Different speciation for bromine in brown and red algae, revealed by in vivo X‐ray absorption spectroscopic studies

Members of various algal lineages are known to be strong producers of atmospherically relevant halogen emissions, that is a consequence of their capability to store and metabolize halogens. This study uses a noninvasive, synchrotron‐based technique, X‐ray absorption spectroscopy, for addressing in vivo bromine speciation in the brown algae E ctocarpus siliculosus , A scophyllum nodosum , and F ucus serratus , the red algae G racilaria dura , G . gracilis , C hondrus crispus , O smundea pinnatifida , A sparagopsis armata , P olysiphonia elongata , and C orallina officinalis , the diatom T halassiosira rotula , the dinoflagellate L ingulodinium polyedrum and a natural phytoplankton sample. The results highlight a diversity of fundamentally different bromine storage modes: while most of the stramenopile representatives and the dinoflagellate store mostly bromide, there is evidence for Br incorporated in nonaromatic hydrocarbons in T halassiosira . Red algae operate various organic bromine stores – including a possible precursor (by the haloform reaction) for bromoform in A sparagopsis and aromatically bound Br in P olysiphonia and C orallina . Large fractions of the bromine in the red algae G . dura and C . crispus and the brown alga F . serratus are present as Br − defects in solid KCl , similar to what was reported earlier for L aminaria parts. These results are discussed according to different defensive strategies that are used within algal taxa to cope with biotic or abiotic stresses.