Winter mortality and growth of juvenile noble crayfish (Astacus astacus) under realistic environmental conditions – Implications for conservation management

IF 2 4区 环境科学与生态学 Q2 LIMNOLOGY
Thomas Klefoth , Sandra Bauschke , Anni Cetin , Lennart Dührkoop , Vanessa Hohnhorst , Vela Räder , Pauline Riemann , Jana Böhme
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Abstract

Noble crayfish (Astacus astacus) are endangered in many parts of Europe. Conservation efforts, including stocking measures, are widely conducted to safeguard the species and associated ecosystem functions. Due to limited availabilities of adult crayfish, juvenile noble crayfish are frequently released into lakes and rivers during autumn, usually without information on their fate and growth during the following winter. To investigate size- and density dependence of winter mortality and growth of newly stocked noble crayfish we conducted a mesocosm experiment in a small artificial lake in northern Germany. The experiment was carried out at water temperatures between 0.7 °C and 9.1 °C from mid-December until mid-March and simulated stocking densities of 20, 60, and 120 crayfish per square meter with unlimited food availability. Winter mortality rates were generally low and strongly size dependent. Specifically, a winter mortality rate of 9.2% was observed and crayfish with a total length (TL) above 34 mm all survived. The relative risk of mortality in dependence of TL increased by 41–94% (95% CI) with every decreasing centimetre of TL at the onset of winter. Increasing density had no effect on winter survival, but tended to reduce growth. Our work indicates that stocking measures of noble crayfish for conservation reasons can decrease costs and increase prospects of success if juveniles larger than 30 mm TL are used as stocking material.

现实环境条件下贵族小龙虾幼虾的冬季死亡和生长——对保护管理的启示
高贵的小龙虾(Astacus Astacus)在欧洲许多地方濒临灭绝。为了保护物种和相关的生态系统功能,广泛开展了包括放养措施在内的保护工作。由于成年小龙虾的数量有限,小龙虾的幼崽经常在秋天被放生到湖泊和河流中,通常没有关于它们在接下来的冬天的命运和生长情况的信息。为了研究新放养的珍稀小龙虾冬季死亡和生长的大小和密度依赖性,我们在德国北部的一个小型人工湖进行了中生态实验。实验于12月中旬至3月中旬在0.7°C至9.1°C的水温下进行,模拟放养密度为每平方米20、60和120只小龙虾,食物供应无限。冬季死亡率一般较低,且与大小密切相关。其中,冬季死亡率为9.2%,全长34 mm以上的小龙虾全部成活。冬季开始时,TL每减少1厘米,死亡率的相对危险度增加41-94% (95% CI)。增加密度对冬季成活率无影响,但有降低生长的趋势。我们的工作表明,如果使用大于30 mm TL的幼虾作为放养材料,出于保护原因而采取的放养措施可以降低成本并增加成功的前景。
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来源期刊
Limnologica
Limnologica 环境科学-湖沼学
CiteScore
3.70
自引率
5.90%
发文量
64
审稿时长
3 months
期刊介绍: Limnologica is a primary journal for limnologists, aquatic ecologists, freshwater biologists, restoration ecologists and ecotoxicologists working with freshwater habitats.
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