Freshwater macrophytes—rooted and free-floating vascular plants inhabiting lakes, rivers, wetlands, and streams—play a foundational role in ecosystem functioning. They regulate nutrient cycles, stabilize sediments, structure food webs, and support biodiversity; their ecological significance is widely acknowledged. However, linkages between the diversity, spatial distribution, and temporal dynamics of macrophyte communities and their associated ecosystem functioning remain understudied, particularly in the context of accelerating global environmental change.
With freshwater ecosystems undergoing unprecedented changes due to climate variability, eutrophication, land-use transformations, invasive species, and hydrological alterations, this proposed session addresses the urgent need to integrate macrophyte community dynamics into broader freshwater ecological research.
Understanding how macrophyte communities respond—and how those responses affect ecosystem functioning in turn—is essential. Notably, recent advances in trait-based ecology have shown how plant life forms, such as emergent and submerged species, exhibit realm-specific adaptations and distinct trait-environment relationships, leading to divergent impacts on ecosystem functions like carbon cycling and nutrient uptake.
The session will bring together limnologists, aquatic botanists, and macroecologist to explore:
Spatial and temporal dynamics of macrophyte community composition across climate and nutrient gradients Functional trait diversity of species and communities and its implications on ecosystem processes, such as denitrification, methane flux, and habitat provisioning The role of macrophytes in mediating responses to disturbances like droughts, floods, habitat degradation or invasive species Comparative studies across freshwater systems globally, with a focus on dataset harmonization and modelling frameworks
We particularly encourage submissions that address the reciprocal relationship between macrophyte communities and ecosystem functions— through field data, experiments, modelling, or synthesis—and that integrate aspects of global change in freshwater systems. Contributions linking macrophyte diversity to biogeochemical states, food web interactions, or remote sensing advances are also welcome.
Lead Organizer: Lars Iversen, McGill University (lars.iversen@mcgill.ca)
Co-organizers:
Lindsay Trottier, McGill University (lindsay.trottier@mail.mcgill.ca)
Yang Liu, McGill University (yang.liu15@mail.mcgill.ca)
Alice Dalla Vecchia, University of Parma (alice.dallavecchia@unipr.it)
Presentations
02:30 PM
QUANTIFYING THE ROLE OF MACROPHYTE LIFE FORMS FOR CARBON SEQUESTRATION IN CONSTRUCTED WETLANDS (11014)
Primary Presenter: Esra Reichert, Uppsala University (esra.reichert@ebc.uu.se)
Macrophyte communities perform an important function in the carbon cycle of inland waters by sequestering carbon in the sediment, but carbon sequestration as an ecosystem service of macrophyte communities is poorly understood, with very few measurements reported in the literature. We measured organic carbon sequestration in the sediments of three constructed wetlands, one supplied by stormwater, one by agricultural run-off, and one by treated wastewater. Using a piston corer we specifically developed for dense macrophyte stands, we took 183 sediment cores from the three sites, which were taken along 40 transects covering all types of macrophyte life forms and site morphologies. Drone imagery combined with ground measurements provided a map of macrophyte identity and annual productivity. We hypothesized that sediment carbon sequestration is positively related to the annual macrophyte productivity, and to the C:N ratio of the biomass. The data indicate that emergent macrophytes may contribute more to carbon sequestration than submerged or free-floating macrophytes, highlighting the roles of productivity and leaf litter recalcitrance in carbon sequestration efficiency. However, high spatial heterogeneity and superimposed morphological properties (e.g. water depth, flow paths) affirm the need to conduct highly resolved sampling. This study presents a working protocol for quantifying carbon sequestration in dense macrophyte stands and shows that macrophyte life forms and wetland morphology should be accounted for when quantifying carbon sequestration in constructed wetlands.
02:45 PM
Respiration is increased by macrophyte structural complexity and epiphytic interactions in stream benthic communities (10196)
Primary Presenter: Claudia Feijoó, Instituto de Ecología y Desarrollo Sustentable (INEDES; CONICET-UNLu) (clasife@yahoo.com.ar)
Complexity of macrophyte architecture could influence metabolic reactivity in streams due to an effective streambed occupation of the macrophyte-epiphyton ensembles, which promotes a more efficient use of solute resources. Here, we assessed the influence of the macrophyte complexity and macrophyte-epiphytic interaction on the community-level respiration in a microcosm experiment. We compared the respiration of two macrophyte species with higher (Elodea ernstae) and lower (Stuckenia striata) architectural complexity. The experiment had four treatments (with five replicates): E. ernstae with (E+) and without (E-) epiphyton, and S. striata with (S+) and without (S-) epiphyton. Respiration was determined using the smart trace Rezasurin (Raz). We did not observe significant differences in epiphytic chlorophyll-a and particulate organic contents among treatments. However, respiratory activity was consistently higher in the species with more complex structure (E. ernstae) than in those with less complex structure (S. striata). In addition, the presence of epiphyton on macrophytes significantly increased the respiratory activity of E. ernstae, but not of S. striata. Our results show that higher macrophyte complexity can increase epiphytic development; and thus, its contribution to the benthic respiration. This suggests that in-stream presence of more complex macrophytic species may reduce dissolved oxygen availability and promote CO2 emissions to the atmosphere.
