Freshwater Ecology & Restoration Biotechnology

Freshwater ecosystems — lakes, rivers, wetlands, streams — cover less than 1% of Earth's surface but support a disproportionate share of biodiversity and provide critical ecosystem services including drinking water, irrigation, fisheries, transportation, and recreation. They are also among the most threatened ecosystems: pollution, eutrophication, flow alteration, habitat degradation, invasive species, and climate change have degraded freshwater ecosystems worldwide. Restoration of these systems is a global priority.

Freshwater restoration draws on ecology, hydrology, engineering, and increasingly biotechnology. While the primary drivers of freshwater degradation are often physical and chemical (nutrient loads, flow alteration, habitat destruction), biological interventions can accelerate recovery and enhance resilience. These interventions include microbiome management, bioremediation of contaminants, biomanipulation of food webs, and the use of molecular tools for monitoring and assessment.

Hrisana Journal welcomes submissions across all aspects of freshwater ecology and restoration biotechnology — from fundamental research on freshwater ecosystems through restoration methods, monitoring tools, and integrated watershed management. Our interdisciplinary scope reflects the systemic nature of freshwater challenges.

Lake eutrophication — excessive nutrient enrichment leading to algal blooms, oxygen depletion, and biodiversity loss — is one of the most widespread freshwater degradation problems. External nutrient load reduction is the foundation of eutrophication control, but internal nutrient loads (from sediments) can delay recovery for decades after external loads are reduced. In-lake interventions including phosphorus inactivation (alum, lanthanum-modified clay), artificial aeration, and biomanipulation can accelerate recovery.

Biomanipulation — altering food web structure to improve water quality — typically involves reducing planktivorous fish (which graze on large zooplankton) to increase large zooplankton (which graze on phytoplankton). With more large zooplankton, phytoplankton biomass is reduced and water clarity improves. The approach has been successful in some shallow lakes but less reliable in deep lakes or those with cyanobacterial blooms that are resistant to zooplankton grazing. Combining biomanipulation with nutrient reduction is often more effective than either approach alone.

Harmful algal blooms (HABs), particularly of cyanobacteria, are an increasing problem in eutrophic waters. Some cyanobacteria produce toxins (microcystins, cylindrospermopsin, anatoxins) that threaten human and animal health. Biological control approaches include: algicidal bacteria that lyse cyanobacteria; cyanophages (viruses of cyanobacteria); and competitor enhancement to outcompete bloom-forming species. These approaches are at various stages of research and have not yet seen widespread deployment, but offer potential tools for HAB management.

River and stream restoration addresses physical habitat degradation (channelization, bank erosion, dam impacts), water quality (pollution, temperature, sediment), and biological communities (fish passage, invasive species, native community restoration). Physical restoration — re-meandering channels, restoring riparian vegetation, removing or modifying dams — sets the stage for biological recovery. Biological interventions can accelerate this recovery and address specific limitations.

Riparian vegetation restoration provides multiple benefits: bank stabilization, shade (temperature control), organic matter input (food web support), nutrient and sediment filtration, and habitat structure. Plant species selection and planting techniques, sometimes combined with microbial inoculation to enhance plant establishment, determine restoration success. Long-term monitoring is essential to track the development of riparian communities and their function.

Bioremediation of contaminated sediments and water in rivers uses approaches similar to those for terrestrial bioremediation. Permeable reactive barriers with organic carbon sources can stimulate reductive dechlorination of chlorinated solvents in groundwater entering rivers. Constructed wetlands and bioreactors can treat agricultural runoff, mine drainage, or urban stormwater before it enters rivers. In situ treatment of contaminated sediments using biostimulation or bioaugmentation has been demonstrated at pilot scale. Hrisana Journal welcomes field studies that report the effectiveness of these approaches.

Environmental DNA (eDNA) has transformed freshwater monitoring. A single water sample can reveal the presence of fish, amphibians, invertebrates, and microorganisms through metabarcoding of eDNA. The method is non-invasive, sensitive to rare species, and scalable to large spatial extents. It is being applied for: detecting invasive species early in their invasion; monitoring endangered species; assessing community composition; and evaluating the effectiveness of restoration interventions. Standardization of methods and interpretation frameworks is an active area of methodological development.

eDNA-based biomass estimation — using digital PCR or metabarcoding read counts to estimate organism abundance — is less mature than presence/absence detection. Challenges include variation in eDNA production rates among species and conditions, transport of eDNA in flowing waters, and degradation rates. However, the method holds promise for population monitoring at scales impractical with traditional approaches, and methodological advances are rapid.

Beyond eDNA, environmental RNA (eRNA) reveals which organisms are metabolically active, providing functional information that eDNA cannot. Environmental proteomics and metabolomics extend the molecular monitoring toolkit further. Integration of these multi-omics methods with traditional monitoring provides a more comprehensive picture of freshwater ecosystem status and trajectory than either approach alone. Hrisana Journal welcomes submissions that advance and apply these methods.

Freshwater microbiomes — the microbial communities of lakes, rivers, and wetlands — drive biogeochemical cycling, organic matter decomposition, and water quality. Microbiome management aims to shift these communities towards states that support desired functions: nutrient removal, pollutant degradation, cyanobacterial bloom suppression. Approaches include: bioaugmentation with specific functional guilds (e.g., denitrifying bacteria for nitrogen removal); biostimulation with substrates or electron acceptors that favour desired organisms; and microbiome transfer from healthy to degraded systems.

Wetland restoration microbiome management is particularly important. Constructed treatment wetlands rely on plant-microbe partnerships to remove nutrients and pollutants, and the assembly and function of wetland microbial communities determines treatment performance. Natural wetland restoration similarly depends on re-establishing microbial communities that drive biogeochemical cycling. Microbiome-aware design of wetlands — selecting plants, substrates, and hydraulic regimes that foster beneficial microbial communities — is an emerging approach.

Climate change poses new challenges for freshwater ecosystems. Warming waters alter species distributions, oxygen solubility, and stratification patterns. More intense storms increase sediment and nutrient loads. Droughts reduce flows and concentrate pollutants. Biotechnology tools — from molecular monitoring to microbiome management to bioremediation — will be essential for understanding and responding to these changes. Hrisana Journal welcomes submissions that address the intersection of freshwater ecology, biotechnology, and climate change. Visit our Submit Manuscript page to begin your submission.