Impact of Climate-induced dynamics on a Coastal Benthic Ecosystem from the West Antarctic Peninsula Francesca Pasotti 2015 Impact of Climate-induced dynamics on a Coastal Benthic Ecosystem from the West Antarctic Peninsula By Francesca Pasotti Promotor: Prof. Dr. Ann Vanreusel Academic year 2014-2015 This thesis is submitted in partial fulfillment of the requirements for the degree of Doctor in Science (Marine Sciences) Committee members Reading Committee Prof. Bruno Danis (Marine Biology Laboratory, Université Libre de Bruxelles, Belgium) Prof. Wim Vyverman (Phycology and Aquatic Ecology Laboratory, Ghent University, Belgium) Dr. Marleen De Troch (Marine Biology Laboratory, Ghent University, Belgium) Examination Comittee Dr. Elie Verleyen (Phycology and Aquatic Ecology Laboratory, Ghent University, Belgium) Dr. Ulrike Braeckman (Marine Biology Laboratory, Ghent University, Belgium) Prof. Dr. Tom Moens (Marine Biology Laboratory, Ghent University, Belgium) Prof. Dr. Magda Vincx (Marine Biology Laboratory, Ghent University, Belgium) Prof. Dr. Doris Abele (Dept. of Functional Ecology, Alfred Wegener Institute, Germany) Prof. Wim Vyverman (Phycology and Aquatic Ecology Laboratory, Ghent University Belgium) Dr. Marleen De Troch (Marine Biology Laboratory, Ghent University, Belgium) Prof. Dr. Ann Vanreusel (promoter, Marine Biology Laboratory, Ghent University, Belgium) Prof. Dr. Dominique Adriaens (chairman, Dept. of Evolutionary Morphology of Vertebrates, Ghent University, Belgium) Aknowledgments The last lines I find myself writing are actually the first in importance for my heart. This PhD thesis would have never been possible without many and several causes and conditions (hence, wonderful people) which shaped my life. First of all, I need to thank my parents and family, who gave me this life, nurtured me when I was little and transmitted me those basic human values which made me go through life in a lighter, yet stronger way. Grazie mille, vi amo. Secondly, I want to thank my partner Inge, who has been supporting me in this last 1.5 years of my life, a time period which has been the hardest from all the possible points of view, yet the best ever. She never lost the patience and gentle touch that characterise her and she gave me an amazing sense of stability and care. Thank you, I really appreciate it. Since we are yet at the family level, let me thank my amazing dog Blu, for all the relaxing walks during the hard times of writing, for the tenderness in the harsh “early wake-up” mornings, and for the loyalty that only a non-human being can show to such a “difficult one” like me. Thank you Bluchie, I love you. Of course I can’t forget to thank my mentor, boss and friend Ann. Thank you for the possibility to carry out marine biology research in one of the most amazing ecosystems in the World, the Antarctic. Thank you for never stop believing in me, also when I was ready to quit. Thank you for understanding my nature, and find “alternative ways” to get the best out of me, without braking me down. Thank you. I wish to thank all my colleagues-friends, those in Belgium and those all around the World (the most “famous” Marleen, Rasha, Jan, Renata, AnnaMaria, Annelies, Isolde, Uli, Peter C., Alain, Ricardo, Leonardo, Doris, Gaby, Lili, Dolo, Susi) for their know-how sharing, their patience, availability, humorism and charisma. I have learnt a lot from all of you, I hope we will keep on learning from one another. A special thank you goes to all my friends (Simo, Michy, Tim, Gloria, Laura, Karel, Benny, Ilias, Peter C., Peter A.) for taking care of my moods, sharing my days and listening/sharing to my “nerd chats”. I care for each and everyone of you, very much. Last but not least, I want to thank all the members of the jury, for improving and ameliorating this thesis work by the many interesting and detailed comments I received during the review, I have found them all very stimulating. Thank you for the work. I wanted to keep these aknowledgments short, just because I am more a person of facts than a person of words. I will certainly show to each and everyone of you the appreciation, gratitude and love I feel towards you, wonderful people of my life, who made this work possible just because life and work are simply one thing, they support and stimulate one another through their constant interactions. <°(((<>< So thank you to all of you who know that I am thanking you ><>)))°> Table of Contents Homo immergunt "A lot of people attack the sea, I make love to it." — Jacques Yves Cousteau Sea explorer (1910 – 1997) Table of contents Summary .......................................................................................... i Samenvatting ............................................................................... viii Chapter I. General introduction 1. Prologue: Anthropogenic climate change .............................. 1 2. The Antarctic and climate change .......................................... 4 2.1. The ecosystem ...................................................................... 4 2.1. Recent environmental changes ............................................ 5 2.2. Biological responses to climate change in Antarctic coastal systems ......................................................................................... 9 3. International context ............................................................ 27 4. Thesis background and scientific approach .......................... 29 4.1. West Antarctic coastal ecosystems: a case study............... 29 4.2. Potter Cove, King George Island, West Antarctic Peninsula30 4.3. Trophic structure at the community level: a stable isotope approach ..................................................................................... 37 4.4. Stable isotopes addition to trace carbon fluxes ................. 45 5. Thesis outline ........................................................................ 45 Chapter II. Spatial analysis Abstract ........................................................................................ 49 1. Introduction .............................................................................. 49 2. Material and Methods .......................................................... 51 2.1. Study sites............................................................................ 51 2.2. Environmental variables ...................................................... 52 Table of contents 2.3. Biota .................................................................................... 54 2.4. Statistical analysis ................................................................ 57 3. Results .................................................................................. 59 3.1. Environmental variables ...................................................... 59 3.2. Biota .................................................................................... 61 4. Discussion ............................................................................. 71 4.1. Faro ...................................................................................... 71 4.2. Isla D .................................................................................... 73 4.3. Creek .................................................................................... 75 5. Conclusions ........................................................................... 77 6. Acknowledgments ................................................................ 77 Chapter III. Trophic interactions Abstract ........................................................................................ 79 1. Introduction .......................................................................... 80 2. Material and Methods .......................................................... 82 2.1. Study site ............................................................................. 82 2.2. Sampling and stable isotope analyses ................................. 83 2.3. Data analysis ........................................................................ 87 3. Results .................................................................................. 90 4. Discussion ........................................................................... 100 4.1. Temporal and spatial glacier retreat effects on benthic trophic interactions .................................................................. 100 Table of contents 4.2. General considerations: functional traits in Potter Cove benthic food web ..................................................................... 106 5. Acknowledgments .............................................................. 109 Chapter IV. Temporal analysis Abstract ...................................................................................... 113 1. Introduction ........................................................................ 113 2. Materials and methods ...................................................... 115 2.1. Study site and sampling strategy....................................... 115 2.2. Environmental variables .................................................... 116 2.3. Meiofaunal abundance and biomass ................................ 117 2.4. Statistical analysis .............................................................. 118 3. Results ................................................................................ 120 3.1. Environmental description ................................................ 120 3.2. Grain size ..........................................................................