Mesozooplankton abundance, biomass and copepod secondary production at the Barents Sea polar front, June 2011

Mesozooplankton (0.25-4 mm) abundance (ind. m-3) and biomass (mg C m-3) and copepod secondary production (mg C m-3 d-1) at four stations (M1-M4) across the Barents Sea polar front, covering Atlantic to Arctic waters (75-78 °N) in June 2011. Mesozooplankton was sampled with a WP-2 net (Hydro-Bios) with 180 µm mesh, 0.57 m diameter net opening and filtering cod-end. Filtration volume was estimated from opening diameter and sampling depth. Three vertical net hauls were taken during day (around noon, WP2-day) and during night (around midnight, WP2-night) at all stations, at fixed depth intervals of 0-50 m, 50-100 m, and 100m-bottom by using a closing mechanism. The content of the cod-end was concentrated over a 90 µm mesh on deck and preserved with buffered formaldehyde at 4 % final concentration. To increase the resolution in the surface and to quantitatively sample the small copepod species and young developmental stages, one GoFlo profile was sampled at daytime at each station in the upper 50 m. Samples were taken from 1, 10, 20, 30, 40 and 50 m depth. The content of the water bottle (30 liters) from each individual depth was concentrated over a 20 µm mesh and preserved with buffered formaldehyde at 4 % final concentration. Mesozooplankton were counted and determined to species and developmental stage under a Leica dissecting microscope at 40x magnification. Mesozooplankton abundance was converted into biomass, based on species and stage-specific carbon weight relationships.
Daily copepod secondary production (mg C m−3 d−1) in the upper 50 m water column was calculated as the sum of the product of biomass and weight-specific growth rate of each individual stage within the copepod population. Copepod growth rate was determined using four different growth rate models, namely Hirst & Bunker 2003 (HB_copepod_secondary_production, based on copepod body weight, chlorophyll a concentration, in-situ water temperature), Hirst & Lampitt 1998 (HL_copepod_secondary_productioncopepod, based on body weight, in-situ water temperature), Huntley & Lopez 1992 (HuLo_copepod_secondary_production, based on in-situ water temperature) and Zhou et al. 2010 (Zhou_copepod_secondary_productioncopepod, based on body weight, chlorophyll a concentration, in-situ water temperature, assimilated food input).

在2011年6月，对跨越巴伦支海极锋（75-78 °N）的四大站（M1-M4）的浮游动物中，介形浮游动物（0.25-4毫米）的丰度（个体每立方米）和生物量（碳毫克每立方米立方），以及桡足类的次级生产（碳毫克每立方米每天）进行了采样。使用Hydro-Bios公司生产的WP-2网（180微米网孔，直径0.57米，过滤尾端）进行介形浮游动物的采样。通过开口直径和采样深度估算过滤体积。在所有站点，于白天（约正午，WP2-day）和夜间（约午夜，WP2-night）在固定深度间隔（0-50米，50-100米，以及100米底部）采用闭合机制进行三次垂直网具拖曳。在甲板上，将尾端内容物浓缩在90微米网孔上，并用4%最终浓度的缓冲甲醛进行保存。为了提高表层分辨率并定量采样小型桡足类物种和幼年发育阶段，在每个站点的上层50米内使用GoFlo剖面在白天进行采样。从1米、10米、20米、30米、40米和50米深度采集样本。将每个个体深度水样瓶（30升）的内容物浓缩在20微米网孔上，并用4%最终浓度的缓冲甲醛进行保存。在Leica解剖显微镜（40倍放大）下对介形浮游动物进行计数并鉴定到物种和发育阶段。根据物种和发育阶段的特定碳重量关系，将介形浮游动物的丰度转换为生物量。在上层50米水柱中的每日桡足类次级生产（碳毫克每立方米每天）通过计算桡足类种群中每个个体阶段的生物量与重量特定生长率的乘积之和来计算。使用四种不同的生长率模型确定桡足类生长率，分别是Hirst & Bunker 2003年模型（HB_copepod_secondary_production，基于桡足类体重、叶绿素a浓度、现场水温）、Hirst & Lampitt 1998年模型（HL_copepod_secondary_productioncopepod，基于体重、现场水温）、Huntley & Lopez 1992年模型（HuLo_copepod_secondary_production，基于现场水温）和Zhou等人2010年模型（Zhou_copepod_secondary_productioncopepod，基于体重、叶绿素a浓度、现场水温、同化食物输入）。