CHEMOSENSORY DISRUPTION: Combined impacts of ocean acidification and metal pollution on lobster olfaction and consequences for fundamental behaviour
Anna-Sara Krång. From IVL Swedish Environmental Research Institute, to Norwegian university of science and technology, NTNU, Trondheim, Norway.
The ability to detect and respond to chemical cues is essential, allowing animals to gan information about their surrounding and behave accordingly. Yet exceedingly few studies consider chemosensory disrupting effects of environmental stressors and existing ecotoxicological tests are not designed to discern them. Thus despite high sensitivity and ecological relevance, chemosensory disrupting effects are not included in the scientific basis for existing directives and legislation.
The overall aim of this research project is to provide improved understanding of the combined impacts of ocean acidification and metal pollution on the chemosensory system of marine organisms, focusing on the ecologically and economically important Norway lobster (Nephrops norvegicus). The combined effects are of extra concern since decreasing pH affects bioavailability and thus the toxicity of metals in seawater.
Chemosensory disruption will be studied at different organisation levels:
1) Effects on chemically mediated behaviour, such as dominance establishment and trade-off between predator avoidance and foraging.
2) Interference with odour detection and transduction, by measuring changes in activity of chemosensory neurons, using electrophysiological techniques.
By identifying neurophysiological mechanisms underlying behavioural changes, this project will lead to better fundamental understanding of chemosensory disruption. The results will help us identify present and future risks and thus better assess and predict consequences of environmental stressors. This will form a basis when local, national (HaV, KemI, Länsstyrelser) and international (REACH) authorities develop assessment criteria to indicate environmental health.
Project Summary Results
Ocean acidification (OA) is a global and rapidly growing environmental problem, linked to the increasing levels of carbon dioxide (C02) in the atmosphere. Knowledge of how OA will affect marine organisms is still limited, although an increasing number of studies show on negative yet variable consequences, particularly on physiological and developmental processes in caicifying organisms. Some animals have shown sensory disorders, including effects on olfaction. Since many marine animals rely largely on their sense of smell for fundamental behaviour such as foraging, social interactions and predator avoidance, such chemosensory disrupting effects could have profound consequences for fitness and survival.
This project investigated effects of OA and pollutants on ecologically and economically important lobsters. The project focused primarily on interference with lobsters' ability to detect and react to odours from food, predators and conspecifics, with consequences for downstream behaviour; such as food search, feeding, dominance establishment, and trade-off between time spent foraging and avoiding predators (when odour cues from food and predotors were applied simultaneously), However, also other kinds of effects on behaviour and physiology were investigated, e.g. general activity level, risk-taking (boldness), metabolism and oxidative stress, as well as survival, growth and development. The focus was early life-stages (early benthic juveniles), which are of particular interest since they are considered extra sensitive and a bottle-neck phase in the lobster life cycle. At the same time, very little is known about lobster juveniles' habitats and behaviour, since they hardly ever have been observed in the wild. Juveniles were reared in their respective treatments, following individual larvae/juveniles to enable identifying brood-specific effects. Realistic OA scenario was used for all experiments, with pH/C02 levels corresponding to predicted values by the end of Century, compared with current levels. By using a combination of behavioural investigations and physiological techniques, this project identified effects from present and future environmental Stressors on different organization level; from increased activity level and risk taking to impaired detection and/or reaction to odour cues and altered metabolism. One interesting outcome of the project was clear differences in susceptibility between juvenile lobsters deriving from different females. This has implications when evaluating data based on population means.
Besides leading to improved understanding of the consequences climate change will have on lobsters and other marine animals, the results could aid developing ecologically relevant assessment criteria to indicate environmental health, with implications for new mitigation directives and legislation. Since lobsters are commercially important, future deteriorating conditions have implications to the fishery sector and for stock management. An indirect result of these experiments is gained knowledge of the early benthic phase of these lobsters, which is beneficiai forfisheries management and conservation. Furthermore, increased knowledge of personalized behaviour related to aggression level and boldness, as well as development of new techniques to identify such behaviour, may contribute to overcome some of the Problems associated with lobster cultivation, with great value to lobster aquaculture industry. This in turn will reduce the fishing pressure on wild lobster populations.
This MoRE project has been a dose collaboration between Dr. Anna-Sara Krång (outgoing researcher), IVL Swedish Environmental Research Institute and Prof. Gunilla Rosenqvist, Norwegian University of Science and Technology (NTNU), Norway. In addition to the research outcomes, the project has reinforced the scientific competence and research profile of the outgoing researcher, through new skills and training within interdisciplinary projects. Leadership and management training have been obtained through organising and leading all scientific parts of the project and taking part of financial management; by applying for Ethics Approval; by attending seminars how to write successful grant proposals and by writing grant proposals. Not least, the international exchange made possible through this project has established and reinforce excellent and long-lasting transnational networks contacts and collaborations between IVL/the Västra Götaland region and NTNU/Norway within the marine environmental and maritime sector.