Murray Foundation Scholarship Report: Melissa Versteeg

Host-directed behaviours within and between anemonefish groups and the role of host health. October 8th, 2023

Dear Trustees of the Murray Foundation,

Thank you all so kindly for supporting me with the Murray Foundational Scholar Scholarship. It was with your support that this year has become a most insightful and productive time, where I was given the opportunity to study anemonefishes in Papua New Guinea (PNG) during an El Nino event and was able to contemplate how I might use my research project moving forward to support other Marine Science students.

I started the PhD position at Newcastle University in October 2022. My project focusses on using anemonefishes as a social model for coral reef fishes with high site dependence (i.e. fishes that have small ecological ranges due to a tight relationship with their immediate habitat), to research how environmental stressors linked to climate change will affect coral reef fishes under future climate change paradigms. By studying environmental factors such as pH, temperature, turbidity and predator density, I aim to understand how important aspects of fish fitness and success, such as reproduction and recruitment, relate to environmental stress exposure. More so, by also looking at the health of the hosting anemone territory, I want to investigate how the relationship between the anemone and the resident anemonefishes may be affected as environments becomes less hospitable. My first fieldtrip, which was largely funded by the Murray Foundation UK, was set to last just a few weeks from the end of February 2023. It was primarily designed to explore the coral reefs of Kimbe Bay, to get a sense of the anemonefish populations, and to trial the monitoring set-up that I would be deploying over the coming years of my research project.

Once in the field, we soon found ourselves in a unique situation. The reefs were in the grips of a severe El Nino event and local water temperatures soared, peaking at well over 34 °C in certain pockets of the reefs. This environmental disturbance created a bleaching event along the inshore reefs that was unprecedented, so I decided to extend my stay to monitor its impacts closely. As the Porites corals across the reefs lost their colours, so too did we observe that the hosting Heteractis magnifica anemones were looking paler by the day. My research objectives of investigating host health parameters and bleaching dynamics thus took on a central focus, and I reshuffled my methods to maximize the research potential. I studied 104 anemones and their associated anemonefishes on an approximately four-day rotation between March and August 2023, across eight inshore reefs. Even with such a short interval between visits, the rate of colour change was astounding. At the start of my fieldtrip many of the anemones would be seen fully expanded and beautifully coloured, with energic anemonefishes producing regular clutches of beady orange eggs. Now we were noting rigid, white, and contracted anemones, with no evidence of fishes breeding. In all of my previous research applications I had emphasised my desire to research bleaching impacts, but now that I was in the midst of it, I felt naïve and selfish to have wished for such a scenario to occur.

Heartbreaking as the bleaching event was, I was well aware of the uniqueness and privilege inherent to my position. I closely monitored temperatures, pH, turbidity, irradiance and salinity, as well as recording the colouration of the anemones, the social group structures of the associated anemonefishes, any migration of anemones, and behaviours of the fishes. We spent between 5-6 hours diving these shallow inshore reefs on an almost daily basis, which meant that I got a really good sense of the anemones and their fishes during the El Nino event and was able to improve my underwater research skills steadily. The intense monitoring schedule also allowed me the rare opportunity to identify irregularities on a very small time scale, or to catch behaviours and patterns which had not been observed in the field previously. An exciting opportunity regarded the recovery of anemones. As we still continued to monitor anemones once water temperatures dropped in June and July, we observed recovery patterns that sparked many new questions for future study. It also highlighted the resilience that these animals possess, where they exhibit an amazing capacity to bounce back once they are able to. Seeing their recovery after months of bleaching became one of the highlights of my trip.

The fieldwork also pushed me to keep up with data management, as I could use observations to sculpt and refine my research objectives or methods by assessing daily and weekly data. As a result, we managed to capture behaviours and phenomena which haven’t been observed before in the wild. An example relates to growth of anemonefishes. During each of the lunar months, I would catch and measure all of the anemonefishes in my study. During April, as it came time to remeasure the fishes for growth, I scanned over the size data and came to the horrified conclusion that something was off. Sizes for a lot of fishes indicated that they hadn’t growth at all, and even that sizes had decreased over the past few weeks! I altered my methods to include more repeats, and went back in to remeasure the fishes. Sure enough, the repeated measurements supported that some fishes were smaller than during the previous measurements. Though the full outcomes are yet to reveal themselves, this particular scenario served as a reminder that it pays to stay critical, humble, and curious in the field, and to flexible adjust my research methods when necessary.

Most of the difficulties I encountered during this year were linked to the start of my programme and securing the finances needed for the project. Once I got to Kimbe Bay, I encountered situations where some of the risks taken didn’t pay off, but these difficulties turned into valuable lessons for future endeavours. Though certain periods felt tough because I was spending long periods of time out in a remote area with relatively few resources, they also enhanced creative problem solving and communication skills. As a results I have generally experienced this year as brimming with potential, insight, and increased admiration of marine environments. The work has had me feeling a tremendous sense of growth, both as a budding academic and on a personal level. Witnessing a global environmental disturbance event of this scale serves to illustrate how powerful and connected our natural world is, and I am proud to have had a small role in documenting it, with hopes of sharing our future findings widely.

