ABSTRACT

The Subtropical Front (STF) and associated biological productivity are topographically locked to the Chatham Rise. Year-to-year differences of upper ocean dynamics and associated responses of phytoplankton are valuable for understanding variability in fisheries biomass as well as providing new knowledge of environmental condition for potential seabed mining in this keystone ecosystem. In-situ observations collected over three consecutive years are used to examine the oceanographic variability on Chatham Rise and its potential causal mechanisms are evaluated from satellite observations and a global atmospheric reanalysis. The water column over Chatham Rise consists of a three-layer structure comprised of a stable intermediate layer sandwiched between a well-mixed surface and bottom layer. The in-situ data showed that different water masses can dominate the surface mixed layer at different times. This variability in surface water masses appears to be related to the position of the STF modulated by wind forcing. Spatial and temporal variability was also observed in the mixed layer depth with the temporal variability driven mainly by wind forcing. A strong relationship was observed between phytoplankton biomass and the depth of the mixed layer with implications for the distribution of biological communities and fisheries at the year-to-year timescale on the Chatham Rise.

摘要

副热带锋面（STF）和相关的生物生产力在地形上被锁定在查塔姆隆起。上层海洋动态和浮游植物相关响应的逐年差异对于了解渔业生物量的变化以及为这一关键生态系统中潜在的海底采矿提供环境条件的新知识很有价值。连续三年收集的现场观测用于检查查塔姆海隆的海洋变化，并通过卫星观测和全球大气再分析评估其潜在的因果机制。查塔姆隆起上空的水柱由三层结构组成，其中稳定的中间层夹在混合良好的表面层和底层之间。这现场数据表明，不同的水团在不同的时间对地表混合层具有主导作用。地表水团的这种变化似乎与受风力调节的 STF 位置有关。在混合层深度中也观察到了空间和时间变化，其中时间变化主要由风力驱动。研究人员观察到浮游植物生物量与混合层深度之间存在密切关系，这对查塔姆海隆逐年时间尺度上生物群落和渔业的分布具有影响。