Despite opposition from environmentalists and some members of his own party, Assembly Speaker Willie Brown (D-San Francisco) has reappointed Beverly Hills real estate investor and political fund-raiser Mark Nathanson, 48, to a second term on the California Coastal Commission. Reappointment of Nathanson, a Republican, was made without fanfare last week in what opponents said was an effort to head off opposition to renaming him to the commission. Sierra Club spokeswoman Paula Carrell said, "We opposed (Nathanson) because he has a bad environmental record." Nathanson, one of four commissioners who serve at the speaker's pleasure, is considered a pro-development vote by environmentalists. Brown's office said the reappointment was made to bring "balance" to the coastal watchdog agency.