Water chemistry and pigment composition of 13 lakes and ponds in Maritime Antarctica

. Abstract: The Antarctic Peninsula has been rapidly warming, resulting in changes to the abundance and surface cover of terrestrial aquatic ecosystems, as well as their ecosystem structure and function. Therefore, comparative studies of aquatic ecosystems across large latitudinal gradients can be useful in better understanding these changes and making more reliable predictions regarding the consequences of climate change. During Turkish Antarctic Expeditions in 2018 and 2019, samples were collected from 10 lakes and 3 ponds across Maritime Antarctica (north-western coasts of the Antarctic Peninsula). These lakes and ponds were located on Ardley, Robert, Livingstone, Galindez, and Horseshoe islands, covering a latitudinal gradient of over 800 km. Snapshot samplings were conducted of the water chemistry, including nutrient, major ion, and trace metal concentrations, as well as pigment compositions representing the primary productivity and plankton community composition. These lakes and ponds had large variations in nutrient concentrations (0.8–771 µg/L PO 4 and 30–886 µg/L total dissolved inorganic N) and conductivity (30–735 µS), representing a trophic status ranging from ultra-oligotrophic to a few eutrophic sites (for example a pond near penguin colonies). The total productivity, measured as the chlorophyll-a (Chl-a) level, was generally low (0.02–3.2 µg/L) in the lakes, reflecting their oligotrophic characteristics. However, the composition of pigments in the water column showed significant variation across the lakes. Both the patterns in the total Chl-a concentrations and pigment compositions reflected the patterns in conductivity and nutrient gradients across the lakes. Overall, the observed patterns suggested a predominant role of nutrient transport from the sea in driving the chemical composition and primary productivity of Antarctic lakes, mediated by the distance to the sea, as well as the activities of seals and penguin colonies.