ABSTRACT

Distributions of the planktonic foraminifers Globigerinoides ruber (d’Orbigny) and Trilobus sacculifer (Brady) from the tropical-subtropical South Pacific Ocean are related to sea surface temperature (SST), chlorophyll-a, nitrate, phosphate, salinity and oxygen to determine whether their niches overlap. Their distributions in the ForCenS database of species in seafloor sediment are studied as proxies for upper ocean data. In the occurrence analysis (MaxEnt) SST is the strongest predictor of niche suitability followed by chlorophyll-a; environments between 0–20° S are the most suitable for both species: niches are undifferentiated. Contrarily, abundance analysis (Random Forests) identifies nitrate and chlorophyll-a as primary variables for Globigerinoides ruber, and SST and chlorophyll-a for Trilobatus sacculifer. Maximum abundances of the former are predicted in the subtropical hyper-oligotrophic zone while maxima of the latter are predicted at its margins and near the West Pacific Warm Pool. The high relative abundance of Globigerinoides ruber in the hyper-oligotrophic zone is attributed to its photosymbiotic relation with on-board dinoflagellates; this compensates for the low primary productivity in the zone. It is the best-adapted planktonic foraminifer in this huge marine ‘desert’ and is a proxy for hyper-oligotrophic environments. The photosymbiotic relation is weaker in Trilobatus sacculifer which primarily depends on particulate nutrition.

摘要

来自热带亚热带南太平洋的浮游有孔虫Globigerinoides ruber（d'Orbigny）和Trilobus sacculifer（Brady）的分布与海面温度（SST），叶绿素a，硝酸盐，磷酸盐，盐度和氧气有关，以确定是否他们的利基重叠。研究了它们在ForCenS数据库中的海底沉积物物种分布，以此作为上层海洋数据的代理。在发生率分析（MaxEnt）中，SST是利基适应性的最强预测因子，其次是叶绿素-a。介于0–20°S的环境最适合两种物种：生态位未分化。相反，丰度分析（Random Forests）确定硝酸盐和叶绿素-a为Globigerinoides ruber的主要变量，和SST和叶绿素-a对Tri草。前者的最大丰度在亚热带超贫营养区被预测，而后者的最大值被预测在其边缘和西太平洋暖池附近。的高相对丰度Globigerinoides曲霉在超贫营养区归因于其具有板上甲藻photosymbiotic关系; 这弥补了该地区较低的初级生产力。在这个巨大的海洋“沙漠”中，它是最适合的浮游有孔虫，并且是超营养环境的代表。该photosymbiotic关系是弱Trilobatus sacculifer这主要取决于颗粒的营养。