Paleoecology explains Holocene chemical changes in lakes of the Nhecolândia (Pantanal-Brazil)
Paleoecology explains Holocene chemical changes in lakes of the Nhecolândia (Pantanal-Brazil)
复制标题
古生态学解释了尼科兰迪亚湖（巴西潘塔纳尔湿地）全新世化学变化
作者：
R. L. Guerreiro;M. McGlue;J. Stone;I. Bergier;M. Parolin;Silane A. F. Silva Caminha;L. Warren;M. L. Assine
本研究的目的是研究历史的静水生态系统盐度在潘塔纳尔湿地南部（巴西）。的时间和控制水化学变化的推断使用海绵骨针和硅藻古生态学的全新世沉积物芯Nhecolândia，一个湖泊区位于化石叶的塔夸里里megafan。最古老的部分的核心包含Heterorotula瘘骨针，表明一个短暂的淡水湖，存在，直到~ 4.6 cal ka BP。Gomphonema和Eunotia属的底栖硅藻出现在约3.2 calkaBP，表明浅水和营养不良的环境。过渡到一个更永久的湖泊，容纳淡水海绵（例如，Corvoheteromeyenia spp.），和硅藻集合体（例如，Cyclotella meneghiniana，Aulacoseira pantanalensis）持续到~ 1.3 cal年BP;在此之后，大多数海绵和硅藻从沉积记录中消失。高丰度的Anomoeoneis sphaerophora和Craticula guaykuruorum在最新的全新世反映了过渡到一个超碱性，盐湖环境。研究结果表明，Nhecolandia的盐湖可能演变的淡水前体由于当地（生物化学）和区域（地理气候）控制水的可用性，这对生物多样性和生态系统服务的模式在潘塔纳尔的影响。
The objective of this research is to examine the history of lentic ecosystem salinity in the southern Pantanal wetlands (Brazil). The timing and controls on hydrochemical changes were inferred using sponge spicule and diatom paleoecology on a Holocene-aged sediment core from Nhecolândia, a lake district situated on a fossil lobe of the Taquari megafan. The oldest portion of the core contains Heterorotula fistula spicules, indicative of an ephemeral freshwater lake that existed until ~ 4.6 cal ka BP. Benthic diatoms of the genus Gomphonema and Eunotia appeared ~ 3.2 cal ka BP, indicating a shallow and dystrophic environment. A transition to a more permanent lake that hosted freshwater sponges (e.g., Corvoheteromeyenia spp.), and diatom assemblages (e.g., Cyclotella meneghiniana, Aulacoseira pantanalensis) endured until ~ 1.3 cal year BP; after this time, most sponges and planktic diatoms disappear from the sedimentary record. High abundances of Anomoeoneis sphaerophora and Craticula guaykuruorum in the latest Holocene reflect a transition to a hyperalkaline, saline lake environment. The results suggest that Nhecolândia’s saline lakes may evolve from freshwater precursors due to local (biochemical) and regional (geo-climatic) controls on water availability, which has implications for patterns of biodiversity and ecosystems services in Pantanal.