The lowland rainforests of south-east Asia are renowned for their exceptional biodiversity but are among the most threatened ecosystems on Earth. Mass flowering events in lowland tropical rainforests are generally triggered by environmental cues, particularly climatic changes such as drought or temperature fluctuations. However, there is increasing evidence that nutrient availability, particularly phosphorus, may also play a critical role in regulating these events and, through them, forest development. Phosphorus is an essential macronutrient for plant growth and productivity, but it is often a limited nutrient in tropical rainforest soils, which are highly weathered and nutrient poor.

In lakes, particles from a diverse range of inorganic, organic and biogenic detritus and volcanic ash can settle through the water column and onto the lake floor. Over time, layers of particles accumulate that can contain a wealth of information about the past environmental conditions in the lake and its watershed. My research aims to answer fundamental questions about how concentrations of essential nutrients, particularly phosphorus, derived from volcanic ash affect tropical forest composition, structure and flowering dynamics. In May 2025, I conducted a two-week fieldtrip to collect lake sediment cores and fresh soil and water samples at the Bulusan Volcano Natural Park, Sorsogon Province, Philippines.  

Lake Bulusan

Bulusan Volcano Natural Park is located in Sorsogon Province, Philippines, and stretches over 3673 hectares. It was first designated as a National Park in 1935. It consists of mixed forests, giant ferns and other plant species including ground orchids. Lake Bulusan itself is a 0.28 km² lake lying at the foothills of Mt Bulusan and has no inlets or outlets; instead it comprises a closed system fed primarily by precipitation and groundwater. The lake location and its ability to catch volcanic ash from volcanic eruptions over time makes it the perfect study site for my PhD project.

Fieldtrip

Conducting the fieldwork in the Philippines was not without challenges. Firstly, all necessary agreements and permits needed to be in place beforehand; this process was carried out during the first 15 months of the PhD project. In the week leading up to the trip, the volcano, which is located close to the fieldtrip site, erupted briefly and put the whole fieldtrip in jeopardy. Luckily the eruption did not cause any danger to the public or surrounding areas.

Our first stop was Manila, where the correct wildlife permit was provided by the Department of the Environment and Natural Resources — Biodiversity Management Bureau (DENR-BMB) to allow us to collect the samples. We then travelled down to Sorsogon Province, where we met up with our local collaborator Dr Ellen Funesto (University of the Philippines — Cebu) and lake coring expert Dr Wes Farnsworth (University of Iceland). After a day of recovery, the team headed into the Bulusan Volcano Natural Park to access Lake Bulusan for lake coring and sampling activities.

The lake coring was done on a semi-luxury 4 Ã— 3 m raft equipped with a table to sit at and an umbrella for shade, and we were assisted by six local fishermen who were all interested in the research and lake coring processes. Two local guides also helped the team navigate around the lake and through the forest, finding the best spots to collect fresh soil samples from the forest surrounding the lake.

Learning about the culture

As we collected samples, we also had time to enjoy some of the Filipino cuisine. With recommendations from our local collaborator, we tasted a range of dishes that are must-tries (at least in our opinion!) when visiting the Philippines, ranging from local fish bangus, through pork sisig to chicken teriyaki from the local chicken shop.

Additionally, the Philippines’ landscape offers scenery unlike anything I have seen before:  beautiful beaches, waterfalls, volcanoes and forest. Beyond the incredible food and stunning environment, the local people in the rural parts of the Philippines are some of the friendliest people I have met. They were welcoming and those who joined us on site to collect samples brought joy to the fieldwork at the natural park.

Next steps

The samples are now back at the BGS headquarters in Keyworth and, over the next few months, we plan to explore the palaeo-nutrient histories hidden within the lake sediments, using core scanning alongside geochemical and stable isotope methods. In addition, there will be a trip to the University of Copenhagen, Denmark, later this year to extract ancient environmental DNA, which will help us understand how nutrient inputs from volcanic ash affect the tropical rainforest system.

Thanks

Thanks to our collaborators Dr Ellen Funesto and Dr Wes Farnsworth; without your assistance and expertise to the team the fieldwork would not have been possible. A special thanks also goes to Eleanor Lacsi De La Cruz from the Provincial Environment and Natural Resources Office (PENRO), who was on site all day and worked hard in both helping coring and securing all the necessary permits to export the samples back to Keyworth.

