Biology Department, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada.
Ontario Ministry of Natural Resources and Forestry, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada.
J Fish Biol. 2020 Jan;96(1):92-101. doi: 10.1111/jfb.14188. Epub 2019 Nov 24.
We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co-habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00' to 47° 30' N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10' to 52° 20' N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ C) and nitrogen (δ N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ C) and a higher trophic elevation (higher δ N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ C- δ N space), particularly in the food chain (δ N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes.
我们比较了两个北方湖泊群中淡水拟杜父鱼的营养生态位与其他共生的饵料鱼的营养生态位，这两个湖泊群的生境和鱼类群落特征存在显著差异。近北方湖泊（北纬 45°00′至 47°30′）较深，分层明显，顶级掠食鱼类为湖红点鲑；而远北方湖泊（北纬 51°10′至 52°20′）较浅，不分层，顶级掠食鱼类为白斑狗鱼和大眼狮鲈。根据肌肉稳定碳（δ¹³C）和氮（δ¹⁵N）同位素比值计算的生态位指标，我们比较了拟杜父鱼和其他饵料鱼的营养生态位。在近北方湖泊中，拟杜父鱼几乎完全生活在深离岸水域，其生态位位置反映出它们对浮游生物生产的依赖性更强（更低的 δ¹³C）和更高的营养级（更高的 δ¹⁵N），与大多数其他饵料鱼相比。此外，近北方湖泊中的拟杜父鱼的营养生态位往往更大（在 δ¹³C- δ¹⁵N 空间中占据更大的面积），特别是在食物链（δ¹⁵N）维度上，比其他共生的饵料鱼更大。相比之下，远北方湖泊中的拟杜父鱼通常生活在近岸，其营养生态位位置和大小与其他共生的饵料鱼相似。本研究说明了拟杜父鱼在北方湖泊中，其实现的营养生态位与栖息地可利用性和鱼类群落组成之间的灵活性。
