210
P.L. Colin
Colin et al. 1997 ) and simply by the appearance of vast numbers of juveniles
(Fig. 7.7 ) where previously there were few or none (Letourneur et al. 1998 ; Chabanet
et al 2005 , PLC personal observation).
Instances of massive recruitment by surgeonfi shes are well documented from a
number of species known to be resident aggregation spawners (Randall 1961 ,
Doherty et al. 2004 , Robertson 1983 ) . While not all family members are known to
aggregate, it seems likely many others will be added as observations increase. The
specialized acronurus larva is useful in that it is easily identifi ed in plankton
samples (Oxenford et al. 2008 ) and is highly adapted for pelagic life. Convict
surgeonfi sh is known to have large fl uxes (“regular broad peaks”) of larvae across
the reef (Dufour and Galzin 1993, Randall 1961 ) . Planes et al. ( 1993 ) reported
successive pulses in recruitment of convict surgeonfi sh in Tahiti, saying they “may
refl ect reproductive periodicity or result from physical oceanic processes”. Sancho
et al. ( 1997 ) documented a recruitment pulse of spotted surgeonfi sh, Ctenochaetus
strigosus , at Johnston Island. Similar pulses have been observed in Palau on several
occasions, most recently in 2009 (Fig. 7.7 ). They appear as large schools of small
individuals on both outer reef slopes and inshore areas, which they would have had
to enter through small tidal channels. Such groups are usually subject to very high
predation, as often there is not suffi cient shelter for fi shes (Doherty et al. 2004). The
schools formed by the massive recruitment of two species of surgeonfi shes in Palau
in 2009 (Fig. 7.7 ) were subject to heavy predation by jacks (Carangidae) and other
piscivores. Over a few weeks the size of school decreased and eventually disappeared, the fi sh presumably either eaten or having successfully taken up residence
Fig. 7.6 Pelagic juvenile Moorish idol, Zanclus cornutus , at the time of recruitment. Photographed at
night, the fi sh has begun to acquire the coloration typical of juvenile fi sh (copyright Mandy T. Etpison)
P.L. Colin
Colin et al. 1997 ) and simply by the appearance of vast numbers of juveniles
(Fig. 7.7 ) where previously there were few or none (Letourneur et al. 1998 ; Chabanet
et al 2005 , PLC personal observation).
Instances of massive recruitment by surgeonfi shes are well documented from a
number of species known to be resident aggregation spawners (Randall 1961 ,
Doherty et al. 2004 , Robertson 1983 ) . While not all family members are known to
aggregate, it seems likely many others will be added as observations increase. The
specialized acronurus larva is useful in that it is easily identifi ed in plankton
samples (Oxenford et al. 2008 ) and is highly adapted for pelagic life. Convict
surgeonfi sh is known to have large fl uxes (“regular broad peaks”) of larvae across
the reef (Dufour and Galzin 1993, Randall 1961 ) . Planes et al. ( 1993 ) reported
successive pulses in recruitment of convict surgeonfi sh in Tahiti, saying they “may
refl ect reproductive periodicity or result from physical oceanic processes”. Sancho
et al. ( 1997 ) documented a recruitment pulse of spotted surgeonfi sh, Ctenochaetus
strigosus , at Johnston Island. Similar pulses have been observed in Palau on several
occasions, most recently in 2009 (Fig. 7.7 ). They appear as large schools of small
individuals on both outer reef slopes and inshore areas, which they would have had
to enter through small tidal channels. Such groups are usually subject to very high
predation, as often there is not suffi cient shelter for fi shes (Doherty et al. 2004). The
schools formed by the massive recruitment of two species of surgeonfi shes in Palau
in 2009 (Fig. 7.7 ) were subject to heavy predation by jacks (Carangidae) and other
piscivores. Over a few weeks the size of school decreased and eventually disappeared, the fi sh presumably either eaten or having successfully taken up residence
Fig. 7.6 Pelagic juvenile Moorish idol, Zanclus cornutus , at the time of recruitment. Photographed at
night, the fi sh has begun to acquire the coloration typical of juvenile fi sh (copyright Mandy T. Etpison)