@article{SchaelickeSobischMartinCreuzburgetal.2019,
  author    = {Sch{\"a}licke, Svenja and Sobisch, Lydia-Yasmin and Martin-Creuzburg, Dominik and Wacker, Alexander},
  title     = {Food quantity-quality co-limitation},
  series = {Freshwater biology},
  volume    = {64},
  journal   = {Freshwater biology},
  number    = {5},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0046-5070},
  doi       = {10.1111/fwb.13272},
  pages     = {903 -- 912},
  year      = {2019},
  abstract  = {Food quantity and quality are highly variable in natural systems. Therefore, their interplay and the associated effects on consumer population growth are important for predator-prey interactions and community dynamics. Experiments in which consumers were exposed to elemental nutrient limitations along food quantity gradients suggest that food quality effects on consumer performance are relevant only at high food quantities. However, elemental nutrients act differently on physiological processes than biochemical nutrients. So far, the interactive effects of food quantity and biochemical compounds on consumer performance have been insufficiently studied. We studied interactive effects of food quantity and biochemical food quality on population growth, including fecundity and survival, of the freshwater rotifer Brachionus calyciflorus. We hypothesised that these life history traits are differently affected by the availability of biochemical nutrients and that food quality effects gain importance with increasing food quantity. In a first experiment, we established food quantity and quality gradients by providing rotifers with different concentrations of a low-quality food, the sterol-free cyanobacterium Synechococcus elongatus, supplemented with increasing amounts of cholesterol. In a second experiment, food quantity and quality gradients were established by providing different proportions of two prey species differing in biochemical food quality, i.e. S.elongatus and the lipid-rich alga Nannochloropsis limnetica, at different total food concentrations. We found that the effects of cholesterol supplementation on population growth increased with increasing food quantity. This interactive effect on population growth was mainly due to food quality effects on fecundity, as effects on survival remained constant along the food quantity gradient. In contrast, when feeding on the mixed algal diet, the food quality effect associated with increasing the proportion of the high-quality alga did not change along the food quantity gradient. The data on survival and fecundity demonstrate the missing interactive effect of food quantity and quality on population growth, as both traits were oppositely affected. Survival was affected by food quality primarily at low food quantity, whereas food quality effects on fecundity were stronger at high food quantity. Our results highlight the significance of essential biochemicals in mediating the interactive effects of food quantity and quality on population growth. The interplay between food quantity and biochemical food quality limitation seems to influence resource allocation patterns in order to optimise survival or reproduction, which may strongly affect population dynamics in variable environments. As opposed to exploring the function of a single nutrient via supplementation, using algae mixtures allowed us to assess food quality effects on consumer performance in a more natural context by taking potential interactive effects of multiple co-limiting nutrients into account.},
  language  = {en}
}
@misc{ParrySchlaegelTiedemannetal.2022,
  author    = {Parry, Victor and Schl{\"a}gel, Ulrike E. and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Behavioural Responses of Defended and Undefended Prey to Their Predator},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1302},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-57759},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-577594},
  pages     = {14},
  year      = {2022},
  abstract  = {Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.},
  language  = {en}
}
@article{ParrySchlaegelTiedemannetal.2022,
  author    = {Parry, Victor and Schl{\"a}gel, Ulrike E. and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Behavioural Responses of Defended and Undefended Prey to Their Predator},
  series = {Biology},
  volume    = {11},
  journal   = {Biology},
  number    = {8},
  publisher = {MDPI},
  address   = {Basel, Schweiz},
  issn      = {2079-7737},
  doi       = {10.3390/biology11081217},
  pages     = {14},
  year      = {2022},
  abstract  = {Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.},
  language  = {en}
}
@article{ParrySchlaegelTiedemannetal.2022,
  author    = {Parry, Victor and Schl{\"a}gel, Ulrike E. and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Behavioural responses of defended and undefended prey to their predator},
  series = {Biology : open access journal},
  volume    = {11},
  journal   = {Biology : open access journal},
  number    = {8},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-7737},
  doi       = {10.3390/biology11081217},
  pages     = {14},
  year      = {2022},
  abstract  = {Many animals that have to cope with predation have evolved mechanisms to reduce their predation risk. One of these mechanisms is change in morphology, for example, the development of spines. These spines are induced, when mothers receive chemical signals of a predator (kairomones) and their daughters are then equipped with defensive spines. We studied the behaviour of a prey and its predator when the prey is either defended or undefended. We used common aquatic micro-invertebrates, the rotifers Brachionus calyciflorus (prey) and Asplanchna brightwellii (predator) as experimental animals. We found that undefended prey increased its swimming speed in the presence of the predator. The striking result was that the defended prey did not respond to the predator's presence. This suggests that defended prey has a different response behaviour to a predator than undefended conspecifics. Our study provides further insights into complex zooplankton predator-prey interactions. Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status.},
  language  = {en}
}
@article{ParaskevopoulouTiedemannWeithoff2018,
