Belgium

Small pelagic fish used to be a major component of commercial fisheries in NW Mediterranean Sea, but landings have drastically fallen over the last decade due to a severe decline in fish size and body condition. This situation seems to result from bottom-up control linked to changes in plankton size and composition. However, mechanisms behind these effects remain to be investigated. Through experiments on a captive population of sardines, we first showed that sardine growth and condition were significantly impacted by food size and quantity. We hypothesized that sardines expended more energy filtering small prey than capturing larger ones. To test whether foraging on smaller prey increases energy expenditure - especially under warming conditions - we conducted a second experiment. We examined the synergic effects of temperature as a direct consequence of climate change and an indirect effect through food modulation (size and quantity) on the energy expenditures of sardines. Interestingly, the energy costs of filtering mode on small particles were twice as high as those of directly capturing large particles. Despite lower digestion energy costs, the daily energy expenditures of sardines fed on small particles were greater than those fed on large items, and the gap widened as temperature increased. These findings highlighted how changes in prey size modified sardines&#39; feeding behaviour, affecting their metabolism, likely altering energy allocation towards life-history traits (e.g., growth or survival) and explaining the current population situation.

SEB Conference 2025

Why sardines shrink in the NW Mediterranean Sea?

mediterranean sea

shrinking

sardine

Welcome Seabirders!  

Welcome to Virtual World Seabird Conference 3 - vWSC3! Whether you are in your office or lab, at home, in a coffee shop or bar poaching some wifi, or at a remote field site or research vessel – we are very excited to welcome you to the third ever World Seabird Conference. 

We would like to thank ALL of you for being so patient as WSC3 was scheduled, postponed, rescheduled, revised to virtual, and scheduled again. Throughout all those iterations there was one message that remained perfectly clear – seabirders were eager to meet and share their science. If we could not meet in person then virtual it would have to be, but a 3rd WSC was something everyone wanted. That support and commitment helped the WSU Board of Directors and Member Societies sort through all of the challenges they faced to plan and hold this conference. 

The list of those that need to be thanked is long and, while we plan on recognizing many during the live closing plenary, it is important to do so here in writing as well. 

The Australasian Seabird Group was our Local Host for our plan to meet in Hobart, Tasmania. They invested substantial time and effort to find venues and plan events that we unfortunately were not able to visit. Nonetheless we appreciate their work on behalf of WSC3 and encourage all of you to thank them when you see their members in Gathertown or elsewhere during our virtual meeting. Their willingness to host created the initial excitement for WSC3 and without that our vWSC would not have been possible.

We also wish to thank the Science Program Committee, the Virtual Committee, and the Early Career Scientist Committee for their hard work planning the logistics, events, and schedule for vWSC3. These committees also had to deal with changing parameters and short timelines that made what is always a challenging task even more challenging. The Travel Awards Committee also invested time and effort in developing procedures for awarding travel funds that ultimately would not be implemented. 

Our ability to shift from an in-person to a virtual meeting, and to do so in a way that would be financially feasible, was due to the effective efforts of The International Fundraising Committee and to our financial sponsors. The IFC raised funds to support WSC3 and then, through the good relationships they built with sponsors, ensured we could re-envision how those funds could be used to support a virtual conference that would be affordable and high-quality.

We all owe the WSU Board of Directors and the Representatives of the Member Societies a great deal of thanks. They are the ones who manage the WSU and, for the past 18 months, have had to have a series of challenging meetings and conversations, have had to make a series of difficult choices, have had to do all of that while considering the short- and long-term health of WSU and the World Seabird Conferences, and did this while also managing their own challenges at their day jobs. We are grateful for their diligence, patience, foresight, and throughout all of the meetings, their collegiality. Also – a 6-year term is quite a commitment!

There would not be a WSC3 without a successful WSC1 and WSC2. Thanks go to the Pacific Seabird Group for their support of WSC1 in Victoria, Canada, and to the African Seabird Group for their support of WSC2 in Cape Town, South Africa. In each of these endeavors and for our current conference we were fortunate to work with a dependable and trustworthy partner in Podium Conferences. Michelle Smith and Marischal de Armond have become valued members of our team and have not only helped us plan conferences but have assisted and advised the WSU Chairs and Board on issues above and beyond conference planning. 

As we embark on our vWSC3 week we extend to all of you our thanks for showing up, for being patient, and most importantly for the work you do with seabirds. We are all part of a unique, global community that shares an interest, a fascination, and a passion for birds that make a living in our world’s oceans. We have advanced the science, conservation, and management of seabirds as well the ecosystems they inhabit. We are consistently impressed and motivated by the work you do. 

