CONTRASTRESS

Contradicting responses to multiple stressors reduce the resilience of zooplankton community

 Partecipanti

Mappa

 Word cloud

Esplora la "nuvola delle parole (Word Cloud) per avere un'idea di massima del progetto.

 Obiettivo del progetto (Objective)

'The aim of the project is to find out what happens within zooplankton communitiy when various chemicals (cyanotoxins and infochemicals) force organisms to use contradictory strategies. Aquatic ecosystems are subject to many anthropogenic stressors, which includes eutrophication with toxic cyanobacterial blooms, chemical pollution (e.g. pesticides) and invasive species linked with climate change. These factors modify populations and whole lake ecosystem as well. Also natural factors like predation, resource competition and food quality may cause substantial changes in populations and communities. Organisms need to use different strategies to cope with these stressors and these strategies exclude each other. This situation may lead to losses in genetic biodiversity or even to exclusion of a species. Zooplankton plays important role in aquatic food webs and it is crucial to know how chemical interactions affect population dynamics and community structure. The aim of this study is to check what are the strategies of individuals to cope with such contrasting conditions and what is their role in biodiversity loss. To answer these questions several approaches will be used to bring together paleolimnology, evolutionary ecology and ecotoxicology. Molecular biology will be included as well in order to asses the genetic biodiversity and to develop a new tool for testing the response of an organism to chemical stressors. Two main hypotheses will be tested (1) Hormesis of a trait is maladaptive (i.e. strategy ‘bigger is better’ decreases fitness and hence indicates a negative response), (2) Interaction of cyanotoxins (hormesis) with fish infochemicals can induce developement of a new zooplankton community. Based on these working hypotheses we set several objectives: - to describe the effects of contradicting chemical signals on life history traits, - testing hormetic effects on several clones of Daphnia adapted to ‘good’ and ‘bad’ conditions, - reconstruct zooplankton com'

Introduzione (Teaser)

Effect of zooplankton on ecosystems

Descrizione progetto (Article)

Various chemicals, such as toxins produced by cyanobacteria and man-made pesticides, and natural factors, such as predation and competition for food, can alter zooplankton populations. Plankton must employ different strategies to deal with these challenges, but these strategies exclude one another, which can result in a loss of genetic diversity or even an entire species.

The 'Contradicting responses to multiple stressors reduce the resilience of zooplankton community' (CONTRASTRESS) project studied the different strategies used by zooplankton. Researchers investigated how individual populations dealt with different conditions and their role in the loss of biodiversity.

Moderate stress such as that produced by bad food conditions or small doses of toxicants can cause Daphnia (commonly called water fleas) to grow bigger and produce larger offspring. This is because larger individuals can cope better with toxins than smaller ones. However, larger size makes Daphnia more vulnerable to predators such as fish.

Sediment cores were taken from lakes known for cyanobacteria blooms and good ecological conditions in the past. This enabled the life strategies of Daphnia that were experienced with cyanobacteria to be compared with those that were not. They were also used for hatching experiments with Daphnia.

Several concentrations of cyanobacteria were tested on Daphnia. It was already known that cyanobacteria interfere with the filtering apparatus of larger Daphnia, thereby significantly hindering their ability to feed. The results of the experiments confirmed the absence of larger species and the effect on biodiversity.

The results of the CONTRASTRESS project contribute to research in the ecology of lake plankton and provide a better understanding of the relationship between zooplankton, cyanobacteria and algae. This will enable better management of the environment and any future restoration programmes for inland waters.