Hi, Aaron de Verés and Alice Wiersma! Welcome to ReefBites.
Aaron and Alice are Bachelors of Science students in the Biological Sciences in Ecology program at the University of Edinburgh and are part of the Undergrads Changing Oceans (UCO) program. UCO is a 16-strong student-led research and outreach group based at the University of Edinburgh. UCO aims to engage undergraduates in marine research training and experience, and engage wider audiences with marine systems and the threats they face. Their research focuses on the drivers and effects of concentration-dependent feeding on microplastics in the sea anemone Exaptasia pallida. Read more about their work and journey below!
Give an elevator pitch of what your research/project is about.
Our project investigates how concentration of microplastics affects the feeding behaviour and physiological response of the sea anemone Exaptasia pallida. This involved experimentally exposing anemones to 4 microplastic treatments: 1) a high concentration, similar to those often used in studies that investigate feeding on and responses to microplastics, 2) an intermediate concentration, similar to measures found in nature, and 3) a concentration lower than environmental levels. We experimentally offered each anemone microplastics at one of the concentrations, mixed with their prey Artemia (brine shrimp). We also offered the intermediate concentration without Artemia as our fourth treatment, to look at whether the anemones selectively fed on microplastics. We measured physiological response using a DIVING-PAM before and after feeding. We also took two measures a day apart prior to microplastic exposure as a control for physiological activity. We quantified microplastic presence on the anemones’ tentacles under the microscope, and after dissolving them in acid, quantified what had been ingested. We found that higher than environmental concentrations of microplastics resulted in higher microplastic presence on the anemones’ tentacles, and higher microplastic ingestion. This throws caution to the many studies which note high ingestion but under abnormally high microplastic concentrations. Higher ingestion was also observed in the presence of prey, suggesting anemones ingest microplastic due to the presence of prey chemical cues rather than by selectively consuming them. Though we detected no clear physiological response it is unclear whether the anemones are resilient to microplastic consumption, whether they are otherwise detrimentally affected, or if their post-exposure response would be slower.
Why is this research/project important and timely?
Pollution is considered a key threat to marine life. Microplastics are of particular concern due to their reported ubiquity in marine habitats, and their inconclusively understood impacts. Ingestion has been reported across a wide range of taxa, but responses vary from fatal to negligible. Before our study, investigations into organismal responses to microplastics have primarily used concentrations of microplastics that far exceed those found in nature, despite readily available data on environmental concentrations. It is important we understand whether microplastics represent a real threat to marine life by investigating responses to naturally found concentrations. Microplastics found on organisms are often used as a proxy for microplastic consumption, but it is unknown whether these measures actually correlate. Studies on Cnidarians are divided over whether feeding on microplastics is driven by chemical cues given by prey in the water, or by cues given by the microplastics themselves. If Cnidarians consume microplastics found around them, and do so selectively under environmentally relevant concentrations, microplastic consumption may lead to mortality through false satiety or infection from pathogens on the microplastics.
What is the broader impact and implication of your findings?
The oceans are facing a multitude of threats. There is general consensus that some (rising temperatures and ocean acidification) are high-risk to marine life. Though it receives high-profile media attention, microplastics research remains less conclusive. Understanding whether marine organisms are actively consuming microplastics, and whether these are causing stress responses at ecologically relevant concentrations is therefore vital. Under the limited time and funding with which we have to act, it is important to know which threats we prioritise in research and responsive action. Sea anemones are a good model organism to investigate the impacts of microplastics as Cnidarians with a similar anatomy and biology to corals, but which are easier to care for in the lab. Stony corals are vitally important reef ecosystem engineers, but ocean acidification is reducing their calcification rates, and high ocean temperatures are increasing mortality due to bleaching. Our research therefore suggests how Cnidarians may respond to relevant microplastic concentrations to build a more complete understanding of the threats they face. We hope to incite further research which investigates this response directly in stony corals, and which also investigates responses under combined stresses so we can more realistically infer how marine organisms are coping in the changing oceans.
How did you come to work in this field/project?
Two years ago, a few of us were volunteering as assistants on scattered projects under the Changing Oceans research group in the University of Edinburgh. With the Changing Oceans staff, we arranged a dynamic and mutually beneficial training program which established Undergrads Changing Oceans. We began by assisting with ongoing experiments and husbandry tasks while simultaneously supporting the staff. We also received tutoring in research project design. As our team grew, we began designing and then carried out our current research project. As 16 students from different degree programs and year groups, we had diverse schedules. However, we used this to our advantage. Our lab work required precisely timed actions throughout each week, so on a rota different team members would come in to make this work. Our training before the experiment ensured our lab work was consistent across team members – we’re really pleased we pulled it off!
What is your top graduate school life hack or survival resource?
We’re not quite in graduate school yet! In terms of getting your foot in the door and surviving undergraduate research however, being proactive is key. If you’re interested in some out-of-class real research, it can be intimidating not knowing what’s out there or how to get involved. The only way to break down this barrier is to start a conversation. Speak to your lecturers, ask to attend their research group meetings. The worst thing that can happen is that they can say no. Someone is likely to have a project requiring a lot of work where an undergraduate could gain some experience helping out though, which could be the beginning of something really exciting.
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