The WSU formed in 2010 because we saw the need for a global organization to address challenges at a global level. Over the past 11 years WSU has grown, adapted, and evolved to become the community that this week is making vWSC3 a reality. Enjoy the week, appreciate and support the friends and colleagues you have made in the community, and if you see us in a virtual hallway please stop and say hello! 

Thank you for the opportunity to serve all of you and the WSU over the past few years,

Nicholas Carlile, Interim Chair, WSU<br>
Patrick Jodice, 2nd Chair of the WSU<br><br>

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3rd World Seabird Conference

Join us for four days of science, networking and virtual engagement with delegates from around the world!

Small pelagic fish used to be a major component of commercial fisheries in NW Mediterranean Sea, but landings have drastically fallen over the last decade due to a severe decline in fish size and body condition. This situation seems to result from bottom-up control linked to changes in plankton size and composition. However, mechanisms behind these effects remain to be investigated. Through experiments on a captive population of sardines, we first showed that sardine growth and condition were significantly impacted by food size and quantity. We hypothesized that sardines expended more energy filtering small prey than capturing larger ones. To test whether foraging on smaller prey increases energy expenditure - especially under warming conditions - we conducted a second experiment. We examined the synergic effects of temperature as a direct consequence of climate change and an indirect effect through food modulation (size and quantity) on the energy expenditures of sardines. Interestingly, the energy costs of filtering mode on small particles were twice as high as those of directly capturing large particles. Despite lower digestion energy costs, the daily energy expenditures of sardines fed on small particles were greater than those fed on large items, and the gap widened as temperature increased. These findings highlighted how changes in prey size modified sardines' feeding behaviour, affecting their metabolism, likely altering energy allocation towards life-history traits (e.g., growth or survival) and explaining the current population situation.

technical paper

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Numerous animals exhibit remarkable adaptations for dynamically altering skin coloration. For instance, chameleons modify guanine crystal spacing in their cells, flounders regulate skin pigment visibility, and cephalopods utilize complex light-diffusing structures to achieve effective camouflage. While shark skin is often perceived as grey, some species demonstrate diverse coloration and camouflage strategies, including countershading and bioluminescence. Recent reports suggest that great white sharks possess dynamic camouflage, as evidenced by the great white shark's skin color changes to a lighter hue when exposed to adrenaline, while melanocyte-stimulating hormone (MSH) causes a darker hue. Our study on blue sharks (Prionace glauca) reveals a potential nanostructural mechanism for this via a direct association between shark coloration and their skin's tooth-like dermal denticles, which are well known for their hydrodynamic properties. We show that each denticle produces highly saturated, non-iridescent color through nanoscale structural interactions within its pulp cavity. Inside denticles, varying spatial interactions between pigment cells and cells packed with complex crystal stacks (likely guanine) mediate the perceived color in different body regions. These cellular associations, however, also offer a palette whereby small changes in tissue architecture can manifest as local color changes. Our optical observations of excised blue shark skin reveal it can transition from blue to green, gold to slate gray in response to external stimuli, such as changes in humidity. This suggests that our identified structural color mechanisms provide a pathway for dynamic camouflage, opening an unexplored window into shark ecological adaptations and novel structural mechanisms for producing mutable colors.

Color dynamics: Novel structural color mechanisms may mediate camouflage strategies of blue sharks

Human-induced environmental changes are increasingly subjecting organisms to stimuli and stressors beyond their evolutionary adaptations. In aquatic ecosystems, certain life stages are expected to be particularly vulnerable, with embryos identified as highly sensitive to environmental stress. Notably, research across diverse taxa indicates that embryos can hatch prematurely, potentially as an adaptive mechanism in response to external stressors, despite potential drawbacks such as underdeveloped behavioral or physiological traits. Surprisingly, in aquatic environments, little research has explored the frequency, causes, and consequences of premature hatching. In this presentation, we give an overview of the current knowledge on premature hatching in aquatic embryos and examine how this process may be exacerbated by human-driven global change. Specifically, we (1) review hatching mechanisms and factors that trigger premature hatching in both experimental and natural settings; (2) assess the biological and ecological consequences of premature hatching across different levels of organization, from individuals to ecosystems; and (3) identify knowledge gaps and propose directions for future research on the causes and implications of this phenomenon. Our review highlights that aquatic embryos exhibit premature hatching in response to a broad range of abiotic (e.g., temperature, oxygen levels, pollutants, light, pH, salinity) and biotic (e.g., predators, pathogens) stressors. Additionally, we provide evidence that rapid thermal ramping can induce premature hatching in fish. Premature hatching is an intriguing yet underexplored area of research and knowledge of the phenomena may play a role in enhancing the resilience of aquatic communities amid ongoing global environmental change.

