Differences in growth and survivorship of zebra and quagga mussels: size matters

Abstract

The zebra mussel (Dreissena polymorpha) and its congener the quagga mussel (Dreissena rostriformis bugensis) are both invaders in freshwater, but have very different invasion histories, with zebra mussels attaining substantially faster rates of spread at virtually all spatial scales. However, in waterbodies where they co-occur, D. r. bugensis can displace D. polymorpha. To determine if the mechanisms for this displacement are associated with different survival and growth, we kept mussels in flow-through tanks for 289 days with two temperature regimes that mimicked the natural surface water (littoral zone) and hypolimnion conditions of Lake Erie. For the littoral zone regime, we used water directly from the surface of Lake Erie (range 4-25°C, average 11.9 ± 0.6°C). For the profundal zone treatment, Lake Erie surface water was chilled to about 6°C (range 5-8°C, average 6.2 ± 0.6°C) for the full duration of the experiment. For each of these temperature regimes, we used three replicate tanks with only zebra mussels present and three replicate tanks with only quagga mussels (150 ind./tank each), and three replicate tanks with both species (75 ind./ tank of each species). Quagga mussels had higher survivorship and grew more than zebra mussels in all treatments. For both species, the size of the mussel entering the winter was critical for survivorship. Larger mussels had a higher survival over the winter in all treatments. For both species, there was a survivorship and growth tradeoff. In the warmer littoral zone treatment both species had higher growth, but lower survival than in the colder profundal zone treatment. Surprisingly, although quagga mussels outperformed zebra mussels, zebra mussel survivorship was better when they were faced with competition by quagga mussels than with just intraspecific competition. In addition, quagga mussels suffered size-specific mortality during the growing season only when facing interspecific competition with zebra mussels. Further experiments are needed to determine the possible mechanisms for these interspecific effects.

Predator‐induced morphological defences in two invasive dreissenid mussels: implications for species replacement

“…Growth of dreissenid mussels is affected by a number of environmental factors such as food supply (Chase & Bailey, ), water temperature (MacIsaac, ; Karatayev et al ., ), depth (Garton & Johnson, ) and water chemistry (Hincks & Mackie, ). Previous studies have revealed a faster growth rate of quagga than zebra mussels, presumably resulting from lower metabolism (Baldwin et al ., ; Stoeckmann, ) and higher assimilation efficiency, especially at low food concentrations (Baldwin et al ., ).…”

Food depletion regulates the demography of invasive dreissenid mussels in a stratified lake

“…Indeed, studies suggesting that dreissenid growth does not occur at low temperatures (Alimov ; Mackie ; Jantz and Neumann ; Morton a,b ) have been based on field observations during the winter, when low temperatures are coincident with low phytoplankton abundance. Our Bayesian regression analysis overcomes this limitation by synthesizing results from both lab (Karatayev et al b ) and field (this study) experiments, and highlights that both factors regulate mussel growth. Although our results suggest that the effect of food on growth are similar in magnitude to that of temperature, this estimate may be conservative because, near‐bottom growth was almost twice as fast in 2015 as in 2016, when our profundal treatments spanned the spring bloom to a greater degree (Fig.…”

“…Gradients in temperature, food, and turbulent mixing among littoral and profundal habitats are most likely responsible for observed differences in mussel growth. Many studies have observed increased growth rates at higher temperatures in quagga (MacIsaac ; Karatayev et al b ) and especially in zebra mussels (reviewed in Karatayev et al b ); similarly, the importance of food as a limiting factor for Dreissena spp. growth is well known (Dorgelo ; Sprung ; Jantz and Neumann ; Schneider et al ; Horvath and Lamberti ).…”

“…Given that both temperature and food regulate mussel growth (MacIsaac ; Karatayev et al b ), we incorporated results from a prior experiment of temperature effects on mussel growth (Karatayev et al b ) to determine the added effect of the food gradient in our study. This lab experiment used water from eastern Lake Erie in a flow‐through system to estimate a relatively precise effect of temperature on mussel growth rates over the range of temperatures observed in our 2015–2016 study and under constant, realistic food conditions.…”

A dominance shift from the zebra mussel to the invasive quagga mussel may alter the trophic transfer of metals

“…The quagga mussel expends less energy on reproduction, shell development and respiration than the zebra mussel, allowing it to invest more energy in soft tissue growth (Stoeckmann, 2003;Casper and Johnson, 2010). Consequently, the quagga mussel is able to grow quicker than the zebra mussel (Baldwin et al, 2002;Karatayev et al, Table 4 Statistically significant inter-specific differences in metal concentrations found between zebra mussel (Dreissena polymorpha) and quagga mussel (Dreissena rostriformis bugensis) tissues sampled in different water types, lakes and rivers. Fig.…”