1. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences TO WHAT EXTENT BIODIVERSITY OF INVERTEBRATES IN INTERMITTENT MED-RIVERS ARE THREATHEND BY CLIMATE CHANGE? Israel as a reference case Avital Gasith, Tel-Aviv University (avitalg@tauex.tau.ac.il)avitalg@tauex.tau.ac.il Photos: Gasith, Shub, Hershkovitz, TAU

2. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences The information on the response of invertebrates in intermittent med- rivers to climate change is limited; it is based on analysis of extreme but episodic events* Present insight is mostly based on environmental and biological background information * e.g., Beche et al, 2006; 2009; Resh et al., 2013

3. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Conclusions There is already evidence for increasing frequency and intensity of extreme climatic events, but so far they are still mostly episodic events; Biological and environmental information suggests that if the rate of GHG emission is restrained as presently expected, there is low likelihood that in the foreseeable future warming up and episodic droughts will have a long-term detrimental impact on invertebrate biodiversity in intermittent med-rivers; However, successive droughts combined with extended heat spells, probably will have detrimental impact on biodiversity;

4. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences supporting arguments (interconnected) Israel as a reference case; evidence exist in other med-climate regions

5. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences a general agreement of warming at an average rate of 0.4–0.8 °C per decade; In most regions of Israel, the amount of rainfall is expected to decrease, though this trend is generally not (yet) statistically significant; Israel Climate Change Information Center The environmental setting in the Eastern Mediterranean

6. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 1. The majority of aquatic invertebrates inhabiting intermittent med-rivers are warm-water eurythermal species

7. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Temperature °C 33 15 22 8 Average (5 sts) maximum (red) and minimum (blue) monthly air temp. in 4 periods: 1951-1965; 1965-1981; 1981-1995; 1996-2010 and for the entire period (bar) Min air temp. Max air temp. In shallow, slowly flowing or standing water (e.g. pools) temperature range can be wider than recorded in air The FW fauna is exposed to warm temperatures

8. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 2. Moreover, the fauna of IR already experienced episodic extreme temperatures in the past

9. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Temperature anomalies (difference from average) for 6 stations over 45 years (1950 – 1994) in Israel A few examples of past extreme temp. (~10 °C higher) for the coastal plain: 22-25.04 1928; up to 43 °C; 9-11.05 1941; up to 45 °C; 29.09-04.10 1943; 42- 44 °C; Multi-annual variability of max. and min. temperatures Ben-Gai et al., 2001

10. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 3. Although present evidence for thermal adaptation is limited, such response to CC should be considered

11. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 4. Intermittent med-river communities are attuned to extreme hydrologic variability associated with seasonal flooding and drying (Gasith & Resh 1999)

12. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Stress and contrasting flow in med-rivers Discharge end of H. Y. Hydrologic Year desiccation stress scouring stress benign conditions WOO

13. Gasith A.: CC & Stream Biodiversity; In memory of Prof. Por and Dr. Ben Eliahu 15.10.15 Fall assemblage Winter assemblage Spring- summer assemblage Fall assemblage Richn., Comp., Dens. Yearly cycle desiccation Scouring flow Seasonal dynamics of community structure in response to sequential contrasting hydrology Fall and winter assemblages consist of invertebrates capable to endure stressful conditions Benign conditions

14. Gasith A.: CC & Stream Biodiversity; In memory of Prof. Por and Dr. Ben Eliahu 15.10.15 Fall assemblage Winter assem. Spring- assemblage Fall assem. Yearly cycle Expected dynamic of Invertebrates assemblages in drought years Richness, Composition, Density Short winter Early and short spring Early & extended summer Summer assemblage Community structure will vary and alternate between wet and dry years Recovery of density and organiztion may take several years (e.g. Beche et al.,2009)

15. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 5. As in the case of temperature, the aquatic fauna of intermittent med-rivers already experienced severe but episodic extreme droughts in the past

16. Average annual rainfall (mm) Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Ninety year rainfall records over Israel (15 sts); (15 year running average in black) drought years 70-80 years ago

17. Anax imperator (photo: A. Gasith) Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences 6.The majority of the invertebrates in intermittent med-rivers are aquatic insects (>90%) which are highly resistant and resilient to hydrologic changes due to a high dispersal capacity They are capable of timely escaping extreme conditions and rapidly recolonize (richness wise) once conditions improve Some (mostly non-insects) avoid desiccation stress using dormant stage strategy

18. Raba (Gasith 4.1.14) Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences HOWEVER, insects life cycle - behavioral adaptation requires presence of wet refuges, in or out of the stream

19. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences...... but if restraining GHG emissions fails?

20. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences A detrimental impact of CC on stream biodiversity would probably be via a change from episodic extreme events to consecutive ones

21. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Natural range rainy winters dry winters Altered range Highest disch. Lowest disch. Disch. consecutive drought years Consecutive droughts - a game changer Wet years provide window of opportunity for recovery No WOO. to recover The competition for water intensifies

22. Average annual rainfall (mm) Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Increased frequency of dry years over wet ones in the last two decades may be a sign for future hydrology phase shift dry years> wet years 12 7

23. Standard precipitation index* Givati, A. (Hydr. Ser. Israel) Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences *The probability of observed precipitation is transformed into and index Simulated and expected droughts in Israel (based on several climate models for different time periods) droughts magnitude, intensity and duration are expected to increase in the future

24. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Moreover, altered precipitation regime will also eliminate refuges thereby accelerate modification of IR biodiversity

25. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences W S SR abc R S SR abc Summing up: Potential impact on fluvial ecosystems PerennialEphemeral abcd W W S SR SR Intermittent

26. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences W S SR abc W S SR SR abcd R S SR abc Expected hydrologic modification and relative strength of ecological impact Perennial Intermittent Ephemeral direction of of change Strength of ecological impact loss of fish; gastropods; crustaceans....

27. Saada stream, Gasith 10.5.08 Disappearance of a perennial stream after 7 consecutive dry years Saada stream, Gasith 25.4.10 Thank you for your attention Saada stream, Gasith 10.5.08 A reminder Anthropogenic degradation of streams is not a prediction, it is still the reality of many streams

29. Intermittent stream invertebrates biodiversity and CC in med-regions; A. Gasith, SFS, Sacramento Ca, May 2016 Zoology, Faculty of Life Sciences Photos: Gasith, Shub, Hershkovitz, TAU “IR invertebrates will not be easily scared off their home, unless.......”