Active and passive vertical motion of zooplankton in a lake

Huber, Andrea M. R.; Peeters, Frank; Lorke, Andreas

doi:10.4319/lo.2011.56.2.0695

Cited by 28 publications

(38 citation statements)

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“…The power spectra describe the distribution of velocity variance as a function of frequency and allows distinguishing high-frequency variations in swimming velocity, e.g., hop and sink, from low-frequency variations associated with changes in swimming behavior or animal migration (Huber et al 2011). The power spectra obtained for the three velocity components of an individual from set 1 reveal that variations in horizontal swimming velocity were not isotropic.…”

Section: Resultsmentioning

confidence: 99%

Three‐dimensional tracking of multiple aquatic organisms with a two camera system

Noß

Lorke

Niehaus

2013

Limnology & Ocean Methods

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A new constraint assignment algorithm and a two-perspective tracking method are presented for threedimensional tracking of motile aquatic organisms. The method aims at providing preferably long tracks of multiple, simultaneously swimming individuals. As an extension to existing tracking and assignment methods, the presented algorithm takes background knowledge about maximum swimming speed and size of the organisms into account. Two strategies, both using the constraint assignment algorithm, were applied to track either a fixed number of objects or to track as many objects as possible in frame-to-frame transitions. Whereas the first strategy provides continuous and distinct tracks of all individuals for the entire measurement sequence, the second strategy does not require interpolation of unresolved positions and is more robust to disappearance or reappearance of organisms within the field of view. Two sets of video records of freely swimming Daphnia magna, differing in abundance, image quality, and record length, are analyzed to assess the tracking success of the proposed algorithm. Although both strategies provide better results for a higher detection rate of organisms, the first strategy is preferable for tracking individuals in tests with smaller organism abundance and higher signalto-noise ratio, whereas the second strategy also provides reasonable pathways under less optimal conditions. Spectral analysis of observed swimming velocities is applied to demonstrate the advantage of obtaining long, continuous, and three-dimensional tracks of moving organisms.

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Section: Resultsmentioning

confidence: 99%

Three‐dimensional tracking of multiple aquatic organisms with a two camera system

Noß

Lorke

Niehaus

2013

Limnology & Ocean Methods

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“…Strong predation pressure triggers avoidance behavior in many zooplankton species (such as Daphnia), resulting in "diel vertical migration" (DVM) behavior. DVM is one of the most important escape responses exhibited by aquatic herbivores (Hays 2003) and it has been shown, that DVM can be a feature in a lake nearly throughout the whole year (Huber et al 2011). Zooplankton species performing DVM spend the night primarily in upper water layers, migrating down the water column at dawn to spend the day in deeper, darker and, colder waters (Lampert 1989).…”

Section: Introductionmentioning

confidence: 99%

Initial size structure of natural phytoplankton communities determines the response to Daphnia diel vertical migration

et al. 2012

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Diel vertical migration (DVM) is a common behavior of many pelagic herbivorous zooplankton species in response to predation pressure. It is characterized by a twice daily habitat shift of the zooplankton species placed in mesh cages that were lowered or raised ("migration") as dictated by the study design; a "no migration" (representing absence of DVM) treatment was also tested. Phytoplankton abundance was measured using chlorophyll-a and biovolume; size distribution of the algae and nutrient availability was also determined in each treatment. The results indicated that DVM had contrasting effects on the two evaluated phytoplankton communities.Comparison of "migration" and "no migration" zooplankton treatments showed that nutrient availability and total phytoplankton biovolume was higher in (1) "no migration" treatments with phytoplankton communities comprising mainly small algae and (2) "migration" treatments with phytoplankton communities of a broader size spectrum of algae. Hence our study showed two different mechanisms of how zooplankton DVM may influence the phytoplankton community dynamics. Nutrient cycling was an important factor in phytoplankton communities of mainly small algae, whereas the refuge effect was the main driver of phytoplankton dynamics in phytoplankton communities of a large size spectrum of algae

