Presentation is loading. Please wait.

Presentation is loading. Please wait.

Topological constraints on the dynamics of wasp-waist ecosystems Ferenc JORDÁN Institute of Ecology and Botany, Hungarian Academy of Sciences, Vácrátót,

Similar presentations


Presentation on theme: "Topological constraints on the dynamics of wasp-waist ecosystems Ferenc JORDÁN Institute of Ecology and Botany, Hungarian Academy of Sciences, Vácrátót,"— Presentation transcript:

1 Topological constraints on the dynamics of wasp-waist ecosystems Ferenc JORDÁN Institute of Ecology and Botany, Hungarian Academy of Sciences, Vácrátót, and Collegium Budapest, Institute for Advanced Study, Budapest, Hungary; Varna, 14 June 2005 UNESCO Regime shifts workshop

2

3 Wasp-waist architecture (simplified)

4 B H

5 BC D E F G H I J Jordán, F., Liu, W.C. and Wyatt, T. Topological constraints on the dynamics of wasp-waist ecosystems. Journal of Marine Systems, in press. A Model food websN = 10 L = 12 equal complexity

6 BC D E F G H I J A Wasp-waist species: D > 3 D in = 0 D out = 0

7 BC D E F G H I J A Wasp-waist species: D > 3 D in = 0 D out = 0

8 G G5 G5 on G1, G3, G4, G7 and G8: direct plus indirect G5 on G2, G9 and G10: only indirect G5 on G5: self-regulatory effect G5 on G6: effect on another wasp-waist G4 G3G1G2 G6 G7G8G9 G10

9 SardineAnchovy Shared predators Apparent competition

10 SardineAnchovy Shared prey Exploitative competition

11 Marine mammals SardineAnchovy Trophic cascade

12 SardineAnchovy Horse mackerel Shared prey Keystone predation

13 Marine mammals SardineAnchovy Horse mackerel Shared predators Shared prey Peruvian upwelling Rich interaction structure: network context, multispecies management Jarre-Teichmann A. (1998). The potential role of mass balance models for the management of upwelling ecosystems. Ecological Applications 8, S93-S103.

14 Topological importance index: TI TI i;j =  k n (  k;j /  l m  k;l ) (  i;k /  k n  i;k ) Jordán F., Liu W-C, and Wyatt T. Topological constraints on the dynamics of wasp-waist ecosystems. Journal of Marine Systems, in press. D C P CD = 1/D C

15 A A D BB CC P BA * P CB + P DA * P CD = P CA P CD P DA P CB P BA P CB P BA P BA * P CB = P CA additive multiplicative

16 ,080,04 0,080,220,280,08 0,04 20,080,050,030,080,130,370,08 0,05 30,090,030,060,090,310,190,09 0,03 40,080,04 0,080,220,280,08 0,04 50,090,030,060,090,240,260,09 0,03 60,080,050,030,080,180,320,08 0,05 70,080,04 0,080,220,280,08 0,04 80,080,04 0,080,220,280,08 0,04 90,080,050,030,080,130,370,08 0,05 100,080,050,030,080,130,370,08 0,05 0,830,420,410,832,032,970,83 0,42 The interaction matrix of web G for n = 8. G

17

18 Relative strength of effects spreading out from G5

19 Relative strength of effects reaching G5

20 The effect spectrum of web G for n = 1, 3 and 8.

21 Regime shifts: topological constraints on the sardine-anchovy interaction G

22 F

23 Indirect vs mixed control regimes Purely indirect is stronger in many cases than mixed (direct plus indirect)

24 Self-regulation Self-regulatory feedback loops are extremely strong for wasp-waist species

25 Overfishing In fished down food webs the probability of mixed interction is reduced, while positive feedback increases leading to alternating states Both – and + loops Only + loops -

26 Invasion Regime shift: jellyfish invades into a second wasp-waist position and replaces anchovy – topology predicts high invadibility Shiganova T. A. (1998). Invasion of the Black Sea by the ctenophore Mnemiopsis leidyi and recent changes in pelagic community structure. Fisheries Oceanography 7,

27 Top-down, K TD Striped bass, #33 Indirect one-step, TI 1 also in the KPP-1 k=3 set Bay anchovy, #22 TI i;j =  k n (  k;j /  l m  k;l ) (  i;k /  k n  i;k ) Chesapeake Bay –important fishes?

28 Conclusions: System topology (architecture) constraints dynamics Certain behaviours are more probable (canalised trajectory) Regime shifts caused biotically are more expected in wasp-waist ecosystems Overfishing increases this effect Vulnerable if invader enters the wasp- waist

29 Acknowledgements : Tim Wyatt CSIC Instituto de Investigaciones Marinas, Vigo, Spain Wei-chung Liu Department of Tropical Veterinary Medicine, University of Edinburgh, UK Vera Vasas and Zsófi Benedek Eötvös University, Budapest The Branco Weiss Fellowship, Society in Science, ETH Zürich The Organisers for the invitation


Download ppt "Topological constraints on the dynamics of wasp-waist ecosystems Ferenc JORDÁN Institute of Ecology and Botany, Hungarian Academy of Sciences, Vácrátót,"

Similar presentations


Ads by Google