Sulphur Damselfish

Photo: Daniel Nicholson · © all rights reserved

Juveniles in electric blue spotting are common along the limestone lip of the cenote where algae films grow in the thin freshwater margin, providing cover and food unavailable in the open sea. Adults defend small algal garden territories along the submerged ledges just below the halocline. The mixture of fresh and salt water creates an unusual growth substrate that supports algal communities distinct from those on the adjacent marine reef.