1 Scientific RepoRts | 6:27234 | DOI: 10.1038/srep27234 www.nature.com/scientificreports Glacial melting: an overlooked threat to Antarctic krill Verónica Fuentes 1 , Gastón Alurralde 2,3 , Bettina Meyer 4,5 , Gastón e. Aguirre 4 , Antonio Canepa 6 , Anne-Cathrin Wöll 7 , H. Christian Hass 7 , Gabriela N. Williams 2,8 & Irene R. schloss 2,9,10 strandings of marine animals are relatively common in marine systems. However, the underlying mechanisms are poorly understood. We observed mass strandings of krill in Antarctica that appeared to be linked to the presence of glacial meltwater. Climate-induced glacial meltwater leads to an increased occurrence of suspended particles in the sea, which is known to afect the physiology of aquatic organisms. Here, we study the efect of suspended inorganic particles on krill in relation to krill mortality events observed in Potter Cove, Antarctica, between 2003 and 2012. The experimental results showed that large quantities of lithogenic particles afected krill feeding, absorption capacity and performance after only 24 h of exposure. Negative efects were related to both the threshold concentrations and the size of the suspended particles. Analysis of the stomach contents of stranded krill showed large quantities of large particles ( > 10 6 μm 3 ), which were most likely mobilized by glacial meltwater. ongoing climate-induced glacial melting may impact the coastal ecosystems of Antarctica that rely on krill. In the summer of 2002, a massive stranding event of the tunicate Salpa thompsoni, and the euphausiid Euphausia superba (hereafter referred to as ‘krill’), which are key components of the Southern Ocean ecosystem, was observed in front of the Argentinean Antarctic Station Carlini (formerly known as Jubany Station) along the shore of Potter Cove (King George Island/25 de Mayo Island, South Shetland Islands, Fig. 1a) 1 . We suspected that high concentrations of suspended particulate material, primarily of glacial origin, may have been associated with this stranding event. Since that event, the beaches of Potter Cove have been surveyed, and repeated stranding events have been recorded (Table 1). Potter Cove is surrounded by the Fourcade Glacier to the North and the East. A detailed description of the area has been published 2 . he glacier has been receding at an increasing rate (up to 1 km since the 1950s 3 ), a trend that has also been observed for other glaciers on King George Island 4 . Glacial retreat causes the massive discharge of sediment-laden meltwater. his discharge was observed in Potter Cove during the summer for more than 20 years 2 . Sediment-laden surface water plumes, called “brown waters”, originate from meltwater creeks as well as from the glacier itself (Fig. 1b). hey are a common feature in the area 5,6 , and the transport of sediments to the sea is a natural process in coastal areas, which occurs each spring. In Maxwell Bay, sediment mass accumulation rates of up to 0.66 g cm -2 yr -1 have been documented during the last 100 years 7 . Due to the present warming, dramatic increases in glacial melting have resulted in a rising particle discharge via surface and sub-surface drainage. his particle discharge is recognized as a threat to coastal ecosystems 8,9 . Large quantities of suspended particles afect the growth and survival of benthic ilter feeders 10,11 by clogging their iltration systems 8 . In copepods, inorganic particles afect feeding eiciency, carbon turnover and egg pro- duction 12 as well as mortality rates 13 . Deleterious efects such as reduced foraging, growth and changes in physio- logical condition have also been observed in ish 14 . 1 instituto de ciencias del Mar (cSic), Barcelona, Spain. 2 Consejo Nacional de Investigaciones Cientíicas y Técnicas (CONICET), Argentina. 3 Instituto de Diversidad y Ecología Animal (IDEA), CONICET-UNC y Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina. 4 Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany. 5 Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany. 6 School of Marine Sciences, Pontiicia Universidad Católica de Valparaíso, Valparaíso, Chile. 7 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Wadden Sea Research Station, List, Germany. 8 Centro para el Estudio de Sistemas Marinos, Puerto Madryn, Chubut, Argentina. 9 Instituto Antártico Argentino, Buenos Aires, Argentina. 10 institut des sciences de la mer de Rimouski, Rimouski, Quebec, Canada. Correspondence and requests for materials should be addressed to I.R.S. (email: ischloss@dna.gov.ar or ireschloss@gmail.com) Received: 11 December 2015 Accepted: 13 May 2016 Published: 02 June 2016 opeN