Nest building in a Mediterranean wrasse (Symphodus ocellatus): are the algae used randomly chosen or actively selected?

To increase their reproductive success, fish species have evolved various strategies, including both simple processes and more complex mechanisms that involve parental care by nest-building. In Symphodus ocellatus, a species that lives in rocky infralittoral zones of the Mediterranean Sea, during the reproductive period, the male builds a nest within a hole or crevice using fragments of algae and/or sand particles. Data on the nesting activity of wrasses are rare, and previous descriptions regarding the algal composition of nests have provided conflicting results. In this regard, it is unclear whether territorial males actively select algal species for nest construction or algal choice is r…