In an era of accelerating global change, it is crucial to pause and reflect on how our actions today affect and alter our planet. Addressing the pressing current and future environmental issues requires international and multidisciplinary research efforts to ensure inclusive, holistic, and innovative solutions. The Early Career Committee (ECC) of the Association for the Sciences of Limnology and Oceanography (ASLO) seeks to enhance global collaboration and networking opportunities for early career researchers (ECRs*). To achieve this, we have hosted a series of online "Amplifying Voices" webinars, highlighting the work of ECRs from underrepresented** groups.
After a successful launch at the ASM in Madison, Wisconsin in 2024, we are excited to bring "Amplifying Voices" to ASM again this year, inviting ECRs worldwide who cannot attend the conference in person to present their research in a pre-recorded format. As we “take the aquatic pulse”, we must recognize that rising temperatures, shifting precipitation patterns, and encroaching sea levels are reshaping aquatic environments. These changes have far-reaching consequences, affecting aquatic ecosystem processes, distribution, behavior, and abundance of freshwater and marine species. For this special “Amplifying Voices” session, we invite all presentations that address the impacts of climate change, industrial byproducts, or tourism pressures, amongst many other topics, on freshwater and marine ecosystems.
Selected talks for the session will be ordered by topic to form a cohesive session broadly addressing climate change issues in aquatic systems. Abstract submission fees are waived for this session, and accepted participants will have their registration fee waived, as they will not be attending the conference in person. Presenters must submit a pre-recorded talk with contact information so viewers can follow up with questions.
Lunch packages will be provided to the first 40 attendees at the start of each session.
*ECR in this context includes both PhD students and non-tenured researchers who have received their highest degree within the last 10 years.
**These include ethnic origin and ethnicity, disability, sex, gender, sexual orientation, geographic location, or any other component of identity underrepresented in science, which may vary in different countries.
Lead Organizer: Bianca Rodríguez-Cardona, International Institute of Tropical Forestry (rodriguez.cardona.bm@gmail.com)
Co-organizers:
Mina Bizic, Technical University of Berlin (mina-bizic@tu-berlin.de)
Rebecca Gladstone-Gallagher, University of Auckland (rebecca.gladstone-gallagher@Auckland.ac.nz)
Pascal Bodmer, Cornell University (pb577@cornell.edu)
Heili Lowman, Duke University (heili.lowman@duke.edu)
Members of the Early Career Committee (ECC), Association for the Sciences of Limnology and Oceanography, ASLO (ec-committee-aslo@googlegroups.com)
Presentations
01:00 PM
MICROPLASTICS ON THE MOVE: ONTOGENIC TRANSFERENCE AND DETOXIFICATION IN CHIRONOMIDS (9818)
Primary Presenter: Dimitrija Savic-Zdravkovic, University of Nis (thedimitrija@gmail.com)
Microplastics (MPs) are pervasive pollutants affecting aquatic ecosystems, with potential to infiltrate terrestrial systems via boundary species. Chironomus riparius, a benthic macroinvertebrate with an aquatic larval and terrestrial adult life cycle, serves as a key vector for MP transfer across these ecosystems. This study examines the impact of a complex MP mixture—polyethylene, polyvinyl chloride, and polyamide—on C. riparius at environmentally relevant concentrations, focusing on ontogenic transference and metamorphosis-driven detoxification mechanisms. Larvae were exposed to MP-spiked sediments under controlled conditions, and life-history traits were monitored. MPs were detected in both adults and exuviae, with higher concentrations in exuviae, suggesting molting during metamorphosis aids in shedding ingested particles. Sublethal effects included delayed development and reduced growth rates, though emergence ratios and mortality remained unaffected. These findings underscore the ecological role of C. riparius in MP pathways and suggest metamorphosis as a natural detoxification mechanism, albeit with potential long-term impacts on population dynamics and ecosystem interactions. This research highlights the urgent need to address MP contamination at the aquatic-terrestrial interface and paves the way for expanded studies across diverse taxa and ecosystems. Acknowledgement - The authors thank the project Plastic Underground – Integrated Cross-Sectoral Solutons to Micro and Nanoplstic Pollution in Soil and Groundwater Ecosystems project HORIZON-MSCA-2021-DN, funded by the European Union's Horizon Europe program under Grant Agreement No. 1010727777
01:05 PM
Modeling particle dispersion and sewage pollution in a subtropical estuary under climate change and extreme events (8781)
Primary Presenter: Paula Birocchi, Universidade de São Paulo (paula.birocchi@usp.br)
