Hernandez et at: Variability in ichthyoplankton abundance and composition in the northern Gulf of Mexico 
197 
Table 2 
Seasonal (X) and peak (*) occurrence of the dominant larval fish taxa collected in plankton samples (n=1634) off the coast of 
Alabama from October 2004 to October 2006. Seasonal classification is based on historic (10-year average) and observed monthly 
mean temperatures for the region, (see Fig. 2). 
Family 
Taxon 
Winter 
Season 
Spring Summer 
Fall 
Elopidae 
El ops saurus 
* 
X 
X 
Ophichthidae 
Myrophis punctatus 
X 
X 
* 
Clupeidae 
Brevoortia patronus 
* 
X 
X 
X 
Etrumeus teres 
X 
* 
X 
Harengula jaguana 
X 
* 
Opisthonema oglinum 
* 
X 
Serranidae 
Centropristis spp. 
X 
X 
* 
Diplectrum spp. 
X 
* 
Serraniculus pumilio 
X 
* 
Carangidae 
Chloroscombrus chrysurus 
X 
* 
Decapterus punctatus 
X 
* 
Lutjanidae 
Lutjanus campechanus 
* 
Gerreidae 
Unidentified 
X 
* 
Sciaenidae 
Cynoscion arenarius 
X 
X 
* 
Cynoscion nothus 
X 
* 
X 
Larimus fasciatus 
X 
X 
* 
X 
Leiostomus xanthurus 
X 
X 
X 
* 
Micropogonias undulatus 
X 
X 
* 
X 
Sciaenops ocellatus 
X 
Labridae 
Unidentified 
X 
* 
Microdesmidae 
Microdesmus spp. 
X 
* 
Scombridae 
Auxis spp. 
X 
* 
Euthynnus alletteratus 
X 
* 
Scomberomorus maculatus 
X 
* 
Stromateidae 
Peprilus alepidotus 
X 
* 
Peprilus burti 
X 
X 
* 
X 
Paralichthyidae 
Citharichthys spilopterus 
* 
X 
X 
X 
Etropus crossotus 
* 
X 
Paralichthys spp. 
X 
X 
* 
X 
Syacium papillosum 
* 
X 
short one-month fall period (November). In one instance, 
the interannual variability in water temperature at 
our sampling site allowed for the same month to be 
designated as a different season during different years 
(December was classified as “fall” in 2004 and “winter” 
in 2005) (Table 1). 
No seasonal pattern in salinity was observed at the 
sampling station (Fig. 3). Salinity observations were 
generally lower and more variable during the first year 
of the study, with values fluctuating between 30.4 and 
34.6 between October 2004 and September 2005. Sa- 
linity was generally higher and less variable between 
October 2005 and October 2006, with values ranging 
between 33.0 and 34.8. 
A total of 504,478 fish eggs and 311,970 fish larvae 
were collected over the course of the survey. Total fish 
egg concentrations during the survey ranged from 0.16 
to 48.3 eggs/m 3 (Fig. 3). Egg concentrations were sig- 
nificantly higher in the spring than in other seasons 
(F=271.3, P<0.0001, spring>summer>fall>winter). Total 
fish larvae concentrations ranged from 0.15 to 35.0 lar- 
vae/m 3 (Fig. 3). Larval concentrations were significantly 
higher during summer and spring seasons (F=206.1, 
P<0.0001, spring=summer>fall>winter). The diversity 
of ichthyoplankton assemblages, exp (H), ranged from 
1.32 to 9.48 and was also highest during the summer 
seasons (F=299.3, P<0.0001, summer>spring>fall>w 
inter) (Fig. 3). Species diversity was significantly re- 
lated to temperature as determined by a least squares 
regression (F=34.7, P<0.001, r 2 = 0.60). Although also 
significantly correlated, the relationships between tem- 
perature and fish egg concentrations (F=4.4, P<0.05, 
r 2 =0.16) and total larval concentrations (F=6.9, P<0.05, 
r 2 = 0.23) were not as strong. No significant relationships 
were observed between salinity and fish eggs (F=0.22, 
P=0.64, r 2 =0.01), total fish larvae (F<0.01, P=0.94, 
