Macrophytes in freshwater and marine realms are foundation species that control a wide range of key ecosystem processes, functions and services. They form habitat for many organisms and provide key benefits, i.e., supporting biodiversity, retaining nutrients, increasing sedimentation, stabilizing sediments, sequestering carbon, regulating greenhouse gaz emissions. However, their sustainable management and implementation as a nature-based solution (NbS) has only been partially recognized, and are contrastingly studied between marine and freshwater macrophytes. Concepts strongly linked to macrophytes use as NbS, such as blue carbon, eutrophication mitigation, or coastal erosion, have often been developed in one realm and remain to be exploited in the other, benefitting from some cross-pollination between limnology and oceanography.
In this session, we invite experts working on different aspects of macrophyte ecology in marine and freshwater habitats to learn from each other, including from their practices, applications and conceptual base related to NbS. We encourage participation of researchers either working on macrophyte across realms or specifically on seaweed, seagrass, saltmarsh on the coast or submerged, floating and emergent macrophytes inland. Specific topics can range from the impact of macrophyte on ecosystem functions and services, macrophyte along environmental gradients, trophic interactions, to innovative monitoring techniques and more conceptual aspects (e.g., resilience, alternative stable state). We will prioritize an equitable participation across realms. We invite both oral and poster format, but we will encourage short talks to leave time for exchange and identify knowledge transfer and innovative connections. In parallel of the event, we will organize formal and informal meetings to identify how to more concretely work together.
Lead Organizer: Morgan Botrel, Université du Québec à Rimouski, Groupe de recherche interuniversitaire en limnologie (GRIL) (morgan_botrel@uqar.ca)
Co-organizers:
Fanny Noisette, Université du Québec à Rimouski (Fanny_Noisette@uqar.ca)
Christian Nozais, Université du Québec à Rimouski (christian_nozais@uqar.ca)
Sabine Hilt, Leibniz Institute of Freshwater Ecology and Inland Fisheries (sabine.hilt@igb-berlin.de)
Presentations
04:30 PM
KNOWLEDGE GAPS IN SUBMERGED MACROPHYTE RESEARCH LIMIT AQUATIC ECOSYSTEM CONSERVATION AND RESTORATION (10675)
Primary Presenter: Sabine Hilt, Leibniz-Institute of Freshwater Ecology and Inland (hilt@igb-berlin.de)
Submerged macrophytes are vital for maintaining good ecological status in freshwater and coastal ecosystems by shaping biodiversity, nutrient cycling, sediment dynamics, and water quality. Yet macrophyte communities are declining worldwide. Drawing on freshwater, marine, and terrestrial plant research, I argue that effective conservation and restoration are hindered by major knowledge gaps across organism, community, and ecosystem levels. At the organism level, understanding of physiological adaptations, life-history traits, and phenology under multiple stressors remains limited. New genomic and transcriptomic tools could clarify genetic diversity, stress tolerance, and adaptive responses, but are still rarely applied to macrophytes, and the roles of pathogens, endophytes, and microbiomes remain poorly known. Freshwater plant research is geographically biased and lacks model species. At the community level, interactions such as facilitation, including boom-bust dynamics of invasive species, are insufficiently understood. At the ecosystem level, macrophytes are underrepresented in models despite their influence on phenomena like alternative stable states. Monitoring gaps—including short time series and limited use of remotely operated vehicles—further impede management. Bridging these gaps requires interdisciplinary research linking genomic and physiological insights with community and ecosystem processes. Strengthening submerged macrophyte research is essential to predict responses to global change, improve restoration, and enhance the resilience of aquatic ecosystems.
04:45 PM
MULTIPLE STRESSOR INTERACTIONS DRIVE UNPREDICTABLE PHYSIOLOGICAL RESPONSES IN SUBMERGED MACROPHYTES (10630)
Primary Presenter: Amine Mohamed Mahdjoub, Humboldt-Universität zu Berlin (amine.mahdjoub@igb-berlin.de)
Submerged macrophytes are central to freshwater ecosystem functioning but are declining globally under multiple anthropogenic stressors. We systematically reviewed 12,858 publications and extracted effect sizes from 124 experiments to identify general patterns in physiological responses and interaction types. Additive effects dominated (50%), indicating that accumulated stressors generally cause negative, but not necessarily amplified, responses. Synergistic interactions were relatively infrequent (14%) despite theoretical expectations of prevalence, though the limited number of experiments testing more than two stressors suggests their frequency may be underestimated. Most studies examined combinations of nutrient enrichment, shading, toxic trace metals, warming, and emerging contaminants such as PFAS and microplastics, typically under simplified 2×2 factorial laboratory designs. Antagonistic interactions often reflected dominance of a single stressor or compensatory responses, whereas synergisms were most frequent with metals combined with co-stressors enhancing bioavailability. Geographic and taxonomic biases were evident, with reliance on a few species and short-term assays. To improve mechanistic understanding, we propose Stuckenia pectinata as a model organism due to its cosmopolitan distribution, experimental tractability, and newly available genomic resources, enabling integration of physiological, molecular, and microbiome approaches. Expanding stressor complexity, experimental duration, and taxonomic breadth will strengthen predictions of macrophyte responses and inform freshwater conservation under global change.
