Primary production and carbon uptake dynamics in the vicinity of South Georgia: balancing carbon fixation and removal
Primary production and carbon uptake dynamics in the vicinity of South Georgia: balancing carbon fixation and removal
复制标题
南乔治亚州附近的初级生产和碳吸收动态：平衡碳固定和清除
DOI：
10.3354/meps242051
复制
发表时间：
2002
影响因子：
2.5
通讯作者：
A. Atkinson
中科院分区：
文献类型：
--
作者：
L. Gilpin;J. Priddle;M. Whitehouse;G. Savidge;A. Atkinson
1996年夏季，在南乔治亚州附近的一系列站点测量了初级产量。沿南乔治亚岛西端东南方向700公里的横断面有五个监测站。三个站点位于南极极锋（PF）以北，平均初级产量为0.41 g C m -2 d -1，而锋以南站点的平均初级产量为0.54 g C m -2 d -1。三个站点位于南乔治亚东部的大陆架断裂和非大陆架区域，记录的初级产量最低（平均0.34 g C m -2 d -1）。在岛屿西北部的另外4个站点，初级产量显著增加：0.8至2.5 g C m -2 d -1（平均1.5 g C m -2 d -1）。光抑制是生产剖面的一个显著特征，导致柱产量低估了4 - 16%。对维持南乔治亚附近有代表性的由30克新鲜质量（FM） m -2磷虾和20克新鲜质量（FM） m -2桡足类组成的后浮游动物群落所需的初级产量进行了评估。两组在最大生长速率下的总C需求量估计为0.93 g C m -2 d -1，其中维持基础代谢（即零生长）所需的C m -2 d -1为0.54 g。当地的初级生产速率远远超过了浮游动物基础代谢所需的碳，同样，最高的区域值也超过了浮游动物最大生长所需的碳。据估计，在磷虾的繁殖季节，维持较高捕食者所需的磷虾生物量可以在合理的最大磷虾生长速率下由当地生产支持。特别是，本研究在南乔治亚西北发现的高初级产量似乎足以维持磷虾的最大生长速度，当它们的生物量为30 g FM m -2时，磷虾产量将超过捕食者的清除。众所周知，来自高纬度地区的平流在为南乔治亚系统提供能量方面很重要。这项研究进一步证明，当地加强初级生产对支持当地食物网也很重要。
Primary production was measured at a series of stations in austral summer 1996 in the vicin- ity of South Georgia. Five stations were occupied along a 700 km transect southeastwards towards the western tip of South Georgia. Three stations were located north of the Antarctic Polar Front (PF) with mean primary production of 0.41 g C m -2 d -1 compared to 0.54 g C m -2 d -1 for the stations south of the front. Three stations were in the shelf break and off-shelf region to the east of South Georgia where the lowest rates of primary production were recorded (mean 0.34 g C m -2 d -1 ). At a further 4 stations north- west of the island, primary production was significantly greater: 0.8 to 2.5 g C m -2 d -1 (mean 1.5 g C m -2 d -1 ). Photoinhibition was a marked feature of the production profiles, resulting in the underestimation of column production by 4 to 16%. An assessment is made of the primary production required to main- tain a representative assemblage of metazooplankton around South Georgia composed of 30 g fresh mass (FM) m -2 krill and 20 g FM m -2 copepods. The total C requirement of both groups at maximum growth rate is estimated as 0.93 g C m -2 d -1 , with 0.54 g C m -2 d -1 required to maintain basal metabolism (i.e. for zero growth). Local primary production rates are well in excess of the C demands for basal metabolism by the metazooplankton, and likewise the highest regional values exceed those for maxi- mum metazooplankton growth. It is also estimated that the krill biomass required to sustain higher predators during their breeding season could be supported by local production at plausible maximum krill growth rate. In particular, high primary production found in this study to the northwest of South Georgia appears to be adequate to sustain maximum growth rate by krill when their biomass is 30 g FM m -2 , when krill production will exceed predator removal. It is already well known that advection from higher latitudes is important in supplying energy to the South Georgia system. This study adds to the evidence that locally enhanced primary production is also important in supporting the local food web.