Expansion of roach populations in the UK & locally

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Windermere Science Project stakeholder meeting presentations.
Elliott on modelling roach expansion

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  • The second reason is historical. The Freshwater Biological Association (or then The Freshwater Biological Association of the British Empire) was founded in 1929, located at Wray Castle from 1931 and, from 1950 onwards, at The Ferry House- both labs on the shores of Windermere.
  • The second reason is historical. The Freshwater Biological Association (or then The Freshwater Biological Association of the British Empire) was founded in 1929, located at Wray Castle from 1931 and, from 1950 onwards, at The Ferry House- both labs on the shores of Windermere.
  • Expansion of roach populations in the UK & locally

    1. 1. Expansion of roach populations in the UK & locally J.A. Elliott, I.J. Winfield, P. Henrys, M. Tanguy, B. James, J. Fletcher, J. Cooper & S.C. Maberly Centre for Ecology & Hydrology, Lancaster & Wallingford
    2. 2. The Roach (Rutilus rutilus) • Fourth most recorded fish species in the UK Database and Atlas of Freshwater Fish (DAFF) • Eurythermal cyprinid (4 to >30 oC) • Preference for warmer temperatures: growth occurs only >12 oC • Omnivorous • Known to have significant impacts on ecosystems
    3. 3. Roach in the UK Red=Roach presence pre-1973 Yellow=Roach presence post-1973 *Data from DAFF Salmonids (e.g. Arctic charr) Cyprinids (e.g. roach)
    4. 4. Windermere: Roach expansion 2n -1 t a e d y -1 ) 50 Gill nets 40 30 20 m 0 1 h s i F ( E U P C 10 0 1995 ‘It is not unlikely that these had been brought as live-bait for pike, as live-baiting is occasionally done by strangers.’ (Watson, 1899) 2000 Year 2005 2010 Pike prey
    5. 5. Roach and temperature
    6. 6. Predicting UK expansion • Aim: To use ecological niche modelling to examine how roach habitat in the UK may change over this century • Method: DAFF data (1973-89) Compare to DAFF data (1990-2006) GLM with binominal response Validate Seasonal air T oC grid means (Met Office)
    7. 7. Creating the model DAFF data (1973-89) Seasonal T oC grid means (Met Office) GLM with binominal response Need a probability threshold Compare to DAFF data (1973-89)??
    8. 8. Probability threshold True positives 0.876 Probability threshold to define a presence value (1) False positives
    9. 9. Compare to observed 1990-2006 DAFF Model Grids tested EncRoach-S* All Changed AUC % Match FPE FNE 0.867 82% 7% 11% 48% 25% 26% *EncRoach-S = Environmental Change & Roach (Seasonal)
    10. 10. Sensitivity to increasing air temperature Air temperature increase (°C) Probability of presence 1 2 3 4
    11. 11. Sensitivity to increasing air temperature Area of UK No. of (total no. grids grids) All UK (2470) 0 Increase in air temperature (oC) 1 2 3 4 Presence 842 1005 1214 1509 1810 % cover Presence 34.1 817 40.7 958 49.1 1083 61.1 1202 73.3 1279 % cover Presence 61.2 25 71.8 47 81.2 93 90.1 153 95.9 211 % cover Scotland Presence (903) % cover 10.7 0 20.2 0 39.9 38 65.7 154 90.6 320 0 0 4.2 17.1 35.4 England (1334) Wales (233)
    12. 12. Next steps & Conclusions • Test the model using UKCIP climate change scenarios • But, if temperature has been restricting Roach habitat range, we could see over this century a rapid increase in the distribution of this ecologically significant fish

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