Seminar Details

Life on the edge: Ecological impacts of climate change and bioinvasions on Levant reefs

Date

28/12/2017

Lecturers

Dr. Gil Rilov - National Institute of Oceanography, Israel Oceanographic and Limnological Research

Abstract

Climate change and bioinvasions are two major drivers of change of marine benthic biodiversity, but understanding if and how this change is manifested in shifts in community traits and ecosystem functions is required. We tested these impacts on eastern Mediterranean reefs, a bioinvasion hotspot and where coastal water temperatures have warmed by around 3 oC in the last three decades. In the field, we have compared three shallow subtidal benthic community types: (1) native brown-algae, Cystoseira, meadows, (2) turf barrens overgrazed by invasive herbivores fish, and (3) areas covered by an alien, calcifying, red algae “shrub”, to test if the habitat and metabolic functions presumably lost in turf barrens (now dominating the reefs) are, at least partially, regained in the expanding alien-macroalgae covered areas. We found that while overall richness was similar in the native and invasive communities, and biomass was partially regained by the alien algae, the community has shifted from overall autotrophic to overall heterotrophic. In long-term mesocosm experiments, we found that under warming and acidification conditions, the Cystoseira community itself becomes more heterotrophic, and more dominated by alien species, although this change was not evident from regular biodiversity indices (e.g. richness). These dramatic alterations in traits and functions mean that the reefs are going through a regime shift to a novel ecological state that will intensify in the future. An increase over the past 40 years in the frequency of synoptic systems that cause prolonged desiccations events in the Middle East rocky intertidal pose an increasing threat to the biological integrity of the unique vermetid reef ecosystem. Using modern mapping and modeling tools we started testing the impacts of this events and link them to community and habitat structure.

To Seminar List
Top