Iniesta had been at the club all of his 22-year career, breaking fully into the team in the 2004-05 season.
Sergio Busquets will now occupy the position as vice-captain while Gerard Pique and Sergi Roberto have joined the four-man leadership team, with the quartet all graduating from the club's academy.
The forward, Barca's all-time record goalscorer with 552 in all competitions, already wears the armband for the Argentina.
Liverpool's Danny Ings joins Southampton on loan
Honestly, if you could bottle character and spirit, his would sell worldwide - he is so incredibly positive and full of energy.
Alzheimer's Breakthrough: Eyes Can Be 'Read' for Early Detection
Other diseases that impair vision that are typical of old age, such as cataracts, were not related to the risk of Alzheimer's. Over the five-year study , 792 cases of Alzheimer's disease were diagnosed by a committee of dementia experts.
French rescuers evacuate 750 campers amid flash floods
Several parts of central and southeast France are on flood alert after a blazing heatwave ended abruptly in storms on Thursday. The mayor of Bagnols, Jean-Yves Chapelet, told BFM-TV many Dutch tourists were among the 350 campers evacuated there.
Messi, who was named Barcelona's second captain in 2015, will now replace Barca's former icon, Andres Iniesta in the role. The Spaniard will break past half a thousand appearances for Barcelona if he remains fit and uninjured throughout their multiple campaigns this season.
Messi, who has been at Barcelona since the age of 13, is one of four players to be given new responsibilities by the Catalan club. Piqué returned from Manchester United in 2008 and has been at the club ever since.
The five-time Ballon d'Or victor will be aiming to lift his first trophy as captain on Sunday when Ernesto Valverde's side take on Sevilla in the Spanish Supercopa.