Data from: Changes in Bivalve functional and assemblage ecology in response to environmental change in the Caribbean Neogene

We documented changes in the relative abundance of bivalve genera and functional groups in the southwest Caribbean over the past 11 Myr to determine their response to oceanographic changes associated with the closure of the Central American Seaway ca. 3.5 Ma. Quantitative bulk samples from 29 localities yielded 106,000 specimens in 145 genera. All genera were assigned to functional groups based on diet, relationship to the substrate, and mobility. Ordinations of assemblages based on quantitative data for functional groups demonstrated strong shifts in community structure, with a stark contrast between assemblages older than 5 Ma and those younger than 3.5 Ma. These changes are primarily due to an increase in the abundance of attached epifaunal bivalves (e.g., Chama, Arcopsis, and Barbatia) and a decrease in infaunal bivalves (e.g., Varicorbula and Caryocorbula). Taxa associated with seagrasses, including deposit-feeding and chemosymbiotic bivalves (e.g., Lucina), also increased in relative abundance compared to suspension feeders. The composition of bivalve assemblages is correlated with the carbonate content of sediments and the percentage of skeletal biomass that is coral. Our results strongly support the hypothesis that increases in the extent of coral reefs and Thalassia communities were important drivers of biologic turnover in Neogene Caribbean benthic communities.本研究记录了过去11 Myr以来加勒比海西南部双壳类（bivalve）属及功能群的相对丰度变化，以探究其对约3.5 Ma中美洲海道（Central American Seaway）封闭引发的海洋学变化的响应。我们从29个采样点采集的定量批量沉积物样本中，共获得145个属的106000件标本。所有属级分类单元均根据其食性、与底质的栖息关系以及运动能力被划分为不同功能群。基于功能群定量数据的群落排序分析显示，群落结构发生了显著转变：5 Ma前的群落与3.5 Ma后的群落之间存在鲜明分异。此类群落变化主要源于附着型表生双壳类（如Chama、Arcopsis及Barbatia）的丰度升高，以及内生双壳类（如Varicorbula与Caryocorbula）的丰度下降。与海草床相关的类群，包括沉积物食性及化能共生双壳类（如Lucina），相较于滤食性类群，其相对丰度同样有所提升。双壳类群落组成与沉积物的碳酸盐含量以及珊瑚骨骼生物量占比呈显著相关关系。本研究结果强有力地支持了下述假说：珊瑚礁与泰来草（Thalassia）群落的分布范围扩张，是新近纪（Neogene）加勒比海底栖群落生物更替的关键驱动因素。