Distribution of trace elements in benthic infralittoral organisms from the western Antarctic Peninsula reveals no latitudinal gradient of pollution

Abstract

Antarctica is considered one of the most pristine regions on Earth, but evidences of global and local anthropogenic pollution exist. Chromium (Cr), lead (Pb) and mercury (Hg) are bioaccumulated and sometimes biomagnified through the trophic web. We aim to determine whether a latitudinal gradient of these trace elements exists in benthic organisms along the rocky shores of the Antarctic Peninsula and the South Shetland Islands. Levels of Cr, Pb, and Hg were measured by ICP-MS in two macroalgae (Palmaria decipiens and Desmarestia anceps or Desmarestia menziesii), one gastropod (Nacella concinna), two starfishes (Odontaster validus and Diplasterias brucei), and suspended particulate organic matter (SPOM) from five sampling sites ranging in latitude from 62°11'17″S to 67°33'47″S. Levels of trace elements differed among sites and species, but no latitudinal gradient was observed for these pollutants. Levels of Hg and Pb in animals were consistent with biomagnifications along the food web, as were higher is starfish than in limpets. However, macroalgae and SPOM are unlikely to be the main primary producers supporting those consumers, as Hg levels in macroalgae and Pb levels in SPOM were much higher than in animals. The levels of trace elements detected were similar or higher than in other Antarctic places and other regions of the world, thus indicating that the Antarctic Peninsula area is as polluted as the rest of the world.

Figure 1

Study area and location of the sampling sites. The map was created using the Free and Open Source QGIS 3.16 software (http://www.qgis.org/) and the Quantarctica 3.2 project (https://www.npolar.no/quantarctica/).

Figure 2

Concentration of Cr and Hg in the different sites and species studied along the Antarctic Peninsula. (A) Cr, values expressed as μg g-1 of dry weight. The values of Cr for the primary producers were much higher than the animal species, so they were represented separately and scale changed accordingly. (B) Hg, values expressed as ng g^-1 of dry weight. Discontinuous Y-axis was used to facilitate visualization. Central lines show the mean, boxes extend to the 25th and 75th percentile, whiskers extend to 1.5 × IQR, dots and asterisks are outliers. SPOM Suspended Particulate Organic Matter, Ds Desmarestia spp., Pd Palmaria decipiens, Nc Nacella concinna, Db Diplasterias brucei, Ov Odontaster validus. The images of species were drawn by the authors of this article.

Figure 3

Concentration of Pb in the different sites and species studied. The values of Pb for the SPOM were in different magnitude order than the benthic species, so they were represented separately and scale changed accordingly. Values are expressed as μg g⁻¹ of dry weight. Discontinuous Y-axes were used to facilitate visualization. Central lines show the mean, boxes extend to the 25th and 75th percentile, whiskers extend to 1.5 × IQR, dots and asterisks are outliers. SPOM Suspended Particulate Organic Matter, Ds Desmarestia spp., Pd Palmaria decipiens, Nc Nacella concinna, Db Diplasterias brucei, Ov Odontaster validus. The images of species were drawn by the authors of this article.

Figure 4

Principal Component Analysis (PCA) score plots. (A) PC 1 vs. PC 2. (B) PC 1 vs. PC 3. (C) PC 2 vs. PC 3.