Housing crisis: Climate change-induced habitat loss impacts on tropical and temperate fishes

Transcription

1 Housing crisis: Climate change-induced habitat loss impacts on tropical and temperate fishes Nicholas K. Dulvy (an a large cast of important people) Canada Research Chair in Marine Biodiversity and Conservation Co-Chair of IUCN Shark Specialist Group Earth to Ocean Research Group, Simon Fraser University, Vancouver, Canada dulvy@sfu.ca

2 Two contrasting case studies

3 With the common theme of habitat loss

4 Habitat complexity in coral reefs: patterns of degradation and consequences for biodiversity Lorenzo Alvarez Filip Isabelle Côté Andrew Watkinson Jenny Gill

5 Caribbean temperature rise and bleaching Gill, J.A., Watkinson, A.R., McWilliams, J.C. & Côté, I.M. (26) Opposing forces of aerosol cooling and El Niño drive coral bleaching on Caribbean reefs. Proceedings of the National Academy of Sciences, 13,

6 Caribbean coral cover has declined rapidly 6 % live coral cover Gardner, T.A., Côté, I.M., Gill, J.A., Grant, A. & Watkinson, A.R. (23) Long-term region-wide declines in Caribbean corals. Science, 31,

7 Key questions What is happening to the complexity of Caribbean reefs? What is the link between coral cover, complexity and fish community structure? Has there been a change in fish trajectories over time?

8 Measuring rugosity 1 = flat 3 = very complex

9 Data collated Search for average rugosity by reef in: Published papers Monitoring programs Personal communications Data All data with (trend coral of cover decline) and temporal replication (effects of coral loss) records studies 37 2 reef sites 16 2 countries to 24 28

10 Architectural complexity has declined in the Caribbean Annual average rugosity Segmented regression Collapse of Acropora skeletons Loss of bioerosion Bleaching and erosion dead coral Alvarez Filip et al (29) Proc. Roy. Soc. B

11 How are the fish doing in the face of Climate change induced region wide habitat loss?

12 What is the link between reef complexity and fishes 15 reefs (data aggregated) 93 fish species Number of spp Number of individuals Biomass Trophic level 2 35 N 2 25 N 2 15 N 87 6 W W W San Miguel de Cozumel Pa Ch Yu Tu Sf Sr Cd Fr Da Jr Hr Pl Cw Ce Ps Punta Celarain Road Punta Chiqueros 1 Km Size structure(slope & intercept) = useful indicator for fish assemblages as many life history characteristics size in marine fishes and it can be a useful proxy of overall productivity of fish assemblages Hierarchical partitioning were used to identify the effect of different habitat variables on fish assemblages (calculates goodness of fit using all combinations of independent variables in the model)

13 4. Coral Coral identity cover complexity relationship is complex!

14 The identity of dominant coral affects the coral rugosity relationship Major reef building coral Most common coral spp: 3. Montastrea Agaricia Porites rugosity coral cover Short lived and low structure corals

15 Species richness Abundance contribution (%) contribution (%) Biomass Trophic level contribution (%) PCA1 Rock Sand Macroalgae Turf Sponges contribution (%) Intercept Slope * contribution (%) contribution (%) PCA1 Rock Sand Macroalgae Turf Sponges Which components of the fish community are explained by coral cover & complexity? species richness abundance biomass trophic level size spectra * *

16 Size class 1 % of variance explained fishes Size 1-2 class 2 cm Size class 3 % of variance explained % of variance explained 3 Size class Porites Montstrea Agaricia Porites OT Montstrea Agaricia % of variance explained % of variance explained OT Ontogenetic shift in dependence on the most complex structure forming reef Coral cover and complexity is most important for the recruitment of juvenile -1 cm * * 2-3 cm 3-4 cm 4-5 cm Size class 5

17 Small fish (<2cm max attainable size) decline as coral lost in fish <2 cm Coral depletion index Graham et al. 28 PLoS ONE

18 Recent region wide decline in reef fishes Paddack, M.J., Reynolds, J.D., Aguilar, C., Appeldoorn, R.S., Beets, J., Burkett, E.W., Chittaro, P.M., Clarke, K., Esteves, R., Fonseca, A.C. et al. (29) Recent Region-wide Declines in Caribbean Reef Fish Abundance. Current Biology, 19,

