Gammarids in Lake Constance : habitat segregation between the invasive Dikerogammarus villosus and the indigenous Gammarus roeselii
Gammarids in Lake Constance : habitat segregation between the invasive Dikerogammarus villosus and the indigenous Gammarus roeselii
复制标题
康斯坦茨湖的Gammarids：入侵的Dikerogammarus villosus和本地Gammarus roeselii之间的栖息地隔离
DOI：
10.1127/1863-9135/2008/0173-0177
复制
发表时间：
2008
影响因子：
1
通讯作者：
K. Wantzen
中科院分区：
文献类型：
--
作者：
John Hesselschwerdt;J. Necker;K. Wantzen
在过去的几十年里，入侵的蓬托-里海伽马marid Dikerogammarus villosus遍布中欧的大河，从而迅速取代了大多数本地伽马marid物种。2003年，在康斯坦斯湖首次发现了长尾草，并预测其将在竞争中胜过当地的长尾草。然而，今天这两个物种在几个地方共存。我们假设，与大多数欧洲水道相比，康斯坦茨湖沿岸地区的基质变异性更高，这使得这两个物种能够共存。为了分析这两种物种对底物的选择，我们将它们单独和一起暴露在湖岸边的围栏中。这些围场包含以下基质的组合：光秃秃的石头，覆盖着Dreissena polymorpha， Chara sp.的石头，Corbicula fl uminea的壳，叶子和沙子。毛毛线虫强烈偏好结构丰富的坚硬基质，如石头，而避免沙子和凋落叶。在占据沙质生境的基质中几乎没有分化。为了将这些结果与自然生境选择进行比较，我们在康斯坦茨湖沿岸测量了上述基质上的伽马虫密度。与围场相比，在湖泊中，多形草覆盖的石头上，长尾草几乎被长尾草取代。即使在绒毛田鼠入侵后4年，在查拉和凋落叶中仍能发现高密度的毛田鼠。根据这些数据，我们假设绿毛线虫通过在未被入侵者占领的基质上定居来躲避绒毛线虫。这些基质类型只存在于天然水体中，而在通常基质丰富度较差的受管制河流中缺乏。
Over the past decades the invasive Ponto-Caspian gammarid Dikerogammarus villosus spread throughout large rivers of central Europe, thereby rapidly displacing most of the native gammarid species. In 2003, D. villosus was fi rst observed in Lake Constance and was predicted to out-compete the native Gammarus roeselii. However, today the two species coexist at several sites. We hypothesized that a higher variability of substrates in the littoral zone of Lake Constance, compared to that found in most European waterways, allows coexistence of these two species. To analyze substrate choice of these two gammarid species we exposed them individually and together in enclosures to the littoral zone in the lake. These enclosures contained a combination of the following substrates: bare stones, stones covered with Dreissena polymorpha, Chara sp., shells of Corbicula fl uminea, leaves, and sand. D. villosus strongly preferred structure-rich hard substrates like stones while avoiding sand and leaf litter. G. roeselii barely differentiated among substrates occupying even sandy habitats. To compare these results with natural gammarid habitat choice we measured gammarid densities on the substrates mentioned above in the littoral zone of Lake Constance. In contrast to enclosures, G. roeselii was virtually displaced by D. villosus on stones covered with D. polymorpha in the lake. Even four years after the invasion of D. villosus, high densities of G. roeselii could still be found in Chara and leaf litter. From these data we hypothesize that G. roeselii takes refuge from D. villosus by colonizing substrates not occupied by the invader. These substrate types only exist in natural waterbodies and are lacking in regulated rivers which generally have poor substrate richness.