Ecotoxicology: New Challenges and New Approaches

Ecotoxicology, New Challenges and New Approaches provides the latest in new challenges for research in ecotoxicology. In six comprehensive chapters, the book deals with the long term effect of stressors on biological communities, the effect of pollutants on the chemical communication among organisms, the impact of multiple stressors and of emerging pollutants (microplastics), and at the use of new technologies (omics) in ecotoxicology.

• Addresses "emerging issues" that pose new challenges for ecotoxicology research
• Resolves several topics, such as the long-term effect of stressors on biological communities and the effect of pollutants on chemical communication between organisms
• Analyzes the impact of multiple stressors and emerging pollutants (microplastics)
• Explains new technologies (omics) in ecotoxicology

• Language: English
• Publisher: Elsevier Science
• Release date: Sep 30, 2019
• ISBN: 9780128212417

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Ecotoxicology

New Challenges and New Approaches

Elisabeth Gross

Jeanne Garric

Edited by

Table of Contents

Cover image

Title page

Copyright

Preface

1: Chemical Ecology and Ecotoxicology

Abstract

1.1 Introduction

1.2 Chemical ecology in aquatic and terrestrial habitats

1.3 The impact of pollutants on allelochemical interactions

1.4 Natural biocides

1.5 Using chemical ecology response factors as alternate end points in ecotoxicology

1.6 Conclusion

2: Pollution Tolerance in Aquatic Animals: From Fundamental Biological Mechanisms to Ecological Consequences

Abstract

2.1 Introduction

2.2 Evidence of tolerance to contaminants

2.3 Mechanisms of defense and the acquisition of tolerance to chemical stress

2.4 Ecological and ecophysiological aspects of tolerance

2.5 Operational consequences of tolerance

2.6 Conclusions

3: Strategies and Consequences of Indigenous and Invasive Freshwater Mussels Living in Cyanobacterial and Anthropogenic Impacted Waters

Abstract

3.1 Life-history traits, strategies and peril of indigenous versus invasive freshwater mussels

3.2 Impact of noxious substances on freshwater mussels

3.3 Mechanisms of detoxification and acclimation

3.4 Acclimation

3.5 Energetic consequences of exposure to harmful substances

3.6 Conclusion

3.7 Acknowledgments

4: Anthropogenic Stressor and Parasite Interactions in Aquatic Environments

Abstract

4.1 Parasites among other confounding factors in environmental monitoring studies

4.2 Parasites in ecotoxicological studies

4.3 A special case of multistress: coinfections

4.4 Conclusion

5: Microplastic in Aquatic Environments

Abstract

5.1 Introduction

5.2 Microplastic in the aquatic environment

5.3 Toxicity of microplastic towards aquatic biota

5.4 Conclusion and future research

6: New Challenges: Omics Technologies in Ecotoxicology

Abstract

6.1 Introduction

6.2 The omics methodologies

6.3 Post-omic concepts

6.4 The organisms involved

6.5 The substances

6.6 The applications

6.7 The challenges

6.8 Conclusion

List of Authors

Index

Copyright

First published 2019 in Great Britain and the United States by ISTE Press Ltd and Elsevier Ltd

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Notices

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

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© ISTE Press Ltd 2019

The rights of Elisabeth Gross and Jeanne Garric to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

Library of Congress Cataloging in Publication Data

A catalog record for this book is available from the Library of Congress

ISBN 978-1-78548-314-1

Printed and bound in the UK and US

Preface

Elisabeth Gross

Jeanne Garric June 2019

With this book, comprising six chapters, we want to highlight current challenges and emerging approaches in ecotoxicology. The individual chapters are diverse in their focus on different aspects, but they all aim to highlight the complexity of situations under which pollutants act at different levels of organisms in our ecosystems. Most of the examples provided are from aquatic ecosystems. The different chapters focus on the following themes: the effect of pollutants on the chemical communication among organisms; the long-term effect of stressors on organisms; the impact of multiple stressors such as the concomitant presence of cyanobacteria or parasites affecting pollutant effects on aquatic invertebrates; the role of emerging pollutants highlighted by the example of microplastics; and the information that can be gained using new omics technologies in ecotoxicology.

The first chapter brings together the different as well as complementary views of the fields of chemical ecology and ecotoxicology, both developed as independent research fields since the late 1950s and named accordingly only in the 1970s. Both fields look at the impact of chemicals on trophic links. While ecotoxicology focuses on trophic transfer of pollutants, chemical ecology looks at the impact of chemical signals affecting predator or prey behavior. As shown in the chapter by Elisabeth Gross, several inorganic or organic pollutants can themselves affect the interactions between predators and prey, but natural compounds involved in chemical ecology can be used instead of, for example, synthetic biocides.

