Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Disregarding the importance of groundwater as an ecosystem ignores its critical role in preserving surface biomes. To foster timely global conservation of groundwater, we propose elevating the concept of keystone species into the realm of ecosystems, claiming groundwater as a keystone ecosystem that influences the integrity of many dependent ecosystems. Our global analysis shows that over half of land surface areas (52.6%) has a medium‐to‐high interaction with groundwater, reaching up to 74.9% when deserts and high mountains are excluded. We postulate that the intrinsic transboundary features of groundwater are critical for shifting perspectives towards more holistic approaches in aquatic ecology and beyond. Furthermore, we propose eight key themes to develop a science‐policy integrated groundwater conservation agenda. Given ecosystems above and below the ground intersect at many levels, considering groundwater as an essential component of planetary health is pivotal to reduce biodiversity loss and buffer against climate change.

Aims: Studies to date have shown rapid killing of bacterial cells when exposed to copper surfaces. The mechanistic action of copper on bacterial cells is so far unknown. Methods and Results: To investigate potential mechanisms involved, meticillin‐resistant Staphylococcus aureus (MRSA) cells (10⁷ CFU) were inoculated onto coupons of copper or stainless steel and stained with either the viability fluorophore 5‐cyano‐2,3‐ditolyl tetrazolium (CTC), to detect respiration, or BacLight™ (SYTO9/propidium iodide), to determine cell wall integrity. Coupons were then observed in‐situ using epifluorescence microscopy. In addition, DNA from cells inoculated onto either copper or stainless steel surfaces was isolated and analysed by agarose gel electrophoresis. An effect on cellular respiration with CTC reduction was evident but no effect on cell membrane integrity (BacLight™) was observed. Results from the DNA isolation indicated a copper‐induced detrimental effect on MRSA genomic material as no bands were observed after exposure to copper surface. Conclusions: The results indicate that exposure to copper surfaces rapidly kills MRSA by compromising cellular respiration and damaging DNA, with little effect on cell membrane integrity. Significance and Impact of the study: This research provides a mechanistic explanation in support of previous suggestions that although copper surfaces do not affect membrane integrity of cells, there is still a rapid antimicrobial effect.

Aims: As copper has been previously suggested as an antimicrobial surface, we tested the effectiveness of copper as an antifungal surface which could be used in air-conditioning systems as an alternative to aluminium. Methods and Results: Coupons of copper (C11000) and aluminium were inoculated with fungal isolates (Aspergillus spp., Fusarium spp., Penicillium chrysogenum and Candida albicans) for various time periods. Culture on potato dextrose agar and an in situ viability assay using the fluorochrome FUN-1 were used to determine whether spores had survived. The results showed increased die off of fungal isolates tested compared to aluminium. In addition, copper also prevented the germination of spores present, thereby reducing the risk of the release of spores. Conclusions: Copper offered an antifungal surface and prevented subsequent germination of spores present. FUN-1 demonstrated that fungal spores entered into a viable but not culturable (VBNC) state on copper indicating the importance of using such methods when assessing the effect of an antifungal as culture alone may give false results. Significance and impact of study: Copper offers a valuable alternative to aluminium which could be used in air-conditioning systems in buildings, particularly in hospital environments where patients are more susceptible to fungal infections.