Microhabitat use by recently settled Sparisoma parrotfishes: ontogenetic shifts and association with algal-gardening damselfishes

Abstract

Little is known about microhabitat use by Caribbean parrotfishes soon after settlement from the plankton. We monitored the abundance and distribution of recently settled Sparisoma spp. (likely mostly S. viride with some S. aurofrenatum) on 6 x 6 m quadrats (n = 9) on the fringing reef front in Barbados (West Indies) every 15 d for 6 mo. Each quadrat was divided into 1 m(2) cells to examine associations between substrate composition and recruit (<1.3 cm standard length, SL) and small juvenile (1.3-3 cm SL) abundance. Recruits and small juveniles tended to use some cells more than others, and their distribution partially overlapped. Both were associated with long turf algae on dead coral. However, small juveniles were also associated with crustose coralline algae and substrate elevation, suggesting a partial ontogenetic change in microhabitat use. Microhabitat associations were similar to those of co-occurring algal-gardening longfin damselfish Stegastes diencaeus and threespot damselfish S. planifrons. Whereas Sparisoma recruits overlapped with longfins and to a lesser extent with threespots, small juveniles overlapped only with threespots. Some of the microhabitat associations with recruits and small juveniles at the cell scale were also found across quadrats. We suggest that the reef front is an important habitat for recently settled Sparisoma in Barbados, where they rely on being cryptic and solitary within turf algae gardens defended by damselfishes to minimize predation. After some growth, they perform a microhabitat shift, perhaps due to increased damselfish aggression. Thus, the early post-settlement dynamics of Caribbean Sparisoma might be strongly influenced by substrate modification by algal-gardening damselfishes.