135 
Abstract — We examined the poten- 
tial for water chemistry to affect the 
width of daily increments in reef fish 
otoliths using both mensurative and 
manipulative methods. We found sig- 
nificant differences in the widths of 
increments in otoliths of the neon 
damselfish (Pomacentrus coelestis) 
collected in different habitats at One 
Tree Island on the Great Barrier Reef. 
We then used manipulative experi- 
ments to determine if natural water 
masses (ocean water vs. lagoon plume) 
could produce different incremental 
widths in otoliths in the absence of 
potentially confounding factors. Fish 
exposed to ocean water had signifi- 
cantly wider otolith increments for 
two of the three experiments. Ele- 
mental analyses indicated that Ba/Ca 
ratios were significantly correlated 
with increment widths for two of the 
three experiments and Sr/Ca ratios 
did not correlate with increment width 
for any experimental period. Varia- 
tion in crystal-lattice orientation did 
not explain differences in increment 
width between treatments. Differ- 
ences in water chemistry can affect 
increment widths in otoliths of reef 
fishes, potentially confounding pat- 
terns previously attributed to growth 
rate or condition alone. 
Manuscript submitted 19 April 2007. 
Manuscript accepted 21 November 2007. 
Fish. Bull. 106:135-142 (2008). 
The views and opinions expressed or 
implied in this article are those of the 
author and do not necessarily reflect 
the position of the National Marine 
Fisheries Service, NOAA. 
The influence of elemental chemistry 
on the widths of otolith increments 
in the neon damselfish ( Pomacentrus coelestis ) 
Michael J. Kingsford (contact author ) 1 
Heather M. Patterson 2 
Matthew J. Flood 3 
Email address for M. J Kingsford: Michael.Kmgsford@jcu.edu.au 
1 School of Marine and Tropical Biology 
Australian Research Council Centre of Excellence for Coral Reef Studies 
James Cook University 
Townsville, Queensland 4811, Australia 
2 Australian Fisheries Management Authority 
Box 7051 Canberra Business Centre 
Canberra, Australian Capital Territory 2610, Australia 
3 Bureau of Rural Sciences 
GPO Box 858 
Canberra, Australian Capital Territory 2601, Australia 
Recent research has elucidated the 
importance of presettlement condition 
and growth rate of reef fish for sur- 
vival and recruitment (Bergenius et 
al., 2002; Hoey and McCormick, 2004; 
Sponaugle and Pinkard, 2004). Stud- 
ies on the condition of presettlement 
fishes have been based on a number 
of measures that include growth rate, 
biochemical development, and behav- 
ior (McCormick, 1998). More com- 
monly, however, widths of increments 
in otoliths have been used as a means 
of examining growth on the assump- 
tion of a good relationship between 
somatic and otolith growth (Campana, 
1999; Meekan et al., 2003). In addi- 
tion, otolith increment widths may 
provide information about the con- 
dition of presettlement fishes; it has 
been demonstrated that fish with 
small lipid reserves generally deposit 
narrower increments than fish with 
adequate lipid reserves (Paperno et 
al., 1997; Molony and Sheaves, 1998). 
Indeed, periods of starvation are 
known to have a substantial influ- 
ence on the increment widths of oto- 
liths (Moksness, 1992; Molony, 1996), 
as can water temperature (Hussy et 
al., 2003; Powell et al., 2004) and the 
onset of metamorphosis into a juvenile 
form (Wilson and McCormick, 1999). 
Thus, the increment widths of otoliths 
are an important, but not necessarily 
simple tool, by which larval condition 
and growth can be assessed. 
Otoliths are composed of an ara- 
gonite lattice deposited on a protein 
matrix; this lattice incorporates trace 
elements, derived mainly from the 
surrounding water mass (Walther 
and Thorrold, 2006), as deposition oc- 
curs (Campana, 1999). Indeed, there 
is a close link between water and oto- 
lith chemistry for some elements (i.e., 
Ba; Bath et al., 2000; Walther and 
Thorrold, 2006); this relationship al- 
lows otolith chemistry to be used as 
a proxy for water chemistry. Although 
the process of elemental deposition is 
not entirely understood at this time, 
it is possible that the chemical com- 
position of the water mass may influ- 
ence increment widths in the otoliths 
by means of otolith chemistry and 
related crystallography, thus poten- 
tially confounding the interpretation 
of these increments. 
Furthermore, some reef fish are ca- 
pable of distinguishing and actively 
choosing particular water masses 
(Doherty et al., 1996; Atema et al., 
2002; Gerlach et al., 2007), presum- 
ably as a means of choosing suitable 
habitat at settlement. This study 
demonstrates that otolith increment 
widths can vary between fish in dif- 
