First Pliocene fish otolith assemblage from the Gulf Coastal Plain, Dauphin Island, Mobile County, Alabama, USA

ABSTRACT

The first Pliocene teleostean otoliths from the Gulf Coastal Plain are described from Dauphin Island, Mobile County, Alabama, USA. The 250 otolith specimens, mainly sagittae, were obtained from shell hash dredged from an offshore Pliocene unit deposited onshore as part of recent beach nourishment. Analysis of the otoliths revealed 22 species from 11 teleostean families. Sciaenid fishes dominate the assemblage and account for 79.6% of the total specimens, while the other 10 families (including indeterminates) comprise approximately 20% of the total. Comparison to modern biological and ecological requirements for the fishes represented by the otoliths suggest a shallow (0–20 m) neritic environment with some brackish and rare deep-water influence. Several of the most abundant taxa indicate shallow, soft bottom estuarine habitat with upstream oligohaline creeks (0.5 to 5.0 ppt salinity) serving as primary nursery area. However, the percentage of marine-only species may indicate more interaction with open estuary and shallow coastal areas and subtropical waters. The lack of invertebrate settlement on the otoliths likely indicates limited surface residence-time. All 22 taxa recovered from the Dauphin Island site are highly significant since they represent the first Pliocene occurrences of these taxa within the Gulf Coastal Plain of North America.

KEYWORDS:

• Neogene
• Graham Ferry Formation
• osteichthyes
• Gulf of Mexico
• teleostei

Acknowledgments

K. A. Johnson (National Marine Fisheries Service, Southeast Fisheries Science Center, Pascagoula, MS), R. Taylor (formerly of the Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St. Petersburg, FL), and J. R. Hendon (Center for Fisheries Research and Development, Gulf Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, MS) generously provided Recent fishes and otoliths. D. Nolf (Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium) also supplied Recent and fossil otolith specimens. W. Schwarzhans (Natural History Museum of Denmark, Zoological Museum, Copenhagen, Denmark) made valuable suggestions regarding the identity and taxonomy of otoliths. J. Dindo (Dauphin Island Sea Laboratory (DISL), Dauphin Island, AL) and J. Valentine (DISL) are thanked for granting us access to collect on the DISL property. The following are thanked for their assistance with collecting the specimens from the locality: M. Graeber (DISL), C. Clay (DISL), R. Dixon (DISL), R. McDonald (DISL), B. Jones (DISL), E. Harney (Alabama Power Company (APCO), Birmingham, AL), S. Harney (APCO), M. Drymon (Mississippi State University Coastal Research and Extension Center (MSU), Biloxi, MS), E. Seubert (MSU), and R. Reid and the Discovering Alabama production and film crew (University of Alabama Museums, Tuscaloosa, AL). This manuscript was improved by the reviewers and editor.

Disclosure statement

No potential conflict of interest was reported by the authors.