首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Responses of three invasive aquatic macrophytes to nutrient enrichment do not explain their observed field displacements
Authors:Cassandra S James  John W EatonKeith Hardwick
Institution:School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
Abstract:In some eutrophic inland waters the invasive aquatic macrophyte Elodea canadensis has been displaced by the morphologically similar species Elodea nuttallii and subsequently E. nuttallii by Lagarosiphon major. We investigated whether differences in the responses of these species and their associated epiphytic floras to five nutrient loadings in the range 30–480 μg L−1 P and 0.21–3.36 mg L−1 N could explain their observed field displacements. The mean relative growth rate (RGR) of E. nuttallii (RGR 0.086 d−1) was significantly higher than that of either E. canadensis (RGR 0.066 d−1) or L. major (RGR 0.063 d−1). All three species exhibited a plastic morphological response to increasing nutrient loadings with mean root weights reduced at the highest nutrient loading compared with the lowest loading by 33, 75 and 56% for E. canandensis, E. nuttallii and L. major, respectively. Mean tissue nitrogen concentrations increased significantly with increasing nutrient loading, with concentrations in E. canadensis (1.83–2.10% dry wt.) significantly higher than either E. nuttallii (1.56–2.10% dry wt.) or L. major (1.50–1.90% dry wt.). Tissue phosphorus concentrations likewise increased with increasing nutrient loadings although this trend was not as pronounced. Epiphyte biomass per unit photosynthetic surface area (PSA) was significantly higher on E. canadensis than on either E. nuttallii or L. major, but did not increase significantly with increasing nutrient loadings. We suggest that differences in species responses to nutrient enrichment do not explain the species displacements observed in the field. E. nuttallii's higher RGR may, regardless of nutrient supply, enable this species to shade out neighbouring species and outpace the establishment of algae on its leaves.
Keywords:Invasive  Submersed macrophyte  Eutrophication  Species displacement
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号