Revealing the nocturnal browsing on seaweeds of purely herbivorous fish using infra-red time-lapse cameras

Abstract

Herbivorous fish are generally considered to be diurnal feeders, but the disappearance of seaweeds at night has been observed in Japan. We conducted field experiments using an infra-red time-lapse camera to identify fish browsing on seaweed at night at two sites on Fukue Island, western Japan. At both sites, brown chub (Kyphosus bigibbus) were photographed around transplanted seaweed from sunset to sunrise, and the seaweed declined after the appearance of K. bigibbus. This study is the first report of nocturnal browsing in a purely herbivorous fish.