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Multiple stressors in rotifer communities: : Effects of predation, climate change, and brownification

Zhang, Huan LU (2017)
Abstract (Swedish)
De flesta vattenlevande organismer på Jorden lever i en miljö där de samtidigt måste hantera flera olika hot och stressituationer, såsom t.ex. predation, klimatförändringar och brunifiering. Trots relativt god kunskap om varje stressfaktor för sig, vet man förvånansvärt lite om hur synergier av samtidigt förekommande hot påverkar organismer. Därför har jag i min avhandling undersökt hur predation, klimatförändringar (temperaturökning) och brunifiering (ökad humushalt) påverkar samhällsdynamiken hos min modellorganism – rotatorier. Jag visar att predation har en betydande inverkan inte bara på populationsstorleken, utan också på hur rotatorierna inducerar försvarsmekanismer. Således får fiskyngel (en stor predator för rotatorierna) längden... (More)
De flesta vattenlevande organismer på Jorden lever i en miljö där de samtidigt måste hantera flera olika hot och stressituationer, såsom t.ex. predation, klimatförändringar och brunifiering. Trots relativt god kunskap om varje stressfaktor för sig, vet man förvånansvärt lite om hur synergier av samtidigt förekommande hot påverkar organismer. Därför har jag i min avhandling undersökt hur predation, klimatförändringar (temperaturökning) och brunifiering (ökad humushalt) påverkar samhällsdynamiken hos min modellorganism – rotatorier. Jag visar att predation har en betydande inverkan inte bara på populationsstorleken, utan också på hur rotatorierna inducerar försvarsmekanismer. Således får fiskyngel (en stor predator för rotatorierna) längden på utskotten hos rotatorien Keratella cochlearis att minska, både genom inducering av kortare utskott och genom att selektivt predera på individer med långa utskott. Vidare demonstrerar jag att rotatorier kan detektera olika typer (storlekar) av predatorer och anpassa sitt försvar (utskott) så att de i möjligaste mån undgår att bli uppätna, antingen genom att sträva efter att bli mindre eller större än predatorns optimala födostorlek.
Mina studier visar också att rotatoriesamhällen etableras tidigare på våren i ett simulerat framtida klimatscenarium, men att också en dominerande predator (cyclopoida copepoder) svarar på liknande sätt och därmed håller antalet rotatorier nere. Vidare visar jag att i ett framtida klimatscenarium med ökande frekvens av extrema temperaturer, kommer cyclopoida copepoder att gynnas av ”värmeböljor” eftersom de har förmågan att låta en del av populationen vila (diapause) som nästan vuxna individer, vilka lika snabbt som rotatorier kan svara på temperaturökningar. Detta betyder att klimatförändringen sannolikt inte leder till någon ”mis-match” situation mellan byte och predator. I ett vidare perspektiv visar mina studier att skillnader i livshistoria påverkar predator-byte interaktionerna, och därmed samhällsdynamiken, i ett framtida klimatscenarium.
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Abstract
Most organisms on Earth live in an environment where they are exposed to multiple pressures, including predation and climate change. In many aquatic ecosystems, organisms have to handle additional challenges such as brownification, co-occurring with climate warming. Despite the growing recognition of impacts of climate warming or brownification on the freshwater communities, little is known on how synergistic effects from multiple environmental changes will affect community dynamics in freshwater ecosystems. In this thesis I investigate the effects of predation, climate changes, and brownification on the rotifer community dynamics.
I show that predation has strong effects not only on population growth but also on inducible... (More)
Most organisms on Earth live in an environment where they are exposed to multiple pressures, including predation and climate change. In many aquatic ecosystems, organisms have to handle additional challenges such as brownification, co-occurring with climate warming. Despite the growing recognition of impacts of climate warming or brownification on the freshwater communities, little is known on how synergistic effects from multiple environmental changes will affect community dynamics in freshwater ecosystems. In this thesis I investigate the effects of predation, climate changes, and brownification on the rotifer community dynamics.
