Hydroid and serpulid recruitment patterns using a new laser microtopography technique

► We analyze the early settlement on recruitment plates immersed at 2 depths. ► A non-destructive technique to get information at organism level during 2 months. ► We combine video survey and microtopography with 15 μm vertical precision. ► We locate, count and measure volumes of every polyp of hydroid colonies. ► There is a negative effect of hydroid colonies on serpulid worm settlement.