560 
Fishery Bulletin 115(4) 
Figure 2 
Mean density (individuals/100 m 2 ) and mean species richness of nekton 
per seine haul at shore zone sampling sites A and B (Fig. 1) during day 
and night in lower Delaware Bay in June-September 2013. Columns with 
the same letter are not significantly different from each other (?<(). 05). 
Error bars indicate standard errors of the means. 
4 Brevoortia 
tyrannus 
4 Mugil 
cephalus 
3- 
□ Day 
II Night 
Figure 3 
Mean density (individuals/100 m 2 ) of dominant species (>1% of total 
catch) per seine haul at shore zone sites A and B (Fig. 1) during day and 
night in lower Delaware Bay in June-September, 2013. Columns with the 
same letter are not significantly different from each other (P<0.05). Error 
bars indicate standard errors of the means. 
94% higher at night than during the 
day (/’<() 001} and was similar be¬ 
tween the 2 sampling sites (P=0.750), 
with no interaction between time of 
day and site (P=0.829; Table 1, Fig. 
2). Diel density differences were also 
found for a number of dominant shore 
zone species but there were no signifi¬ 
cant differences between sites or in¬ 
teraction effects. Bay anchovy, weak- 
fish, spot (Leiostomus xanthurus ), and 
blue crab occurred in the shore zone 
in significantly higher densities at 
night, whereas bluefish had signifi¬ 
cantly higher density during the day 
(Fig. 3). Mean species richness per 
seine haul in the shore zone was 62% 
higher (PcO.OOl) at night (7.3 [stan¬ 
dard error (SE) 0.8]) than during the 
day (4.5 [SE 0.8]) and was similar for 
the 2 sampling sites (P=0.108), with 
no interaction (P=Q.837; Fig. 2). 
In the adjacent nearshore sampling 
area (Table 2), density was dominat¬ 
ed by bay anchovy (73%), spot (11%), 
and weakfish (9%). Several species 
were unique to either the shore zone 
or nearshore sampling areas (Tables 
1 and 2). Nearshore fish density was 
not significantly different during day 
and night (P=Q.19, Table 2) and no 
species-specific differences in day and 
night densities were found (Table 2). 
Species richness per tow in the adja¬ 
cent nearshore sampling area was not 
statistically different (P=Q.14) during 
the night (8.8 [SE 0.9]) and day (6.7 
[SE 0.8]). 
The size range of dominant spe¬ 
cies was generally similar during the 
day and night in the shore zone and 
nearshore (Table 3), with the excep¬ 
tion of the size range of Atlantic men¬ 
haden (Brevoortia tyrannus , P=0.002) 
and striped mullet (Mugil cephalus, 
PcO.OOl). Larger Atlantic menhaden 
were present in the shore zone during 
day and not at night and larger striped 
mullet were present in the shore zone 
during the night and not during the 
day (Table 3). It is noted, however, 
that only 4 Atlantic menhaden were 
captured during night sampling. 
Ordination of shore zone and near¬ 
shore density data by NMD8 shows 
diel differences in the species as¬ 
semblage in the shore zone but not 
in the nearshore area (Fig. 4). Per- 
mutational MANOVA shows that the 
diel period significantly explained 17% 