The work would not have been possible without the support of a huge number of people, especially the DENR-BMB, PENRO and DENR regional offices who issued the permits and have supported the project over the last two years.

About the author

Christopher Bengt is a second-year PhD student enrolled at Lancaster University. His PhD is funded through the Envision Doctoral Training Partnership and the BGS University Funding Initiative.

Pesticide pollution can be extremely damaging to the environment. Pesticides are intrinsically toxic chemicals capable of inflicting a wide range of effects on wildlife, which can in turn cause lasting damage to wildlife populations and ecosystems. Despite these concerns, more research needs to be undertaken to understand the level of pesticide pollution in English rivers.

New research has assessed the , which are currently on the market and being used in various applications, including agriculture. The research also evaluated the pollution by such pesticides in the waters and sediments of two English rivers; the River Tone in Somerset, which runs through Taunton, and the River Wensum in Norfolk, which runs through Norwich. The data generated by the study represents one of the most comprehensive assessments of pesticides in any English river catchment to date and is widely applicable to other river catchments across the UK.

Water, sediments, fish and invertebrates were collected along the two rivers and analysed for 52 pesticides. The study, undertaken by BGS in collaboration with the University of Nottingham, found that the veterinary pesticide fipronil was measured at high concentrations. Fipronil is commonly used by vets as an anti-flea treatment for dogs and likely gets into our rivers by dogs accessing these waterways. In addition, propiconazole (a systemic fungicide commonly used in agriculture) was found at elevated concentrations in sediments from the rivers Tone and Wensum.

Neonicotinoids, a group of neuro-active insecticides, are used in agriculture to help prevent crops from being eaten by pests and were found in both of the rivers. At one-third of the sites sampled, the level of neonicotinoids exceeded the chronic threshold for aquatic invertebrates, meaning they will be affecting the health of these organisms.

Modern chemical pesticides have positive applications, such as veterinary medicines helping prevent fleas in domestic pets and in UK agriculture where herbicides, insecticides and fungicides can help prevent food shortages by protecting crops from various pests.

However, our research has highlighted that these pesticides are now present in English rivers and could potentially pose threats to the local wildlife. To help mitigate the risk to ecosystem health, additional protective measures are needed to promote more environmentally sustainable practices, alongside the introduction of stricter regulation around the most high-risk pesticides to help protect our rivers from further impact.

Christopher Vane, head of BGS Organic Geochemistry.

The research has highlighted that further studies need to be completed in order to determine the effects that modern pesticides could have on ecosystems of rivers. BGS will also complete additional research in other countries over the next few years, which will continue to assess which pesticides are present in rivers.

The research paper, ‘, is available to read.

My name is Christopher Bengt and I am first-year PhD student enrolled at Lancaster University and I am being hosted at the BGS by the Stable Isotope Facility. My PhD is funded through the and the 51ÁÔÆæ University Funding Initiative. My research aims to understand fundamental questions about how tropical forest composition, structure and flowering dynamics are affected by the concentrations of essential nutrients, importantly phosphorus, in the soil. 

My previous research 

Prior to taking this post, I completed my master degree (MRes) in biological science at Birkbeck, University of London, where I studied the extraction of DNA from archaeological animal bones. This work involved using a number of analytical methods to assess the level of damage to the bones, indicating the extent of preservation of ancient DNA. Whilst studying, I also worked on immune response to vaccines and infectious diseases as a laboratory technician at the World Health Organisation Pneumococcal Serology Reference Laboratory at University College, London. All these skills stand me in good stead for my PhD, which will have significant laboratory and fieldwork requirements.  

Tropical rainforests 

Tropical rainforests are the oldest living and most complex ecosystems on Earth, with evidence from fossils and pollen dating back 70 million years. Being in the tropics, the rainforests have a stable climate consisting of warm temperatures, high precipitation levels and high levels of solar irradiation, providing essential conditions for highly productive forests. The stable climate, abundant resources and millions of years of evolution mean biodiversity in tropical rainforests has flourished, resulting in countless species with specialised adaptations.  

