Antarctic ascidians under increasing sedimentation: physiological thresholds and ecosystem hysteresis

TORRE, L.; ALURRALDE, G.; LAGGER, C.; ABELE, D.; SCHLOSS, I.R.; SAHADE, R.

MARINE ENVIRONMENTAL RESEARCH

ELSEVIER SCI LTD

Año: 2021

0141-1136

Glacier melting sediment inputs affect coastal ecosystems on the Antarctic Peninsula. In Potter 43 Cove  (South  Shetland  Islands,  Antarctica),  the  shift  from  an  ?ascidian  dominated?  to  a  ?mixed? 44 assemblage  has  been  linked  to  sedimentation.  However,  in  recently  described  newly  ice-free  areas 45 ascidians  became  dominant  in  spite  of  total  suspended  particulate  matter  (TSPM)  concentrations, 46 which  are  the  highest  measured  in  Potter  Cove.  Here,  we  compared  the  gut  content  and  energy 47 reserve of three ascidian species at three stations under different TSPM regimes. All analyzed species 48 had  a  higher  gut  content  with  lower  %OM  at  these  newly  areas.  A  theoretical  relationship  between 49 the  scope  for  growth  for  the  targeted  ascidians  and  TSPM  explained  assemblages´  recorded  change 50 but failed to explain current ascidians distribution. The results may indicate the existence of a TSPM 51 threshold that allows the spatial coexistence of alternative stable states at benthic Potter Cove system.