Tolerance to contaminants will allow certain populations and species to cope with anthropogenic pollution, and thus certain pollutants can act as selective forces causing microevolution in populations. However, our knowledge on the mechanisms responsible for such a tolerance, as well as its ecological consequences, are only slowly emerging. In the second chapter, Claude Amiard-Triquet outlines the different questions of intra- and interspecific variability of tolerance, or cross-tolerance to pollutants.

Alien invasive species and eutrophication are two further pressing issues on aquatic ecosystems. In freshwater systems, native mussels are in extreme competition with different alien invasive mussels. As filter feeders, these organisms – irrespective of whether they are native or not – can be important bioindicators on ecosystem health, and can be used to study the impact of anthropogenic pollution. Yet, pollution by fertilizers often causes the development of cyanobacterial blooms, and the related cyanobacteria species often produce toxins that also affect mussels. Claudia Wiegand shows in the third chapter how cyanobacterial toxins and selected pollutants differentially affect native and alien mussels.

Continuing the view on multiple stressors that affect organisms, the next chapter investigates the interactions between anthropogenic stressors and parasites in aquatic organisms. Multiple abiotic and biotic factors affect the biochemistry, physiology and behavior of aquatic organisms. As a result, the response towards anthropogenic pollutants can also be affected by the presence of parasites in organisms. Parasites can affect not only the level of bioaccumulation but, also the response of certain biomarkers used to identify the effects of certain pollutants. In Chapter 4, Laëtitia Minguez and Laure Giambérini provide a detailed overview on the interaction of individual and co-infections by parasites with pollutant effects on aquatic organisms.

The past few years showed an explosion of studies focusing on the impact of plastic pollutions, specifically that of small particles in the size of micro- or nanoplastics. In their chapter, Messika Revel, Amélie Châtel and Catherine Mouneyrac provide a thorough overview on the distribution, origin and fate of microplastics in aquatic environments. Reliable studies need to apply sophisticated sampling and analytical methods, and not all of those are widely available and applicable to the vast diversity of plastic pollution currently observed. Depending on the type of microplastic, its interaction with other pollutants and the type of organisms affected (e.g. filter feeders), the effects can be severe, strongly impeding ecological interactions in aquatic ecosystems.

Omics technologies, such as genomics, transcriptomics, proteomics and metabolomics, were developed at the end of the 1990s and are now increasingly spreading into ecotoxicology. These techniques can offer a better view of the mechanisms of toxicity of certain pollutants, and provide an overview of the effects on physiological processes that are affected. However, these studies are more or less limited to sequenced species, and require a rigorous planning of experimental conditions used due to the limited number of replication possible, as outlined by Odette Prat and Davide Degli-Esposti in the last chapter of this book.

With this volume, we end a series of books presenting a broad overview on essential topics in aquatic and terrestrial ecotoxicology. The series is published so far only in French (https://iste-editions.fr/collections/serie-ecotoxicologie). The first volume focuses on the gradient of toxic effects from molecules to populations and gives examples on the modelling of such effects. The second volume investigates how contaminants can affect field communities and the ecosystems functioning. The third volume is devoted to bioavailability, a major process controlling the toxicity of contaminants for organisms. Finally, the fourth volume presents diverse approaches to detect toxicological effects in the field, in studying animal and plant populations.

With this volume – published first in English – we hope to provide readers here with a range of stimulating new views, outlining the complexity of environmentally realistic ecotoxicological studies.

1

Chemical Ecology and Ecotoxicology

Elisabeth Gross

Abstract

The main aim of this book is to show new options and challenges in ecotoxicology. One big challenge is the better inclusion of ecological relevance in ecotoxicological tests, and another is the incorporation of other possible stressors and disturbances into risk evaluation. The aim of this chapter is to show how concepts in chemical ecology can help answer these questions. In fact, chemical ecology and ecotoxicology are two research fields which have much in common.

Keywords

Biocides; Chemical Ecology; Chemical fingerprints; Infodisruptors; Kairomone perception; Pesticides; Pheromone perception; Synthetic organic pollutants; Terrestrial habitats

1.1 Introduction

The main aim of this book is to show new options and challenges in ecotoxicology. One big challenge is the better inclusion of ecological relevance in ecotoxicological tests, and another is the incorporation of other possible stressors and disturbances into risk evaluation. The aim of this chapter is to show how concepts in chemical ecology can help answer these questions. In fact, chemical ecology and ecotoxicology are two research fields which have much in common.