The effect of volcanoes on tropical ecosystems 

Unexpectedly for such diverse and productive ecosystems, rainforest soils are often of poor quality, with low concentrations of nutrients including carbon, nitrogen, potassium, and phosphorus. However, in areas such as the Philippines (my study area), volcanic eruptions can deposit nutrient-rich ash directly into the tropical rainforest environment. Volcanic ash is composed of fine rock particles that can be expelled and then deposited over vast areas, many kilometres from the original site of eruption. These particles contain essential nutrients such as potassium and phosphorus, and it is hypothesised that these may be critical for soil enrichment.  

Whilst volcanic eruptions can pose an immediate threat to local ecosystems, the aftermath may help foster these fertile environments. The relationship between volcanoes and nutrient-rich soils underscores the dual nature of these natural phenomena that are both destructive and transformative.  

Past records of climate 

To better understand the relationship between volcanoes and tropical ecosystems, we must explore past records of volcanic activity and forest productivity. These are often best found within lake sediment archives.  

Lakes serve as repositories of environmental history through the sediments that accumulate at their bottoms. The sediments are composed of organic and inorganic materials and encapsulate a wealth of information, telling us about crucial nutrients (including phosphorus) and serving as archives of ecological changes. My project will analyse both the nutrient makeup of the lake sediments and the ancient DNA preserved within them. In combination, these records will allow us to investigate the links between nutrient dynamics, ecosystem productivity and plant and tree diversity.  

For my project, I will undertake a fieldtrip to Lake Bulusan at Mount Bulusan, one of the most active volcanoes in the Philippines, which is surrounded by rainforest. Cores of the sediment from the lake will be brought back to the UK to interrogate the geochemical signatures trapped within them. The sediment cores will also be sent to the University of Copenhagen, Denmark, to extract and analyse modern and ancient DNA.  

These records should tell us more about how climate, volcanic activity and biological history are linked throughout the last 2000 years. This multiproxy approach will uncover critical information regarding the modern phosphorus cycle and soil limitations, as well as the true impact volcanic events have had on the phosphorus cycle in the palaeorecord and, in turn, the development and flowering of the surrounding tropical forest. The findings could potentially offer a ‘step change’ in our understanding of tropical forest development in volcanically active regions.  

About the author

Christopher Bengt is a first-year PhD student enrolled at Lancaster University. His PhD is funded through the and the 51ÁÔÆæ University Funding Initiative.

In south England and the Midlands, about 70 per cent of drinking water is sourced from groundwater. This groundwater is home to a wide variety of microscopic organisms that have interactive relationships with the surrounding abiotic and biotic environments, together constituting the groundwater microbial ecosystem. These microbes provide useful services, including pathogenic microbe inactivation and pollutant biodegradation: essentially, the microbes help maintain the quality of the groundwater we consume.

With increasing scientific understanding of groundwater ecosystem services, the water supply companies and Government agencies that are responsible for environmental and public health are paying more attention and investigating the best ways to protect undisturbed groundwater ecosystems. However, this can be difficult because the groundwater and microorganisms are out of sight, making it very tricky to study them. There is also no clear knowledge about what an undisturbed baseline microbial ecosystem should look like or how it can be protected.

This problem is the focus of my PhD, which I am working on at the BGS office in Wallingford, Oxfordshire. For fieldwork, I need to travel all over the Midlands to collect microbial samples from groundwater, which is why I recently travelled to Nottinghamshire and buddied up with Ankita Bhattacharya, another BUFI student who is based at BGS headquarters in Keyworth.

Our fieldwork was carried out at the groundwater pumping stations of Severn Trent Water, where raw groundwater is pumped before it is sent to the supply chain. We collected samples to determine environmental DNA (eDNA), nutrients and the age of the groundwater and we recorded different physiochemical parameters like pH, conductivity, dissolved oxygen and groundwater temperature in as many as 11 locations in and around Nottingham.

Having a field buddy made the otherwise exhausting fieldwork experience truly enjoyable for both of us. We got a chance to explore Nottinghamshire in a different way and have seen huge farmlands, chaotic animal farms, dense forests, peaceful villages, quiet lanes and busy roads. We drove on roads with both smooth concrete and no concrete at all, across landscapes with gentle, sloping floodplains and up steep hill roads with hairpin bends, all of which made the experience memorable.

