Declining nutrient availability and metal pollution in the Red Sea

Abstract

Reconstructing sediment accumulation rates reveals historical environmental shifts. We analyzed 15 element concentrations and accumulation rates in two Red Sea sediment cores over 500 years. Post-1870s, the South Red Sea experienced a significant drop in element accumulation rates, with a noticeable decline in nutrients like magnesium (−8.52%), organic carbon (−14.9%), nitrogen (−14.0%), phosphorus (−16.4%), sulfur (−17.2%), and calcium (−17.8%). This suggests a potential reduction in nutrient inflow from the Indian Ocean, possibly due to warming-induced ocean stratification. Conversely, the North Red Sea saw an increase in all element accumulation rates after the 1870s, highlighting a rise in trace elements such as iron (4.56%), cadmium (8.69%), vanadium (12.6%), zinc (13.8%), copper (14.4%), chromium (17.6%), and nickel (19.5%), indicative of increased anthropogenic coastal activities. We introduce the term “Cai-Agusti Marine Crisis Conflux” to encapsulate the escalating thermal stress, nutrient depletion, and elemental pollution in the Red Sea, underscoring potential risks to its ecosystems and global implications.