Summarizing 16 years of Levant rocky shore ecological monitoring and experiments: trends, surprises and lessons learnedInvasion Ecology

Gil Rilov^1,2

¹National Institute of Oceanography, Israel Oceanographic & Limnological Research (IOLR), Israel - ²University of Haifa, Israel

Rocky shore ecosystems are fast changing in increasingly growing coastal hotspots due to global stressors like climate change and bioinvasions. One of those hotspots in the southeast Mediterranean Sea, which is rapidly warming and experiences high rates of invasions due to its proximity to the Suez Canal. It also hosts the unique and threatened biogenic ecosystem - vermetid reefs. Since 2009, a seasonal monitoring program at several sites along the Israeli coast, and a series of lab and field experiments revealed interesting ecological patterns and alarming news regarding the fate of its native biodiversity. We have witnessed (1) very strong seasonality with the highest diversity in the cold seasons, suggesting that summer is already too warm for many species, (2) occasional widespread algal beaching and mortality of algae and invertebrates due to prolonged desiccation events that are becoming more frequent, (3) the total collapse and comeback of one of the most dominant invaders, the mussel Brachidontes pharaonis, and (4) the arrival and proliferation of new invaders. We have also tested the thermal tolerance of several native and invasive species, and have demonstrated (5) the high vulnerability of some important natives and the high resilience of tropical invaders to future warming. We have also experimentally showed (6) that future sea level rise will drown the vermetid reefs and completely shift coastal biodiversity and ecosystem functioning. Together, these findings suggest that this coast is and will continue to go through profound ecological transformations that challenge traditional ways of conservation and may require the adaptation to the alien environment.