Active export of carbon and nitrogen at Station ALOHA by diel migrant zooplankton
Active export of carbon and nitrogen at Station ALOHA by diel migrant zooplankton
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DOI：
10.1016/s0967-0645(00)00174-0
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发表时间：
2001-01-01
影响因子：
3
通讯作者：
Landry, MR
中科院分区：
文献类型：
--
作者：
Al-Mutairi, H;Landry, MR
低营养副热带太平洋的浮游动物洄游比例高，颗粒通量低，是一个由洄游介导的物质出口跨越光带底部的区域，对元素收支尤其重要。为了评估Stn出口流量的大小。在ALOHA(22°45'N, 158°w)，我们测定了1994-1996年26次游船中洄游动物的大小结构生物量，并使用异速生长方程计算了洄游动物在白天深度（温度）下呼吸碳（DIC）和排泄铵（DIN）的代谢损失。深度整合（155m）迁移生物量年际变化范围为286 ~ 457 mg DWm(-2)，季节变化范围为285 ~ 550 mg DWm(-2)（秋季与春季），总体平均为394 mg DWm（-2）。2 ~ 5mm级段始终占主导地位。年迁移通量在0.22 ~ 0.37 mmol DIC m(-2) d（-1）和0.033 ~ 0.055 mmol DIN m(-2) d（-1）之间变化，总体平均为0.304 mmol C和0.045 mmol N m(-2) d(-1)（占捕集器PC和PN通量的15%和20%）。春季通量最高，分别为0.405 mmol C和0.060 mmol N m(-2) d(-1)；捕集器PC和PN分别占18%和24%)。强迁移类群（即白天几乎不存在于光带的类群）以Pleuromamma和Euphausia spp.和Aetideid桡足类为主，占总生物量估算值的40%。利用平均巡航生物量结构和温度信息。根据不同文献衍生的代谢关系和假设，迁移通量估计通常在碳的20%和氮的25%之间变化。在相同的基础上进行比较时，与高营养、低叶绿素的赤道太平洋相比，低营养区域的迁移通量估算值（以捕集通量计）更高。与大西洋相比，亚热带太平洋的移民生物量的长期平均值要高得多（2至3倍），但由于大西洋白天深度的温度较高（18度对9度），移民通量估估值相似。包括采样不足的微颗粒、溶解的有机排泄、深度死亡损失和区域间粪便运输的影响，相对于DIC和DIN代谢损失，碳的平均通量估计约为两倍（占捕集器PC的30%），氮的平均通量估计约为三倍（占捕集器PN的57%）。2001爱思唯尔科学有限公司版权所有。
With a high proportion of diel migratory zooplankton and low particle fluxes, the oligotrophic subtropical Pacific is a region where migrant-mediated export of materials across the base of the euphotic zone should be particularly important for elemental budgets. To assess the magnitude of this export flux at Stn. ALOHA (22 degrees 45'N, 158 degreesW), we determined size-structured migrant biomass on 26 cruises (1994-1996) and used allometric equations to compute metabolic losses of respiratory carbon (DIC) and excreted ammonium (DIN) at the migrant's daytime depth (temperature). Depth-integrated (155m) migrant biomass varied interannually from 286 to 457 mg DW m(-2) and seasonally from 285 to 550 mg DW m(-2) (fall versus spring), with an overall average of 394 mg DWm(-2). The 2-5 mm size-fraction always dominated. Migrant fluxes varied from 0.22 to 0.37 mmol DIC m(-2) d(-1) and from 0.033 to 0.055 mmol DIN m(-2) d(-1) between years, with an overall average of 0.304 mmol C and 0.045 mmol N m(-2) d(-1) (15 and 20% of trap PC and PN fluxes). The fluxes were highest in the spring (0.405 mmol C and 0.060 mmol N m(-2) d(-1); 18 and 24% of trap PC and PN). Strong migratory taxa, defined as those that were virtually absent from the euphotic zone during the day, were dominated by Pleuromamma and Euphausia spp. and Aetideid copepods and accounted for 40% of the total biomass-derived estimates. Using mean cruise biomass structures and temperature information from Stn. ALOHA, migrant flux estimates with different literature-derived metabolic relationships and assumptions typically varied within 20% for carbon and 25% for nitrogen. When compared on the same basis, migrant flux estimates as % trap fluxes were higher for oligotrophic regions compared to the high-nutrient, low-chlorophyll equatorial Pacific. Long-term averages of migrant biomass were substantially (two- to three-fold) higher in the subtropical Pacific compared to the Atlantic, but migrant flux estimates were similar due to higher temperatures (18 versus 9 degreesC) at daytime depths in the Atlantic. Including the effects of undersampled micronekton, dissolved organic excretion, mortality losses at depth and inter-zonal fecal transport, mean flux estimates were about doubled for carbon (30% of trap PC) and approximately tripled for nitrogen (57% of trap PN) relative to those for DIC and DIN metabolic losses. (C) 2001 Elsevier Science Ltd. All rights reserved.