Ecotoxicology is a relatively young field resulting from a series of pollution accidents affecting humans and the environment in the 1950s (Vasseur 2018). The birth of the concept of chemical ecology also happened during the late 1950s (Whittaker and Feeny 1971, Hartmann 2008). Thus, the terms ecotoxicology and chemical ecology emerged almost at the same time, reflecting a new view of and new approaches to emerging challenges. Both fields have a somewhat different focus, yet they have more in common than just the prefix eco. Both look at the impact of compounds on organisms; while ecotoxicology focuses mainly on anthropogenic pollutants, chemical ecology concentrates on natural metabolites produced by certain species and affecting others. I propose to take a close look at chemical ecology and assess its utility within ecotoxicology. In the following, I will outline several research fields within chemical ecology that are of interest for ecotoxicology. This cannot be a comprehensive overview of these topics, but will rather be a spotlight on findings and research questions that in the future can be stimulating for both fields. Ultimately, this should allow interested researchers to discover and explore new approaches, which might lead to a better understanding of ecological interactions in a world of multiple stressors.

Chemical ecology came into the focus of the broader scientific community in the late 1950s. At that time, the essential role of plant secondary metabolites for plant–insect interactions became apparent, and evolutionary scientists suggested that their diversity evolved under the selection pressure of herbivory (Hartmann 2008). Ecotoxicology started out with a closer look at the whole food web in order to understand the observed effects of biomagnification or bioamplification of pollutants, and effects on top predators, based on the observations made, for example, in the Bay of Minamata (Japan) and in Clear Lake (USA) (Vasseur 2018, Wiener and Suchanek 2008). Thus, both fields emerged in the context of studies focusing on trophic links between consumers and their food source.

Chemical ecology focused in the beginning mainly on the first trophic levels, looking at the chemical communication between primary producers and their herbivores. The chemical quality of the host plants determines the amount of herbivory, specifically the content and type of defensive secondary metabolites. So-called specialized herbivores are adapted to feed on host plants bearing many toxic secondary metabolites and often have a tight link with their host plants so that they are specialized only on one species or genus of plants. Generalist herbivores instead eat a large variety of different plants with no or low concentrations of deterrent plant secondary metabolites. Usually, host plants through volatile compounds attract herbivores (Dicke and Baldwin 2010). An intriguing idea was to test the use of such volatiles to attract pest insect species to traps and thus minimize herbivore damage on cultured plants such as crops, fruit orchards or commercial timberland (Witzgall et al. 2010, Pickett et al. 1997, Cook et al. 2007). The field is now extremely large, including all types of (secondary) metabolite-related allelochemical interactions within the plant and animal kingdom, and with microorganisms such as fungi and bacteria (Watson 2003, Pawlik 1992, Lenoir et al. 2001, Kusari et al. 2012, Hay 1996, Ferrari et al. 2010, Cembella 2003, Dobretsov et al. 2013, Iason et al. 2012).

The abovementioned different initial viewpoints in ecotoxicology (focusing on top predators and effects of the trophic transfer of pollutants) and chemical ecology (focusing on plant–herbivore interactions and thus the lower trophic levels) might suggest substantial conceptual differences in focus between both fields (Figure 1.1). Yet, there is a common base, and this is to explore relevant trophic links within an ecosystem and to identify which factors influence these trophic links. The amount of ecological studies focusing on different trophic links within ecotoxicology has been increasing over the last 30 years (Relyea and Hoverman 2006), enhancing our knowledge of direct and indirect effects of pollutants on biotic interactions, and including the fact that there are interactions between pollutants and chemical cues, with ultimate effects on trophic links.

Figure 1.1 Conceptual framework for trophic interactions considered in ecotoxicology and chemical ecology. Red arrows describe top-down and bottom-up links in a typical four-level food chain (simplified). Ecotoxicology (yellow arrows) focuses mainly on trophic transfer by bioamplification or biomagnification. Chemical ecology focuses on the role of allelochemicals in trophic links: both top-down and bottom-up (green arrows). Allelochemical interactions can thus modify the strength of a given trophic link and will thus ultimately affect the strength of the trophic transfer of pollutants. For more details, please see the text. For a color version of this figure, see www.iste.co.uk/gross/ecotoxicology.zip

