206
P.L. Colin
Llopiz and Cowen ( 2009a, b ) found in the Straits of Florida high incidences of
food in guts of larval fi shes, including many from families with aggregation spawning,
and a surprising diversity of feeding strategies, based on gut contents. Rapid gut
evacuation and no evidence of nocturnal feeding was prevalent in scombroid larvae
(based on sampling larvae after sunset) and it is likely reef fi sh larvae from these
waters do the same. However the possibility exists that some reef fi sh larvae might
be able to feed if in shallow water on nights with a near full moon as this provide
considerable illumination in shallow water.
Interestingly Miller ( 2009 ) suggests that leptocephali larvae probably feed on
particulate matter in the water column, such as marine snow, faecal pellets and discarded apendicularian house and that such larvae would not compete for food with
those of perciform fi shes, which are believed to feed on crustacean zooplankton.
Other fi sh larvae from aggregation families utilize additional types of planktonic
organisms for food which may be abundant. Sampey et al. ( 2007 ) found that the one
surgeonfi sh larva and nemipterid (sea bream) larvae had eaten appendicularians
(larvaceans), while Llopiz and Cowen ( 2009a ) found appendicularians to be
important food items of surgeonfi sh larvae and snapper larvae. Recognition of the
importance of these other planktonic groups, such as appendicularians, compared
to those traditionally considered primary food items (copepods crustaceans) for
larval reef fi shes, also complicates the examination of zooplankton density and
larval feeding.
7.6 Life in the Pelagic Environment – Late Stages
Once fi ns and other structures are completely developed, the larva enters its end
form, the settlement stage (also known as the “pelagic juvenile”). There may some
persistence of “larval” characters (Quere and Leis 2010 ) , but these are eventually
lost after settlement. Consistent feeding is probably still important, but fi sh can
survive short periods without feeding, and for some it appears they do not feed
during metamorphosis. They develop the capability to potentially move towards
preferred settlement environments as swimming ability is suffi cient to match or
exceed most current regimes encountered and any sensory systems can detect
sonic, olfactory and other cues. The fi sh settle from the pelagic environment into
benthic habitats.
The literature concerning the biology of settlement stage coral reef fi shes is far
larger than that dealing with earlier life history stages. Settlement stage fi shes can
be captured in a number of manners, identifi ed while alive, used in experiments, and
have large otoliths with information on life history recorded in them. Species with
spawning aggregations are often among those captured by light traps and nets, and
some are quite abundant compared to other species in overall samples. The bluehead wrasse and surgeonfi shes are among the most common larvae captured and are
resident aggregators with long spawning seasons. Others, typically transient aggregators, such as most of the groupers, are not so common, and make it diffi cult for
P.L. Colin
Llopiz and Cowen ( 2009a, b ) found in the Straits of Florida high incidences of
food in guts of larval fi shes, including many from families with aggregation spawning,
and a surprising diversity of feeding strategies, based on gut contents. Rapid gut
evacuation and no evidence of nocturnal feeding was prevalent in scombroid larvae
(based on sampling larvae after sunset) and it is likely reef fi sh larvae from these
waters do the same. However the possibility exists that some reef fi sh larvae might
be able to feed if in shallow water on nights with a near full moon as this provide
considerable illumination in shallow water.
Interestingly Miller ( 2009 ) suggests that leptocephali larvae probably feed on
particulate matter in the water column, such as marine snow, faecal pellets and discarded apendicularian house and that such larvae would not compete for food with
those of perciform fi shes, which are believed to feed on crustacean zooplankton.
Other fi sh larvae from aggregation families utilize additional types of planktonic
organisms for food which may be abundant. Sampey et al. ( 2007 ) found that the one
surgeonfi sh larva and nemipterid (sea bream) larvae had eaten appendicularians
(larvaceans), while Llopiz and Cowen ( 2009a ) found appendicularians to be
important food items of surgeonfi sh larvae and snapper larvae. Recognition of the
importance of these other planktonic groups, such as appendicularians, compared
to those traditionally considered primary food items (copepods crustaceans) for
larval reef fi shes, also complicates the examination of zooplankton density and
larval feeding.
7.6 Life in the Pelagic Environment – Late Stages
Once fi ns and other structures are completely developed, the larva enters its end
form, the settlement stage (also known as the “pelagic juvenile”). There may some
persistence of “larval” characters (Quere and Leis 2010 ) , but these are eventually
lost after settlement. Consistent feeding is probably still important, but fi sh can
survive short periods without feeding, and for some it appears they do not feed
during metamorphosis. They develop the capability to potentially move towards
preferred settlement environments as swimming ability is suffi cient to match or
exceed most current regimes encountered and any sensory systems can detect
sonic, olfactory and other cues. The fi sh settle from the pelagic environment into
benthic habitats.
The literature concerning the biology of settlement stage coral reef fi shes is far
larger than that dealing with earlier life history stages. Settlement stage fi shes can
be captured in a number of manners, identifi ed while alive, used in experiments, and
have large otoliths with information on life history recorded in them. Species with
spawning aggregations are often among those captured by light traps and nets, and
some are quite abundant compared to other species in overall samples. The bluehead wrasse and surgeonfi shes are among the most common larvae captured and are
resident aggregators with long spawning seasons. Others, typically transient aggregators, such as most of the groupers, are not so common, and make it diffi cult for