Soil features in rookeries of Antarctic penguins reveal sea to land biotransport of chemical pollutants

Abstract

The main soil physical-chemical features, the concentrations of a set of pollutants, and the soil microbiota linked to penguin rookeries have been studied in 10 selected sites located at the South Shetland Islands and the Antarctic Peninsula (Maritime Antarctica). This study aims to test the hypothesis that biotransport by penguins increases the concentration of pollutants, especially heavy metals, in Antarctic soils, and alters its microbiota. Our results show that penguins do transport certain chemical elements and thus cause accumulation in land areas through their excreta. Overall, a higher penguin activity is associated with higher organic carbon content and with higher concentrations of certain pollutants in soils, especially cadmium, cooper and arsenic, as well as zinc and selenium. In contrast, in soils that are less affected by penguins’ faecal depositions, the concentrations of elements of geochemical origin, such as iron and cobalt, increase their relative weighted contribution, whereas the above-mentioned pollutants maintain very low levels. The concentrations of pollutants are far higher in those penguin rookeries that are more exposed to ship traffic. In addition, the soil microbiota of penguin-influenced soils was studied by molecular methods. Heavily penguin-affected soils have a massive presence of enteric bacteria, whose relative dominance can be taken as an indicator of penguin influence. Faecal bacteria are present in addition to typical soil taxa, the former becoming dominant in the microbiota of penguin-affected soils, whereas typical soil bacteria, such as Actinomycetales, co-dominate the microbiota of less affected soils. Results indicate that the continuous supply by penguin faeces, and not the selectivity by increased pollutant concentrations is the main factor shaping the soil bacterial community. Overall, massive penguin influence results in increased concentrations of certain pollutants and in a strong change in taxa dominance in the soil bacterial community.

Direct and Indirect Effects of Penguin Feces on Microbiomes in Antarctic Ornithogenic Soils

“…Soil microbiomes are sensitive indicators of global change and integral part of biogeochemistry ( Oyugi et al, 2006 ; Varin et al, 2012 ; Santamans et al, 2017 ), particularly the biogeochemistry of carbon and nitrogen ( Kevin et al, 2014 ). The microbiome structure supporting its functions seems to be associated with an array of environmental factors in Antarctica, in a habit-specific manner.…”

“…Some known factors include soil surface vegetation ( Teixeira et al, 2010 ), organic carbon (OrC) ( Tytgat et al, 2016 ), moisture ( Lavian et al, 2001 ), and phosphorus ( Chong et al, 2009 ; Roesch et al, 2012 ; Kim et al, 2014 ). Moreover, animal (penguins) activities, such as trampling and feces, have also been recognized to have a significant impact on soil microbial communities ( Wang et al, 2015 ; Santamans et al, 2017 ). Animal feces could improve soil phosphorus ( Zhu et al, 2014 ), organic matter, nitrogen (e.g., NO 3 - -N, and NO 2 - -N) ( Legrand et al, 1998 ; Barrett et al, 2006 ; Aislabie et al, 2008 ).…”

Limnology and Aquatic Microbial Ecology of Byers Peninsula: A Main Freshwater Biodiversity Hotspot in Maritime Antarctica

“…In general, the site shows a smooth topography where only a few formations of volcanic origin, such as Chester Cone (188 m) and Cerro Negro (143 m), stand out ( Figure 2). Soils with an ornithogenic character, particularly in the coastal region, are also typical in the site [24,25], with a penguin occupation that started approximately 1000 years ago [26]. Photographs of some representative lakes from Byers Peninsula: (a) Lake Limnopolar; (b) Lake Cerro Negro; (c) Lake Somero; (d) Lake Refugio; (e) Lake Turbio; (f) Chester Cone Lake.…”

“…Some members of the bacterial phylum Chloroflexi have otherwise a major role in the eutrophic and impacted coastal lakes [33], particularly in the coastal eutrophic waters (Figure 4). Certain members of this phylum are important in the microbial assemblages of sites impacted by guano inputs, both in lacustrine sediments and soils, respectively [25,50]. Other taxa incidentally present in the bacterioplankton assemblages, particularly in coastal lagoons, are orders such as Clostridiales and Bacillales (Figure 4), which are also common in soils from the site affected by penguin depositions [25], mostly linked to fecal drops from marine animals.…”

“…Certain members of this phylum are important in the microbial assemblages of sites impacted by guano inputs, both in lacustrine sediments and soils, respectively [25,50]. Other taxa incidentally present in the bacterioplankton assemblages, particularly in coastal lagoons, are orders such as Clostridiales and Bacillales (Figure 4), which are also common in soils from the site affected by penguin depositions [25], mostly linked to fecal drops from marine animals. Even in the inland lakes, although they show a lower relevance, allochthonous bacterial taxa originating from the fecal drops of skuas and terns occur [33,51].…”