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“…The methodology for studying zooplankton is rapidly evolving from the use of Hansen-type plankton nets to highly sophisticated acoustic (Hembre and Megard 2003;Lorke et al 2004;Rinke et al 2007;Huber et al 2011) or optical technologies (Herman 1988;Herman and Harvey 2006;Liebig et al 2006;Patoine et al 2006). The latter are even able to visualize individual zooplankton and count them in their natural environment (for a review, see Benfield et al 2007).…”

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confidence: 99%

“…Instruments that are currently used to measure scattering from zooplankton vary in their design, and some of them are actually manufactured for other purposes. The Acoustic Doppler Current Profiler (ADCP), for example, is primarily used for measuring current velocity, but it has also been adopted for the assessing of zooplankton biomass (Flagg and Smith 1989;Lorke et al 2004;Rinke et al 2007;Huber et al 2011). ADCP uses the Doppler effect to record vertical current profiles.…”

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“…Volume backscatter strength is a logarithmic quantity, a 3-4 dB difference, which has been empirically shown to represent a doubling in the biomass of zooplankton (Warren and Wiebe 2008; see also the present results). The results of acoustic measurements have been related to conventional net samples either empirically (Hembre and Megard 2003;Huber et al 2011) or theoretically, applying assumptions regarding the target strengths of individual organisms (Sutor et al 2005). The latter method is valid only when the zooplankton community is dominated by a few species that provide a strong acoustic target.…”

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confidence: 99%

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Intercalibration of an acoustic technique, two optical ones, and a simple seston dry mass method for freshwater zooplankton sampling

Rahkola-Sorsa

Voutilainen

Viljanen

2014

Limnology & Ocean Methods

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A thorough comparison is made of conventional and automated zooplankton sampling techniques. The findings offer tools for complementing netted and weighed zooplankton biomasses with estimates based on acoustic and optic techniques, and thereby fill a gap in our knowledge concerning the suitability of acoustic and optic techniques for freshwater zooplankton sampling. Plankton abundance in six large boreal lakes with varying characteristics was determined by four independent methods: one acoustic (Acoustic Doppler Current Profiler), two optic (laboratory versions of the Optic and Laser Optic Plankton Counter), and a simple seston dry mass (DM) method. The combined DM of Chaoborus and medium-sized zooplankton (300-500 μm) explained 63% of the original variability in the acoustic backscatter strength. The correspondence between the optical measurements and DM was especially good in the case of medium-sized zooplankton. Thus the LOPCderived biomass (ESD 351-500 μm) explained 90% of variation in the DM of zooplankton of size 300-500 μm. The medium-sized fraction consisted mainly of small Cyclopoida and copepodite stages of Eudiaptomus and Daphnia. Both optical devices, and particularly the LOPC, are reliable for analyzing preserved net samples of freshwater zooplankton, but in situ estimation of zooplankton abundances on the basis of ADCP results is not reliable without simultaneous net or optical sampling. Acoustic results can be calibrated by reference to DM or LOPC-derived biomass estimates. The combined use of acoustic and optical techniques clearly improves the spatio-temporal resolution of zooplankton measurements and can thus provide closer insights into ecosystem dynamics, including the forces which regulate plankton communities. *Corresponding author. E-mail: minna.rahkola@uef.fi AcknowledgmentsWe thank the skilful staff of the R/V Muikku for carrying out the sampling in the field, and all the ex-workers of the former Ecological Institute for their assistance in the laboratory. We are grateful to Greta Waissi-Leinonen, Irina Dushkina, and Matti Koistinen for running the OPC and LOPC routines and Kirsti Kyyrönen for drawing the map. We also thank professors (emeritus) Kalevi Salonen and Jouko Sarvala for their helpful comments and suggestions that improved the clarity of the manuscript. Malcolm Hicks kindly revised the English language of the manuscript.

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Active and passive vertical motion of zooplankton in a lake

Cited by 28 publications

References 38 publications

Three‐dimensional tracking of multiple aquatic organisms with a two camera system

Three‐dimensional tracking of multiple aquatic organisms with a two camera system

Initial size structure of natural phytoplankton communities determines the response to Daphnia diel vertical migration

Intercalibration of an acoustic technique, two optical ones, and a simple seston dry mass method for freshwater zooplankton sampling

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