I got back to Newcastle a couple of weeks ago, and I am already waist-deep in data analysis. Besides looking at the data to see if we may have indeed witnessed ‘shrinking’ fishes, I am developing environmental stress profiles across the reefs. Results will answer to what extend we need to monitor anemones on a smaller local scale when trying to assess environmental stressors and subsequent plasticity or sensitivity among anemonefishes. I believe that there may be much more variability than we currently consider, and that even small differences in exposure patterns across and within reefs can activate resilience and resistance over time. The data on social dynamics will also be analysed to inspect the relationship with host health, and I want to focus on better understanding aspects of recovery following environmental stress.

Next on the agenda are several conferences which I hope to attend. I have been accepted to present some of my initial work at the Indo Pacific Fisheries Conference, the Reef Conservation UK conference, as well as the British Ecological Society conference of this year. Such meetings provide an exciting opportunities to gauge how a wide audience views my research, as well as creating opportunities to engage with experts in the field. I am also hoping that these conferences will connect me to people who have worked on local-international development, which has become a major objective for my project moving forward into the next few years. The NGO that hosts our research in Kimbe Bay, Mahonia Na Dari (https://www.mndpng.org/) is a local centre focussed on educational outreach, conservation activities, and research. Through frequent conversations with Mahonia team members and local community members, I have come to appreciate the advantages that arise from my position as a researcher with a western European background. Exchanges with individuals who have studied marine- or ecology-based programmes at national universities in PNG revealed a stark difference in the educational, political, and research-oriented landscapes of PNG compared to Western countries. As a result, access to desirable practical research is very limited for students there, and university-based field projects are fraught by financial difficulties and logistical constraints. As a consequence, many PNG students end up finishing their studies with only a theoretical foundation, and have to finance travelling abroad to develop the practical skills required for a career in marine sciences if they are able to.

As such, I want to use my second fieldtrip (February 2024) to launch a training programme with Mahonia Na Dari, which aims to attract marine students in PNG to our research site, so that they can assist in and lead the continued and future research on Kimbe Bays coral reef ecosystems. My first goal is to secure seed funding to train up several students who can assist in my research. Following this dive and research training, these students can take up roles as research assistants in other projects too, and could collaborate with any other researchers on site. Moreover, I will actively recruit students to help with data quantification and analysis and hope to include them in the eventual publication of the work. I believe that this programme can strengthen the position that Mahonia Na Dari takes on with regards to national and international research, in addition to offering young academics a springboard into a fruitful career in Marine Sciences where their practical field experience and skill matches their theoretical education.

Expanding inclusive and diverse collaboration is fundamental to robust and impactful science, as underrepresentation of local knowledge and expertise can inadvertently lead to bias and incomplete results. By mindfully including local scientists, we hope to enrich current and future research and will increase the potential practical implications and directions of our work. I am hopeful that my second year will entail a successful combination of cross-continental collaborations in marine research at Kimbe Bay, with novel and insightful results to better understand the future of coral reef fishes and how to best protect them.

I have added some photos of the research, the site, and the incredible anemonefishes. Should you have any questions, or would you be interested in discussing my future plans in-depth, please don’t hesitate to contact me.

Thank you again for your time and support,

Melissa Versteeg

GoPRO

GoPros are used to film anemonefish behaviours when they are actively breeding. The cameras are placed in close proximity to the anemone using a tripod. The videos are ‘tagged’ in the beginning of each recording so that the first frames on film display group ID, date, and breeding status for easy identification during video analysis later on. (2) A small tripod is placed close to the anemone so that measurements of salinity, light level, temperature, and pH can be collected. This design allows small-scale investigation of differences in environmental stressors, which will be modelled to predict anemonefish population dynamics such as group stability and reproduction.

Turbidity

Turbidity is measured using a LiCOR PAR (= photosynthetically active radiation) sensor. Profiles are taken from 16 meters depth to investigate the light levels available to anemones for photosynthesis. Like corals, anemones host endosymbiotic algae (Symbiodinium) which produce sugars via photosynthetic processes in return for shelter in the host. This algae can be expelled from the hosting anemone, which results in bleaching.

Measurement

Each lunar month, anemones are caught in-situ for photographing and measurements. Every anemonefish has a unique stripe pattern, allowing identification of individuals within a social group. By measuring their size we can answer questions about how growth patterns relate to environmental and social factors.

Sun Set

One of the amazing sunsets we would be privy to after a day’s work.

An unprocessed comparison of colouration patterns in an anemone over time. The upper left photo was taken on March 15th , while the bottom right photo stems from July 9th of 2023. Following severe bleaching (middle photo), this anemone slowly started recovering, with colouration coming in from the margins of the anemone’s oral disc. (8) Abiotic sensors are placed next an anemone which still has a healthy colouration density, despite warm water temperatures, at Mark’s reef, Kimbe Bay.
The abiotic sensors are placed next to an anemone which had been fully bleached, but is now showing recovery signs, on Hanging Gardens reef on the same day. The observant viewer may notice that the anemonefishes are concentrated in the area where the anemone tentacles are more coloured. Why this behaviour is observed, and how it may serve the fishes and the hosting anemone is yet to be answered.

A male guards a clutch of newly laid eggs.

By photographing the egg clutches, we can quantify reproductive output for analysis. This male clearly was not going to make it easy for us to photograph the clutch!

Kimbe Bay, Papua New Guinea.

Kimbe Bay, Papua Niew Guinea.