The aim of this chapter is to highlight several topics where ecotoxicology and chemical ecology strongly interact. Section 1.2 focuses on the main questions asked in the chemical ecology of aquatic and terrestrial habitats, and outlines similarities and differences of so-called allelochemical interactions between these habitats. Section 1.3 describes the impact of selected pollutants on allelochemical interactions. Most, but not all, examples will be from aquatic habitats and describe the impact of different groups of inorganic and organic pollutants on the so-called infodisruption (Lurling and Scheffer 2007, Lurling 2012), i.e. the disturbance of normal chemical communication or allelochemical interactions. Section 1.4 outlines current knowledge in the chemical ecology of natural biocides. A large range of plant or microbial secondary metabolites with different modes of action have been identified as potential natural pesticides (section 1.4.1). They offer interesting alternatives to synthetic pesticides, yet they might also have ecotoxicological effects. Quite a range of natural fouling compounds have been isolated from various organisms based on chemical ecology studies (section 1.4.2); however, only a few of those are commercially available. Finally, section 1.5 outlines how response factors commonly used in chemical ecology can help in interpreting ecologically relevant effects of pollutants on biotic interactions. This includes a closer look at the impact of pollutants on the production of plant secondary metabolites.

1.2 Chemical ecology in aquatic and terrestrial habitats

In our daily life, most of us probably appreciate fragrant smells, such as odors from preferred personal care products, a flower bouquet or a good meal. Unconsciously, at least mostly, humans are also capable of perceiving natural odors emitted by others and which inform them about important behavioral states such as aggression, fear or sexual attraction. Other organisms often have a much more highly developed capacity to identify and distinguish smells and to adapt their behavior and development accordingly.

Odors and other chemical signals are of paramount importance for all organisms. Animals and many other organisms such as microorganisms or motile algae use chemical cues to orient themselves in their natural environment and to recognize their biotic and abiotic surroundings. This orientation is possible due to sophisticated, specific and dynamic blends of different, mostly volatile organic compounds (or odorants), called infochemicals (Klaschka et al. 2016, Dicke and Sabelis 1988). These infochemicals, individual compounds or mixtures, transfer information for pollinators, or about possible mating partners, food sources or potential predators. They are often highly specific and with differential information content for sender or receiver. In chemical ecology, a defined terminology exists to describe the different functions of these infochemicals used at the intra- or interspecific level (Table 1.1) (Klaschka 2008, Dicke and Sabelis 1988).

Table 1.1

The term allelochemical is also used in a wider context, describing (secondary) metabolites, by which organisms of one species affect the growth, fitness, behavior, or population biology of organisms of another species, excluding (primary) metabolites predominantly used as resources by the second species (Whittaker and Feeny 1971). This implies that allelochemicals can also be non-volatile metabolites, for example, feeding deterrents and toxins present in plants. Furthermore, there are some differences between the terrestrial and aquatic habitats, as some, but not all aquatic infochemicals, are volatile (Lurling and Scheffer 2007, Fink 2007).

The role of volatile organic compounds as infochemicals among terrestrial organisms, and specifically between plants and herbivores, is a long known fact (Dicke and Baldwin 2010), and evidence for their role beyond pheromones is only emerging in the aquatic habitat (Fink 2007). Algal volatile organic compounds, which are the cause of foul source-water odor, are considered a nuisance and possible threat to human health (Lee et al. 2017). In contrary to perceptions considering them as metabolic waste products, these algal volatiles often have an ecological function in biotic interactions of algae and cyanobacteria with other organisms (Watson 2003).

Terrestrial plants emit volatiles to attract pollinators, but a specific odor bouquet can also deter some herbivores, or attract predators or parasitoids of their herbivores (Dicke and Baldwin 2010). This double strategy is necessary to enhance the fitness of plants, as an overly high attractiveness might enhance the risk of tissue loss or even death due to herbivory. There are important differences between plants and their major herbivores in the terrestrial and aquatic habitats (Vermeij 2016, Hay and Steinberg 1992), specifically regarding the dominant types of plants and herbivores. In aquatic systems, there are further differences between marine and freshwater habitats (Bakker et al. 2016). Although the vast majority of studies in chemical ecology have focused on plant–herbivore interactions in terrestrial and to a lesser extent marine systems, evidence for allelochemical interactions in fresh water is increasing. More research is still needed to confirm or reject a notion of limited chemical defenses in freshwater plants (Gross and Bakker 2012).

Many aquatic organisms, including algae (Frenkel et al. 2014) and marine invertebrates (Pawlik 1992), use sex pheromones to facilitate