Continuing defined benefit scheme closures have left three in ten schemes planning to outsource administration, according to research.
The pensions industry must become more transparent on costs and charges and hold firm on the merits of auto-enrolment, delegates heard.
Complying with auto-enrolment regulations is going to be an "absolute minefield" for certain employers and they must start planning accordingly, delegates heard.
Labour has called on the government to stick to the schedule for auto-enrolment.
One in three workers will opt out of their employer's pension scheme, according to a Populus poll for the National Association of Pension Funds.
Pension funds are developing a code of conduct around charging transparency which will see customers told "in pounds and pence" how much of their savings are lost in management charges.
The coalition is considering delaying auto-enrolment and a delay of more than 12 months will mean the reform package is effectively over, former Chancellor Alistair Darling told reporters.
Companies could face provider shortages should auto-enrolment planning continue to stall, Mercer warns.
The Pensions Bill which raises the state pension age to 66 by 2020 has passed its third reading in the House of Commons with 287 votes to 242.
Professional Pensions is set to conduct a survey on auto-enrolment to discuss the current level of knowledge and preparation in the marketplace.