My research interests
The Arctic Ocean is undergoing rapid change, and biological processes are responding in complex and interconnected ways. My research focuses on understanding and predicting the direction and magnitude of these changes. To pursue this, I integrate physical and biological datasets, combining in situ observations, satellite products, and model simulations. My overarching goal is to advance our understanding of biophysical interactions driven by climate change in polar regions. I am particularly interested in how large-scale atmospheric and ocean circulation changes—and the loss of ice and snow - affect marine primary producers, and how these shifts influence dissolved oxygen and carbon dynamics in the ocean.
Current research projects
OpKROP aims to synthesize and analyse long-term environmental and biological time-series from two Arctic fjords—Kongsfjorden and Isfjorden—to improve understanding of ecosystem change.
As a PDRA, I contribute to the project’s core objective by synthesizing and analysing long-term datasets from both fjords.
KANG-GLAC investigates how ocean-driven warming affects marine-terminating glaciers in south-east Greenland, reconstructing glacier, ocean, and ecosystem change over the Holocene to understand past ice-sheet dynamics and future trajectories.
As a PDRA, I analyse physical oceanographic data collected during the project’s oceanographic cruises, and collaborate with biologists to interpret how glacier melt interacts with marine ecosystems.
GIANT (Greenland Ice Sheet to AtlaNtic Tipping points) is a pioneering project that investigates whether accelerating melt from the Greenland Ice Sheet could trigger a critical climate tipping point—the disruption of North Atlantic ocean circulation—and explores the potential for early-warning indicators.
As a PDRA, I contribute to the collection and interpretation of new observational data to help detect emerging signals of change in the coupled ice–ocean system.
Selected past research projects
FACE-IT
FACE-IT investigates how rapid environmental change in Arctic coastal zones affects biodiversity, ecosystem functioning, and local communities.
As a PDRA in the modelling team, I contributed to improving gas exchange parameterizations, evaluated fjord model simulations, and helped synthesize observational data to characterize the biogeochemical state of an Arctic fjord. I also developed a model to predict kelp biomass from underwater light measurements in Arctic fjords—data-limited environments undergoing rapid environmental change
Nansen Legacy
The Nansen Legacy is a large Norwegian research programme that studies how climate change is transforming the northern Barents Sea ecosystem. It provides year-round observations and modelling to support future sustainable management of the region.
As a PDRA in the modelling team, I contributed to estimating total phytoplankton biomass and detecting trends in the Barents Sea by integrating multiple data sources, including in situ observations, biogeochemical model outputs, and satellite products.
VITALS
VITALS – Ventilation, Interactions and Transports Across the Labrador Sea- project examined how physical processes in the Labrador Sea regulate oxygen, carbon, and heat exchange between the ocean and atmosphere. The project combined observations and modelling to improve predictions of climate-relevant ocean ventilation.
As a PhD researcher in the modelling team, I helped develop and test the biogeochemical model used in VITALS. I applied this model to investigate oxygen transport in the Labrador Sea and to assess how changes in sea ice and atmospheric forcing influence marine productivity in the Arctic Ocean.
Castro de la Guardia, L., Bartsch, I., Hop, H., Niedzwiedz, S., Düsedau, L., Diehl, N., Krause-Jensen, D., Sejr, M., Ager, T.G., Gattuso, J.-P., Schlegel, R.W., Miller, C.A., Filbee-Dexter, K. and Duarte, P. (2025), Predicting potential Arctic kelp distribution and lower-depth biomass from seafloor irradiance. Limnol Oceanogr Methods. https://doi.org/10.1002/lom3.70018
Duarte, P., Castro de La Guardia, L., Assmy, P., Wold, A., Fransson, A., Chierici, M., Bailey, A., Hodson, A., Alexander, A., Magalhães, C., Gabrielsen, G. W., Albretsen, J., Frank, L., Tripathy, S. C., Smerdou, C., Gordillo, F. J. L., Cobos, P., Velázquez, D., Convey, P., ... Rodriguez-Castro, J. (2025). Ecosystem metabolism and nitrogen budget of a glacial Fjord in the Arctic. Scientific Reports, 15(1), Article 22946 (2025) . https://doi.org/10.1038/s41598-025-06953-3
Schlegel, R. W., Singh, R. K., Gentili, B., Bélanger, S., Castro De La Guardia, L., Krause-Jensen, D., Miller, C. A., Sejr, M., & Gattuso, J. P. (2024). Underwater light environment in Arctic fjords. Earth System Science Data, 16(6), 2773-2788. https://doi.org/10.5194/essd-16-2773-2024
Bensi, M., Nilsen, F., Ferré, B., Skogseth, R., Moskalik, M., Korhonen, M., Vogedes, D., Kovacevic, V., Paladini, F., Ingrosso, G., Langone, L., Giordano, P., Inall, M., Mano, B. Z., Sundfjord, A., Bailey, A. N., Foss, Ø., Daase, M. N., Castro de la Guardia, L., ... Jones, E. (2024). The Atlantification process in Svalbard: A broad view from the SIOS Marine Infrastructure network (ARiS). In SESS Report 2024, Chapter 5. Svalbard Integrated Arctic Earth Observing System (SIOS). https://doi.org/10.5281/zenodo.14425672
