Cuttlefish capsule: An effective shield against contaminants in the wild.

Increasing anthropogenic pressures in estuaries are responsible for the rise of contaminants in several compartments of these ecosystems. Species that benefit from the nursery services provided by estuaries are exposed to such contaminants (e.g. metals and metalloids). It is therefore relevant to understand if marine invertebrates that use these areas as spawning grounds accumulate contaminants in their tissues throughout embryogenesis. This study aimed to quantify As, Co, Cr, Cu, Mn, Ni, Se, Pb, V and Zn concentrations in both capsule and embryos of the common cuttlefish (Sepia officinalis) in Sado Estuary (Portugal). Moreover, embryos at their initial, intermediate and final stage of development were collected in sites subjected to different anthropogenic pressures. In general, the capsule accumulated higher element concentration throughout embryogenesis which indicates that the capsule acts as an effective barrier against contaminants uptake by the embryo. Although the capsule becomes thinner throughout embryogenesis, embryo's protection does not seem to be compromised at later development stages. Additionally, the higher concentrations of As, Cu, Se and Zn in the embryo in comparison to the capsule suggests important biological roles during the embryogenesis of this cephalopod mollusc.