The biological response to the 1977 regime shift in the California Current
The biological response to the 1977 regime shift in the California Current
复制标题
DOI：
10.1016/s0967-0645(03)00135-8
复制
发表时间：
2003-01-01
影响因子：
3
通讯作者：
Miller, AJ
中科院分区：
文献类型：
--
作者：
McGowan, JA;Bograd, SJ;Miller, AJ
海洋中物理学和生物学之间最不为人所知的相互作用是发生在十年尺度上的相互作用。但这个时间尺度是重要的，因为一些最伟大的生态事件发生在这个时间尺度上。对加州海流系统50多年的测量显示，生态系统发生了重大变化，包括浮游动物生物量出现了大规模的十年下降，沿着的是海洋上层温度的上升。温度变化是一个相对突然的转变1976-77年左右，同时与阿留申低压系统的加强与其他流域范围的变化。这种强化通过改变净表面热通量、湍流混合和水平输送的模式在海洋中产生温度异常。在南加州流浮游动物的平均丰度的变化已被归因于沿海上升流的强度的变化，从北方的营养丰富的水的水平运输的变化，或由于变暖，增加分层，所有这些都可能受到阿留申低压的波动。在这里，我们表明，温跃层的加深伴随着变暖，并增加了水柱的分层，导致植物营养物质的供应减少到上层。这是观测到的浮游生物减少和随后生态系统变化的最可能机制。上层海洋热含量的全球性变化，伴随着相对于净生产临界深度的分层和混合层加深的增加，可能导致浮游生物丰度的普遍下降。(C)2003爱思唯尔有限公司。保留所有权利。
Among the least understood interactions between physics and biology in the oceans are those that take place on the decadal scale. But this temporal scale is important because some of the greatest ecological events take place on this time scale. More than 50 years of measurement in the California Current System have revealed significant ecosystem changes, including a large, decadal decline in zooplankton biomass, along with a rise in upper-ocean temperature. The temperature change was a relatively abrupt shift around 1976-77, concurrent with other basin-wide changes associated with an intensification of the Aleutian Low-pressure system. This intensification generates temperature anomalies in the ocean by altering the patterns of net surface-heat fluxes, turbulent mixing, and horizontal transport. Changes in the mean abundance of zooplankton in the southern California Current have been attributed to variations in the strength of coastal upwelling, variations in the horizontal transport of nutrient-rich water from the north, or increased stratification due to warming, all of which could be affected by fluctuations in the Aleutian Low. Here we show that a deepening of the thermocline accompanied the warming and increased the stratification of the water column, leading to a decrease in the supply of plant nutrients to the upper layers. This is the most likely mechanism for the observed plankton decline, and subsequent ecosystem changes. A global change in upper-ocean heat content, accompanied by an increase in stratification and mixed-layer deepening relative to the critical depth for net production, could lead to a widespread decline in plankton abundance. (C) 2003 Elsevier Ltd. All rights reserved.