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Oral Presentation

Abstract

Secondary compounds produced by terrestrial invasive plants can cross terrestrial-aquatic boundaries via senesced leaves, leading to altered patterns of aquatic biodiversity and ecosystem functioning. Prior attempts to examine the impacts of invasive leaves on wetland communities have primarily employed the use of leaf leachates and focal taxa inhabiting relatively low trophic positions, and additional studies are needed to examine impacts on higher-order consumers and potential additive/synergistic effects of leachates and leaf decomposition. Using cattle-tank mesocosms across multiple experiments, we observed that the addition of senescent leaves of Amur Honeysuckle (Lonicera maackii) to native leaves resulted in mass mortality of Hyla chrysoscelis tadpoles and Ambystoma maculatum larvae, despite previous laboratory observations indicating survival of the latter was unaffected by L. maackii leachates. These results were associated with significant decreases in dissolved oxygen associated with rapid decomposition of L. maackii, but we also observed changes in water clarity in L. maackii mesocosms that could impact visual and chemosensory cues. Surviving larval amphibians also experienced dramatic reductions in benthic macroinvertebrate density and diversity, large increases in larval mosquito abundance, and seemingly no impacts on zooplankton prey across multiple experiments. Adult H. chrysoscelis avoided ovipositing in mesocosms with L. maackii, suggesting long-term consequences of invasion for recruitment. These results occurred despite our use of considerably lower effective leachate concentrations than previous laboratory studies, thereby highlighting the importance of experimental venue in identifying mechanisms of biodiversity loss due to species invasions.

Comments

Josey L. Berta (1), Alexis L. Robison (2), Kurt J. Regester (2), Abigail A. Odegard (1), and E. Taylor Allen (1)

(1) Eastern Kentucky University

(2) Pennsylvania Western University Clarion

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Senesced leaves of an invasive species (Lonicera maackii) alter community composition and ecosystem function in experimental wetlands

Secondary compounds produced by terrestrial invasive plants can cross terrestrial-aquatic boundaries via senesced leaves, leading to altered patterns of aquatic biodiversity and ecosystem functioning. Prior attempts to examine the impacts of invasive leaves on wetland communities have primarily employed the use of leaf leachates and focal taxa inhabiting relatively low trophic positions, and additional studies are needed to examine impacts on higher-order consumers and potential additive/synergistic effects of leachates and leaf decomposition. Using cattle-tank mesocosms across multiple experiments, we observed that the addition of senescent leaves of Amur Honeysuckle (Lonicera maackii) to native leaves resulted in mass mortality of Hyla chrysoscelis tadpoles and Ambystoma maculatum larvae, despite previous laboratory observations indicating survival of the latter was unaffected by L. maackii leachates. These results were associated with significant decreases in dissolved oxygen associated with rapid decomposition of L. maackii, but we also observed changes in water clarity in L. maackii mesocosms that could impact visual and chemosensory cues. Surviving larval amphibians also experienced dramatic reductions in benthic macroinvertebrate density and diversity, large increases in larval mosquito abundance, and seemingly no impacts on zooplankton prey across multiple experiments. Adult H. chrysoscelis avoided ovipositing in mesocosms with L. maackii, suggesting long-term consequences of invasion for recruitment. These results occurred despite our use of considerably lower effective leachate concentrations than previous laboratory studies, thereby highlighting the importance of experimental venue in identifying mechanisms of biodiversity loss due to species invasions.