Thematic session.
Lead Organizer: Michele Burford, Griffith University (M.Burford@griffith.edu.au)
Co-organizers:
Roxanne Razavi, SUNY ESF (nrazavi@esf.edu)
Presentations
02:30 PM
SPATIAL EXTENT AFFECTS ESTIMATES OF PROCESS CONTRIBUTIONS TO POND METACOMMUNITY ASSEMBLY (10184)
Primary Presenter: Thomas Mehner, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) (thomas.mehner@igb-berlin.de)
Metacommunities are defined as local communities linked with the regional diversity pool via dispersal. The contributing local assembly processes environmental filtering, dispersal limitation and species interactions can be estimated by joint species distribution models (jSDM). However, the three processes may have differently strong contributions at varying spatial extents. We collected empirical data on pond metacommunities, encompassing presence/absence data of fishes, amphibians, zooplankton and benthic macroinvertebrates, in 170 ponds from 30 pondscapes in six European countries. We run jSDMs at three spatial extents, namely the semi-continental (all countries), the regional (countries separated) and the local (ponds in 1-2 pondscapes per country) extents. The pure and shared contributions of space to metacommunity assembly were minor in all models, while environment and species associations contributed strongly. The strongest pure contribution of environment was found for the regional scale, while species interactions were a strong contributor at the semi-continental scale, but also co-contributed with environment at the local scale. Important environmental predictors were pond hydroperiod, trophic state and coverage by macrophytes. Negative species associations at the local scale can plausibly be interpreted as predator-prey or competitive interactions, but positive associations dominate at all spatial extents. The contribution of the three community assembly processes differed among sites and species, suggesting a strong internal structure of pond metacommunities.
02:45 PM
Weaving trait co-occurrence networks from local to landscape scales to disentangle drivers of community functional structure. (10639)
Primary Presenter: David Cunillera-Montcusí, IFREMER (david.cunillera@dcm.cat)
Functional composition of communities arises from the interaction between local environment and species traits, reflecting the interplay between local filters and species performance. Yet, trait-based approaches often overlook regional heterogeneity, which is defined by geographic or environmental distances between communities. This limits our ability to disentangle the role of local or regional drivers for functional assembly and hinders our understanding of both global change impacts and community functioning dynamics. To address this, we expanded a functional network approach, shifting the focus from species–trait associations to trait–trait co-occurrences, enabling us to evaluate how network structure evolves from local to regional scales while integrating spatial and environmental gradients. We developed this approach using simulated and empirical metacommunities from 56 Swedish lakes (20 years) and 36 rivers (11 years). We progressively merged communities by spatial proximity, environmental similarity, or random selection, constructing trait co-occurrence networks at each step and calculating several network indices to track structural shifts across scales (e.g., edge density, graph strength). Our results revealed scale dependency in metacommunity functional structure by showing that lake functional assembly was primarily driven by environment, while river functionality was mostly driven by geographical proximity. By bridging local and regional perspectives from a metacommunity standpoint, our method expands current understanding of trait-functional assembly.
03:00 PM
30 Years of Plankton Monitoring in Lake Champlain: What have we learned? (11091)
Primary Presenter: Timothy Mihuc, SUNY Plattsburgh (mihuctb@plattsburgh.edu)
The Lake Champlain Basin Program has conducted Long-Term Monitoring in Lake Champlain since the mid-1990s. This includes water quality monitoring and biological monitoring focused on planktonic communities. Long-term records (1992-present) for native zooplankton in Lake Champlain illustrate the impact of invasive species on community structure over the past three decades. Zooplankton exhibited shifts in composition associated with invasive species, including a decline in rotifer and Mysid abundance in the mid-1990s, following invasion of zebra mussels (Dreissena polymorpha). More recent community alterations can be attributed to invasion of the Alewife (Alosa pseudoharengus) in 2006-08, Spiny Waterflea (Bythotrephes longimanus) in 2014 and Fishhook waterflea (Cercopagis pengoi) in 2018. These patterns represent major changes in community structure with potential implications for the Lake’s food web dynamics. In addition, altered Diel Vertical Migration (DVM) behavior was observed in Lake Champlain following the Spiny Waterflea and Fishhook waterflea invasions. We also detected a decline in Mysis diluviana abundance following the zebra mussel invasion in Lake Champlain along with changes in population size structure over the past 3 decades. In addition, we compared phytoplankton community composition in Lake Champlain from 1970 to present demonstrating long-term shifts in composition of cyanobacteria and other taxa. Patterns in Lake Champlain’s pelagic plankton communities illustrate the threat that invasive species and/or altered thermal regimes may pose to the ecological integrity of freshwater ecosystems.
