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Diet of capelin (Mallotus villosus) in the Eastern Canadian Arctic inferred from stomach contents and stable isotopes
Polar Biology ( IF 1.7 ) Pub Date : 2020-07-04 , DOI: 10.1007/s00300-020-02707-1
Wesley R. Ogloff , Steve H. Ferguson , Ross F. Tallman , Gail K. Davoren

Capelin (Mallotus villosus), a sub-Arctic forage fish, has become abundant in the Canadian Arctic in recent decades, with consistent spawning documented; however, the trophic role of capelin in these systems is unknown. We investigated the diets of small, immature (70–129 mm), medium, mature (130–174 mm), and large, mature (175–219 mm) capelin in Pangnirtung Fjord, Nunavut during and prior to spawning in June–July, 2015–2016 using stomach contents and stable isotopes, respectively. Ontogenetic niche shifts were observed in both cases. Small, immature capelin consumed predominantly small copepods (primarily Clausocalanidae) and had a narrow isotopic niche (SEAC: 0.11 ‰2). In contrast, medium-sized, mature capelin consumed a mix of Calanus copepods, amphipods, and mysids and had a broad isotopic niche (SEAC range: 0.23–0.51 ‰2), while large, mature capelin consumed higher proportions of large prey types (primarily Calanus hyperboreus and amphipods) and had a narrower isotopic niche (SEAC range: 0.09–0.26 ‰2). A higher percentage (by dry biomass) of capelin eggs (73–100%) were consumed by mature capelin in 2016, when ice cover in the fjord delayed the initiation of sampling by ~ 10 days after spawning had begun, relative to 2015 (0–9%). Non-egg prey types primarily consisted of amphipods (77–100% by dry biomass, mostly ice-associated Apherusa glacialis) in 2016 and primarily pelagic Calanus copepods (64–99%) in 2015. As capelin diet was broadly similar to other Arctic forage fishes, such as polar cod (Boreogadus saida), high dietary overlap may occur. Findings provide baseline data to examine future changes in capelin diet as well as their trophic interactions in the Canadian Arctic.

中文翻译:

从胃内容物和稳定同位素推断加拿大东部北极毛鳞鱼(Mallotus villosus)的饮食

毛鳞鱼(Mallotus villosus)是一种亚北极饲料鱼,近几十年来在加拿大北极地区变得丰富,产卵记录一致;然而,毛鳞鱼在这些系统中的营养作用尚不清楚。我们在 6 月至 7 月产卵期间和之前调查了努勒维特 Pangnirtung Fjord 的小型、未成熟(70-129 毫米)、中型、成熟(130-174 毫米)和大型、成熟(175-219 毫米)毛鳞鱼的饮食, 2015-2016 分别使用胃内容物和稳定同位素。在这两种情况下都观察到个体发育的生态位变化。小的、未成熟的毛鳞鱼主要消耗小型桡足类(主要是 Clausocalanidae)并且具有狭窄的同位素生态位(SEAC:0.11‰2)。相比之下,中等大小的成熟毛鳞鱼混合了桡足类、片脚类和糠虾,具有广泛的同位素生态位(SEAC 范围:0.23–0.51 ‰2),而大的、成熟的毛鳞鱼消耗更高比例的大型猎物(主要是Calanus hyperboreus 和片脚类动物),并且具有更窄的同位素生态位(SEAC 范围:0.09–0.26 ‰2)。与 2015 年相比,2016 年成熟的毛鳞鱼消耗了更高百分比(按干生物量计)的毛鳞鱼卵(73-100%),当时峡湾的冰盖在产卵开始后延迟了约 10 天(0 –9%)。2016 年的非蛋猎物类型主要包括片脚类动物(干生物量的 77-100%,主要是与冰相关的 Apherusa glacialis)和 2015 年的主要是远洋 Calanus 桡足类(64-99%)。由于毛鳞鱼的饮食与其他北极地区大体相似饲料鱼,如极地鳕鱼 (Boreogadus Saida),可能会出现高度的饮食重叠。研究结果提供了基线数据,以检查毛鳞鱼饮食的未来变化以及它们在加拿大北极地区的营养相互作用。
更新日期:2020-07-04
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