In recent years, the expansion of kelp aquaculture has sparked growing interest not only for its economic potential but also for its environmental implications, particularly in the realm of carbon sequestration. New research from Bigelow Laboratory advances this conversation by unveiling innovative environmental DNA (eDNA) methodologies capable of accurately and cost-effectively quantifying kelp-derived biomass in marine sediments beneath commercial kelp farms. Published in PLOS One, this groundbreaking study introduces a suite of molecular tools that promise to refine how scientists assess the ecological footprint of kelp farming and its role in blue carbon storage.
The team of researchers focused their efforts on the seafloor sedimentary environments beneath commercial kelp farms situated in the Gulf of Maine, where Saccharina latissima, commonly known as sugar kelp, is extensively cultivated. Traditionally, analyzing the origin and quantity of organic carbon within sediments has relied on bulk stable isotope techniques, which, although useful, cannot distinguish contributions from individual species and tend to be expensive and labor-intensive. This limitation has hindered precise evaluations of the carbon sequestration potential attributed specifically to kelp biomass, a gap this study aims to close.
Central to the research is the use of eDNA, genetic material shed into the environment from living organisms, which can be extracted and analyzed to reveal species-specific presence and abundance within environmental samples. The study applied two key molecular methods: metabarcoding and digital polymerase chain reaction (dPCR). Metabarcoding involves extracting and amplifying all DNA in a sample, enabling researchers to characterize the entire biological community residing in the sediment. This approach exposed subtle variations in benthic community composition between sediment inside kelp farms and nearby control areas, providing compelling evidence that kelp farms themselves exert minimal disruption on seafloor fauna.
While metabarcoding yielded valuable ecological insights, it fell short in detecting sugar kelp DNA with sufficient sensitivity. To overcome this, the researchers developed a species-specific dPCR probe tailored to Saccharina latissima. This cutting-edge technique allows for the precise quantification of target DNA molecules down to single gene copy levels. Analogous in sensitivity and specificity to high-precision diagnostic tests, the dPCR method furnished highly accurate measurements of kelp biomass embedded within sediment matrices, marking a leap forward in non-invasive ecological monitoring.
Analyses revealed that sediment samples collected directly beneath kelp farms contained modestly but consistently higher levels of sugar kelp DNA relative to adjacent sites. This pattern confirms that biomass originating from commercial kelp farms does, to some extent, settle and integrate into benthic sediments. However, the team cautions that the measured DNA quantities represent conservative estimates. The rapid degradation of kelp DNA compared to other plant materials means that actual biomass accumulation may be underestimated. Such nuances underscore the complexity of interpreting eDNA signals within dynamic marine sediment environments.
From a broader ecological perspective, the study’s findings bolster the notion that kelp farming can be conducted with limited negative impacts on underlying benthic communities. The observed minimal community disruption contrasts with concerns often associated with other forms of aquaculture, such as finfish farming, which can induce pronounced sediment hypoxia and biodiversity loss. This favorable environmental profile strengthens kelp aquaculture’s appeal as a sustainable blue economy practice capable of generating both environmental and economic value.
Importantly, the research underscores the potential of refined molecular monitoring tools to advance “blue carbon” accounting frameworks, an emerging field dedicated to quantifying and optimizing the ocean’s role in carbon capture and storage. By enabling precise measurements of kelp-derived carbon deposits, these tools may empower stakeholders, including policymakers and farmers, to better understand, manage, and perhaps even monetize the carbon sequestration services provided by kelp ecosystems. Such insight could lead to innovative incentive schemes that reward kelp farmers for enhancing sediment carbon burial.
Despite these promising developments, the authors emphasize the need for further research to disentangle the dynamic processes governing kelp biomass deposition and DNA persistence in sediments. Longitudinal and spatially extensive sampling will be necessary to characterize variability among different farms and geographic regions, as preliminary data suggest larger and older farms globally may show more substantial organic carbon accumulation. Integrating molecular data with biogeochemical and sedimentological analyses will be crucial to constructing robust models of carbon transfer and fate.
The researchers also highlight the importance of linking DNA quantifications to actual biomass estimates, a relationship complicated by DNA degradation and environmental transport mechanisms. Efforts are ongoing to calibrate molecular signals against biomass using experimental and field data, which will enhance the predictive power of eDNA tools for carbon accounting. These advances promise to overcome previous methodological constraints, rendering kelp farms not only productive but also transparent actors in global climate mitigation strategies.
In closing, this study exemplifies the transformative potential of environmental DNA technologies to revolutionize marine ecosystem monitoring. By providing fine-scale, species-specific data on kelp biomass in sediments, the methods offer a scalable and economical approach to assess the ecological and climate-related functions of kelp aquaculture. As coastal blue carbon strategies gain momentum, the integration of molecular ecology into aquaculture management could represent a paradigm shift in fostering resilient and climate-positive ocean stewardship.
This investigation was supported by the National Science Foundation’s Established Program to Stimulate Competitive Research and the Builders Initiative Foundation. It also benefits from collaborative partnerships with researchers at the University of Maine’s Darling Marine Center and the University of British Columbia. Among the key contributors from Bigelow Laboratory are Shane Farrell and Nichole Price, who contributed to expanding the scientific rigor and interdisciplinary scope of the project.
Subject of Research: Cells
Article Title: Using eDNA tools to examine the impact of kelp farming on underlying sediments
News Publication Date: 5-Sep-2025
Web References:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0331416
http://dx.doi.org/10.1371/journal.pone.0331416
Image Credits: Brittney Honisch, Bigelow Laboratory
Keywords: Aquaculture, Seaweeds, DNA, Carbon sequestration, Sediment