03:15 PM
A Framework for Trait Inclusion in Fourth Corner Models: Application to Zooplankton Communities in Ontario Lakes (11421)
Primary Presenter: Sarah Rijkenberg, Ontario Tech University (sarah.rijkenberg@ontariotechu.net)
Characterizing zooplankton communities through functional traits offers a powerful complement to taxonomic approaches, yet no standardized framework guides the inclusion in ecological models. We develop and demonstrate a generalizable framework to evaluate trait inclusion in fourth corner RLQ models, using data from 45 lakes across Ontario, Canada. Taxonomic abundance, functional traits, and environmental variables were integrated to test how environmental and anthropogenic factors structure zooplankton communities. Bayesian regression provided quantitative support for including traits, after which RLQ and fourth corner analyses were applied. While ecoregion did not differ based on environmental variables alone, RLQ identified distinct community gradients along axes of nutrient productivity and lake depth. Fishing pressure was associated with shifts in feeding strategy rather than body size, with filter-feeders associated with low pressure lakes and raptorial feeders with high pressure lakes. Rotifers, often excluded from such analyses, comprised a substantial proportion of observed communities highlighting the importance of their inclusion. We recommend broader adoption of trait-based approaches across zooplankton and other taxa, as they reveal community patterns not captured by environmental gradients and taxonomy alone.
03:30 PM
ENVIRONMENTAL DISEQUILIBRIUM IN CANADIAN FRESHWATER BIOINDICATOR COMMUNITIES (11553)
Primary Presenter: Cindy Gao, McGill University (cindy.gao@mail.mcgill.ca)
Freshwater monitoring programs worldwide rely on tracking shifts in the abundances of macroinvertebrate bioindicator species, whose populations are thought to reflect freshwater ecosystem health. However, extensive evidence has demonstrated that ecological communities frequently exhibit environmental disequilibrium, where lagged responses to environmental change result in communities composed of species that are mismatched to the observed environment. Here, we use the Canadian Aquatic Biomonitoring Network (CABIN) data, which provides long-term hydrological, chemical, nutrient, and macroinvertebrate measurements, to investigate freshwater macroinvertebrate communities across 100 Canadian watersheds for environmental disequilibrium. Our preliminary results reveal spatial patterns: bioindicator communities in eastern Canadian watersheds are exhibiting environmental disequilibrium, whereas northern and western communities appear closer to environmental equilibrium. Further, using Latent Variable Models, we find that environmental disequilibrium significantly alters the relationships between macroinvertebrate bioindicator taxa and local water chemistry, challenging the reliability of bioindicator-based environmental assessments. Our findings highlight the need for adaptive strategies that incorporate community-environment mismatches, providing insights for more reliable ecosystem monitoring under ongoing environmental change.
03:45 PM
ENVIRONMENTAL FILTERING DOMINATES ZOOPLANKTON COMMUNITY ASSEMBLY IN PONDS (10994)
Primary Presenter: Feride Avci, Middle East Technical University (ferideavci18@gmail.com)
Ponds are biodiversity hotspots and ideal ecosystems for studying community assembly of different organisms due to being numerous, having small size, discrete boundaries and being in a network. Zooplankton, rapidly respond to environmental change and provide functional links within food webs. However, the drivers shaping zooplankton functional diversity in small waterbodies remain understudied. We examined zooplankton functional traits, community-weighted means, and standardized functional diversity indices across 52 ponds in Ankara, Türkiye. Using trait-based metrics and null-model standardized effect sizes, we assessed whether zooplankton communities are structured by habitat filtering or by limiting similarity. We found clear functional convergence, demonstrating strong environmental filtering. Several traits including feeding strategies, habitat preferences, and stoichiometric categories showed significant convergence relative to null expectations. In contrast; species richness, functional dispersion, and body size did not respond to single environmental variables, indicating that no single factor drives community assembly. The results point to the combined influence of multiple co-occurring stressors producing a multi-filtering scenario. Overall, zooplankton communities in these ponds are shaped by synergistic habitat filters rather than trait divergence, highlighting their vulnerability to land and water use. Understanding how multiple stressors jointly structure pond communities is essential for designing conservation strategies for these overlooked ecosystems.
CS004A Community Ecology
Description
Time: 2:30 PM
Date: 14/5/2026
Room: 524C