Arsenic, cadmium, copper and zinc in two marlin species from the southern Gulf of California: Risk assessment and variations with environmental factors

This study assesses the health risks of As, Cd, Cu, and Zn in 109 specimens of Makaira nigricans and 461 specimens of Kajikia audax from the Gulf of California between 2007 and 2015. Analysis were made by inductively coupled plasmaoptical emission spectrometry (ICPOES). Anomalies of SST and Chl-a were obtained from composite satellite images. The ONI values were obtained from the NOAA. Multivariate methods using Euclidean distances were used to analyze the relationship of elemental concentrations with species variables and environmental factors using Principal Components Analysis (PCA) and hierarchical agglomerative clustering. Average median concentrations (µg g^-1 wet weight) in M. nigricans were Zn (6.480) > As (0.405) > Cu (0.316) > Cd (0.044), and in K. audax Zn (7.228) > As (1.445) > Cu (0.355) > Cd (0.099). As concentrations peaked in 2012 (M. nigricans) and 2013 (K. audax), while Cd levels declined in 2014–2015 (K. audax). In M. nigricans, Cu concentrations were significantly lower in 2014 while in K. audax Cu levels were significantly lower in 2014. With respect to Zn, concentrations of K. audax were significantly higher in 2012 and 2013. Total hazard quotients (HQ) values were below risk thresholds. In M. nigricans Zn increased significantly with Cu, As and Cd and Cu with As and Cd. In K. audax Cu increased with As and Cd, Zn increased with Cu and As with Cd. Elemental concentrations varied with Chl-a; Cd levels increased in M. nigricans, while Cu and As levels increased in K. audax. In M. nigricans Cu increased with LJFL and total weight. In K. audax, As, Cd and Zn increased with LJFL and total weight. Correlations were confirmed by PCA. Cluster and SIMPROF analysis revealed that Cd, Cu and Zn had similar patterns in both species; however, As was significantly higher in the striped marlin.