Comparison of Endohelminth Parasites in Alligator Gar (Atractosteus Spatula) and Spotted Gar (Lepisosteus Oculatus) from Sabine Lake

Alligator gar (Atractosteus spatula) and spotted gar (Lepisosteus oculatus) are predatory, primitive fishes with a long evolutionary history. Both species are native to North America and are distributed through the gulf coast. The parasites of these 2 species are understudied throughout their range, but particularly in coastal Texas. This study examined the endohelminth parasite communities of these 2 species in a unique study habitat (Sabine Lake Estuary). A helminth survey of 40 alligator gar and 40 spotted gar was conducted on specimens captured from Sabine Lake in the spring and summer of 2018. Parasitic intensity and Shannon-Wiener diversity were calculated for each fish individually and then regressed against host size and habitat salinity to determine if these variables influence parasite community. The communities of the 2 species were then compared using Shannon-Wiener diversity, Percent Similarity index, and a mixed effect model. From these samples, 13 parasite species were identified (5 trematodes, 4 nematodes, 2 cestodes, and 2 acanthocephalans), 10 of which were shared by both host species. Host size and salinity were not found to be significant predictors of parasite community diversity. This study is significant as a survey of endohelminths from Sabine Lake that documents new host and localities for several parasite species as well as highlighting the diversity of parasite species found in gar captured from a saline environment.