Invasion of littoral zones by adventive macrophyte species can facilitate major changes in the ecology of lakes. In Lake Wanaka, a large alpine New Zealand lake, the macrophytes Lagarosiphon major and Elodea canadensis (Hydrocharitaceae) have invaded parts of the lake where they form tall dense plant beds throughout mid-depths (2–7 m) of the littoral zone. We investigated differences in plants, benthic invertebrates, fish, and food webs characterizing native and exotic plant beds in mid-depths of the littoral zone. The 3× higher plant biomass and 2× higher plant surface area in exotic than in native plant beds (quillworts, milfoils, and charophytes) contributed to greater standing stocks and productivity of epiphyton in the exotic plant beds. Invertebrate communities were less dense (1890/m2 vs 4030/m2) and less diverse (richness = 9 vs 12) in native than in exotic plant beds because of differences in biomass, productivity, and physical structure of native and exotic plant communities. Invertebrate communities in native beds were dominated by snails, oligochaetes, and nematodes, whereas chironomids, snails, and caddisflies were dominant in exotic beds. Stable isotope signatures (13C and 15N) and dietary analyses indicated that Potamopyrgus antipodarum, the dominant invertebrate taxon in both bed types, consumed mostly epiphyton. In native beds, consumption of sedimentary fine benthic organic matter by oligochaetes and nematodes made significant contributions to C flow, whereas, in exotic beds, consumption of epiphyton by grazers (e.g., snails, caddisflies, and chironomids) was an important pathway for C flow. Macrophytes made only small contributions to C flow in either bed type. The dominant native fish in Lake Wanaka, the bully Gobiomorphus cotidianus, was more abundant in exotic than in native beds, but bully predation rates on snails were significantly lower in exotic than in native beds. Invasion by adventive macrophyte species can cause significant shifts in lake productivity, species composition, and foodweb dynamics.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.