Spanik et al.: Using DNA barcoding to improve taxonomic resolution of the diet of Lutjanus campechanus 127 
80°W 79°W 
Atlantic Ocean 
All collections 
Prey barcoded 
Depth contours 
=— 165 im 
= 105 in 
- 70m 
200 kilometers 35m 
[ER ep | ee ijt | 
15m 
78°W 77°W 
Figure 3 
Map showing locations where red snapper (Lutjanus campechanus) were caught in 2017 and 
2018 from Cape Hatteras, North Carolina (NC), to Saint Lucie, Florida. Black circles indicate 
capture locations for all red snapper collected. Gray squares indicate capture locations for red 
snapper from which prey items in stomach contents were sampled and identified with DNA 
barcoding. Depth contours are indicated by lines in various shades of gray. SC=South Carolina; 
GA=Georgia. 
(O. holbrookii) (accession number GU702414.1). Ophidii- 
dae is a paraphyletic family that has not been resolved 
well taxonomically. A neighbor-joining phylogeny gener- 
ated in the Barcode of Life Database indicates that 
sequences from these specimens formed a monophyletic 
clade that includes bank cusk-eel and shorthead cusk-eel 
(O. dromio), both of which occur in the study area; there- 
fore, we conservatively identified these specimens to 
genus. Specimens with sequences having top matches in 
GenBank to the scup (Stenotomus chrysops) (accession 
number HQ025017.1) or to the longspine porgy (S. capri- 
nus) (accession number KJ012441.1) were identified con- 
servatively as Stenotomus sp. because there is a difference 
of only one base pair (1%) between these reference 
sequences in GenBank and because both species occur 
within the study area. 
Overall, the diet of red snapper captured along the 
Atlantic coast of the southeastern United States was 
diverse, with 42 invertebrate and 28 vertebrate taxa iden- 
tified (Table 1). Generally, shrimp taxa composed the most 
important prey category consumed by red snapper in our 
study, on the basis of the IRI value (39.95%), followed by 
fish species (34.38%) and crab species (19.04%) (Fig. 5). 
More specifically, the most important prey taxa in the diet 
of red snapper, according to the IRI, were the brown rock 
shrimp (Sicyonia brevirostris), unidentified fish, portunid 
crabs, and the longspine swimming crab (Achelous spini- 
carpus), with IRI values of 32.58%, 28.85%, 7.14%, and 
5.99%, respectively. Unidentified fish species composed the 
most dominant prey category by number (%N=12.97%) and 
occurred most frequently (GFO=24.76%), and the brown 
rock shrimp was the leading component of the diet by 
