Changes in trace elements during lactation in a marine top predator, the grey seal

Area of Science:

• Marine Mammal Biology
• Environmental Toxicology
• Reproductive Physiology

Background:

• Lactation is a major energetic cost for pinnipeds, yet trace element dynamics during this period are poorly understood.
• Understanding trace element mobilization is crucial for assessing marine mammal health and reproductive success.

Purpose of the Study:

• To investigate trace element changes in grey seals during lactation and post-weaning fast.
• To assess maternal transfer of elements via placenta and milk.
• To evaluate contamination levels and compare exposure with other seal populations.

Main Methods:

• Longitudinal study of 21 mother-pup grey seal pairs from Scotland.
• Sequential collection of blood, milk, blubber, and hair samples.
• Analysis of 11 trace elements (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, Zn).

Main Results:

• All tested trace elements, except Cadmium (Cd), transferred from mother to pup via milk.
• Placental transfer and accumulation of elements during gestation confirmed by pup lanugo analysis.
• Grey seals showed higher Lead (Pb) exposure than other phocids but lower Mercury (Hg) exposure than North Sea harbour seals.
• Blood and blubber element concentrations fluctuated significantly during lactation.

Conclusions:

• Grey seals possess weak or absent placental and mammary barriers for non-essential metal transfer.
• Rapid trace element fluctuations during lactation necessitate careful consideration in biomonitoring.
• Further research is needed on the health impacts of these physiological trace element changes in seals.