19 Summary 8% decline in coral cover Collapse of reef and 85% loss of most complex reefs Montastrea provides the most complex reefs Coral cover and complexity has higher abundance of small size classes of fishes Region wide fish collapse but only recently

20 Species and assemblage responses to climate-induced habitat loss in the North Sea

21 1.6 o C rise in North Sea bottom temperatures over last 25 years North Sea Bottom temperature o C Year

22 Warming in both summer and particularly winter Difference in mean annual temperature between 198s and 199s and 2s Dulvy, N.K., S.I. Rogers, S. Jennings, V. Stelzenmüller, S.R. Dye & H.R. Skjoldal. 28. Climate change and deepening of the North Sea fish assemblage: a biotic indicator of regional warming. Journal of Applied Ecology 45:

23 Spatial variation in winter bottom temperature Cool Period Warm period Warming greatest in shallow SE North Sea

24 Interannual variability in autumn isotherm habitat area

25 Loss of cold habitats: temperature sensitivity of isotherms Spatial extent of thermal habitat (log km 2 ) 1e+6 1e+4 1e+2 1e+ 2 o C isotherm o C 3 o C 4 o C 5 o C 9 o C 7 o C 8 o C Mean winter sea bottom temperature o C

26 Range expansion of southern species bib Range expansion of southern species 342 km Perry, Low, Ellis & Reynolds (25) Climate change and distribution shifts in marine fishes. Science 38,

27 Range contraction of northern fish species haddock 216 km Perry et al. (25) Science

28 Deepening of North Sea fishes megrim anglerfish cod saithe sole bib

29 Most species are deepening Decadal change in depth anomaly (m decade -1 ) Apart from warm-water, species with southern affinities Not all trends are significant low power in single species trends and gazillions of tests pogge scaldfish grey gurnard witch megrim angler hake lemon sole plaice cuckoo ray four-bearded rockling sole lesser weaver bib wolffish solenette cod long rough dab dab haddock whiting ling saithe starry ray lesser spotted dogfish spurdog Norway pout poor cod Deepening Shallowing

30 Gain power relative to noise by aggregating species distribution anomalies by traits Thermal preference & range (warm vs. cold, narrow vs. wide) Biogeograhic origin (S vs. N) Life history (small vs. large) Ecology (abundance & occupancy) Exploited vs. otherwise

31 Most assemblages are deepening all boreal luscitanian S boundary N boundary warm cold cold spec. warm spec. large small less abundant abundant less common widespread target bycatch nontarget except Small-bodied, warm-tolerant, nontarget species with Northern range limit in North Sea Bib scaldfish Mean depth anomaly (m decade -1 ) solenette

32 Rising abundance of small, Lusitanian, southern species scaldfish solenette log number log number yearlist yearlist bib sole log number log biomass yearlist yearlist

33 Assemblage-wide depth response to local & regional climate variability mean depth anomaly (m) of fish community Deeper Shallower st PCA of - Sea Bottom Temperature - Salinity - Atlantic inflow - Gulf Stream Index - North Atlantic Oscillation 2 Dulvy, Rogers, Jennings, Stelzenmüller, Dye & Skjoldal (28). Climate change and deepening of the North Sea fish assemblage: a biotic indicator of regional warming. Journal of Applied Ecology, 45,

34 Deepening of North Sea fishes North Sea bottom temperatures have warmed by 1.6 o C in last quarter century The whole fish assemblage has deepened by 3.6 m decade -1, 22 species have deepened by 5.6 m decade -1 The latitudinal response is heterogeneous due to Northward shift of abundant, widespread thermal specialists & Southward shift of relatively small, abundant southerly species with limited occupancy and a northern range boundary (benefiting from indirect impact of fishing not enough fear!) Depth response more coherent than the latitudinal response

35 Acknowledgements Lorenzo Filip-Alvarez Isabelle Cote Jenny Gill Andrew Watkinson Stephen Dye Vanassa Stelzenmüller Simon Jennings Stuart Rogers Hein Rune Skjoldal Manuel Barange UK Department for Environment Fisheries and Rural Affairs Mexican Council for Science and Technology (CONACYT) Mexican Secretary of Public Education (SEP) scholarship Mexican Commission of Natural Protected Areas (CONANP) and the PNAC