How is the Lake Champlain
food web changing?
Introductions of non-native species to Lake Champlain continue to change the Lake’s food web. In the last 20 years, the invasions of zebra mussel and alewife have altered plankton populations. These invasions have contributed to changing algae populations at the lower levels of the food web, and have affected the reproduction rates of some sport fish at the upper levels. The more recent arrival of spiny waterflea will cause further changes to the food web.
In Lake Champlain, the invasive zebra mussel was first discovered in 1993. Within a few years, it had displaced several native mussel species on the Lake bottom in many areas by encrusting and suffocating them. In 2003, alewife first arrived in the Lake. Data collected by the Vermont Department of Fish and Wildlife and the U.S. Fish and Wildlife Service have shown a significant reduction in native smelt populations in several parts of Lake Champlain in the years since alewife became established, suggesting that alewife are outcompeting and displacing smelt (Figure 15).
New invasive species continue to arrive both in the Lake and in the terrestrial watershed, in many cases outcompeting and displacing native species by using resources previously available to the native species. In 2014 the spiny waterflea, a tiny invasive crustacean, was discovered throughout most of Lake Champlain, and this new species is expected to cause further alterations of the base of the food web over time.
These seemingly small changes in the food web in some areas of the Lake can have significant repercussions to biodiversity across the whole ecosystem. It takes many years of research to show the impacts from some of the 50 non-native species on the native species. The cumulative effects of non-native species on the Lake Champlain ecosystem are unknown and difficult to measure, though they undoubtedly occur.