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Pacific Islands present unique challenges for water resource management due to their environmental vulnerability, dynamic climates, and heavy reliance on groundwater. Quantifying connections between meteoric, ground, and surface waters is critical for effective water resource management. Analyses of the stable isotopes of oxygen and hydrogen in the hydrosphere can help illuminate such connections. This study investigates the stable isotope composition of rainfall on O'ahu in the Hawaiian Islands, with a particular focus on how altitude impacts stable isotope composition. Rainfall was sampled at 20 locations from March 2018 to August 2021. The new precipitation stable isotope data were integrated with previously published data to create the most spatially and topographically diverse precipitation collector network on O'ahu to date. Results show that δ18O and δ2H values in precipitation displayed distinct isotopic signatures influenced by geographical location, season, and precipitation source. Altitude and isotopic compositions were strongly correlated along certain elevation transects, but these relationships could not be extrapolated to larger regions due to microclimate influences. Altitude and deuterium excess were strongly correlated across the study region, suggesting that deuterium excess may be a reliable proxy for precipitation elevation in local water tracer studies. Analysis of spring, rainfall, and fog stable isotope composition from Mount Ka'ala suggests that fog may contribute up to 45% of total groundwater recharge at the summit. These findings highlight the strong influence of microclimates on the stable isotope composition of rainfall, underscore the need for further investigation into fog's role in the water budget, and demonstrate the importance of stable isotope analysis for comprehending hydrologic dynamics in environmentally sensitive regions. [ABSTRACT FROM AUTHOR]

The recent Land Back movement has catalysed global solidarity towards addressing the oppression and dispossession of Indigenous Peoples' Lands and territories. Largely absent from the discourse, however, is a discussion of the alienation of Indigenous Peoples from Water by settler-colonial states. Some Indigenous Water Protectors argue that there cannot be Land Back without Water Back. In response to this emergent movement of Water Back, this review of research by Indigenous and non-Indigenous writers traces the discursive patterns of Indigenous Water relationships and rematriation across themes of colonialism, climate change, justice, health, rights, responsibilities, governance and cosmology. It advances a holistic conceptualization of Water Back as a framework for future research sovereignty, focusing mainly on instances in Canada, Australia, Aotearoa New Zealand, and the United States. We present the findings on the current global Waterscape of Indigenous-led research on Indigenous Water issues. Water Back offers an important framework centring Indigenous ways of knowing, doing, and being as a foundation for advancing Indigenous Water research. [ABSTRACT FROM AUTHOR]

Climate change models project an increase in the frequency and duration of drought globally. Changes in rainfall are expected to have particularly detrimental effects on seedlings due to their inability to reach deep water sources. We conducted a greenhouse experiment to test how the timing of watering affects seedling performance, physiology, and morphology in a keystone island endemic tree, Metrosideros polymorpha. Seedlings were grown for 60 days in one of five conditions: control treatment with daily watering to 100% field capacity (FC), a 28-day pulse drought with no water, and three groups maintained at 80% FC and watered every 2, 7, or 14 days. Seedling drought tolerance depended on the duration of drought; growth for plants watered to 80% FC every 2 or 14 days was comparable to 100% FC plants, but was reduced in the 28-day pulse drought and 7-day 80% FC. Survival was high in all treatments except the pulse drought. Stomatal conductance, chlorophyll content, and C:N ratio were positively related to height and biomass under drought. Traits associated with resource investment, fluorescence, and water use were plastic in their expression, shifting under drought compared to control conditions. M. polymorpha seedlings exhibit trait plasticity that allows them to tolerate drought, but its duration and intensity influence their survival and growth. Our results highlight the need for experimental studies manipulating temporal variation in water with explicit consideration of the role of trait plasticity in drought tolerance. [ABSTRACT FROM AUTHOR]

Abstract: Tropical ecosystems offer a unique setting for understanding ecohydrological processes, but to date, such investigations have been limited. The purpose of this paper is to highlight the importance of studying these processes—specifically, how they are being affected by the transformative changes taking place in the tropics—and to offer an agenda for future research. At present, the ongoing loss of native ecosystems is largely due to agricultural expansion, but parallel processes of afforestation are also taking place, leading to shifts in ecohydrological fluxes. Similarly, shifts in water availability due to climate change will affect both water and carbon fluxes in tropical ecosystems. A number of methods exist that can help us better understand how changes in land use and climate affect ecohydrological processes; these include stable isotopes, remote sensing, and process‐based models. Still, our knowledge of the underlying physical mechanisms, especially those that determine the effects of scale on ecosystem processes, remains incomplete. We assert that development of a knowledge base concerning the effects of transformative change on ecological, hydrological, and biogeochemical processes at different spatio‐temporal scales is an urgent need for tropical regions and should serve as a compass for emerging ecohydrologists. To reach this goal, we advocate a research agenda that expands the number and diversity of ecosystems targeted for ecohydrological investigations and connects researchers across the tropics. We believe that the use of big data and open source software—already an important integrative tool/skill for the young ecohydrologist—will be key in expanding research capabilities. [ABSTRACT FROM AUTHOR]

The article reports that Mauna Kea, Hawaii's Land Board issued a lease for the construction of a single telescope and filed a Conservation District Use Application on behalf of the Thirty Meter Telescope (TMT) Corporation for the proposed construction of what would be the most massive observatory yet. It mentions Governor David Ige announced construction of the long-contested Thirty Mile Telescope (TMT) would resume the following week.