The Impacts of Invasive Zebra and Quagga Mussels on North American ( Diporeia ) and European ( Monoporeia ) Amphipods

This review synthesizes the international literature on the effects of the invasive bivalves zebra (Dreissena polymorpha) and quagga mussels (D. rostriformis bugensis) on the amphipods Diporeia hoyi and Monoporeia affinis, which are keystone species in North American and Eurasian freshwater ecosystems, respectively. These amphipods play a central role in benthic–pelagic coupling and constitute a critical food source for many fish species, however, on both continents, their populations are often severely affected by global warming, eutrophication, pollution, and invasive species, resulting in declines in density and complete extirpation from multiple waterbodies. The introduction of invasive dreissenids has been associated with a dramatic decline of Diporeia in some American lakes. These impacts, however, vary strongly between Dreissena species and among lakes. While zebra mussels usually do not have a strong lake-wide effect on these amphipods, quagga mussels cause severe declines, and in some cases, the extirpation of Diporeia, as documented in the four lower Laurentian Great Lakes, resulting in declines in some commercially and recreationally important fish species. In smaller inland lakes, the negative impact of quagga mussels on amphipods, while still significant, appears to be less severe, potentially due to greater availability of alternative food resources, including terrestrially derived detritus. The ongoing rapid expansion of quagga mussels across Eurasia raises concerns about their future interactions with Monoporeia populations and potential adverse effects on Eurasian fisheries. Based on patterns observed in the Great Lakes, the largest Eurasian lakes (e.g., Onega, Ladoga, and Vänern) may be particularly vulnerable to strong quagga mussel-driven restructuring of benthic food webs.