05:00 PM
Global Ecological Roles and Model Networks of Submerged Aquatic Vegetation Using AI-Aided Analysis (10092)
Primary Presenter: Tianyu Fu, Tianjin University (futianyu@tju.edu.cn)
Submerged aquatic vegetation (SAV), including freshwater macrophytes and marine seagrasses, is fundamental to global aquatic ecosystems, regulating carbon, nitrogen, and phosphorus cycles while providing key services such as water purification and carbon sequestration. Drawing on an AI-aided analysis of 219 ecosystems, we identified primary ecological functions of SAV: flow attenuation, sediment stabilization, nutrient retention, carbon storage, oxygen production, competition with other primary producers, food provision, and habitat refuge. This functional portfolio is strongly conserved across lakes and reservoirs, rivers and streams, palustrine wetlands, estuaries and brackish lagoons, and marine shelves (mean pairwise Bray–Curtis similarity = 0.924, range 0.883–0.958). In contrast, mechanistic understanding remains highly fragmented: process-based frameworks cluster by ecosystem type (modularity = 0.854), with only 5.7% reused beyond their original domain. Overall, these findings reveal both the similarity of SAV roles across ecosystems and the fragmented nature of process-based modeling, underlining the need for integrative strategies to connect ecological understanding and modeling efforts globally.
05:15 PM
Effects of artificial heating on periphyton and submerged macrophytes in temperate lakes (10470)
Primary Presenter: Michal Brzozowski, Poznan University of Life Sciences (michal.brzozowski@up.poznan.pl)
Experiments investigating the impacts of climate warming on aquatic primary producers and their interactions have often been conducted in laboratories or mesocosms, with contradictory results. Meanwhile, evidence at the ecosystem level remains scarce. We investigated the impact of artificial heating in a unique system of lakes in Konin, Poland, which is warmed by ~2°C by a power plant, using nearby non-heated lakes as a reference. Periphyton substrates and pre-grown macrophytes (Myriophyllum spicatum, Chara rudis) were deployed at five depths for four weeks. To quantify environmental effects, we used generalised additive models including both fixed predictors and random effects. Periphyton biomass increased significantly with warming and light availability, while grazer abundance had no effect. Macrophyte survival was strongly determined by light, with both species showing reduced survival under shaded conditions. Importantly, temperature had no direct effect on macrophyte survival, whereas periphyton biomass showed a negative effect, indicating that warming influenced macrophytes indirectly through increased periphyton shading. Overall, our results show that warming enhances periphyton biomass and strengthens shading pressure on submerged vegetation. Thus, the primary mechanism by which climate warming threatens macrophytes in temperate lacustrine ecosystems is indirect through periphyton-driven light limitation rather than direct thermal stress.
05:30 PM
Major loss in algal species over 150 years of data: is ocean heating driving species loss in a biodiversity hotspot and how can it inform effective restoration? (10618)
Primary Presenter: Bayden Russell, University of Hong Kong (brussell@hku.hk)
We are in the midst of a global biodiversity crisis, with global heating and extreme events reshaping entire communities. Key amongst our concerns is the loss of habitats which support biodiversity and enhance ecosystem function. In many coastal marine systems, seaweeds are not only the major primary producers but also form extensive habitats. Yet, data on the effects of ocean heating and marine heatwaves on these algal assemblages is restricted to a few well-studied regions. Here, we have assembled a database of algal species records from the temperate-tropical climatic transition zone along the southern coast of China spanning ~170 years. We found that up to 150 species of algae have potentially been lost from the waters of Hong Kong, possibly representing poleward range shifts of a large percentage (>60% of recorded species) of the algal community. We then used in situ physiological measurements and laboratory warming experiments to demonstrate that warming winter (not summer) water temperatures over the past 3 decades have shortened the winter growth season for forest-forming Sargassum spp. Therefore, to save these once extensive seaweed forests from local extirpation we have begun implementing pre-treatment of juveniles in an attempt to “heat harden” them to future proof restoration attempts. Higher survival of heat-treated juveniles after out-planting points to potential early success, but also provides information to improve outcomes in future up-scaling of seaweed forest restoration.
05:45 PM
ROOTED IN THE FUTURE: AN ECR PERSPECTIVE OF AQUATIC PLANT RESEARCH (10183)
Primary Presenter: Antonella Petruzzella, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) (antonellabio@gmail.com)
Aquatic ecosystems face complex and interconnected challenges — from climate change and unprecedented biodiversity loss to pressing management questions. Now, more than ever, we must take a diversified approach and incorporate fresh perspectives to tackle these challenges. Fresh perspectives can emerge from the development of new technologies and methods, interdisciplinary approaches, and growing computational power, while remaining deeply rooted in overarching ecological principles, rigorous science, and the historical development of the field. Here, we explore how early career researchers (ECRs) in the aquatic plant community see the future of macrophyte research. Based on a recent survey of 147 ECRs, the discussion highlights the priority areas where the field can expand, innovate, and respond to global ecological demands. We present potential theoretical, technological, and methodological advances, weaving in our own perspectives. Finally, we discuss the challenges that ECRs face in research, as well as the importance and opportunities for developing professional and social networks that facilitate engagement, information exchange, knowledge generation, and foster lasting collaborations to advance aquatic plant science. Through this talk, we reflect on how ECRs are building a macrophyte science that critically engages with the past, while extending its roots into the future. Strategic collaboration with, and among, the next generation will be key to effectively addressing environmental challenges.
SS035B Bridging the Gap in Macrophyte Research Across Realms: From Ecological Concepts to Nature-Based Solutions in Marine and Fresh Waters
Description
Time: 4:30 PM
Date: 14/5/2026
Room: 520D