond, perches have been set for kingfishers, which flash turquoise as they hunt sticklebacks. These small fish are not only prey for the kingfishers but also a sign of clean, well-oxygenated water.
The Second Pond is more than a tranquil view. Like all the ponds in the Jungle, it is a living thread to the Victorian era, when Heligan’s mild Cornish climate sparked a passion for subtropical gardens. In those days, ponds were designed to dazzle the eye and provide humidity for exotics such as tree ferns and gunnera. Henry and Pete’s work keeps that heritage alive while ensuring the ponds remain rich habitats for modern wildlife.
By late afternoon, the Second Pond lay open to the sky once more. Visitors might see only a shimmer of water in the Jungle’s chain of ponds, but below the surface, change is already unfolding. Submerged plants stretch toward the light, oxygen levels rise, and the pond’s wildlife enters another season in a safe and balanced sanctuary.
