Human‐induced salinity changes impact marine organisms and ecosystems

Abstract

Climate change is fundamentally altering marine and coastal ecosystems on a global scale. While the effects of ocean warming and acidification on ecology and ecosystem functions and services are being comprehensively researched, less attention is directed toward understanding the impacts of human-driven ocean salinity changes.The global water cycle operates through water fluxes expressed as precipitation, evaporation, and freshwater runoff from land. Changes to these in turn modulate ocean salinity and shape the marine and coastal environment by affecting ocean currents, stratification, oxygen saturation, and sea level rise. Besides the direct impact on ocean physical processes, salinity changes impact ocean biological functions with the ecophysiological consequences are being poorly understood. This is surprising as salinity changes may impact diversity, ecosystem and habitat structure loss, and community shifts including trophic cascades. Climate model future projections (of end of the century salinity changes) indicate magnitudes that lead to modification of open ocean plankton community structure and habitat suitability of coral reef communities. Such salinity changes are also capable of affecting the diversity and metabolic capacity of coastal microorganisms and impairing the photosynthetic capacity of (coastal and open ocean) phytoplankton, macroalgae, and seagrass, with downstream ramifications on global biogeochemical cycling. The scarcity of comprehensive salinity data This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Long-term warming and human-induced plankton shifts at a coastal Eastern Mediterranean site

“…Nevertheless, other factors than those included in the study could have played a role in these changes. For example, salinity changes due to climate warming may impact planktonic organisms (e.g., through changes in respiration, disruption of cellular processes) and their habitats (e.g., changes in water column stratification) 136 . However, an analysis of a salinity dataset acquired at the study site, as shown in Supplementary Fig.…”

Alternative splicing plays a nonredundant role in greater amberjack (Seriola dumerili) in the adaptation to ambient salinity fluctuations

“…Furthermore, this imbalance has been found to be amplified by human activities (Omerspahic et al, 2022; Röthig et al, 2023). For instance, brine discharge during seawater desalination can lead to an abnormal increase in salinity of the receiving water body in coastal marine environment, while the enhanced urban drainage may freshen nearshore seawater (Omerspahic et al, 2022; Röthig et al, 2023). Salinity fluctuations in seawater would alter the dissolved oxygen level, nutrient concentration, and stratification of the oceans, thereby posting an adverse impact on the respiration, metabolism, reproduction, and even disease immunity of marine organisms (Lehtonen et al, 2016; Guo et al, 2020; Galkanda-Arachchige et al, 2021; Lu et al, 2022; Lacy et al, 2023; Röthig et al, 2023).…”

“…Till 2017, the mean salinity contrast between the low and high salinity regions had increased by more than 5% (Cheng et al, 2020). Furthermore, this imbalance has been found to be amplified by human activities (Omerspahic et al, 2022; Röthig et al, 2023). For instance, brine discharge during seawater desalination can lead to an abnormal increase in salinity of the receiving water body in coastal marine environment, while the enhanced urban drainage may freshen nearshore seawater (Omerspahic et al, 2022; Röthig et al, 2023).…”

“…For instance, brine discharge during seawater desalination can lead to an abnormal increase in salinity of the receiving water body in coastal marine environment, while the enhanced urban drainage may freshen nearshore seawater (Omerspahic et al, 2022; Röthig et al, 2023). Salinity fluctuations in seawater would alter the dissolved oxygen level, nutrient concentration, and stratification of the oceans, thereby posting an adverse impact on the respiration, metabolism, reproduction, and even disease immunity of marine organisms (Lehtonen et al, 2016; Guo et al, 2020; Galkanda-Arachchige et al, 2021; Lu et al, 2022; Lacy et al, 2023; Röthig et al, 2023). For example, the increased water salinity was found to disrupt the normal energy allocation, and physiological and metabolic processes of fish, such as grass carp ( Ctenopharyngodon idella ) and African catfish ( Clarias gariepinus ), and finally inhibit their growth and survival (Smyth and Elliott, 2016; Zidan et al, 2022; Liu et al, 2023).…”

“…For example, the increased water salinity was found to disrupt the normal energy allocation, and physiological and metabolic processes of fish, such as grass carp ( Ctenopharyngodon idella ) and African catfish ( Clarias gariepinus ), and finally inhibit their growth and survival (Smyth and Elliott, 2016; Zidan et al, 2022; Liu et al, 2023). Moreover, salinity change-induced biodiversity loss of plankton, macroalgae, coral reef, and seagrass may cause trophic collapse of marine ecosystem and lead to drops in fishery yield, which threaten ecosystem functions and food supply to human (Röthig et al, 2023).…”