This study investigates the effects of freshwater discharge variability on residence and flushing times, as well as bacterial concentrations, under climate change and extreme events. The Estuarine and Coastal Ocean Model (ECOM) was coupled with the Opendrift particle tracking model and applied to Cananéia-Iguape Estuarine-Lagoon Complex (CIELC) located in Brazil. Results revealed that mean bacterial concentrations near Valo Grande channel (VGC), the main freshwater tributary, reached up to 1032 CFU/100 mL for thermotolerant coliforms and 465 CFU/100 mL for enterococci during summer, surpassing legal limits. Flushing times ranged between 5-18 hours at the northern inlet and 37- 115 hours at the southern inlet of the CIELC. Particles retention was highest in the central region of CIELC. The storm tide scenario associated with intense river discharge through VGC accelerated particle release through the estuarine inlets presenting shorter residence time of 6 days, contrasting with the atmospheric blocking which presented a longer residence time of 25 days. Projected river discharge variations under climate change are expected to impact residence time, while T90 bacterial decay indicates that CIELC acts as a sink for bacteria and organic matter.
01:10 PM
Environmental Impacts of Wastes and Contaminants from Aquaculture and Their Remediation Techniques (9666)
Primary Presenter: Solomon Melaku Birhanu, Addis Ababa University (solomon.melaku@aau.edu.et)
World food production needs to increase as the human population is increasing too steadily over the years. On the other hand, global food production sectors are being compromised at an alarming rate due to urbanization and industrialization. Aquaculture and capture fisheries are the two major food-producing sectors with a huge potential to feed the growing population. Aquaculture production has been the fastest food-producing sector in the world for the past several decades; on the other hand, a world capture fishery has stagnated over the last two decades and is expected to continue in such a manner for the coming years. Therefore, to meet the global demand for fish with relatively stable capture fisheries, world aquaculture production will need to increase. Hence, the intensification of aquaculture has appeared as a feasible substitute to strengthen food fish production to fulfill the breach in supply. However, this increase in aquaculture intensification requires amplified inputs such as feed, and drugs which in turn increases the ecological effects of the sector and compromises its sustainability. Although the environmental impacts of intensive aquaculture are multifaceted, wastes and contaminants produced from aquaculture setups such as nutrients (N and P) and chemicals (Therapeutics, disinfectants, herbicides, and insecticides) contribute the highest share. As a result of this wastes and contaminants eutrophication and public health concerns due to chemical residues in aquaculture products have been most discussed in the past. As a result of the above-mentioned concerns about the impacts of aquaculture, several techniques with different approaches have been in place in the past to mitigate these environmental impacts. Amongst are, Integrated agriculture aquaculture systems (IAA), integrated multi-trophic aquaculture systems (IMTA), recirculating aquaculture systems (RAS), and limited and/or zero water exchange systems (biofloc technology) as the main water reuse systems while removal of nutrients (nitrogen and phosphorus) and chemical contaminants from aquaculture effluents through nitrogen removal techniques and use of natural or constructed wetlands are the main approaches currently employed to treat wastes and contaminants in intensive aquaculture. Therefore, in this review, an overview of the environmental impacts of aquaculture and the mitigation techniques mentioned above are discussed in detail. Keywords: Contaminants, Environmental Impacts, Waste Reuse, Waste Recycling
01:15 PM
Impact of benzyl butyl phthalate on freshwater phytoplanktons (9817)
Primary Presenter: Tamara Petronijevic, University of Nis (tamara.petronijevic@pmf.edu.rs)
Phthalates are synthetic compounds widely used in the production of plastics and various consumer goods, frequently accumulating in aquatic ecosystems. As substances that are affected by climate change through the increasing rates of leaching from plastics caused by higher temperatures, they deserve huge attention in investigations related to climate change. An increase in the temperature from 25 to 35 °C can elevate phthalate leaching by more than a factor of 10. Benzyl butyl phthalate (BBP) as one of the most used phthalates, can be found in the fresh waters. The impact of benzyl butyl phthalate on freshwater organisms remains underexplored, especially in the context of climate change. This study examines the effects of BBP on the growth of freshwater cyanobacteria (Microcystis sp. and Anabaena sp.) and green microalgae (Chlorella sp., and Scenedesmus sp.) under controlled laboratory conditions. Cyanobacteria and microalgae were exposed to five concentrations of BBP, with growth monitored spectrophotometrically through chlorophyll a production, an indicator of cellular proliferation. BBP concentrations in the culture media were determined using gas chromatography-mass spectrometry (GC-MS). Results indicate that BBP has a dose-dependent inhibitory effect on the growth of tested cyanobacteria and microalgae strains. These findings contribute to understanding BBP's ecological impact in freshwater environments, with implications for climate change-influenced pollution dynamics.
