Changes in the tissue concentrations of trace elements during the reproductive cycle of Noah's Ark shells (Arca noae Linnaeus, 1758).

Concentrations of 23 trace elements (TEs; essential: Co, Cu, Fe, Mn, Mo, Se, V, Zn; non-essential: Ag, Al, As, Ba, Cd, Cr, Cs, Li, Ni, Pb, Rb, Sr, Ti, Tl, U) in whole soft tissues of Noah's Ark shell (Arca noae) were determined monthly during one year (March 2013-February 2014) at two sampling sites in the central part of the Eastern Adriatic Sea. Our aim was to detect the influence of reproductive cycle and changes in the environmental factors on the variabilities of TEs' contents. Higher concentrations of Pb, Ba, V, Mo, Mn and Fe were found at potentially contaminated site in Pasman channel, whereas higher concentrations of Tl, Ni, Li, Cr, Cd, Ti and Se were found at reference site in Nature Park Telascica. Since several bioaccumulated TEs were associated to mean gonadal index, in TEs monitoring in A. noae, animal gonadal status has to be considered.

Endoliths in Lithophaga lithophaga shells--Variation in intensity of infestation and species occurrence.

Pronounced differences with respect to the extent of infestation and the degree of Lithophaga lithophaga shell damage inflicted by euendolithic taxa at two sites in the Adriatic Sea representing different productivity conditions, are described. Shells collected from the eastern part of Kastela Bay, which is characterized by higher primary productivity, have significantly more shell damage then the shell collected from a site on the outer coast of the island of Ciovo exposed to the oligotrophic Adriatic Sea. The presence of endoliths and their perforations were detected in different layers of the shell, including solidly mineralized parts of the skeleton and within the organic lamellae incorporated into the shell. Phototrophic endoliths were not observed in the specimens. The most serious damage to L. lithophaga shells was the boring clionaid sponge Pione vastifica, which was more common in shells collected from Kastela.