03:00 PM
Realm-specific adaptations undermine terrestrial predictions of leaf economics in freshwater plant communities (10357)
Primary Presenter: Lindsay Trottier, McGill University (lindsay.trottier@mail.mcgill.ca)
The leaf economic spectrum bridges plant demography with terrestrial biodiversity gradients, community ecology, and ecosystem functions, providing a framework for the mechanisms underlying ecosystem change. However, it is unclear whether this framework applies to aquatic plant communities, and how their biogeography is shaped by their unique adaptations to life in water. Here, we show that leaf phenotypes in freshwater plant communities are a product of unique selection from both general and realm-specific trait-environment relationships. Across 6953 European lake and river communities, high bicarbonate and phosphorus concentrations, and warm temperatures select for acquisitive leaf traits in emergent plant communities, aligning with terrestrial predictions. Conversely, acquisitive submerged plant communities are favoured by high bicarbonate and low temperature, independent of phosphorus. We attribute these differences to freshwater-specific adaptations which distinctly impact the leaf economics of submerged plants due to the challenging conditions (in terms of light and gas availability) they experience under water. As such, our knowledge of terrestrial leaf economics cannot be applied to the aquatic realm, especially with respect to temperature, which is key for predicting vegetation responses across global climatic gradients. This highlights the importance of realm-specific approaches for linking functional traits to ecosystem functioning and biodiversity.
03:15 PM
Constancy of macrophyte assemblage and abundance in 3 protected Adirondack lakes over 8 decades – implications for management of local and regional stressors (11218)
Primary Presenter: Kimberly Schulz, SUNY ESF (kschulz@syr.edu)
Macrophytes are important primary producers and defining structural organisms in littoral zones. Species composition, diversity and biomass of macrophytes in temperate zone lakes have been altered by anthropogenic perturbations, including nutrient loading increases, sediment runoff, road salt, acidification and introduction of non-native macrophyte species. The Huntington Wildlife Forest (HWF), a 6,000 hectare research field station within the Adirondack Park, has been managed by the State University of New York College of Environmental Science and Forestry for almost 100 years. In 1940, a comprehensive survey of the littoral zone vegetation of 5 lakes at HWF was conducted, including qualitative and semi-quantitative surveys of the species composition and relative abundance of littoral vegetation of 5 lakes within the boundaries of the Huntington Wildlife Forest (Heady, 1942). We repeated those surveys 80 years later, at 3 of the lakes at Heady’s sites, using the original semi-quantitative methods paired with quantitative scuba collection methods. We compared species composition and dominance in both time periods. We accessed current species composition for the 2 other now publicly accessible lakes in Heady’s publication. These lakes have higher qualitative density scores, and presence of invasive macrophytes. In contrast, the protected lakes had nearly identical species composition and relative abundance as in the historical surveys, suggesting resilience of macrophyte assemblages to climate change and acid deposition, but susceptibility to invasive species.
03:30 PM
Revegetation of littoral zones in snowmaking reservoirs: field assessment of aquatic plant establishment and biodiversity responses (11039)
Primary Presenter: Benjamin Gerfand, Université Savoie Mont Blanc (gerfand.benjamin@gmail.com)
Alpine freshwater ecosystems are biodiversity hotspots providing key ecosystem services but face threats from climate change and human activities. Snowmaking reservoirs have rapidly expanded in alpine regions in response to declining snow cover and growing winter tourism. The banks of the artificial waterbodies are often mineral, steep, and poorly vegetated, and can act as ecological traps. This study experimentally assessed the feasibility of littoral revegetation using coir macrophyte rolls as a Nature-based Solution in a high-elevation snowmaking reservoir in the French Alps, and whether such revegetation can initiate successional trajectories comparable with the regional species pool. Four native plant species were introduced and monitored over two years. Helophytes showed high survival (>97%), clonal expansion, and flowering, while hydrophytes initially grew but their longer-term persistence appears difficult under the specific management regime of the reservoir. Additional species colonized the rolls spontaneously, signalling the onset of secondary succession. Nearby waterbodies hosted 29 macrophyte species, indicating potential for gradual natural recolonization. We will also present preliminary results on amphibians, aquatic invertebrates, odonates, and zooplankton to provide a broader assessment of biodiversity responses. Overall, our findings indicate that coir rolls can establish functional littoral zones in snowmaking reservoirs, and targeted ecological design can help reconcile operational needs with alpine biodiversity conservation.
03:45 PM
Continental-wide functional responses of a native and an invasive macrophyte to local environmental conditions (11022)
Primary Presenter: Alice Dalla Vecchia, University of Parma (alice.dallavecchia@unipr.it)
Freshwater biodiversity and ecosystem functioning are threatened by invasive macrophytes, which degrade habitat structure and disrupt key ecological processes. To support effective management and conservation, we need to identify how local, freshwater-specific drivers shape the distribution and performance of these species. Here, we present the first results from the project “Predicting DIVErsity of INvasive aquatic plants”, which investigates the mechanisms driving invasion performance in aquatic plants. We sampled 53 populations of the invasive Elodea nuttallii and 55 populations of the native Trapa natans (with invasive potential) across broad geographic and environmental gradients in Europe. For each population, we quantified leaf traits related to resource-use strategies (leaf area, specific leaf area, leaf dry matter content, pigment concentrations and nutrient content) and measured water and sediment variables. Using multivariate models, we describe trait-environment relationships, highlighting which conditions trigger a more performative response for these species. Therefore, our findings reveal habitats that are particularly vulnerable and where conservation or management actions should be prioritized. These continental-scale trait–environment relationships provide a baseline for the next phase of the project, in which we will compare species’ responses between native and invasive ranges by sampling and analysing the same species in North America.
SS036A Macrophyte Communities and Ecosystem Functioning in a Changing Freshwater World
Description
Time: 2:30 PM
Date: 13/5/2026
Room: 524C