I show that predation has strong effects not only on population growth but also on inducible morphological defenses in rotifers. Larval fish feed extensively on rotifer prey and reduces spine length of a common rotifer (Keratella cochlearis) both through induction of shorter spines and selective predation on long-spined individuals. Furthermore, I demonstrate that rotifer prey can detect and respond appropriately in opposite directions to different sizes and feeding modes of predators by being plastic in spine and body size.
My studies show that rotifer community will start to establish earlier in spring under a climate-warming scenario, whereas it would also decline earlier due to increased predation pressure. Furthermore, I show that in a future climate scenario with increased temperature variations and frequency of extreme temperatures, predatory copepods benefit from heat waves due to their ability of initiating diapause at an almost adult stage and rapidly responding to temperature variation, while rotifers suffer from a higher predation pressure. Hence, in a broader perspective my studies suggest that differences in life history traits will affect predator-prey interactions, and consequently alter community dynamics, in a future climate change scenario. However, the effects of brownification on establishment and growth in the rotifer community were less pronounced, or even negligible. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr. Declerck, Steven, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Climate change, community dynamic, brownification, heat wave, inducible defense, rotifer, plasticity, multiple stressors, Predation, prey
pages
129 pages
publisher
Lund University, Faculty of Science, Department of Biology
defense location
Lecture hall “Blå hallen”, Ecology building, Sölvegatan 37, Lund
defense date
2017-11-02 09:00
ISBN
978-91-7623-427-3
978-91-7623-426-6
language
English
LU publication?
yes
id
abfadb33-fe06-4b7d-9812-303e2a775f94
date added to LUP
2017-10-09 11:16:22
date last changed
2017-10-11 14:38:13
@phdthesis{abfadb33-fe06-4b7d-9812-303e2a775f94,
  abstract     = {Most organisms on Earth live in an environment where they are exposed to multiple pressures, including predation and climate change. In many aquatic ecosystems, organisms have to handle additional challenges such as brownification, co-occurring with climate warming. Despite the growing recognition of impacts of climate warming or brownification on the freshwater communities, little is known on how synergistic effects from multiple environmental changes will affect community dynamics in freshwater ecosystems. In this thesis I investigate the effects of predation, climate changes, and brownification on the rotifer community dynamics.<br/>I show that predation has strong effects not only on population growth but also on inducible morphological defenses in rotifers. Larval fish feed extensively on rotifer prey and reduces spine length of a common rotifer (Keratella cochlearis) both through induction of shorter spines and selective predation on long-spined individuals. Furthermore, I demonstrate that rotifer prey can detect and respond appropriately in opposite directions to different sizes and feeding modes of predators by being plastic in spine and body size.<br/>My studies show that rotifer community will start to establish earlier in spring under a climate-warming scenario, whereas it would also decline earlier due to increased predation pressure. Furthermore, I show that in a future climate scenario with increased temperature variations and frequency of extreme temperatures, predatory copepods benefit from heat waves due to their ability of initiating diapause at an almost adult stage and rapidly responding to temperature variation, while rotifers suffer from a higher predation pressure. Hence, in a broader perspective my studies suggest that differences in life history traits will affect predator-prey interactions, and consequently alter community dynamics, in a future climate change scenario. However, the effects of brownification on establishment and growth in the rotifer community were less pronounced, or even negligible.},
  author       = {Zhang, Huan},
  isbn         = {978-91-7623-427-3},
  keyword      = {Climate change,community dynamic,brownification,heat wave,inducible defense,rotifer,plasticity,multiple stressors,Predation,prey},
  language     = {eng},
  pages        = {129},
  publisher    = {Lund University, Faculty of Science, Department of Biology},
  school       = {Lund University},
  title        = {Multiple stressors in rotifer communities: : Effects of predation, climate change, and brownification},
  year         = {2017},
}