Salt marshes, abundant and fertile coastal habitats, provide critical ecosystem services. Humans have significantly altered these ecosystems since the Middle Ages through activities like reclamation, land conversion, species introduction, and pollution. These impacts have disrupted food webs, increasing top-down control. Invasive species, runaway consumer effects, and sea level rise are major threats. Ecosystem-based management is crucial for protection. Salt marshes have long been used for agriculture, fishing, and livestock grazing. Human activities such as diking, drainage, and urban development have altered hydrology, leading to subsidence and loss of marshes. Salt marshes have been converted to farmland, salt works, and urban areas, often at the expense of ecosystem services. Invasive species like Spartina have altered native plant communities and ecosystem functions. Pollution, including metal and nutrient inputs, has affected salt marsh biogeochemistry and species composition. Eutrophication has shifted plant zonation, favoring species like Spartina. Nutrient-rich runoff from human activities has led to increased consumer control, threatening marshes. Climate change and sea level rise further threaten salt marshes, altering their structure and function. Salt marshes provide essential ecosystem services such as coastal protection, nitrogen filtration, and habitat for fish and wildlife. However, human activities have compromised these services. Restoration efforts are needed to mitigate past impacts and preserve the ecological value of salt marshes. Effective management must consider all ecosystem services and avoid single-impact prioritization.Salt marshes, abundant and fertile coastal habitats, provide critical ecosystem services. Humans have significantly altered these ecosystems since the Middle Ages through activities like reclamation, land conversion, species introduction, and pollution. These impacts have disrupted food webs, increasing top-down control. Invasive species, runaway consumer effects, and sea level rise are major threats. Ecosystem-based management is crucial for protection. Salt marshes have long been used for agriculture, fishing, and livestock grazing. Human activities such as diking, drainage, and urban development have altered hydrology, leading to subsidence and loss of marshes. Salt marshes have been converted to farmland, salt works, and urban areas, often at the expense of ecosystem services. Invasive species like Spartina have altered native plant communities and ecosystem functions. Pollution, including metal and nutrient inputs, has affected salt marsh biogeochemistry and species composition. Eutrophication has shifted plant zonation, favoring species like Spartina. Nutrient-rich runoff from human activities has led to increased consumer control, threatening marshes. Climate change and sea level rise further threaten salt marshes, altering their structure and function. Salt marshes provide essential ecosystem services such as coastal protection, nitrogen filtration, and habitat for fish and wildlife. However, human activities have compromised these services. Restoration efforts are needed to mitigate past impacts and preserve the ecological value of salt marshes. Effective management must consider all ecosystem services and avoid single-impact prioritization.