Wildlife officer Dave Johnson oversaw improvements to the waterside landscape around the lake in Queen Mary’s Gardens, which was de-silted and given a makeover.
Poor water quality risked damaging plants so 560sq m of common reeds went down.
The reed beds, which lock up nutrients and deter algae growth, include water mint, yellow flag iris and purple loosestrife and were funded by SITA Trust. Support came from the friends’ group and Royal Parks Foundation in partnership with BNP Paribas.
The reeds attract a range of birds, insects and amphibians, including dragonflies, damselflies, newts, frogs and toads, said assistant park manager Andy Williams.
"Birds including two black swans are returning to a vastly improved habitat. When it matures it will provide more shelter for other waterfowl such as mallards and coots but deter non-native geese whose excrement adds phosphates to the lake."