Global change and premature hatching of aquatic embryos

Larval fitness strongly determines a marine species' performance and population recruitment, influencing its role in ecosystem dynamics. As part of the planktonic food web, sea urchin larvae contribute to nutrient cycling and overall ecosystem stability. However, how environmental stressors like ocean acidification (OA) impact energy allocation and metabolic regulation during their development remains unclear. This study investigated how sea urchin larvae regulate their energy fuel to maintain homeostasis under normal conditions and how they respond to stress. Our results indicated that sea urchin larvae experienced a high-energy-demand phase before feeding. Our results indicated that sea urchin larvae experienced a high-energy-demand phase before feeding. However, under OA stress, mortality increased after feeding began, when energy consumption had already declined. Whether this is due to an imbalance between food supply and energy demand requires further investigation.

Unraveling the Energy Physiology of Sea Urchin Larvae in Response to Environmental Change

Many marine calcifiers produce their shells and skeletons by the intracellular formation of an amorphous mineral precursor. Here calcification and pH regulation are intrinsically linked due to the pH-dependency of the carbonate system. However, the pH conditions within CaCO3 forming vesicles and how they are affected by changes in environmental pH remain little understood.
Here we study the function of a proton channel Otop2l in mediating proton permeability between the marine environment and the calcification vesicles inside of calcifying primary mesenchyme cells (PMCs) of the sea urchin larva. Intracellular and intra-vesicular pH recordings using pH sensitive dyes demonstrated a high proton permeability of PMCs that also affects pH in endocytotic vesicles in with the mineral precursor is formed. Functional characterizations of the proton channel Otop2l in heterologous expression systems demonstrate an activation by Ca2+ and Mg2+, two ions that are highly enriched in the calcification vesicle. Life-cell recordings using simultaneous tacking of pH and calcium ions in endocytosed vesicles demonstrate a trafficking of Ca2+  and alkaline CO3 2-  rich vesicles that exocytose their contents to the mineralization front.
Based on these findings we propose that calcifying cells of the sea urchin larva use an “open” calcification system to promote high carbonate saturation states in sub-cellular compartments to promote CaCO3  production which can be considered energetically advantageous. Our results also suggest a partly separate trafficking of Ca2+  and CO3 2-  -rich vesicles to the site of mineralization which leads us to rethink the concept of vesicular mineralization.

A proton channel regulates vesicular pH relevant for calcification in the sea urchin larva

The origin of bipedal locomotion in lizards is unclear. Earlier suggestions for a speed or endurance advantage were not supported, with speed being similar for bipedal strides, compared with quadrupedal strides, and the percentage of strides that each species ran bipedally, being negatively related to running endurance. Modelling studiesby Aerts et al.suggest bipedalism in lizards may be a consequence of a caudal shift in the body centre of mass, combined with quick bursts of acceleration, causing a torque moment at the hip lifting the front of the body. This model was supported with a significant acceleration threshold between quadrupedal and bipedal runs, and the percentage of bipedal strides that each species ran, being  positively related to body size and the proximity of the body centre of mass to the hip. However, variation in morphology could only account for 56% of the variation in acceleration thresholds, suggesting that limb and tail dynamics have a significant influence on bipedalism. Our analysis revealed that angular acceleration of the trunk about the hip, and of the tail about the hip were both important predictors of extended bipedal running, along with increased temporal asymmetry of the ground reaction force profile. Together, these results show that bipedalism may have first arisen as a consequence of acceleration and a rearward shift in the BCOM, but subsequent linages have exploited this consequence to become bipedal more often, suggesting that bipedalism in lizards may convey some advantage.

The evolution of bipedalism in Australian agamid lizards.

The study of the evolution of form requires knowledge of the evolutionary history, selective pressures and structural constraints that have been imposed on organisms. In this context, the 10,000 species of crown birds are a very useful model. The evolutionary history of these dinosaurs is well documented in the fossil record, while the very high ecological diversity of present-day species provides information on selective constraints. The common body plan, imposed by specialisation in flight, provides a homogeneous structural framework. The highly conserved pelvic locomotor system has played a fundamental role in the evolution of birds, enabling them to colonise all continental, aerial and aquatic environments. The hind limbs are used for walking, and sometimes running or swimming. They are essential for taking off and landing. So birds use them in very different mechanical contexts. The study of the function of the pelvic system provides crucial information for identifying the properties that arise from the structure of the bird body and that have enabled their extraordinary radiation. It illustrates the contribution of functional morphology to our understanding of the evolution of shape.

