The Miami Heat has picked up its team option on guard Mario Chalmers

And now there are three.

Point guard Mario Chalmers has become the third Miami Heat player secured on the books for 2010-11. The Heat has picked up the option on his rookie contract. The team had until June 30, the official end of the 2009-10 season, to make its decision.

Chalmers now joins Michael Beasley and Daequan Cook as the only Heat players locked into 2010-11 salaries. Still to be determined are the player option held by center Joel Anthony, who faces a June 24 deadline, the player option held by Dwyane Wade, and the Heat’s buyout decision on the final three years of the contract of James Jones.

Both Wade and Jones are expected to become unrestricted free agents, with the decisions on those matters due by June 30, a day before the NBA’s free-agency negotiating period begins.

Chalmers, who earned $756,000 this past season, is now guaranteed $854,389 for what will be the final season of his contract. If he proves invaluable, the Heat can elect to designate him a restricted free agent at season’s end, allowing the team the opportunity to match any outside offers.

With the salary cap, which will be announced just prior to the July 8 start of the offseason signing period, expected to fall at roughly $56 million for 2010-11, the addition of Chalmers reduces the team’s total available cap space by a net $380,785 (after incorporating one fewer roster charge).

Had the team instead chosen to decline its option on Chalmers, it could have subsequently re-signed him to the very same minimum contract at the end of the off-season, with no impact to the team’s cap room. Such an approach, however, was not without its significant risks. Chalmers would have become an unrestricted free agent in the interim, free to sign with any team.