Benthic trophic interactions in an Antarctic shallow water ecosystem affected by recent glacier retreat

FRANCESCA PASOTTI; LEONARDO ARIEL SARAVIA; MARLEEN DE TROCH; MARIA SOLEDAD TARANTELLI; RICARDO SAHADE; ANN VANREUSEL

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2015

1932-6203

AbstractThe western Antarctic Peninsula is experiencing strong environmental changes as a consequenceof ongoing regional warming. Glaciers in the area are retreating rapidly andincreased sediment-laden meltwater runoff threatens the benthic biodiversity at shallowdepths. We identified three sites with a distinct glacier-retreat related history and differentlevels of glacial influence in the inner part of Potter Cove (King George Island, South ShetlandIslands), a fjord-like embayment impacted since the 1950s by a tidewater glacierretreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13Cand δ15N stable isotope analysis) at the three sites to investigate possible glacier retreatrelatedinfluences on benthic trophic interactions. The isotopic niches were locally shapedby the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopicniche widths were found at the site that has become ice-free most recently, and narrowerniches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance(e.g. via ice-growler scouring) species with different strategies could settle. The siteat the earliest stage of post-retreat development was characterized by an assemblage withlower trophic redundancy. Generally, the isotopic niche widths increased with increasingsize spectra of organisms within the community, excepting the youngest assemblage,where the pioneer colonizer meiofauna size class displayed the highest isotopic nichewidth. Meiofauna at all sites generally occupied positions in the isotopic space that suggesteda detrital-pool food source and/or the presence of predatory taxa. In general icescour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulatingtrophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) overtime driving the benthic assemblages into a more compact trophic structure with increasedconnectedness and resource recycling.