The sixth report of the Intergovernmental Panel on Climate Change (IPCC-AR6) stated that temperature increases can negatively impact marine species’ performance and survival. In addition, the rise in temperature in marine ecosystems during the last few decades has proven climate warming. Temperature is a fundamental physical, regulatory factor in aquatic organisms, and this effect is expressed particularly strongly in the control of all reproductive processes from gamete development and maturation, ovulation and spermiation, spawning, embryogenesis and hatching, to larval and juvenile development and survival. The impacts of climate change, encompassing events like heat waves, droughts, and alterations in rainfall patterns, have led to significant consequences for the availability and variability of freshwater resources. These unpredictable impacts of climate change may provide complications for resource managers and policymakers.

Marine ecology and ecosystems, particularly coral reef ecosystems are the most productive and biodiverse environments globally. These ecosystems are vital in delivering essential environmental services such as biodiversity support and nutritional resources for food security and livelihoods. Offshore resources, environment, and space have become important material bases to support human society’s and marine ecosystems’ sustainable development (Ren et al., 2024). Park et al. presented a study on Siphonophores, which are highly polymorphic and complex marine organisms and abundant in marine ecosystems. However, various factors may affect the occurrence of siphonophores, including water temperature, salinity, zooplankton biomass, and trophic niche. The species with high contributions to distinguishing the water mass groups show species-specific correlations with water temperature and salinity. This suggests that diphyids can be used as indicator species for currents and hydrological factors influencing water mass. Changing climate conditions are well documented to affect species distribution patterns and migratory phenology, especially for thermally constrained species refugia. A marine mammal, Trichechus manatus, was used (Hieb et al.) as a model to understand how other thermally constrained species may expand their ranges into higher latitudes due to the impact of climate change. Cyanobacterial blooms, observed globally in freshwater systems and cyanobacterial cultures, commonly show the simultaneous presence of multiple toxins and represent another potential negative impact in aquatic environments.

Identifying an odour-producing microorganism is also important to understand its odour compounds using a molecular approach. Qiu et al. resolved the identification of the main odour-producing microorganisms in water bodies by predicting functional genes from microbial metagenomics. This approach represents a significant advance in the monitoring of drinking water. This might help to improve taste and odour problem management.

Coral reefs and their biota face substantial anthropogenic pressure, decreasing coral reefs globally due to anthropogenic stress, including overfishing, nautical tourism, global climate change impact and sedimentation (Hoeksema et al., 2022; Massei et al., 2023). The East Asian finless porpoise, Neophocaena asiaeorientalis sunameri, ranks among the most endangered species with a rapidly decreasing population in the Northwest Pacific. Nonetheless, the East Asian finless porpoise is highly vulnerable to anthropogenic threats due to fishing by artisanal fishers, bycatch and habitat disruption. Kim et al. reported new distribution records for Nasitrema spp., an important group of pathogenic parasites in Neophocaena and other marine mammals.

This Research Topic unveiled novel findings regarding the distribution of pathogenic parasites and investigated Siphonophores, essential components of marine ecosystems and food chains. Furthermore, a key odour-producing microorganism in water bodies was identified. Additionally, the study suggests that species constrained by thermal conditions might extend their habitats towards higher latitudes in response to the influence of climate change.

AH: Conceptualization, Writing – original draft. UA: Writing – review & editing. MH: Writing – review & editing. HS: Writing – review & editing.