Torre et al.: Abundance and diversity of fish species and blue crab in Delaware Bay 
557 
Figure 1 
Map of the nearshore zone and the shore zone where sampling 
occurred during June-September 2013. Nearshore sampling oc¬ 
curred adjacent to the shore zone -200-500 m from the shore¬ 
line. Shore sampling occurred along two -400 m stretches of 
Delaware Bay beach. Black circles denote the 10 sampling lo¬ 
cations at each shore zone site that were evenly spaced -20 m 
from each other. Eight seining hauls (2 during the day and 2 at 
night) were conducted at 2 randomly chosen locations at site A 
and at site B each sampling week. 
2003; Yeoh et al., 2017). In a recent work 
(Torre and Targett, 2016), we reported 
habitat-specific differences in the shore 
zone nekton assemblage between beach 
and riprap in Delaware Bay and noted 
diel differences in abundance for some, 
but not all, species. 
We examined differences in abundance 
and diversity of fishes and blue crab ( Cal- 
linectes sapidus ) in the sandy beach shore 
zone and adjacent nearshore of Delaware 
Bay. Specifically, total nekton density, spe¬ 
cies richness, and the density of individu¬ 
al species during the day and night were 
compared. In addition, sampling occurred 
concurrently with research that identi¬ 
fied feeding patterns of selected dominant 
species (Torre and Targett, 2017) and this 
concurrence provided an opportunity to 
assess the potential role of predator-prey 
dynamics of the shore zone nekton over 
the diel temporal range. 
Materials and methods 
Study area 
Delaware Bay is a coastal plain estuary 
and one of the largest estuaries on the 
U.S. east coast (Bryant and Pennock, 
1988; Pennock and Sharp, 1994). Un¬ 
vegetated shore zones represent 74% of 
the bay’s shoreline which is characterized by shallow, 
gradually sloping, sandy or muddy beaches that are of¬ 
ten subject to wave erosion (de Sylva et al. 1 ; Lathrop 
et al. 2 ). The shore zone and nearshore waters support 
high densities of small forage and juvenile fish, and 
are feeding and spawning areas of adult fish (Shuster 3 ; 
de Sylva et al. 1 ; Able et al., 2007; Boutin, 2008). The 
fish fauna of Delaware Bay are dominated by species in 
the families Engraulidae, Atherinopsidae, Sciaenidae, 
Moronidae and Clupeidae (de Sylva et al. 1 ; Bryant and 
Pennock, 1988; Torre and Targett, 2016). Blue crab are 
also abundant in Delaware Bay throughout their life 
history (Epifanio et al., 1984). 
9 The study area in lower Delaware Bay (Fig. 1) 
included a gradually sloping beach area and a near¬ 
shore habitat composed of course sand and sandbars 
running parallel to shore -200-500 m from low tide 
(tidal range ~1.4 m). Sampling sites were two ~400-m 
stretches of sandy beach and a single 300-mxl200-m 
area of nearshore habitat adjacent to the shore zone 
sites. The 2 stretches of beach (sites A and B; Fig. 1) 
were separated by a wooden pier, open beneath and 
perpendicular to the shoreline, and were >100 m from 
the pier. Each stretch of beach consisted of 10 potential 
seining locations, with their centers evenly spaced -40 
m apart (Fig. 1). 
1 de Sylva, D. P., F. A. Kalber Jr., and C. N. Shuster Jr. 
1962. Fishes and ecological conditions in the shore zone of 
the Delaware River estuary, with notes on other species col¬ 
lected in the deeper water. Univ. Delaware Mar. Lab., Info. 
Ser. Publ. 5, 164 p. Dep. Biol. Sci., Univ. Delaware, Newark, 
DE. [Available from website.] 
2 Lathrop, R. G., Jr., M. Allen, and A. Love. 2006. Mapping 
and assessing critical horseshoe crab spawning habitats of 
Delaware Bay, 36 p. Cent. Remote Sens. Spatial Anal., Rut¬ 
gers Univ., New Brunswick, NJ. [Available from website.] 
3 Shuster, C. N., Jr. 1959. A biological evaluation of the 
Delaware River estuary. Univ. Delaware Mar. Lab., Info. 
Ser. Publ. 3, 75 p. Dep. Biol. Sci., Univ. Delaware, Newark, 
DE. [Available from website.] 
Macrofauna sampling 
Shore zone sampling was conducted with a ~36-m bag 
seine (1.2 m high; 3.5-mm mesh) every 2 weeks from 
June through September 2013. Eight seine hauls were 
taken each sampling week, 2 during daytime and 2 at 
night, at each of the 2 sites (Fig. 1). Specific seining 
locations were randomly chosen from the 10 possible at 
each site (Fig. 1); and if the second location was adja¬ 
cent to the first, a different one was randomly selected 
to minimize effects of spatial autocorrelation. Day sam¬ 
pling occurred between 1 h after sunrise and 1 h before 
sunset, and night sampling between 1 h after sunset 
