The effects of lake productivity and late‐summer hypolimnetic oxygen on the size and shape of Cisco Coregonus artedi were examined in 27 Minnesota lakes. Geometric morphometry analyses of specimens captured in vertical gill nets indicated that Cisco in more productive lakes with hypoxic hypolimnia were larger, with deeper bodies, shorter snouts and caudal peduncles, and longer fins. Cisco in unproductive lakes with oxygenated hypolimnia were smaller, with slender bodies, longer snouts and caudal peduncles, and shorter fins. The effect of hypolimnetic oxygen on depths utilized by Cisco and the resulting vulnerability to predation was an important driver of shape and fin length. Deeper body depths and longer fin lengths were possibly a response to greater vulnerability to predation when hypoxic hypolimnia limit coldwater refugia for Cisco, which are forced to inhabit shallower depths near warmwater predators such as Walleye Sander vitreus and Northern Pike Esox lucius. Differences in size and shape relationships of Cisco in lakes on and off the Canadian Shield were also detected. The availability of late‐summer habitat, depth‐mediated predation risk, and growth potential appear to be important ecological drivers of morphological variation in Cisco.

中文翻译：

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思科在湖泊生产力梯度上的形态变化

湖泊生产力和夏末低氧氧气对Cisco Coregonus artedi大小和形状的影响在明尼苏达州的27个湖泊中进行了检查。对垂直刺网中捕获的标本进行几何形态分析表明，思科在缺氧性低氧血症的生产力更高的湖泊中体形较大，身体更深，鼻子和尾柄较短，鳍片较长。缺氧性充血性低氧的湖泊中的思科较小，身体细长，鼻子和尾柄较长，鳍片较短。低氧氧气对思科使用的深度的影响以及由此导致的对捕食的脆弱性是形状和鳍长度的重要驱动力。当缺氧性低氧血症限制了思科的冷水避难所时，更深的体深和更长的鳍长可能是对更大的捕食脆弱性的反应，思科被迫在浅水深处栖息在浅水处，例如Walleye Sander玻璃体和北派克Esox lucius。还发现了加拿大盾构内外湖泊中思科的大小和形状关系的差异。夏末栖息地的可用性，深度介导的捕食风险和增长潜力似乎是思科形态变异的重要生态驱动力。