Lake and Pond Management for Wildlife

The Royal Parks are home to a startling array of wildlife, much of which depends on the many ponds, lakes and watercourses which dot the landscapes. Some are natural bodies of water, others have modified over the centuries and many have been created specifically for either decorative or ecological reasons.

The Serpentine in Hyde Park was created by Charles Bridgeman, gardener to Queen Caroline, by damming the River Westbourne to create a natural-looking artificial lake; the Longford River which winds through Bushy Park was created on the instructions of Charles I to provide water for Hampton Court Palace and then later redirected to create Heron Pond and Leg-of-Mutton Pond. Even the more formal ponds, such as Round Pond in Kensington Gardens, attract wildfowl and provide safe havens for thousands of birds.

Whatever their origins, each body of water provides a habitat of some kind for aquatic life, which in turn supports so much more of the biodiversity in the parks. There are a number of lake and pond management techniques we use to help maintain and develop that biodiversity, as well as ways to make it accessible for learning.

Lake and pond water quality management

Oxygen is one of the necessities for life on earth. Without it most plants and animals simply cannot survive, and aquatic flora and fauna are no different – they rely on oxygen dissolved in the water. If levels get low, perhaps because of sluggishly flowing streams or too much decomposing plant matter, then plants start to die and the animals which rely on them do too.

The more formal bodies of water, like the Round Pond in Kensington Gardens, are very obviously man-made and have man-made mechanisms designed to keep them healthy. Two freshwater inlets (you might have seen them, two mushroom-shaped projections above the water) inject cool, fresh water pumped from boreholes deep below the Italian Gardens and the Lido. This ensures that the water doesn’t stagnate or overheat in summer and is controlled from consoles at each location. Park teams regularly manage lake and pond water quality by inspecting the water for signs of imbalance (excess algal growth is a key one) and adjusting the flow accordingly.

The water’s journey doesn’t stop there – it sluices through an outlet and pipes to the Long Water, helping to oxygenate the more wildlife-focused lake. From there it mingles with its sister the Serpentine, whose outflow goes through The Dell and on eventually, via tunnel, to the Thames, following roughly the same course as the river Westbourne which originally flowed through what is now Kensington Gardens and Hyde Park.

Lake and pond management in action

Bushy Park’s waterways are less obviously man-made but are subject to no less rigorous pond management regime. On the slow-flowing floodplain of the park the dangers to aquatic life are gradual and more subtle but all the more closely monitored because of this. The Longford River separates into multiple strands through the Woodland Gardens, and this slows the water’s movement, losing energy and dropping sediment more easily.

It’s also moving through deciduous woodland which drops tonnes of leaves into the courses in the autumn and winter. This mix is why, following surveys in 2018 and August 2020, we took the decision to desilt and work on some key parts of the waterways to help boost waning oxygenation and the plant and animal life which relies on it.

Right in the heart of this project were Fisher’s Pond and its feeder streams in the Waterhouse Woodland Gardens. The slow flow of the water through these sections had led to silting up which meant that plant life wasn’t thriving as well as it could and its dependent animals, both in and out of the water, could be better served too. Carefully designed works, overseen by heads of conservation, landscape and ecology collaborating with our dedicated Mission: Invertebrate project group and park management, were undertaken through the autumn/winter of 2020 to desilt the pond and waterways.

The pond itself went from being a few inches deep, even near the centre, to becoming a deeper and more vital space. The waterways around it were dredged and banks renaturalised to wind back and forth more like a natural river, rather than in an artificially straight line. This offers the water a chance to flow faster and more naturally, carrying life-giving oxygen to all parts of the system as well as a diversity of habitat niches that host all sorts of aquatic life.

The results of these works are still developing at the time of writing, but this spring there have been sightings of bullheads and other native fish which are rarely spotted. The rich alluvial mud which was taken from the pond and streams has been used to create new habitat and a basis for native planting around the edges of the water which is starting to take root. The streams are visibly clearer and animal life is more abundant. As 2021 progresses we’re hoping to see both the flora and fauna thrive, giving new life and new resilience to the ecosystem of the park for generations to come.

