Biology subjects

Tollrian, R.

Publications and source records attributed to Tollrian, R..

3 recordsLinked to original sources

bioRxiv2024

Fish predation induces drifting and emergence in an experimental stream mesocosm system

Predator-prey interactions are important drivers of adaptation in aquatic communities, shaping the behaviour of invertebrates with cascading effects on community dynamics. Behavioural responses, such as moving with the downstream current (drift) or altering the timing of emergence, can be initiated and reduces the risk of encountering predators. This study aimed to examine the effects of indirect and direct predation pressure on drift behaviour and emergence patterns of aquatic invertebrates. Using an experimental mesocosm setup (ExStream), we analysed how the number of drifting and emerging invertebrates changed with elevated levels of chemical cues from fish (indirect predation, Gasterosteus aculeatus and Cottus rhenanus) and subsequent additional direct predation by Cottus rhenanus over a 9-day period. Our findings show that most of the analysed invertebrate groups displayed noticeable responses to either indirect, direct, or both forms of predation. Furthermore, our study revealed a significant impact of predation on emergence patterns, reducing the number and the size of emergent invertebrates. Given the importance of drift and emergence in dispersion and in facilitating resource flows into terrestrial systems, our findings indicate a strong effect of predation on the communities.

ecology↗

bioRxiv2024

Salinisation and warming disrupt predator-induced drift behaviour in aquatic predator-prey interactions

Predators act as a major selective force impacting biological communities in riverine ecosystems. Often predation risk is mediated by chemical cues upon which prey species display distinct morphological or behavioural defences. For stream invertebrates, predator-induced behaviours can be drifting and hiding. However, anthropogenic stressors increasingly impact freshwater ecosystems, with predicted consequences on the chemical information transfer, potentially affecting anti-predator behaviour. Despite this, knowledge and research on the extent to which these stressors may affect evolved predator-induced behaviour and subsequent ecosystems is scarce. Therefore, we conducted an outdoor mesocosm experiment (ExStream system) at a lowland stream in Germany, in which we investigated the effects of direct and indirect fish predation on invertebrate communities under different stressor conditions. As stressors, we tested elevated salinity (ambient vs + 136 mg/L NaCl), elevated temperature (ambient vs. + 3.4{degrees}C), and the combination of both. Our findings reveal distinct predator-induced drift behaviour, characterised by a greater number of drifting invertebrates and a concurrent reduction in overall invertebrate numbers in the communities. Increased salinity and temperature hampered the predator-induced drift behaviour. Our results support the possibility that stressors negatively impact the preys ability to perceive predators presence and respond appropriately. This disruption may alter predator-prey relationships, thereby affecting communities and potentially ecosystem functions. Highlights[vrecto] We hypothesised that anthropogenic stressors disrupt predator-induced behaviours in invertebrate prey species. [vrecto]Predator-induced drift behaviour was experimentally studied under ambient and elevated salinity and temperature conditions. [vrecto]Fish exposure elicited predator-induced drift behaviour, which decreased the number of invertebrate individuals of the communities. [vrecto]Elevated salt and elevated temperatures alone and in combination did not induce drift behaviour. [vrecto]We found that both stressors disrupted predator-induced drift behaviour, altering the anti-predator response of invertebrate prey. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=78 SRC="FIGDIR/small/601583v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1eef03borg.highwire.dtl.DTLVardef@1ddda7corg.highwire.dtl.DTLVardef@332bdaorg.highwire.dtl.DTLVardef@1842dbb_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2021

Facing the green threat: A waterflea's defenses against a carnivorous plant

Water fleas of the family Daphniidae are keystone species in many lentic ecosystems and, as most abundant filter feeders, link the primary production to higher trophic levels. As a response to the high predatory pressures, water fleas have evolved a range of defenses, including inducible defenses against animal predators. Here we show in Ceriodaphnia dubia a first example of such defenses induced by the presence of a coexisting plant predator, i.e. the carnivorous southern bladderwort (Utricularia australis, Lentibulariaceae), which possesses ultrafast underwater suction traps. When the bladderwort is present, C. dubia shows changes in morphology, life-history and behavior. While the morphological and behavioral adaptations improve C. dubias survival rate in the presence of this predator, the life-history parameters likely reflect trade-offs for the defense. Our study demonstrates plant-induced animal defenses, implying their potential relevance in freshwater ecosystems and contributing to an overall yet underestimated biodiversity of inducible defenses. Open Research StatementData is not finally prepared for upload yet. Once most fitting file types are determined and metadata is created we aim to upload all raw data as supporting information.

ecology↗