  author    = {Paraskevopoulou, Sofia and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Differential response to heat stress among evolutionary lineages of an aquatic invertebrate species complex},
  series = {Biology letters},
  volume    = {14},
  journal   = {Biology letters},
  number    = {11},
  publisher = {Royal Society},
  address   = {London},
  issn      = {1744-9561},
  doi       = {10.1098/rsbl.2018.0498},
  pages     = {5},
  year      = {2018},
  abstract  = {Under global warming scenarios, rising temperatures can constitute heat stress to which species may respond differentially. Within a described species, knowledge on cryptic diversity is of further relevance, as different lineages/cryptic species may respond differentially to environmental change. The Brachionus calyciflorus species complex (Rotifera), which was recently described using integrative taxonomy, is an essential component of aquatic ecosystems. Here, we tested the hypothesis that these (formerly cryptic) species differ in their heat tolerance. We assigned 47 clones with nuclear ITS1 (nuITS1) and mitochondrial COI (mtCOI) markers to evolutionary lineages, now named B. calyciflorus sensu stricto (s.s.) and B. fernandoi. We selected 15 representative clones and assessed their heat tolerance as a bi-dimensional phenotypic trait affected by both the intensity and duration of heat stress. We found two distinct groups, with B. calyciflorus s.s. clones having higher heat tolerance than the novel species B. fernandoi. This apparent temperature specialization among former cryptic species underscores the necessity of a sound species delimitation and assignment, when organismal responses to environmental changes are investigated.},
  language  = {en}
}
@misc{DragoWeithoff2021,
  author    = {Drago, Claudia and Weithoff, Guntram},
  title     = {Variable Fitness Response of Two Rotifer Species Exposed to Microplastics Particles},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1248},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-55261},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-552615},
  pages     = {13},
  year      = {2021},
  abstract  = {Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5-25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO2) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO2 beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs.},
  language  = {en}
}
@article{DragoWeithoff2021,
  author    = {Drago, Claudia and Weithoff, Guntram},
  title     = {Variable Fitness Response of Two Rotifer Species Exposed to Microplastics Particles},
  series = {Toxics},
  volume    = {9},
  journal   = {Toxics},
  number    = {11},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2305-6304},
  doi       = {10.3390/toxics9110305},
  pages     = {13},
  year      = {2021},
  abstract  = {Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5-25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO2) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO2 beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs.},
  language  = {en}
}
@article{DragoPawlakWeithoff2020,
  author    = {Drago, Claudia and Pawlak, Julia and Weithoff, Guntram},
  title     = {Biogenic aggregation of small microplastics alters their ingestion by a common freshwater micro-invertebrate},
  series = {Frontiers in Environmental Science},
  volume    = {8},
  journal   = {Frontiers in Environmental Science},
  publisher = {Frontiers Media},
  address   = {Lausanne},
  issn      = {2296-665X},
  doi       = {10.3389/fenvs.2020.574274},
  pages     = {11},
  year      = {2020},
  abstract  = {In recent years, increasing concerns have been raised about the environmental risk of microplastics in freshwater ecosystems. Small microplastics enter the water either directly or accumulate through disintegration of larger plastic particles. These particles might then be ingested by filter-feeding zooplankton, such as rotifers. Particles released into the water may also interact with the biota through the formation of aggregates, which might alter the uptake by zooplankton. In this study, we tested for size-specific aggregation of polystyrene microspheres and their ingestion by a common freshwater rotifer Brachionus calyciflorus. The ingestion of three sizes of polystyrene microspheres (MS) 1-, 3-, and 6-mu m was investigated. Each MS size was tested in combination with three different treatments: MS as the sole food intake, MS in association with food algae and MS aggregated with biogenic matter. After 72 h incubation in pre-filtered natural river water, the majority of the 1-mu m spheres occurred as aggregates. The larger the particles, the higher the relative number of single particles and the larger the aggregates. All particles were ingested by the rotifer following a Type-II functional response. The presence of algae did not influence the ingestion of the MS for all three sizes. The biogenic aggregation of microspheres led to a significant size-dependent alteration in their ingestion. Rotifers ingested more microspheres (MS) when exposed to aggregated 1- and 3-mu m MS as compared to single spheres, whereas fewer aggregated 6-mu m spheres were ingested. This indicates that the small particles when aggregated were in an effective size range for Brachionus, while the aggregated larger spheres became too large to be efficiently ingested. These observations provide the first evidence of a size- and aggregation-dependent feeding interaction between microplastics and rotifers. Microplastics when aggregated with biogenic particles in a natural environment can rapidly change their size-dependent availability. The aggregation properties of microplastics should be taken into account when performing experiments mimicking the natural environment.},
  language  = {en}
}
@article{ColangeliSchlaegelOberteggeretal.2019,
  author    = {Colangeli, Pierluigi and Schl{\"a}gel, Ulrike E. and Obertegger, Ulrike and Petermann, Jana S. and Tiedemann, Ralph and Weithoff, Guntram},
  title     = {Negative phototactic response to UVR in three cosmopolitan rotifers: a video analysis approach},
  series = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica},
  volume    = {844},
  journal   = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica},
  number    = {1},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0018-8158},
  doi       = {10.1007/s10750-018-3801-y},
  pages     = {43 -- 54},
  year      = {2019},
  language  = {en}
}