The Pliocene Elizabethtown otolith assemblage (Bladen County, North Carolina, USA) with indications of a primary fish nursery area

Abstract

ABSTRACT Bulk sampling of Pliocene (2.5–3.1 Ma, Piacenzian) beds at the Elizabethtown locality (Bladen County, North Carolina) produced 745 teleostean otoliths (17 taxa, representing extant fish off the U.S. Atlantic coast). Sciaenids dominate the assemblage (8 taxa; 44.4% of the total) and account for an extremely large percentage of total specimens (93.2%). The number of species (richness) at Elizabethtown is relatively small, and percentage abundance indicates a very large unevenness with Micropogonias undulatus and Leiostomus aff. L. xanthurus (91.4% of the specimens). Otolith assemblages from Elizabethtown and Lee Creek Mine, one of the most extensively studied North Carolina Pliocene sites, were compared. Assemblages were extremely dissimilar (percentage similarity measurement of 3.3%). Modern distributions of M. undulatus and L. aff. L. xanthurus are very strong indicators of shallow, soft bottom estuarine creeks and bays. The preponderance of juvenile M. undulatus (99.5% represent 1-year-old or less) is a strong indicator for a primary nursery area. This specialised habitat explains the dominance of juvenile Atlantic croakers and spots, the high percentage of fishes distributed in freshwater, brackish, and marine environments, and the paucity of marine-only species. The specialised habitat indicated at Elizabethtown would also account for the pronounced difference between the Elizabethtown and Lee Creek otolith assemblages.