Olympic gold medallist Etienne Stott was arrested on Waterloo Bridge as police cleared Extinction Rebellion activists from the final section of carriageway.
The London 2012 canoe slalom champion was carried from the bridge by four officers on Sunday evening as he shouted about the "ecological crisis".
It came as the protests calling for the government to declare a climate emergency were set to enter a second week on Monday - though organisers said they would pause disruption to the capital.
Nearly 1,000 people were arrested during the first seven days of Extinction Rebellion demonstrations.
Activists have stopped traffic in a series of demonstrations across London, with actions including fixing a boat at the junction of Oxford Street and Regent Street, occupying Waterloo Bridge and disrupting the DLR by climbing on a train.
A total of 963 people had been arrested as of 7pm on Sunday, while 40 have been charged in connection with the protests.
But members of Extinction Rebellion are suggesting temporarily ending the disruptive tactics to focus on political negotiations as they enter the eighth day of campaigning.
A spokesman said there would be no escalation of activity on Bank Holiday Monday, but warned the disruption could get "much worse" if politicians were not open to their negotiation requests.
The group will no longer hold a picnic on the Westway by Edgware Road Underground station, which would have stopped traffic on the busy A-road on the last day of the long Easter weekend.
Instead, at Marble Arch - the only police-sanctioned protest space - activists will meet to "vision what's going to happen in the coming week".
The group wants to negotiate with mayor of London Sadiq Khan, as well as the Met to agree that they be allowed to continue their protests at one site in the capital.
Members would commit to not disrupting other areas in exchange for Mr Khan speeding up the implementation of the Declaration of Climate and Ecological Emergency, as well as considering setting up a London Citizens' Assembly.
They will also set up a political taskforce to take forward public negotiations with the government, warning they are prepared to scale up action depending on how much progress is made.
Neither the Met nor the Mayor's office would say whether they were considering the proposals.
Reporting by Press Association.