Iris Preiss1,2, Gil Rilov1,2, Ilana Berman-Frank1
1University of Haifa, Israel - 2National Institute of Oceanography, Israel
Climate change, and bioinvasions are major drivers of ecosystem change. The Israeli Mediterranean Sea is a hotspot of both drivers that totally transform the coastal reef biodiversity including increasing loss of native species, and establishment of hundreds of thermophilic invasive populations. Over the last 3 years, the invasive Indo-Pacific urchin, Diadema setosum, has become abundant along the coast. Our study aimed to assess the distribution of D. setosum, define its thermal tolerance to increasing seawater temperatures, and assess its potential ecological impacts through grazing. Coastal surveys revealed highly clustered populations with hundreds of individuals in some locations but absence in others. Thermal performance curve (TPC) experiments under a wide temperature range (16-36°C), assessed respiration rates (proxy for metabolic rates), food assimilation rates (feeding) and Gonad-Somatic Index (GSI), and gonad histology (reproduction potential) revealed that performance increased from 16°C to peak at 28-30°C above which we observed some decline but mortality occurred only at 36°C. TPC models indicate a Topt for metabolic rates at 27°C, feeding at 21°C, and reproduction potential at 23°C. Gonad histology revealed similar patterns. The ecological impact of the urchin was assessed in field and lab experiments. Grazing rates on turf-covered boulders in and outdoor mesocosm system under ambient and +3°C and at two densities showed that boulders were grazed to bare rock within one month with not much difference among treatments. A field caging experiment showed similar results. These findings indicate that the while this urchin is suffering mass mortalities in its native distributional range, as an invader in the Mediterranean it is resilient to current and future climate warming and has the potential for severely impacting the Mediterranean coastal reef communities.
Biography
Iris Preiss is a PhD candidate, at the IOLR and the University of Haifa, Israel. Following a B.Sc. at Life Sciences, and a M.Sc. in Marine Ecology, both of the Tel Aviv University, Israel, Iris was enthusiastic to explore the next quest. Her concerns to climate change, combined with her endless curiosity to the marine environment have led her to the lab of Prof. Gil Rilov. Under the FutureMARES project Iris researched the invasion of the sea urchin, Diadema setosum, to the rocky reefs.