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.

摘要

来自美国阿拉巴马州莫比尔县的多芬岛描述了来自墨西哥湾沿岸平原的第一批上新世硬骨类耳石。这 250 个耳石标本，主要是矢状面，是从最近沉积在岸上的近海上新世单元挖掘出来的贝壳哈希中获得的，这是最近海滩营养的一部分。对耳石的分析揭示了来自 11 个硬骨鱼科的 22 个物种。Sciaenid 鱼类占总标本的 79.6%，而其他 10 个科（包括不确定科）约占总数的 20%。与耳石代表的鱼类的现代生物和生态要求的比较表明浅（0-20 m）浅海环境具有一些微咸和罕见的深水影响。几个最丰富的分类群表明浅，软底河口栖息地，上游寡盐小溪（0.5 至 5.0 ppt 盐度）作为主要育苗区。然而，仅海洋物种的百分比可能表明与开放的河口和浅海沿岸地区以及亚热带水域有更多的相互作用。耳石上没有无脊椎动物沉降可能表明表面停留时间有限。从多芬岛遗址回收的所有 22 个分类群都非常重要，因为它们代表了这些分类群在北美墨西哥湾沿岸平原内的第一次上新世出现。耳石上没有无脊椎动物沉降可能表明表面停留时间有限。从多芬岛遗址回收的所有 22 个分类群都非常重要，因为它们代表了这些分类群在北美墨西哥湾沿岸平原内的第一次上新世出现。耳石上没有无脊椎动物沉降可能表明表面停留时间有限。从多芬岛遗址回收的所有 22 个分类群都非常重要，因为它们代表了这些分类群在北美墨西哥湾沿岸平原内的第一次上新世出现。