稀有鮈鲫对不同生境的选择性偏好

对不同生境的识别和选择性偏好是保障鱼类生存和繁衍的重要能力之一。以稀有鮈鲫（Gobiocypris rarus）为研究对象，使用沙、水草和石块在观测水缸中进行多种排列组合以构建不同的生境类型，基于在各区域的停留时长和中线跨越次数两项参数，测试稀有鮈鲫对不同生境类型的偏好以及营养状态、生境组成物数量、环境照度对该行为影响。结果表明，稀有鮈鲫对不同的生境类型具有明显的选择性偏好，对仅水草生境偏好程度最高，对仅石块生境的偏好程度最低。该偏好行为在24 h的禁食后变化不显著（P > 0.05），但生境组成物数量和环境照度对该行为具有显著影响（P < 0.05），其偏好程度随水草数量和照度的增加而增加，在包含8棵水草及1 000 lx的照度下最高。

The Selective Preference of Rare Minnow (Gobiocypris rarus) to Different Habitats

The identification and selective preference for different habitats is one of the important abilities to ensure the survival and reproduction of fish. The preference of Rare Minnow (Gobiocypris rarus) for different habitat and the effects of nutrient status, number of components and environmental illumination on this behavior were tested. Sand, aquatic plants, and stones were used in a variety of permutations and combinations in tank to create different habitat types. The behavior was quantified based on the time spent of fish in each area of tank and frequency of midline crossing. The effects of nutrient status, number of components and environmental illumination was tested under following condition respectively by the controlling the variable method: (1) Two groups of nutritional status of fish: food-deprived and well-fed. Fish of food-deprived was stopped feeding for 24 h; (2) Four groups of ambient illumination: 500 lx, 1 000 lx, 1 500 lx, 2 000 lx; (3) Four groups of number of components: one, two, four, eight aquatic plants. Data were checked for assumptions of normality and assumptions of homogeneity of variance by using Kolmogorov- Smirnov and Levene tests and were analyzed by One Way Analysis of Variance and least significant difference (multiple-comparison tests). Statistical process and tests were done using the SPSS and Office Excel. Results showed that Rare Minnow had obvious preference to different habitat types (P < 0.05), and this preference degree was highest when containing only aquatic plants, and was lowest when containing only rocks (Fig. 2 and Fig. 3). This preference was not affected after food-deprived of 24 h (P > 0.05, Fig. 5), but was significantly affected by the number of habitat components (P < 0.001, Fig. 4) and environmental illumination (P < 0.001). It increased with the increase of number of aquatic plants and illumination, and was most obvious when containing 8 aquatic plants (Fig. 4) or under the illumination of 1 000 lx (Fig. 6). In conclusion, this study demonstrates that Rare Minnow had obvious preference to environment composed of aquatic plants and this preference was affected significantly by some environmental factors such as illumination and number of habitat components.