麦穗鱼属狭域种与广布种的感应流速比较及长麦穗鱼保护启示

COMPARSION OF THE INDUCTION VELOCITY BETWEEN NARROW ENDEMIC AND WIDESPREAD FISHES IN THE GENUS PSEUDORASBORA AND ITS CONSERVATION IMPLICATIONS FOR PSEUDORASBORA ELONGATE

  • 摘要: 为明确狭域种长麦穗鱼(Pseudorasbora elongata)和广布种麦穗鱼(Pseudorasbora parva)的趋流性差异, 以及是否因此导致其适应性的不同, 为长麦穗鱼保护提供科学依据。以二者为研究对象, 采用递增流速法对其感应流速进行测量。结果表明: 长麦穗鱼体长(7.7±1.3) cm的绝对感应流速为(2.88±1.00)—(9.63±2.28) cm/s, 相对感应流速为(0.47±0.11)—(1.09±0.24) BL/s, 不同体长组间绝对感应流速和相对感应流速均存在显著性差异(P<0.05)。麦穗鱼体长(7.2±0.9) cm的绝对感应流速为(5.25±0.82)—(7.91±1.03) cm/s, 相对感应流速为(0.83±0.10)—(0.94±0.10) BL/s, 除7.0—8.0与8.0—9.0 cm体长组外, 其余各体长组间绝对感应流速与相对感应流速均存在显著性差异(P<0.05)。两种麦穗鱼的绝对感应流速、相对感应流速与体长间均呈极显著正相关(P<0.001)。长麦穗鱼的绝对感应流速及相对感应流速均显著性低于麦穗鱼(P<0.05), 表明狭域种长麦穗鱼比广布种麦穗鱼对水流有更高的敏感性, 这可能是长麦穗鱼分布区域狭窄的重要原因之一。因此, 在长麦穗鱼栖息地的保护中, 应充分考虑其趋流性特征。在满足安全行洪的条件下, 河道整治应遵循河道的自然宽窄变化和起伏, 避免线型渠化。此外, 在长麦穗鱼分布河段, 尽量降低水坝密度, 增大水坝间隔。

     

    Abstract: In order to find out the difference of rheotaxis between narrow range species Pseudorasbora elongata and widespread species Pseudorasbora parva, and whether differences in flow sensitivity contribute to their contrasting distribution patterns, with the aim of informing conservation measures for P. elongata. In this study, we examined the induction velocity for P. elongata and P. parva with the increasing velocity protocol. The results showed that absolute induction velocity (AIF) was (2.88±1.00), (6.81±1.20), (9.63±2.28) cm/s, and relative induction velocity (RIF) was (0.47±0.11), (0.83±0.11), (1.09±0.24) BL/s for body length of 5.0—7.0, 7.0—8.5, 8.5—9.0 cm for P. elongate, respectively. Both AIF and RIF differed significantly among length groups (P<0.05). The AIF and RIF for body length of 5.0—7.0, 7.0—8.0, 8.0—9.0 cm was (5.25±0.82), (7.34±0.46), (7.91±1.03) cm/s, and (0.83±0.10), (0.98±0.06), (0.94±0.10) BL/s for P. parva, respectively. Except for the groups between 7.0—8.0 cm and 8.0—9.0 cm, there were significant differences in AIF and RIF between the other body length groups (P<0.05). The AIF and RIF were positively correlated with body length for both two species (P<0.001). Independent-samples t test showed that the AIF and RIF of P. elongata were significantly lower than that of P. parva (P<0.05). The greater sensitivity of the narrow-ranged P. elongata to water flow, compared to the widespread P. parva, is likely a key factor constraining its distribution. Therefore, conservation of P. elongata habitats should fully account for its rheotactic characteristics. River realignment should follow natural variations in channel width and morphology while meeting flood-discharge safety requirements. In addition, in the sections where the P. elongata has been distributed, the density of lower head dams should be reduced to maximize free-flowing intervals, and removal should be considered where feasible.

     

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