Measuring the impacts of extreme events

Ongoing global change is expected not only to shift the average levels of pCO2, temperature, pH or oxygen by regionally-variable amounts but also to increase the occurrence and intensity of transient extreme events. It has recently been suggested that increased variation, rather than changes in mean values, may represent the greater threat to species survival, stressing the need to experimentally study the effects of environmental variations and especially extreme events on ecosystems and their functions.

On the Israeli coast, desiccation is an important stressor not just for organisms living at the high-shore levels. Although the broad rocky platforms of vermetid reefs are found mostly at low shore levels, during specific climatic conditions, when dry winds blow from land (easterlies), they can be exposed to air (and thus to desiccation) for several days, or in extreme situations even weeks, causing considerable stress to the entire intertidal community. Such prolonged desiccation events (PDE) may alter in strength and frequency under climate change.

 

We have recently shown that two low-shore macroalgal species have very different capacity to recover from desiccation. In a collaborative work with Tel Aviv University we also have climatic evidence that the frequency of weather systems causing PDE (mostly the Red Sea Trough) has doubled over the past 40 yrs, suggesting that extreme desiccation events are increasing on the Levant coast.

Our aim in future studies on this topic is to follow those PEDs more closely and their ecological impacts and recovery potential following PEDs of different durations, as well as their impacts on ecosystem functions.