Invasive species and biodiversity management

In most cases, all our efforts go into allowing species to thrive. Sometimes though, that means taking measures against non-native ones which have been introduced, usually by accident, though sometimes by design. For example, terrapins kept in home aquaria have been released when they grow larger than their owners anticipated. Similarly, carp kept in home ponds are sometimes removed and rehomed illegally and there’s always the danger of the American Signal crayfish. Aquatic plants can also crowd out native ones and a recent set of improvements to ponds in Richmond Park had removal of these at its heart.

As well as removing silt, clearing overhanging vegetation and deepening ponds like Bishops’ pond, golf course island pond, Ham Cross pond and Dann’s Valley pond, the Mission: Invertebrate team, working with the ecology team, identified several alien species to be removed. The Holly Lodge centre pond had a population of Nuttall’s waterweed excised (you might recognise this American species, it’s often found in home aquaria), as did White Ash pond, while Gallows pond was host to invasive New Zealand pigmy weed. When removed, the plants are heaped together at a secure location some distance from any water, covered in geotextile membrane and composted.

Habitat creation and protection

As mentioned before, the parks are home to a huge array of bodies of water, created for many different reasons over the centuries. Often biodiversity was not first among these so one of the continuing strands of work we carry out is to enhance the water quality to encourage its biodiversity as much as we can.

For example, the Serpentine may have been created from a series of small fishponds, but the safety of juvenile fish was not the first thing on Queen Caroline’s mind, or that of the engineers who helped her build it. The lake offers little natural cover for them so at selected points, especially near the bridge which divides it from the Longwater, we’ve installed underwater cages which are filled with sticks and other debris to create areas of safety for the fry of many species. This material decays over time so regular re-stockings help keep the young fish safe.

Another more extensive example is a set of works that were carried out in and around the lake in The Regent’s Park. This body of water fulfils many roles, offering sanctuary to native and migratory waterfowl and space to escape on a hired boat, as well as being an important refuge for native aquatic species.

In late 2020 and early 2021, a programme of works was carried out to deepen the lake in selected places, cooling it and providing better refuge for larger fish. The material taken from the base of the lake was used to enhance littoral areas (those around the edge of the water) by offering more sloping and shallow-water habitat, ideally suited to semi-aquatic plants. As well as enhancing the reedbeds we already had, more planting was put in place around both the margins of the lake (think marsh marigolds, spearworts, rushes and pond sedge) and in sunken cages where submerged and floating native plants could be allowed to thrive (hornwort, water violets, starwort and white waterlilies). Between them these plants not only add further oxygen to the water but also provide shelter and food for aquatic animals, all the while offering a beautiful vista for visitors to enjoy.

Learning opportunities

As well as highlighting the thriving wildlife within the parks, we’re always seeking new ways to allow visitors to learn about it too.

The LookOut in Hyde Park is a purpose-built learning centre with ponds within its enclosed grounds, that school groups have been enjoying since it was opened in 2010. In addition to these small ponds, the larger bodies of water nearby also offer a great opportunity for learning.

The Longwater in Kensington Gardens is a more ecologically-focused lake than its sister, the Serpentine, and it’s here that we recently created a brand new pond dipping platform to allow more people to explore freshwater ecology in the parks. To do this we created a pond within a lake – a semi-circular gravel bund, five metres in radius, ten metres across at the bank, planted with marginal and aquatic species with a bird-proof fence and fish carefully excluded to allow aquatic invertebrates and amphibians to thrive. A simple but sturdy wooden platform gives access and on a good day several school groups can explore the rich wildlife to be found just below the surface.

Planning for a resilient future

As an organisation, The Royal Parks is both old – the landscapes date back for hundreds of years – and very young, our charity having been created in 2017. We are the caretakers and caregivers for nearly five thousand acres of parkland, crossed and dotted by bodies of water old and new.

By caring for each and every one of these, improving them wherever we can to provide greater biodiversity and more resilience to the challenges of climate change, we hope to play our part in creating a better future.