Invasive Species Compendium

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Abstract

Vegetation response and juvenile northern pike (Esox lucius) outmigration following connectivity enhancement of a Typha dominated coastal wetland.

Abstract

We examined if restored connectivity within a freshwater coastal wetland, dominated by invasive Typha × glauca, can increase the ecological condition, as assessed by a Floristic Quality Index (FQI), and improve habitat to benefit northern pike (Esox lucius) reproduction. Using an aquatic excavator to simulate natural rivulets, channels were excavated within monotypic Typha stands to create a link to upslope wet meadows. Following excavation, we found channels were rapidly colonized by native vegetation, resulting in higher FQI scores and percent cover of short-emergent vegetation compared to natural reference channels. Excavated channels also retained a community of vegetation with more native species five years following excavation. Fish emigration surveys revealed that excavated channels functioned as early-life habitat and had higher abundances of young-of-the-year northern pike than reference channels. A seven-year dataset (2011–2017) of northern pike outmigration at channel connectivity and pothole complexes was strongly related to water level conditions during the spawning and emigration period. We conclude that the enhancement methods increased the ecological condition of the vegetation community (i.e., FQI) suppressed by invasive Typha while the associated northern pike reproductive success highlights the importance of habitat connectivity and periodic flooding within coastal wetlands.