Contribution of the study of bird bipedalism to the understanding of the evolution of shape

The human heel pad loses some of its shock absorbing properties during ageing. It is unclear whether this results from “wear and tear” or from the physiology of ageing itself. To help answer this question, we have studied the mechanical behaviour of the heel pad in populations reflecting a diversity of locomotor habits, footwear and substrate use: Europeans, Ju|’hoan traditional hunter-gatherers from Namibia, and Indian shod and barefoot volunteers. This work builds on seminal studies from the 1990s by Peter Aerts and collaborators on the mechanical properties of the heel pad.
We have collected ultrasound images of the heel pad at different loads, Shore heel hardness, plantar pressures and impact acceleration during walking, and Digital Image Correlation-based plantar skin deformation. For the European population we have also obtained MRI foot scans for subsequent Finite Element Modelling.
Our preliminary analyses indicate that the heel pad tends to get thicker with ageing and that in vivo deformation is greatest in the macro-chamber. Shore hardness correlates weakly with dynamic heel pad elasticity. Skin thickness and heel pad behaviour differs between the populations studied.

The ageing human heel pad: assessing mechanical behaviour in the lab and in the field.

Animals can sleep variably, with substantial flexibility in sleep duration and distribution, in response to ecological conditions. However, robustly quantifying sleep variation, across individuals and populations, is challenging in small animals such as lizards. Using recently developed miniature loggers, we recorded sleep in 19 wild-caught individuals of the Peninsular rock agama lizard (Psammophilus dorsalis). First, we validated the use of electrooculogram (EOG) as a proxy for sleep in lizards by comparing it to diel variation in arousal response. We then compared three populations each from urban and rural environments, for EOG-derived sleep parameters (sleep duration, and bout frequency, duration, and interval), and behaviourally-measured sleep intensity (latency to arousal). Finally, we simulated a predation attempt that induced acute stress in these individuals and tested for changes in sleep response by population type. Lizards slept mostly at night, with a total sleep time of on average 11.7h, typically in 60 min bouts separated by 8 min of wake state. Sleep characteristics did not differ between urban and rural lizards, though daytime sleep bouts were shorter and more consolidated in urban lizards. Contrary to evidence from mammals, acute stress did not impact sleep, overall or with respect to populations; therefore, a greater diversity of animal taxa must be investigated to determine how sleep varies across populations and in response to ecological stressors. In robustly measuring sleep-wake patterns in small vertebrates at a population level, our study paves the way for quantifying sleep responses over longer time periods, in mesocosms and in the wild.

Urbanization and acute stress do not influence sleep expression in lizards

SUMOylation is essential in plant and animal cells, but it remains unknown how SUMO components act in concert to modify specific targets in response to environmental stresses. In this study we characterise every SUMO component in the Arabidopsis root to create the first complete SUMO Cell Atlas in eukaryotes.  This unique resource reveals wide spatial variation, where SUMO proteins and proteases have sub-functionalized in both their expression and subcellular localisation. During stress SUMO conjugation is mainly driven by tissue specific regulation of the SUMO E2 ligase. Stress-specific modulation of the SUMO pathway reveals unique combinations of Proteases being targeted for regulation in distinct root tissues by salt, osmotic and biotic signals. Our SUMO Cell Atlas resources reveal how this PTM influences cellular and tissue scale adaptations during plant development and stress responses. We provide the first comprehensive study elucidating how multiple stress inputs can regulate an entire PTM system.

The Arabidopsis SUMO Cell Atlas reveals divergence in cell-type and subcellular location of its components to fine-tune stress responses

Fungal pathogens continue to pose substantial threats to global food security, causing some of the most devastating crop diseases worldwide. We present a pioneering investigation into the infection-related development of the rice blast fungus,Magnaporthe oryzae, employing a quantitative mass spectrometry-based phosphoproteomic approach. Our study maps 8,005 phosphosites on 2,062 fungal proteins, providing a detailed landscape of the phosphorylation events that orchestrate plant infection. This reveals a profound re-wiring of phosphorylation-based signalling cascades during fungal infection, shedding light on the dynamic molecular responses elicited byM.oryzae. To unravel the broader significance of these findings, we undertook a comparative analysis of phosphosite conservation across 41 fungal species, revealing phosphorylation signatures linked to plant-associated fungal lifestyles, biotrophic and hemibiotrophic fungal infections. As the Pmk1 MAP kinase is a key orchestrator of plant infection in many plant pathogenic fungi, we then used parallel reaction monitoring to identify Pmk1 MAPK substrates. Our investigation defines 32 putative substrates of Pmk1, revealing a complex network of regulatory interactions. This led to identification of a novel regulator, Vts1, which undergoes Pmk1-dependent phosphorylation and is indispensable for the manifestation of rice blast disease. Vts1 is a SAM domain protein that plays an essential function in appressorium morphogenesis, septin aggregation and re-polarisation. Using an analogue-sensitive Pmk1 mutant, parallel reaction monitoring, and subsequent site-specific mutagenesis, we show that a single Pmk1-dependent phosphorylation event is necessary for its function as a virulence determinant during rice blast disease.

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Color dynamics: Novel structural color mechanisms may mediate camouflage strategies of blue sharks

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