No man is an island. That timeworn credo is an apt sentiment for small businesses on Long Island, which are affected by conditions beyond their control. During May’s National Small Business Month, let’s look at how prevailing conditions impact the region’s local businesses. Most businesses on Long Island are small businesses. In fact, more than 80 percent in Nassau and Suffolk counties have fewer than 10 employees, notes Stacey Sikes, acting president and CEO of Long Island Association.