01:20 PM
SPATIAL AND SEASONAL PATTERNS IN MACROPHYTE-ASSOCIATED TOXIC CYANOBACTERIA AND THEIR TOXINS: A CASE STUDY FROM A TEMPERATE LAKE (9684)
Primary Presenter: Nikola Stankovic, University of Nis (nikola.stankovic@pmf.edu.rs)
Benthic cyanobacteria produce potent toxins, with anatoxins (ATXs) implicated in numerous recent dog poisoning incidents. Some benthic cyanobacteria attach to submerged macrophytes, facilitating transport to beaches and posing potential risks to humans and animals. The specific interactions and conditions supporting macrophyte-associated cyanobacteria are not well understood. Climate change, with its impact on temperature and seasonal shifts, further complicates cyanobacterial dynamics, potentially enhancing the spread and toxicity of these microorganisms.We analyzed macrophyte-associated cyanobacteria occurrence across transects and depths in Lake Tegel (Berlin, Germany) monthly for one year, beginning in May 2023. This dimictic temperate lake has experienced macrophyte recolonization due to nutrient load reduction, increased water clarity, and a quagga mussel invasion in 2013. Cyanobacteria presence on macrophytes was assessed microscopically, with ATXs quantified from biofilms and water samples analyzed for nutrient concentrations. We focused on Fontinalis antipyretica, a rootless wintergreen water moss occasionally washed ashore. Samples were collected from four transects and two additional locations. Only one additional site consistently showed high toxin levels. Microcoleus, a known toxic genus, was linked to sample toxicity, and Oscillatoriales and Nostocales were identified microscopically, by cultivation, and PCR. PCR indicated anaC-osc genes in samples with the highest ATX levels. An underwater camera detected dense red-brown mats covering macrophytes in October and November, which correlated with peak toxin concentrations (ATX-a 418 µg/g d.w., DhATX 68.6 µg/g d.w., HATX 0.8 µg/g d.w.).
