Effect of temperature on zooplankton vertical migration velocity

Abstract

Zooplankton diel vertical migration (DVM) is an ecologically important process, affecting nutrient transport and trophic interactions. Available measurements of zooplankton displacement velocity during the DVM in the field are rare; therefore, it is not known which factors are key in driving this velocity. We measured the velocity of the migrating layer at sunset (upward bulk velocity) and sunrise (downwards velocity) in summer 2015 and 2016 in a lake using the backscatter strength (VBS) from an acoustic Doppler current profiler. We collected time series of temperature, relative change in light intensity chlorophylla concentration and zooplankton concentration. Our data show that upward velocities increased during the summer and were not enhanced by food, light intensity or by VBS, which is a proxy for zooplankton concentration and size. Upward velocities were strongly correlated with the water temperature in the migrating layer, suggesting that temperature could be a key factor controlling swimming activity. Downward velocities were constant, likely because Daphnia passively sink at sunrise, as suggested by our model of Daphnia sinking rate. Zooplankton migrations mediate trophic interactions and web food structure in pelagic ecosystems. An understanding of the potential environmental determinants of this behaviour is therefore essential to our knowledge of ecosystem functioning.

A low‐cost underwater particle tracking velocimetry system for measuring in situ particle flux and sedimentation rate in low‐turbulence environments

“…c shows that ρ P varied between 999 and 1013 kg m −3 , with an average of 1002 kg m −3 . These values were smaller than in vitro estimations of zooplankton carcasses by Kirillin et al () and Simoncelli et al (), but the excess density ρ P − ρ W was in agreement with in situ measurements of marine snow (Alldredge and Gotschalk ).…”

Contrasting Controls on Microzooplankton Grazing and Viral Infection of Microbial Prey

“…Swimming velocity of motile predators can vary up to 3-fold with temperature ranging from 5 to 20 • C (Larsen et al, 2008), but temperature dependence is highly species specific and can depend on acclimation state (Beveridge et al, 2010). Temperature can influences transport through energetic effects on Brownian motion and metabolic activity of motile organisms (Beveridge et al, 2010;Simoncelli et al, 2019). Temperature can also influence encounter through modifications in fluid viscosity, and is a factor influencing virus adsorption rates (Moldovan and Wu, 2007;Tokman et al, 2016).…”

Optimal light conditions for Daphnia filtration

“…For example, the swimming velocity of Daphnia is altered by the toxicity of the water (Bownik, 2017), by turbulence (Serra et al, 2019a(Serra et al, , 2018Seuront et al, 2004), and by temperature (Simoncelli et al, 2018). Low turbulence in the aquatic media enhances ingestion rates and therefore the filtration capacity of Daphnia (Serra et al, 2019a(Serra et al, , 2018Seuront et al, 2004).…”

“…Light can also be considered crucial for the growth of Daphnia as daily and seasonal vertical Daphnia migrations through the water column have been observed as being dependend on the light climate (Simoncelli et al, 2018). In experiments conducted at 20°C, the maximum size of Daphnia decreases when the period of daylight is increased and reproduction takes place earlier when there is a higher number of eggs (Martínez-Jerónimo, 2012).…”