Influence of marine vertebrates on organic matter and trace element levels in Antarctic soils

The presence of marine vertebrates in reproductive colonies contributes to the input of organic matter into the local environment and it is believed that trace elements are subsequently remobilized from the excreta of these animals. In this study, we investigate the influence of marine vertebrates on trace elements levels (As, Cd, Co, Cu, Fe, Li, Lu, Mg, Mn, Ni, Pb, Sb, Sc, Se, Sm, Sn, Sr, Tb, U and Zn) and soil organic matter (SOM) content from five locations with and without marine vertebrate influence in Admiralty Bay, King George Island, South Shetland Islands. Soils were acid digested using microwave, elements were quantified using inductively coupled plasma mass spectrometry and SOM was calculated by loss-on-ignition. The non-influenced and vertebrate-influenced soils had similar concentrations of most of trace elements assessed, however we observed a significant increase in SOM that was positively correlated with the concentrations of As, Cd, Se, Sr and Zn. Although marine vertebrates do not appear to significantly influence trace element concentrations in the soils examined here, this conclusion is based on a limited overall sample size and there is evident input of organic matter linked with increased concentrations of elements correlated with SOM, indicating a possible ornithogenic influence. Contrasting our results with other studies, we conclude that soil elemental levels are an interplay between local geology, vertebrate diet and colony size. Further studies with increased sample size are required to obtain a better understanding of marine vertebrate influence on trace element levels in Antarctic soils.