01:25 PM
Cyanobacterial sensitivity and response to hydrogen peroxide treatment (9816)
Primary Presenter: Nada Tokodi, University of Novi Sad (nada.tokodi@dbe.uns.ac.rs)
Oxidative stress caused by reactive oxygen species like hydrogen peroxide (H2O2) is a critical factor in aquatic ecosystems, often triggered by environmental changes such as high light exposure, pollution, or management strategies like chemical treatments to control harmful blooms. Understanding how cyanobacteria respond to such stress is essential for predicting bloom dynamics, assessing the risks associated with toxin production, and developing effective mitigation strategies. To address these questions, we determined the impact of H2O2 on growth, photosynthesis efficiency, toxin production (cylindrospermopsin and microcystins), and the expression of toxin-related genes (cyr and mcy) of different freshwater cyanobacteria. The selected strains of Raphidiopsis raciborskii, Microcystis aeruginosa and Aphanizomenon flos-aquae, originating from several different localities around the world, represent a diverse range of toxin-producing and non-toxin-producing cyanobacteria. The relative growth trends reveal significant strain-specific differences, with A. flos-aquae 2012/KM1/D3 exhibiting the steepest decline, suggesting a severe impact on its growth. In contrast, R. raciborskii KLL07 showed the least growth reduction, indicative of greater resilience. PSII activity data further supports these observations, with KLL07 showing a marked increase in PSII efficiency at 24 and 48 hours, whereas strains like CS-506 and 2012/KM1/D3 experienced pronounced declines. These results suggest that KLL07 has a robust adaptive mechanism to maintain photosynthetic efficiency and growth under stress, whereas other strains are more susceptible to damage, possibly due to differences in their genetic or physiological responses. Additional data for the toxic strains R. raciborskii and M. aeruginosa, including toxin gene expression and toxin production, provided further insights into their responses to oxidative stress. Expression of the cyr genes in R. raciborskii during H2O2 exposure showed some fluctuations compared to the control, however, statistical analysis did not reveal any significant differences. In contrast, the results for mcy gene expression in M. aeruginosa revealed a downregulation during H2O2 exposure. Furthermore, exposure to 5 mg/L H2O2 resulted in a significant decrease in the intracellular cyanotoxin content (CYN or MC per mL) for all investigated toxic strains after 48 hours of treatment. These findings highlight that oxidative stress affects not only growth and photosynthesis, but also impacts toxin production and gene expression, with toxic strains showing variable responses in their ability to regulate toxin biosynthesis pathways under stress conditions suggesting potential differences in their adaptive mechanisms and resilience to environmental stressors. This variability could have significant ecological implications, influencing bloom toxicity and treatment in natural ecosystems. Keywords: hydrogen peroxide, Raphidiopsis raciborskii, Microcystis aeruginosa and Aphanizomenon flos-aquae, growth, PSII efficiency, toxicity Acknowledgements and Funding The authors would like to thank the student Robert Maziarz and Semko Walat. Nada Tokodi was supported by postdoctoral funding from Narodowa Agencja Wymiany Akademickiej (NAWA) with ULAM grant number PPN/ULM/2019/1/00219. This publication is based upon work from COST Action CYANOACTION (Nr. CA23160) supported by COST (European Cooperation in Science and Technology).
01:30 PM
Comparison of different techniques for seagrass (Posidonia oceanica) restoration (9812)
Primary Presenter: Gema Hernan, Mediterranean Institute for Advanced Studies (CSIC-UIB) (gemahernanm@gmail.com)
Coastal ecosystems, particularly seagrass meadows, are vital for ecological and socio-economic stability, providing essential ecosystem services such as habitat provision, nutrient cycling, and blue carbon sequestration. Among seagrasses, Posidonia oceanica, endemic to the Mediterranean Sea, plays a critical role but faces significant threats from human activities and environmental disturbances. Restoration of degraded P. oceanica meadows has garnered interest, with active restoration methods increasingly employed to counteract its slow natural recovery. This study aims to evaluate the feasibility and efficacy of different restoration techniques for P. oceanica using detached plagiotropic rhizomes. Experimental restoration was conducted at two sites in Mallorca, Spain, using four anchoring methods: big steel staples coated with beeswax, small garden staples, bamboo sticks, and calcite structures (the latter tested at one site only). Fragments were planted in shallow zones of dead matte, where anthropogenic pressures such as anchoring had been eliminated, and monitored over 2 years to assess the success of establishment and production of new shoots. Logistic and environmental indicators were also assessed to provide a comprehensive evaluation of each technique, a part lacking in most restoration experiments. Preliminary results highlight variability in restoration success across methods, with implications for optimizing restoration strategies. This research contributes to advancing cost-effective and ecologically sound practices for seagrass restoration, addressing critical gaps in understanding the ecological and logistical feasibility of P. oceanica restoration efforts.