Myers, P. G., et al. (2023). An overview of the NEMO modelling for the BaySys Project. Elementa: Science of the Anthropocene, 12(1), 0011. https://doi.org/10.1525/elementa.2022.00111
Castro de la Guardia, L., Hernández Fariñas, T., Marchese, C., Amargant-Arumí, M., Myers, P. G., Bélanger, S., Assmy, P., Gradinger, R., & Duarte, P. (2023). Assessing net primary production in the northwestern Barents Sea using in situ, remote sensing and modelling approaches. Progress in Oceanography, 219, Article 103160. https://doi.org/10.1016/j.pocean.2023.103160
Castro de la Guardia, L., Filbee-Dexter, K., Garrido, I., Reimer, J., MacGregor, K. A., Konar, B., Iken, K., Johnson, L. E., Archambault, P., Sejr, M. K., & Mundy, C. J. (2023). Increasing depth distribution of Arctic kelp with increasing light during longer open water days. Elementa: Science of the Anthropocene. https://doi.org/10.1525/elementa.2022.00051
Buchart, L., Castro de la Guardia, L., Xu, Y., Ridenour, N., Marson, J. M., Deschepper, I., Hamilton, A. K., Grivault, N., & Myers, P. G. (2022). Future Climate Scenarios for Northern Baffin Bay and the Pikialasorsuaq (North Water Polynya) Region. Atmosphere - Ocean, 60(2), 102-123. https://doi.org/10.1080/07055900.2022.2067028
Filbee-Dexter, K., MacGregor, K. A., Lavoie, C., Garrido, I., Goldsmit, J., Castro de la Guardia, L., Howland, K. L., Johnson, L. E., Konar, B., McKindsey, C. W., Mundy, C. J., Schlegel, R. W., & Archambault, P. (2022). Sea Ice and Substratum Shape Extensive Kelp Forests in the Canadian Arctic. Frontiers in Marine Science, 9, Article 754074. https://doi.org/10.3389/fmars.2022.754074
Izett, R. W., Castro de la Guardia, L., Chanona, M., Myers, P. G., Waterman, S., & Tortell, P. D. (2022). Impact of Vertical Mixing on Summertime Net Community Production in Canadian Arctic and Subarctic Waters: Insights From In Situ Measurements and Numerical Simulations. Journal of Geophysical Research: Oceans, 127(8), Article e2021JC018215. https://doi.org/10.1029/2021JC018215
Singh, R. K., Vader, A., Mundy, C. J., Søreide, J. E., Iken, K., Dunton, K. H., Castro de la Guardia, L., Sejr, M. K., & Bélanger, S. (2022). Satellite-Derived Photosynthetically Available Radiation at the Coastal Arctic Seafloor. Remote Sensing, 14(20), Article 5180. https://doi.org/10.3390/rs14205180
Myers, P. G., Castro de la Guardia, L., Fu, C., Gillard, L. C., Grivault, N., Hu, X., Lee, C. M., Moore, G. W. K., Pennelly, C., Ribergaard, M. H., & Romanski, J. (2021). Extreme High Greenland Blocking Index Leads to the Reversal of Davis and Nares Strait Net Transport Toward the Arctic Ocean. Geophysical Research Letters, 48(17), Article e2021GL094178. https://doi.org/10.1029/2021GL094178
Lukovich, J. V., Jafarikhasragh, S., Myers, P. G., Ridenour, N. A., Castro de la Guardia, L., Hu, X., Grivault, N., Marson, J., Pennelly, C., Stroeve, J. C., Sydor, K., Wong, K., Stadnyk, T. A., & Barber, D. G. (2021). Simulated impacts of relative climate change and river discharge regulation on sea ice and oceanographic conditions in the Hudson Bay Complex. Elementa: Science of the Anthropocene, 9(1), 00127. https://doi.org/10.1525/elementa.2020.00127
Castro de la Guardia, L., Garcia-Quintana, Y., Claret, M., Hu, X., Galbraith, E. D., & Myers, P. G. (2019). Assessing the Role of High-Frequency Winds and Sea Ice Loss on Arctic Phytoplankton Blooms in an Ice-Ocean-Biogeochemical Model. Journal of Geophysical Research: Biogeosciences, 124(9), 2728-2750. https://doi.org/10.1029/2018JG004869
Marchese, C., Castro de la Guardia, L., Myers, P. G., & Bélanger, S. (2019). Regional differences and inter-annual variability in the timing of surface phytoplankton blooms in the Labrador Sea. Ecological Indicators, 96, 81-90. https://doi.org/10.1016/j.ecolind.2018.08.053
Castro De La Guardia, L., Myers, P. G., Derocher, A. E., Lunn, N. J., & Terwisscha Van Scheltinga, A. D. (2017). Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective. Marine Ecology Progress Series, 564, 225-233. https://doi.org/10.3354/meps11964
Castro De La Guardia, L., Hu, X., & Myers, P. G. (2015). Potential positive feedback between Greenland Ice Sheet melt and Baffin Bay heat content on the west Greenland shelf. Geophysical Research Letters, 42(12), 4922-4930. https://doi.org/10.1002/2015GL064626
Kaminski, M. A., Niessen, F., Bazhenova, E., Castro de la Guardia, L., Coakley, B., de Vernal, A., et al. (2015). Modern agglutinated Foraminifera from the Hovgård Ridge, Fram Strait, west of Spitsbergen: Evidence for a deep bottom current. Annales Societatis Geologorum Poloniae, 85(1), 309–320.
Hamilton, S. G., Castro de la Guardia, L., Derocher, A. E., Sahanatien, V., Tremblay, B., & Hauard, D. (2014). Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS ONE, 9(11), e113746. https://doi.org/10.1371/journal.pone.0113746.
Castro de la Guardia, L., Derocher, A. E., Myers, P. G., Terwisscha van Scheltinga, A. D., & Lunn, N. J. (2013). Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century. Global Change Biology, 19(9), 2675-2687. https://doi.org/10.1111/gcb.12272