Volatile Organic Compounds from Marine Plants: Effects on the Behaviour of Benthic Invertebrates

Doctoral Thesis / Dissertation , 2015 , 240 Pages , Grade: PhD

Biology - Ecology

Marine organisms rely on chemical cues - most as scents - to obtain information (i.e. infochemicals) about their environment. Volatile organic compounds (VOCs) from plants represent one group of infochemicals that can shape ecological interactions and the structure of the ecosystems through the influence of behaviour of receivers. However, there is still little evidence about the ecological importance of VOCs on the structure and interactions of mesograzers community within ecosystems like the Mediterranean seagrass Posidonia oceanica.

The studies presented in this thesis were designed, using behavioural choice assays, to investigate the effects of epiphytes-borne VOCs from Posidonia oceanica on the associated benthic invertebrates and further clarify how their responses to these putative infochemicals could affect the spatial organization of this stable community. The objectives of this thesis were: 1) to standardize a behavioural choice method for benthic invertebrates (e.g. static chambers vs. flumes and the determination of the species-specific minimum number of replicates); 2) to define the existence of associative behavioural patterns of invertebrates (i.e. molluscs and decapods) to epiphyte-borne VOCs at the community level; 3) to identify the roles of VOCs as infochemicals (e.g. food or toxins cues); and 4) to investigate the behavioural responses to infochemicals within the range of pH levels predicted for the end of this century. Species-specific behaviours of mesograzers to VOCs depended on the method of investigation, the concentration of VOCs tested, body constraints and animal ecology.

Overall, the contribution of this thesis to knowledge is that, within ecosystems like the seagrass P. oceanica, co-evolutionary patterns of infochemicals create microhabitats and the coexistence of herbivores on a single plant leaf. These findings support a better understanding of the entire ecosystem for further coastal management also in prevision of near-future climate changes.

Inhaltsverzeichnis (Table of Contents)

• Abstract
• Acknowledgements
• Chapter 1: Introduction
• 1.1: Marine Plants and Invertebrate Behaviour
• 1.2: Posidonia oceanica and its Associated Invertebrates
• 1.3: Volatile Organic Compounds as Infochemicals
• 1.4: Aims and Objectives
• Chapter 2: Materials and Methods
• 2.1: Study Species and their Ecology
• 2.2: Experimental Design and Setup
• 2.3: Data Analysis
• Chapter 3: Results
• 3.1: Behavioural Responses to VOCs in Static Chambers
• 3.2: Behavioural Responses to VOCs in Flumes
• 3.3: The Influence of pH on Invertebrate Behaviour
• Chapter 4: Discussion
• 4.1: The Role of VOCs in Shaping Invertebrate Behaviour
• 4.2: The Impact of Ocean Acidification on Invertebrate Communities
• 4.3: Implications for Ecosystem Management
• References

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This thesis investigates the influence of volatile organic compounds (VOCs) from marine plants, specifically epiphytes on *Posidonia oceanica*, on the behaviour of benthic invertebrates. The study aims to understand how these infochemicals shape ecological interactions and the structure of the mesograzer community within Mediterranean seagrass ecosystems. The main objectives are:

• Standardize a behavioural choice method for benthic invertebrates.
• Define the existence of associative behavioural patterns of invertebrates to epiphyte-borne VOCs.
• Identify the roles of VOCs as infochemicals (e.g. food or toxins cues).
• Investigate the behavioural responses to infochemicals within the range of pH levels predicted for the end of this century.

Key themes include:

• The role of VOCs as infochemicals in marine ecosystems.
• The influence of infochemicals on the behaviour and spatial organization of benthic invertebrates.
• The impact of ocean acidification on invertebrate behaviour and community structure.
• The implications of these findings for the management of coastal ecosystems.

Zusammenfassung der Kapitel (Chapter Summaries)

• Chapter 1: Introduction: This chapter provides a background on the ecological significance of marine plants and their infochemicals, with a focus on *Posidonia oceanica* and its associated invertebrates. It introduces the concept of volatile organic compounds (VOCs) as infochemicals and outlines the research objectives of the thesis.
• Chapter 2: Materials and Methods: This chapter details the study species, experimental design, and analytical methods used in the research. It describes the procedures for collecting data on invertebrate behaviour in response to VOCs from epiphytes, including static chambers and flumes, and outlines the statistical approaches used for data analysis.
• Chapter 3: Results: This chapter presents the findings of the study, including the observed behavioural responses of benthic invertebrates to VOCs in both static chambers and flumes. It also investigates the influence of varying pH levels on invertebrate behaviour.
• Chapter 4: Discussion: This chapter discusses the significance of the findings, exploring the role of VOCs in shaping invertebrate behaviour and the impact of ocean acidification on invertebrate communities. It further highlights the implications of these findings for the management of coastal ecosystems.

Schlüsselwörter (Keywords)

This thesis focuses on the crucial roles of volatile organic compounds (VOCs) from marine plants as infochemicals shaping the behaviour of benthic invertebrates within Mediterranean seagrass ecosystems. The research delves into the ecological importance of VOCs in structuring the community of mesograzers, particularly focusing on the influence of epiphytes on *Posidonia oceanica*. Key themes include the standardization of behavioural choice methods for benthic invertebrates, the identification of associative behavioural patterns, and the investigation of the effects of ocean acidification on invertebrate behaviour and community structure. These findings contribute to a better understanding of the complex interactions within these ecosystems, providing valuable insights for the effective management of coastal environments.

• College: The Open University
• Course: Marine Chemical Ecology
• Grade: PhD
• Author: Emanuela Butera (Author)
• Publication Year: 2015
• Pages: 240
• Catalog Number: V368922
• ISBN (eBook): 9783668475267
• ISBN (Book): 9783668475274
• Language: English
• Tags: volatile, organic, compounds, marine, plants, effects, behaviour, benthic, invertebrates