Incidence of 49 elements in the blood and scute tissues of nesting hawksbill turtles (Eretmochelys imbricata) in Holbox Island

Abstract

Due to progressive urban development along the Mexican Caribbean coastline, it is crucial to gauge the impact of anthropogenic contamination of marine ecosystems through biomonitoring procedures.In the current study, we quantified the concentration of 49 inorganic elements in the blood and scute tissues of clinically healthy nesting hawksbill sea turtles (Eretmochelys imbricata). The elements were classified into four groups: Group A: essential mineral elements with toxic potential; Group B: non-essential elements with high toxicity; Group C: toxic non-essential minority elements and Trace Elements (TE); and Group D: rare-earth elements (REE) and other TE. Almost all the samples in both tissues showed perceptible levels of all the quantified elements. The only element identified with a correlation between blood and scute was arsenic (As), which could indicate a fast excretion through this type of keratinized tissue. The bio-accumulation of inorganic elements is a complex process, requiring the simultaneous examination of different tissues to evaluate the exposure. Our study reinforces the usefulness of scute tissue as a non-invasive sampling technique for the evaluation of persistent pollutants in marine turtles.

Trace elements concentration in blood of nesting Kemp’s Ridley turtles (Lepidochelys kempii) at Rancho Nuevo sanctuary, Tamaulipas, Mexico

“…Although high concentrations can be toxic and cause neurological and dermal damage and decreased sea turtle hatching success [ 14 , 66 , 67 ]. The concentrations identified in this study were lower than those reported in other species of sea turtles worldwide [ 14 , 34 , 68 , 69 ].…”

“…Previous studies have shown that the distribution of essential and toxic elements in sea turtle blood presents higher levels of essential elements than toxic ones [62,69,70]. This distribution may be affected when intoxication or pathological responses occur; for example, a study in Brazil reported higher concentrations of Pb compared to Zn and Cu in C. mydas when these turtles presented fibropapillomatosis [50].…”

A Pilot Study of Mercury Distribution in the Carapace of Four Species of Sea Turtles from Northeastern Brazil

“…We found the Hg levels were in a similar range for all studied species, except in E. imbricata which presented very low concentrations. Although our results for this single individual cannot be extrapolated to the species level, similarly low Hg levels have been previously reported in scutes of E. imbricata (Escobedo-Mondragón et al 2021, 2023. E. imbricata forage on a low trophic level, mainly on sponges, but also on other reef-encrusting organisms (Bjorndal 1997) which may or may not contain low Hg concentrations (e.g., Orani et al 2020 for sponges, and Rizzini et al 2016).…”

Determination of heavy metals in blood of nesting Kemp’s Ridley turtles (Lepidochelys kempii) at Rancho Nuevo sanctuary, Tamaulipas, Mexico

“…Although high concentrations can be toxic and cause neurological and dermal damage and decreased sea turtle hatching success [11,70,71]. The concentrations identified in this study were lower than those reported in other species of sea turtles worldwide [11,13,72,73].…”

“…Previous studies have shown that the distribution of metals in sea turtle blood presents higher levels of essential elements than toxic ones [66, 73, 74]. This distribution may be affected when intoxication or pathological responses occur; for example, a study in Brazil reported higher concentrations of Pb compared to Zn and Cu in C. mydas when these turtles presented fibropapillomatosis [53].…”