The eDNA we collected will be sequenced to identify the different microbial species present in groundwater. I will then compare the ecosystem collected from the groundwaters of different regions to find variations in undisturbed ecosystems. As part of my project, I will also address the reasons for microbial ecosystem variations and take samples for environmental variables through sampling for chemical analysis of dissolved organic matter, dissolved nitrogen and dissolved carbon.

Funding

Both of Archita and Ankita are studying under the .

About the authors

Archita Bhattacharyya (Wallingford) and Ankita Bhattacharya (Keyworth) are both BUFI PhD students studying at BGS.

Marine scientists have long acknowledged the global importance of understanding deep-sea hadal biodiversity for habitat management. So far, however, efforts have been largely focused on shallower waters, typically in the upper 5000 m of the ocean.

In April 2019, the record-breaking Five Deeps Expedition provided a rare and exciting opportunity to apply state-of-the-art technology to observe the biodiversity and geodiversity of these deep-sea environments. A team of marine researchers, led by Alan Jamieson of Newcastle University, made the first crewed descent to the bottom of the Java Trench (also known as the Sunda Trench) – an arc-shaped, deep ocean trench some 3200 km long located in the eastern Indian Ocean, south and west of the islands of Sumatra and Java.

The world first — and only — fully certified crewed vessel capable of diving to full ocean depth, the DSV Limiting Factor acquired a video transect from the deepest point of the trench up a near-vertical escarpment in waters more than 7000 m deep. The team, which includes marine researchers from BGS and Newcastle University, recently confirmed their extraordinary discoveries in an open-access paper published in .

Applying new technology to the largely unexplored depths of the Indian Ocean produced an extraordinary set of rare and unique discoveries in just five days.

The Java Trench is largely unexplored and it was a unique opportunity to be able to freely explore such complex terrain and observe the distribution of biological species and geological formations that make up these habitats.

Heather Stewart, BGS Marine Geologist.

One of the least understood of the world five oceans, the Indian Ocean is the third largest, spanning 70.56 millionkm² and accounts for 19.8percent of the global ocean volume.

The complex sea-floor geomorphology of the Indian Ocean hosts subduction trenches, seamounts, ridges, plateaux, coral atolls and fracture zones. Despite a wealth of research into the coastal marine biodiversity of the ocean, few previous research expeditions have explored water depths exceeding 5000 m, leading to a significant knowledge gap.

At 7192 m depth (more than five times the height of Ben Nevis) the team managed to capture some of what are thought to be entirely new species from the deepest point of the trench, using the submersible and fleet of autonomous scientific landers. During the five-day expedition they observed new species of hadal snailfish as well as an extraordinary-looking animal believed to be a stalked ascidian, otherwise known as a sea squirt, that by luck drifted past the video camera. The first hadal were found as well as the deepest and were also observed.

Researchers steered the submersible from the soft-sedimented trench axis up a 150 m-high, near-vertical escarpment and across a plateau at a depth of around 7050 m. The exposed rock face of the escarpment hosted areas of debris formed by structural weaknesses in the bedrock eventually failing leaving piles of debris at the base of steep sections. Orange, yellow and white colours pick out these bedrock fractures in a spectacular display of chemosynthetic bacterial communities that live off fluids oozing from the cracks in the rock face.

Ideally we would return and do many more submersible surveys to explore a greater area of sea floor on a variety of geomorphological and geological features. We could then assess how common these chemosynthetic communities are and figure out how important a role they play in the food web at these extreme depths.

Heather Stewart.

We’re very excited by the potential for more studies. Research like this will help to steer the first steps towards more hypothesis-driven and less exploratory-driven science at full ocean depth.

Eventually, this will bridge the gap between this type of observational research and the early taxonomic work completed in the 1950s, to lift the quality of research from the deep water hadal zones closer to that of its shallower counterparts.

Alan Jamieson, Newcastle University senior lecturer.

New research has revealed that an abrupt change in climate conditions in the North Atlantic around 800 years ago played a role in a decline in Atlantic salmon populations returning to rivers. Human exploitation reduced their populations still further.

Using state-of-the-art geochemistry, a team of scientists has discovered that large-scale changes in the marine habitat, brought on by a transition from a warm to a cold climate and what is now known as the Little Ice Age (approximately 1300 to 1850 CE), corresponded with a decline in salmon in the River Spey, Scotland. The study, published in the international journal The Holocene, was led by the University of Southampton, working with BGS.