01:35 PM
Unravelling the causes and implications of recovery lags in intertidal shellfish populations (9059)
Primary Presenter: Rebecca Gladstone-Gallagher, University of Auckland (rebecca.gladstone-gallagher@auckland.ac.nz)
Disturbances such as heat waves can wipe out populations of marine species, and often recovery does not follow population growth models. This is challenging for species management and the communities and ecosystems they facilitate. We viewed a heat wave induced shellfish die off in New Zealand as an opportunity to test hypotheses about the causes of recovery lags (e.g., loss of facilitation feedbacks causing hysteresis vs. misalignment of biophysical conditions). We also explore how these population shifts ripple out across the community and ecosystem. We removed adult intertidal cockles in 9m2 plots at 23 intertidal soft sediment sites across 4 estuaries in Aotearoa New Zealand that reflect differing levels of exposure, mud content, and natural cockle density. Over the next year we measured shifts in several cockle population parameters and the macrofauna community composition when adult cockles were absent indicating the potential for broken feedbacks. There were also biophysical drivers of these shifts indicating potentially multiple drivers of deviations from population growth models. We use these multiple lines of enquiry to delve into the possible causes for recovery lags in ecosystems that have experienced mass mortality of a key species. Our project addresses the globally outstanding challenge of translating resilience and disturbance-recovery theory into real-world ecology as well as considering how climate change may alter ecosystems.
01:40 PM
Dissolved Trace Metals and Cu Cycling in a Tropical Small Mountainous River in Costa Rica: The Reventazon-Parismina Basin (9077)
Primary Presenter: Ana Vasquez Vargas, Tongji University / Latin American University of Science and Technology (anacvv211@outlook.com)
Small mountainous river systems (SMR) underlain by volcanic lithology substantially contribute to silicate weathering yields and the associated CO2 consumption. Identifying the sources of trace metals and stable isotopes in dissolved and weathered pools provides insights into metal cycling processes and controlling mechanisms that affect river chemistry. The identification of natural and anthropogenic sources is essential for understanding modern river flux and constraining oceanic mass balance. This study provides the first systematic geochemical analysis of source-to-sink processes in Central America and the first Cu isotopic dataset for a volcanic catchment. Bioactive metals (Cu, Ni, and Mo) are highly correlated with volcanic-derived weathering and dissolved organic carbon (DOC), whereas Zn, Cd, and Cr mainly reflect anthropogenic contributions. Dissolved Cu (DCu) mean of 18.9 nM and the δ65Cu values of 0.69 ± 0.08 ‰ (2σ, n= 9) are closely related to the global riverine average. Our results indicate that DCu displays minimal evidence of anthropogenic contributions, suggesting that the gradual increase downstream is driven by natural processes, such as physical erosion, chemical weathering, and organic complexation. Conversely, the δ65Cu values suggest a major contribution from agricultural sources. Here, we present the first trace metal and Cu isotope data in the dissolved pool of the Reventazon-Parismina Basin sampled from its source to the estuary. This study aims to decipher the natural and anthropogenic sources in the catchment’s geochemical pool and constrain the mechanisms driving Cu isotopic variations in one of the larger catchments in Costa Rica.
01:45 PM
Evaluation of River Okura's physico-chemical parameters: Implications for environmental sustainability in Dekina local government area, Kogi state, Nigeria. (9813)
Primary Presenter: Efe Ogidiaka-Obende, University of Delta, Agbor (efeogis@yahoo.com)
River Okura is an important water resource in Dekina Local Government Area, Kogi State, Nigeria, supporting various human activities, including fishing, recreation, irrigation, and source of domestic water supply. However, the river's water quality is under threat from anthropogenic activities, such as domestic waste disposal, agricultural runoff, and industrial effluent. Due to the anthropogenic activities around Okura River, there is need for continuous monitoring of the physico-chemical parameters. The objective of the study therefore, was to evaluate the physico-chemical parameters of River Okura and assess its environmental sustainability. Water samples were taken twice monthly from the month of August, 2019 to January 2020, alternatively morning and evening. Three months of rainy season and three months of dry season. The water samples for the four locations were analyzed for temperature, pH, water transparency/turbidity, dissolved oxygen (DO), nitrate, phosphate/phosphorus and sulphate using standard methods. During the course of the research work, it was observed that the temperature ranges between 24.05-25.50 while the overall average pH value of 6.16, the average turbidity ranges between 141.44cm to 152.21cm. The dissolved oxygen of Okura River overall average level was 6.52mg/l, the average monthly sulphate ranges from 0.77mg/l to 7.65mg/l while the average phosphate level ranged between 0.76 to 5.89mg/l. This study revealed the impact of anthropogenic activities on Okura River, Kogi State. This was revealed by the physico-chemical parameters observed during the period of the study. Although the parameters measured were within the safe limits for fish growth, however, there is a gradual decline in the water quality and hence the need for a continuous pollution monitoring program of the river to prevent overload.
