Climate change, macroalgae, and the fate of groundwater dependent ecosystems in Kona

American Sāmoa | Wednesday, July 26 from 1:00-2:30 p.m.Hawaiʻi | Wednesday, July 26 from 2:00-3:30 p.m.Palau | Thursday, July 27 from 9:00-10:30 a.m.CNMI & Guam | Thursday, July 27 from 10:00-11:30 a.m.FSM | Thursday, July 27 from 10:00-11:30 a.m. (Weno) / 11:00 am-12:30 p.m. (Palikir)RMI | Thursday, July 27 from 12:00 – 1:30 p.m.

A Pacific RISCC Webinar via Zoom

Webinar overview:

Climate change has the potential to impact groundwater dependent marine ecosystems in Hawaiʻi. How sensitive are native and invasive limu (macroalgae) to current conditions and future changes?

July’s Pacific RISCC webinar will feature:

  • Dr. Celia Smith, Professor of Botany at the School of Life Sciences, UH Mānoa;
  • Dr. Veronica Gibson, Postdoctoral Fellow at He’eia National Estuarine Research Reserve;
  • Dr. Jade Delevaux, Senior Scientist at Seascape Solutions; and
  • Dr. Angela Richards Donà, Physiological-Ecology Research Fellow at UH Mānoa.

Webinar Abstract:

Co-managing groundwater dependent ecosystems (GDE) relies in part on understanding the biology of key marine organisms, but is hampered by gaps of fundamental cultural and scientific information. Recently, our multidisciplinary collaboration examined these complex interactions in four ways: interviews of lineal descendants of the Kona region; hydrological modeling to predict outcomes of scenarios for climate change and forest protection via changes in submarine groundwaters discharging (SGD) into GDE; and spatial models to predict changes in limu, under these changed regimes. Our fourth approach – data-intensive studies of photosynthetic capacity and growth of native marine algae such as limu pālahalaha, Ulva lactuca, document this alga’s response to the full range of native habitat parameters in healthy GDE.

In contrast, the physiological capacities for a commonly co-occurring invasive seaweed, Hypnea musciformis, were similarly challenged over the full range of Kona GDE conditions. Overall, our results revealed marked increases in growth and photosynthesis for limu pālahalaha across the SGD gradient, but substantial sensitivity by the invasive species to low salinity conditions, despite elevated nutrient concentrations typical of healthy SGD. These findings are supported by our 2022 field assessments, finding no Hypnea musciformis detected in the limu pālahalaha zone.

In the context of predicted climate change reductions for SGD, these contrasting physiological results strongly suggest that maintenance of quality and quantity of SGD appears critical to maintenance of healthy populations of limu pālahalaha as well as their GDE. Importantly, these studies also highlight the need to conserve SGD to ensure the longevity of traditional practices such as harvesting native limu, by the Hawaiian community in these GDE.

Speaker details:

Dr. Celia Smith is a marine botanist and Professor of Botany at the School of Life Sciences, University of Hawaiʻi at Mānoa. For the last three decades, Celia and her students in the “Limu Lab” have documented impacts of invasive marine algae in Hawaiʻi’s coastal reefs and explored new tools for reef management. Celia’s recent collaborations have extended to the biology of our remarkable native algal flora – the limu of Hawaiʻi, as well as mesophotic ecosystem studies and collaborations with the colleagues in the Water Resources Research Center and University of Hawaiʻi Economic Research Organization. She has published over 125 papers, yet her most favorite professional activity is listening to and talking story with the Hāna community about limu, during the annual Hāna Limu Festival. She is currently Co-Director of the Marine Biology Graduate Program at UH Mānoa.

Dr. Veronica Gibson is currently a postdoctoral fellow, and Wetland Researcher, at Heʻeia National Estuarine Research Reserve, having recently graduated from the Limu Lab, Botany Graduate Program, UHM. Veronica used the tools of ecohydrology and physiological ecology, for her PhD research studying limu and invasive seaweeds co-occurring in submarine groundwater discharge-influenced reef regions on Oʻahu. She also has interests in biocultural systems and interviewed Kānka ʻŌiwi lineal descendants/resource managers from her home, the Kona coast of Hawaiʻi island. She is dedicated to mentoring and career pathway development for local students and Pacific Islanders.

Dr. Jade Delevaux is a Senior Scientist at Seascape Solutions and a Senior Fellow consultant at the Natural Capital Project at Stanford University. Trained as a geographer, her work focuses on the effects of global change on coupled human-natural systems in tropical environments. She obtained her PhD in Natural Resources and Environmental Management from the University of Hawaiʻi. Her favorite part of her work is co-developing science and solutions with communities and government agencies.

Dr. Angela Richards Donà is a physiological-ecology research fellow in the Limu Lab, UHM. Trained as a coral biologist, her recent research focused on manipulative physiological experiments that examine the effects of climate change on native corals and their pigment systems to avoid stress. Currently, she leads the studies that physiologically compare native and invasive seaweeds. Angela obtained her PhD in the Marine Biology Graduate Program, UHM. Her favorite part of her work is seeing photosynthetic acclimations and adaptations as unifying processes in coral and algal reef ecology.


Please check out the recent publication! Okuhata, B.K., Delevaux J.M.S., Donà A.R., Smith C.M., Dulai G.H., El-Kadi A.I., Stamoulis K., Burnett K.M., Wada C.A., and Bremer L.L. (2023), “Effects of Multiple Drivers of Environmental Change on Native and Invasive Macroalgae in Nearshore Groundwater Dependent Ecosystems”, Water Resources Research, 59(7) 1-19