Spatiotemporal Distribution and Ecological Risks of Trace Metals in a Marine Protected Area of the Northwestern Arabian Gulf

Dissolved bio-essential trace metals (Cu, Zn, Co, Ni, and Fe) in seawater and 17 elements in surface sediments were studied to assess the metal contamination and associated ecological risks in the Sulaibikhat Bay Marine Protected Area (MPA) in the northwestern Arabian Gulf. Dissolved metals were mostly at low to moderate levels and within the limits of most international water quality standards. However, dissolved Cu concentrations (0.54 to 4.73 µg L−1) in the MPA stations (MPA-1 and MPA-2) exceeded the Oslo–Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) ecotoxicological assessment thresholds, suggesting possible adverse ecological effects. Sediment showed higher levels of Cd, Cr, Ni, V, Cu, and Zn at stations within the MPA, with Principal Component Analysis (PCA) linking these enrichments to nearby industrial and desalination discharge sources. The calculated enrichment factor (EF) and geoaccumulation index (Igeo) values confirmed moderate to substantial anthropogenic contributions for Cd, Cr, and Ni, while the major lithogenic elements were derived from natural mineralogical inputs. A pollution load index (PLI) > 1 at stations MPA-1, MPA-3 and MPA-4 in Sulaibikhat Bay indicated cumulative metal contamination. Ecological risk assessment criteria classified sediments within the MPA and Sulaibikhat Bay as having a moderate level of ecological risk, with Cd identified as the principal contributor. The toxicological indices, namely mean Effect Range Median Quotient (m-ERM-Q) and mean Probable Effect Level Quotient (m-PEL-Q), indicated a low-to-moderate probability of adverse biological effects due to Cu and Ni exposure in the MPA. In contrast, the reference station in the Kuwait Bay showed very low contamination and negligible ecological risk. These findings stress the need for continuous monitoring and effective source control to protect the ecosystem of this newly established MPA in Kuwait.