01:50 PM
Combining eDNA and Image Analyses to determine the impacts of Warming and Dissolved Organic Carbon (DOC) Disturbance on Freshwater Communities (9661)
Primary Presenter: Gülce Yalçın, Middle East Technical University; Ecosystem Implementation and Research Center (ygulce@metu.edu.tr)
Shallow lake ecosystems are particularly prone to climate-driven disturbances, including warming and pulses of dissolved organic carbon (DOC) loading. Climate models predict a 1.1–6.4°C increase in temperature during the 21st century, alongside altered precipitation patterns and flush floods. In lakes receiving floodwaters, excessive DOC inputs stimulate heterotrophic bacterial production, shifting dominance from photosynthetic production to the microbial loop (ML). Warming may interact with DOC flux, potentially intensifying these effects. Given the limited understanding of these drivers on biodiversity and ecosystem functions, an in situ mesocosm experiment (4x4) was conducted at METU Mesocosm System I, Türkiye, from 05 July to 05 August 2021. Treatments included DOC (8 ppm), 4°C warming (H), combined warming and DOC (HD), and controls (C). Traditional microscopy, FlowCAM, and eDNA techniques were used to examine bacterial, ciliate, phytoplankton, and zooplankton communities. We hypothesized that elevated temperature and DOC (i) would synergistically increase bacterial biomass and shift community structure towards species adapted to high carbon and temperature, (ii) would influence ciliate biomass, composition, and size through “trophic interactions” with changing zooplankton dynamics, and (iii) would promote mixotrophs in the phytoplankton while reducing overall biomass due to DOC’s light-limiting effects. These three different methods provided complementary results to be thoroughly discussed in the presentation.
01:55 PM
VITAMIN B12 AND KEY DRIVERS IN AQUATIC ECOSYSTEMS: A COMPREHENSIVE REVIEW OF SEVEN DECADES OF RESEARCH (9101)
Primary Presenter: Mohammad Salar Sohrabi, University of Eastern Finland (salar.sohrabi@uef.fi)
We reviewed the literature on field measurements of vitamin B12 (cobalamin) and discussed the environmental factors that regulate its availability and distribution. Synthesized by certain bacteria and archaea, vitamin B12 is essential for over 50% of phytoplankton taxa and may influence their growth and community composition. Vitamin B12 encompasses several structurally similar variants, discussed in detail when possible, and we distinguish between the concentrations of dissolved and particulate forms. Overall, vitamin B12 concentrations showed spatial, vertical, and temporal variability. Spatial variability was ecosystem-dependent; for example, freshwater ecosystems generally exhibited higher concentrations of dissolved and particulate B12 than marine ecosystems, possibly due to higher nutrient and cobalt concentrations. Within marine ecosystems, coastal waters consistently had higher concentrations of vitamin B12 than open ocean. Several studies have reported significant vertical stratification in both dissolved and particulate vitamin B12 fractions, which appears related to differences in production and/or degradation of vitamin B12 and the abundance of phyto- and bacterioplankton. Particulate B12 concentrations were higher in spring and summer, while dissolved B12 peaked in winter and fall, likely due to increased phytoplankton biomass during the warmer months. This review provides an overview of analytical developments in vitamin B12 analysis, current concentration estimates, and identifies knowledge gaps and environmental factors linked to its dynamics.
AV01 - Amplifying Voices in Climate Change Impacts on Aquatic Systems
Description
Time: 1:00 PM
Date: 30/3/2025
Room: W207AB