Density effects on the clearance rate of the zebra mussel Dreissena polymorpha: flume study results

Abstract

Zebra mussel filtration rates and regulating factors have been addressed earlier in a number of studies. Still, only a few of them have taken into consideration the refiltration phenomenon, and therefore the direct extrapolation of experimental results may only give the potential filtering capacity, and hence, over-or underestimate the actual amount of seston being removed by zebra mussels in an ecosystem. The current experimental study aimed to gain insight into the refiltration effect on the clearance rate of the zebra mussels at relatively high seston concentrations, and its potential role in controlling the filtration efficiency of the zebra mussel population. The experiment was conducted in a laboratory flume following the Latin squares design with one fixed (mussel density) and three random factors (initial total particulate matter (TPM) concentration, flume ''wall effect'' and distance from the flume inflow area) considered. The results showed the significant effects of mussel density and the TPM concentration on the effective clearance rate (ECR) of zebra mussels. The higher ECR values were obtained at denser mussel clumps and lower TPM concentrations. The flume ''wall effect'' had no significant effect on the ECR, whereas the distance from the flume inflow area appeared to have a significant impact. A positive relationship between ECR and the zebra mussel density was most evident in the proximity of the TPM source. Based on the results, we assume that at high TPM concentration, refiltration may assert itself by the elevated net clearance rate of mussels within dense clumps compared to that of mussels at relatively low individual densities. This should be taken into consideration while modelling and assessing the role of the zebra mussel in energy flow and redistribution of organic matter in an ecosystem.

Effects of an invasive consumer on zooplankton communities are unaltered by nutrient inputs

“…Reports of zebra mussel clearance rates vary widely, with available literature showing anything in the range of 5–574 ml mussel −1 h −1 (Elliott et al ., ), and can depend strongly upon spatial configuration, even declining as density increases due to refiltration (Yu & Culver, ; Elliott et al ., ; Zaiko & Daunys, ). Theoretically our low, medium and high densities were able to process approximately 46, 93 and 187 L day −1 , respectively (using averaged individual clearance rates of clumped zebra mussels from Yu & Culver, and Zaiko & Daunys, ), but this approximately linear increase is probably an overestimation as often the lowest mussel clearance rates occur at the highest densities. However, we cannot say why there was a nutrient effect only at the medium density, and whether this effect was due to an increase or reduction in mussel impacts with added nutrients.…”

“…Nutrient enrichment in the medium mussel treatment further shifted community composition 'leftwards', an apparent exacerbation of the general effect of invasion on community composition (although the higher nutrient communities were not that different from individual communities observed in the other density treatments). Reports of zebra mussel clearance rates vary widely, with available literature showing anything in the range of 5-574 ml mussel À1 h À1 (Elliott et al, 2008), and can depend strongly upon spatial configuration, even declining as density increases due to refiltration (Yu & Culver, 1999;Elliott et al, 2008;Zaiko & Daunys, 2012). Theoretically our low, medium and high densities were able to process approximately 46, 93 and 187 L day À1 , respectively (using averaged individual clearance rates of clumped zebra mussels from Yu &Culver, 1999 andZaiko &Daunys, 2012), but this approximately linear increase is probably an overestimation as often the lowest mussel clearance rates occur at the highest densities.…”

“…Nutrients were added as a gradient of concentrations ranging from oligotrophic to eutrophic, and mussel densities were based on a range of low, medium and high natural mussel densities. Although zebra mussel impacts are often expected to increase linearly as density increases, mussel clumping can increase refiltration (filtration of water recently ejected by other mussels), often leading to lower filtration rates at higher mussel densities (Yu & Culver, ; Elliott, Aldridge & Moggridge, ; Zaiko & Daunys, ). Examination of this stressor interaction over a gradient of intensities will provide a better assessment of threshold concentrations and the potential for non‐additive interactions between two important, global stressors that frequently co‐occur.…”

Bioaccumulation of microcystins in invasive bivalves: A case study from the boreal lagoon ecosystem

“…In this study we address the bioaccumulation of microcystins by the invasive zebra mussel Dreissena polymorpha (Pallas 1771), widely distributed and being acknowledged as powerful biofilter (Karatayev and Burlakova, 1994;Karatayev et al, 2002;Nicholls, 2001;Vanderploeg et al, 2002;Zaiko and Daunys, 2012). D. polymorpha has an intrinsically high clearance rate that is approximately 10 times that of other freshwater filter-feeding bivalves (Vanderploeg et al, 2002).…”

“…D. polymorpha has an intrinsically high clearance rate that is approximately 10 times that of other freshwater filter-feeding bivalves (Vanderploeg et al, 2002). On the other hand, zebra mussel filtration capacity is highly dependent on the environmental conditions and population structure, and may vary in a wide range (Zaiko and Daunys, 2012).…”