These results can help us understand some of the controls on salmon populations prior to and during major human exploitation.

Our study shows that historically, beavers – common in Scotland hundreds of years ago – do not appear to have significantly impacted salmon numbers. This is very relevant today, as the animals are being reintroduced to UK rivers and a debate continues about their potential impact on migratory species like salmon.

Prof David Sear, professor of geography and environmental science at the University of Southampton and lead author of the study.

This research benefited from state-of-the-art geochemistry which enabled us to fingerprint salmon abundance over hundreds of years. We show that climate has been an important influence of salmon numbers, which is very relevant today due to the speed of climate change.

Prof Melanie Leng, BGS, co-author.

Atlantic salmon lay their eggs in the gravels of headwater streams, where their young live for a year or two before migrating out to sea. Here, they feed and grow into adults, eventually returning to the river to spawn, where many then die. The sperm, eggs and carcasses are rich in marine nutrients, which can be detected in sediment hundreds of years later.

Using core samples from Loch Insh on the River Spey, the scientists collected and measured marine-derived nutrients (MDNs), which give an understanding of the historic population levels of salmon. The team also examined a 150-year record of net-catch data from the lower Spey to help calibrate the MDN record.

The scientists were able to construct a 2000-year record of both salmon-derived nutrients and variations in climate conditions.

The findings show:

• bigger salmon populations (inferred from changes in MDNs) in the past reduced during a cooling climate at around the same time humans began to exploit them, leading to a major decline in the fish over the last 800 years
• larger salmon populations in the past occurred at a time when rivers were also inhabited by beavers, which suggests migratory fish are capable of co-existing with beavers; this is an important concern of anglers around current beaver reintroductions
• migratory fish, such as salmon, bring marine nutrients into our nutrient-poor upland rivers and probably represented a major boost to aquatic and wetland ecosystems in the past, with a decline in nutrients negatively affecting these ecosystems today

It is the first study to use MDNs to measure Atlantic salmon, although the method has previously been used for Pacific salmon in north-west USA and Canada.

An international research team led by the Justus Liebig University Giessen and the University of Cologne, in collaboration with BGS, gained these new insights into evolution by drilling deep into the sediments of Lake Ohrid.

The 1.4-million-year-old lake on the border between Albania and North Macedonia is not only the oldest lake in Europe, but with more than 300 endemic species, i.e. species that only occur there, it is also the most species rich.

To study the evolutionary dynamics of Lake Ohrid since its formation, the scientists combined the environmental and climate data of a 568-meter-long sediment core with the fossil records of over 150 endemic diatom species.

Dr Jack Lacey, a geochemist from BGS, used chemical data from the mud to understand past changes in the hydroclimate of Lake Ohrid.

The combination of our data and the fossil diatom record of Lake Ohrid provide us with a link between geological processes, environmental change, and the biological evolution of endemic species within the lake.

Using geochemical data from the layers of mud that built up over time at the bottom of Lake Ohrid, we have unravelled a 1.4-million-year history of lake development and climate change, that are interwoven and captured in the sediment record.

Dr Jack Lacey, BGS Geochemist.

The data show that shortly after the formation of the lake, new species emerged within a few thousand years. Many of them died out again very quickly in the relatively small and shallow lake.

The research team explains this by the fact that young lakes of small size offer many new ecological opportunities, but are also particularly sensitive to environmental changes such as fluctuations in temperature, lake level, and nutrient availability.

The geochemistry of lake muds is a recorder of past changes in rainfall and major shifts in the water level of Lake Ohrid.

After the lake became deeper and larger, as indicated by shifts in the geochemistry, the speciation and extinction processes slowed down dramatically.

The scientists attribute this to fewer new habitats emerging, the species richness approaching an ecological carrying capacity, and an increasing environmental and climate buffering of the lake.

The finding that, in the history of Lake Ohrid, a volatile assemblage of evolutionarily short-lived species developed into a stable community of long-lived species provides a new understanding of the evolutionary dynamics in ecosystems.

The study, which has now been published in the journal Science Advances, has importance for future biodiversity research.

Citation

Wilke, T, et al. 2020. . Science Advances, Vol. 6(40), eabb2943. DOI: https://doi.org/10.1126/sciadv.abb2943

About the author