Elemental composition of Demospongiae from the eastern Atlantic coastal waters

The elemental composition (Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr and Pb) of 30 coastal and two deep-sea Demospongiae specimens, belonging to 19 different species and collected in the eastern Atlantic Ocean along the Portuguese coastal area, Madeira and Angola, has been determined by energy-dispersive X-ray fluorescence spectrometry (EDXRF). In some species, a selective enhanced accumulation of particular elements was observed, unrelated to sampling location. This was the case with nickel which is accumulated to a considerable extent by Suberites carnosus specimens, and zinc which is accumulated by Hymeniacidon perlevis. Very high levels of bromine were also observed, particularly in sponges with low contents of silicon. As expected, silicon is the dominant element, varying between 1 and 33% (dry weight) of the specimens analysed.