Gerard and Muhling: Variation in the isotopic signatures of juvenile Lut/anus griseus 
103 
Table 2 
Results of pairwise permutational multivariate analysis of variance (PERMANOVA) of juvenile gray snapper ( Lutjanus 
griseus) otolith stable isotope signatures among sampled years, for sampling sites Old Dan Bank, and Sprigger Bank, Florida 
Bay. 
Years compared 
Test statistic (pseudo-F) 
P-value 
Number of permutations 
Old Dan Bank 
2001, 2002 
1.53 
0.09 
995 
2001, 2004 
1.84 
0.05 
993 
2001, 2005 
1.11 
0.30 
992 
2002, 2004 
2.76 
<0.001 
992 
2002, 2005 
1.50 
0.10 
981 
2004, 2005 
2.13 
0.01 
979 
Sprigger Bank 
2001, 2002 
1.65 
0.07 
990 
2001, 2004 
1.27 
0.23 
984 
2001, 2005 
1.52 
0.11 
979 
2002, 2004 
2.26 
0.01 
989 
2002, 2005 
2.86 
<0.001 
989 
2004, 2005 
2.26 
0.02 
988 
1.2 i 
0.8 - 
O 
- 0.4 - 
- 0.8 
A 
▲ 
0 
X X A 
X 
O 
A a o 
o° o 
OO 0 
x O 
0 
O * 
0 
X 
0 
o 
A 
0 2001 
A 2002 
A 
0 2004 
X 2005 
-2 
0 
5 13 C 
Figure 4 
Scatter plot depicting variation in juvenile gray snapper (Lut- 
janus griseus) stable isotope otolith signatures (6 18 0 and 6 13 C) 
from the summer of 2001, 2002, 2004, and 2005 from Old Dan 
Bank, Florida Bay. 
California. Their results showed a substantial 
degree of temporal variation in chemical signa- 
tures between collection periods. Assessing the 
temporal variation of isotopic signatures is use- 
ful for potential determination of environmental 
change or lack of site fidelity in fishes within 
Florida Bay. Preliminary results from acoustic 
telemetry on juvenile gray snapper in a Florida 
coastal Atlantic marine estuary, Loxahatchee, 
and otolith chemical signature analysis of juve- 
nile gray snapper in Florida Bay indicate high 
site fidelity (Lara et al., 2008). Based on these 
results, it is probable that the variations shown 
during annual sampling of the same sites in 
Florida Bay are a result of differences in envi- 
ronmental conditions such as temperature and 
salinity, possibly resulting from changes in wa- 
ter management practices or weather events. 
Significant differences between both oxygen 
and carbon isotopic signatures in otoliths were 
present between sampled years. However, dif- 
ferences with respect to carbon were more pro- 
nounced than differences in respect to oxygen. 
Otolith carbon isotopic signatures can be affected 
by water temperature and salinity (Elsdon and 
Gillanders, 2002), and by the trophic position 
and diet of the fish (Shiao et al., 2009). 
Historically, Florida Bay has experienced dramatic 
changes in salinity levels as a result of changes in wa- 
ter management practices and land use upstream. The 
impact of salinity changes on juvenile fish habitats, 
such as seagrass beds and mangroves, and on fishes 
is still unknown. The positive relationship between 
oxygen isotopic ratios and salinity makes it possible 
to look closer at salinity levels of portions of Florida 
Bay from 2000 to 2005. Kelble et al. (2007) exam- 
ined mean annual Florida Bay salinity from 1998 
through 2004 using flow-through system data from 
survey cruises. Results showed low salinity levels in 
the summer of 2002 (29-34%c), and much higher sa- 
linity levels in the summer of 2004 (37-42%c). Otolith 
carbon isotopic signatures from both Sprigger Bank 
and Old Dan Bank were significantly lower in 2002 
than in 2004 — a result that may have reflected the 
lower salinity conditions in 2002. Oxygen isotopic 
signatures, however, were similar between these two 
years at both sites. 
The formation of otolith carbonate is an inorganic 
reaction where calcium carbonate is precipitated from 
