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P.L. Colin
morphological characters to assist with identifi cation. Often it is impossible to
identify larvae to species (particularly early stages). Placing them into a genus or
family can be diffi cult, inhibiting many types of ELH research (Leis and McCormick
2002 ) . Leis and Rennis ( 1983 ) , Leis and Trnski ( 1989 ) and Leis and Carson-Ewart
( 2000 ) provide available taxonomic information on many shallow water Indo-west
Pacifi c (IWP) ELH stages while Richards ( 2006 ) has done so for the western Atlantic
(WA) region. Other methods, such as use of otolith increments and chemistry, have
allowed new perspectives on ELH.
7.2 Taxonomic Range of Aggregation Spawning
Both aggregation and non-aggregation spawning occur within various families of
reef fi shes and their eggs and larvae do not appear to differ markedly among cofamilials according to spawning strategy (see Appendix ) (see also Chap . 4 ).
Aggregation- and pair-spawning by related species (and even within a single species
in some wrasses-Labridae and parrotfi shes-Scaridae) often occur simultaneously on
the same reef area, their eggs mixing in open water. Whether there is anything
different or benefi cial for ELH between aggregation and non-aggregation spawners
is uncertain but nonetheless central to the question of why aggregation spawning
exists at all. It appears at the time of fi rst feeding that the density of larvae in the
open ocean from a very large aggregation spawning may not be signifi cantly higher
than for other types of spawning (see Chap. 6 ). Once they start feeding a few days
after hatching, how larvae can be sustained by the generally low zooplankton
populations found in most tropical waters is crucial. Chapter 6 indicated some
biophysical mechanisms that potentially concentrate the larvae, the food items they
need and potential predators. Other mechanisms might reduce the density of larvae
through predation and dispersal so they become less concentrated.
7.3 Early Life History Stages of Coral Reef Fishes
Most fi shes with spawning aggregations have planktonic eggs. A limited group of
aggregating species has eggs which develop on the bottom (see Appendix) and
whose dispersal and pelagic life does not start until hatching. Knowledge of larval
stages and behaviour usually comes from capture of specimens using plankton nets,
light traps and other techniques, as well as rearing of eggs in culture. Some in situ
studies are being undertaken, mostly with settlement stage fi shes (Leis et al. 1996,
2003 ; Paris et al. 2008 ) . The ELH stages of aggregating fi shes are typical of other
reef fi shes, and those stages can be broken down as follows:
Eggs (pelagic) – These can be of variable shape, but most often nearly spherical; typically ranging from about 0.6 to 1.2 mm diameter; larger for eels (up to 4 mm), and
some non-perciform groups like Fistularia and tetradontiforms. Some parrotfi shes
P.L. Colin
morphological characters to assist with identifi cation. Often it is impossible to
identify larvae to species (particularly early stages). Placing them into a genus or
family can be diffi cult, inhibiting many types of ELH research (Leis and McCormick
2002 ) . Leis and Rennis ( 1983 ) , Leis and Trnski ( 1989 ) and Leis and Carson-Ewart
( 2000 ) provide available taxonomic information on many shallow water Indo-west
Pacifi c (IWP) ELH stages while Richards ( 2006 ) has done so for the western Atlantic
(WA) region. Other methods, such as use of otolith increments and chemistry, have
allowed new perspectives on ELH.
7.2 Taxonomic Range of Aggregation Spawning
Both aggregation and non-aggregation spawning occur within various families of
reef fi shes and their eggs and larvae do not appear to differ markedly among cofamilials according to spawning strategy (see Appendix ) (see also Chap . 4 ).
Aggregation- and pair-spawning by related species (and even within a single species
in some wrasses-Labridae and parrotfi shes-Scaridae) often occur simultaneously on
the same reef area, their eggs mixing in open water. Whether there is anything
different or benefi cial for ELH between aggregation and non-aggregation spawners
is uncertain but nonetheless central to the question of why aggregation spawning
exists at all. It appears at the time of fi rst feeding that the density of larvae in the
open ocean from a very large aggregation spawning may not be signifi cantly higher
than for other types of spawning (see Chap. 6 ). Once they start feeding a few days
after hatching, how larvae can be sustained by the generally low zooplankton
populations found in most tropical waters is crucial. Chapter 6 indicated some
biophysical mechanisms that potentially concentrate the larvae, the food items they
need and potential predators. Other mechanisms might reduce the density of larvae
through predation and dispersal so they become less concentrated.
7.3 Early Life History Stages of Coral Reef Fishes
Most fi shes with spawning aggregations have planktonic eggs. A limited group of
aggregating species has eggs which develop on the bottom (see Appendix) and
whose dispersal and pelagic life does not start until hatching. Knowledge of larval
stages and behaviour usually comes from capture of specimens using plankton nets,
light traps and other techniques, as well as rearing of eggs in culture. Some in situ
studies are being undertaken, mostly with settlement stage fi shes (Leis et al. 1996,
2003 ; Paris et al. 2008 ) . The ELH stages of aggregating fi shes are typical of other
reef fi shes, and those stages can be broken down as follows:
Eggs (pelagic) – These can be of variable shape, but most often nearly spherical; typically ranging from about 0.6 to 1.2 mm diameter; larger for eels (up to 4 mm), and
some non-perciform groups like Fistularia and tetradontiforms. Some parrotfi shes