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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TERMS-Ocean (Transgenerational Ecophysiological Responses to Multiple Stressors in a changing Ocean)

Teaser

Summary

Global oceans are currently changing at a faster rate than at any other time over the last 300 million years, exposing marine animals to multiple environmental changes. Seawater temperatures are rising (climate change) and the oceans are becoming more acidic (ocean acidification; OA). At the same time, extreme climatic events are becoming more common and particularly in coastal areas, seasonal and daily variability in environmental conditions is predicted to increase. Coastal marine invertebrates are globally important in terms of the ecosystem services and functions that they provide, hence it is vital to determine whether they can adapt and evolve to cope with these multiple environmental stressors at the rate at which they are occurring. One mechanism that marine animals may use to help cope with increasing temperature and OA, is Transgenerational Plasticity (TGP). TGP is where the observable characteristics (e.g. size) in offspring change in response to the environment that their parents were exposed to during reproduction. When offspring display TGP, it makes them more able to cope with the conditions their parent was exposed to than they would have been if their parents had not experienced those conditions. The TERMS-Ocean project examines the role of TGP in the sea urchin Paracentrotus lividus in response to temperature and OA; sea urchins are common marine animals, integral to ecosystems. The aim of the project is to understand the potential for this mechanism to offer a means of coping with multiple environmental changes occurring at the same time in nature. Although TGP has previously been shown to be an important mechanism for coping with changes in a single environmental condition (for example temperature OR OA), prior to the TERMS-Ocean project, there was little evidence as to whether animals could use TGP in response to multiple environmental changes occurring together. My findings will contribute important new insights into our understanding of the future of our oceans. Society is becoming increasingly dependent on the oceans for food and other services and functions they provide. Consequently, it is imperative that we gain a better understanding of how future changes in environmental conditions will affect the health of our oceans and the animals living in them.

The overall project objectives are:
Obj. 1: Evaluate at the physiological responses of adult sea urchins to the combined effects of elevated temperatures and OA.
Obj. 2: Investigate the effects of parental exposure to multiple stressors (elevated temperature and OA) on the larval development of P. lividus offspring to test for Transgenerational Phenotypic Plasticity.
Obj. 3: Examine the effects of parental exposure to multiple stressors (elevated temperature and OA) on post-settlement juvenile development in P. lividus.

Work performed

The TERMS-Ocean project consists of four work packages (WP), with specific deliverables and milestones.

WP1: Research methods, aquaria set-up, sample collection and adult physiology.
My research methods were developed in the first six months of the fellowship. I set up aquariums and carried out carbonate chemistry to confirm I had the desired environmental parameters (milestone 1.1). As well as the planned temperature and ocean acidification (OA) treatments, I also added variability. Half the treatments remained static while the other half followed temperature and OA changes observed over a tidal cycle. I collected adult urchins farmed in Ireland and maintained them on my system for several months. I then examined the physiology of the adults maintained across the different experimental systems (milestone 1.2).

WP2: Larval and juvenile development.
All adults maintained across my systems were very healthy and after a couple of months were gravid. I collected eggs and sperm from adults, carried out fertilisation assays, and developed larvae (milestone 2.1). I was unable to develop enough larvae to settlement stage and consequently adapted my research a little to ensure I was collecting excellent data during early development.

WP3: Analysis of samples.
I analysed all samples and prepared data for publications.

WP4: Interpretation and consolidation of data.
I have now presented my findings at two international conferences (deliverables 1.1, 2.1, 4.3) and am preparing data for publication (deliverables 4.1, 4.2).

OVERVIEW OF RESULTS: I found that egg sizes were influenced by both climate and environmental variability whereas sperm parameters (e.g. straight-line velocity) were only influenced by environmental variability. Fertilisation success did not vary across conditions, but a high amount of inter-individual variability was observed within each condition. Larval survival was influenced by climate, and the interaction of climate and variability. Larval development appeared to be influenced by both climate and variability, with individuals from parents maintained in today-variable conditions developing the fastest.

ADDITIONAL WORK: During my research I identified that different individuals responded differently to temperature and OA. This led me to look at the individual differences in sperm between males. I found males that initially had a poor fertilisation success improved under OA conditions, whereas males that were good fertilisers got worse under OA conditions. These findings are published in Proceedings of the Royal Society B.

Final results

The TERMS-Ocean project has produced data that furthers our understanding of the impacts that climate change and ocean acidification (OA) will have on marine species. Importantly, it brought to light the importance of individual variability in the responses of organisms to environmental change. My data suggest that when looking at responses at an individual level rather than a population level, it becomes evident that not all individuals are impacted by environmental change in the same manner, and while some individuals are negatively affected by environmental change, others thrive under predicted future ocean conditions.

My work has led to advances in our understanding of the impacts of climate change on marine species. These findings will be useful for fisheries, who can explore the potential to target specific genetic lines which may yield higher crops in the future. They will also be useful for policy makers and of interest to the general public and scientific audiences.

The TERMS-Ocean project has led to one publication at the time of writing, with a further 2 currently being prepared for submission. As a part of the project, I have given talks at two international conferences (Larval Biology Conference, USA and the Gordon Research Seminar/Conference on Ocean Global Change Biology, USA). I have also given public talks at schools.

My project also led to a successful collaboration with Prof. Maria Byrne at the University of Sydney, Australia. This collaboration included a month-long visit to Prof. Byrneâ€™s lab in Sydney, allowing me to continue my professional development above and beyond what was expected for this fellowship and in line with the progression of a successful career in research.