Trade off-based zooplankton feeding strategies in a global model Fi Prowe 1,2 Ken Andersen 2 Andy Visser 2 Thomas Kiørboe 2 Bei Su 1 Markus Pahlow 1 Andreas Oschlies 1 1 GEOMAR Helmholtz Centre for Ocean Research Kiel 2 Centre for Ocean Life, DTU Aqua, Denmark October 14, 2015 DynaTrait Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 1 / 10
Motivation Global zooplankton feeding strategies Low zooplankton diversity in models Ambush observations generic PFT model herbivore TL3 herbivore TL2 Z z p P Oithona sp.: obligate ambusher abundance fraction of total copepods (NMFS-COPEPOD database, Australian Antarctic Data Centre) Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 2 / 10
Motivation Global zooplankton feeding strategies Low zooplankton diversity in models Ambush observations generic PFT model herbivore TL3 herbivore TL2 carnivore Z z p 1 p 2 P 1 P 2 Oithona sp.: obligate ambusher abundance fraction of total copepods (NMFS-COPEPOD database, Australian Antarctic Data Centre) Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 2 / 10
Motivation Global zooplankton feeding strategies Low zooplankton diversity in models Ambush observations generic PFT model herbivore TL3 herbivore TL2 carnivore Z z Prowe p 1 p 2 P 1 P 2 Oithona sp.: obligate ambusher abundance fraction of total copepods (NMFS-COPEPOD database, Australian Antarctic Data Centre) Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 2 / 10
The model Trade-offs Feeding interactions are predator-prey-encounters predator trade-off traits & encounter size motility encounter rate = f (size selectivity, velocity, escape, threshold) prey trade-off nutrient uptake vs. edibility Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 3 / 10
The model Trade-offs Feeding interactions are predator-prey-encounters predator trade-off traits & encounter size motility encounter rate = f (size selectivity, velocity, escape, threshold) prey trade-off nutrient uptake vs. edibility Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 3 / 10
The model Trade-offs Feeding interactions are predator-prey-encounters predator trade-off mortality ambusher cruiser encounter rate (motility) traits & encounter size motility encounter rate = f (size selectivity, velocity, escape, threshold) prey trade-off nutrient uptake vs. edibility Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 3 / 10
The model Trade-offs Feeding interactions are predator-prey-encounters predator trade-off mortality ambusher cruiser encounter rate (motility) traits & encounter size motility encounter rate = f (size selectivity, velocity, escape, threshold) prey trade-off nutrient uptake vs. edibility Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 3 / 10
The model Trade-offs Feeding interactions are predator-prey-encounters predator trade-off mortality ambusher cruiser encounter rate (motility) traits & encounter size motility encounter rate = f (size selectivity, velocity, escape, threshold) prey trade-off encounter rate (predation) non motile nutrient uptake motile nutrient uptake vs. edibility Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 3 / 10
The model Structure & aim Encounter-based feeding interactions are diverse encounter model herbivore TL3 herbivore TL2 A carnivore C coupled to global MITgcm emergent community structure a c idealized e.g. basic nutrient dynamics 1 step more complex m n M N for testing hypotheses n small non-motile M large motile a small ambusher C large cruiser Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 4 / 10
Results 1. Ambusher fraction model predicts ambush biogeography Prowe Prowe Oithona sp.: proxy for A "best" estimate: highest values on top heterogeneous data (# taxa, months, total abundance) Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 5 / 10
Results 1. Ambusher fraction Ambusher fraction in detail model 2 main food chains: n, m c A N, (m) C C never dominates A biomass fraction Oithona abundance fraction m a and m,c A no feeding of C feeding threshold? find observations tune params, sensitivity tests Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 6 / 10
Results 1. Ambusher fraction Ambusher fraction in detail model 2 main food chains: n, m c A N, (m) C C never dominates m a and m,c A no feeding of C feeding threshold? find observations tune params, sensitivity tests Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 6 / 10
Results 1. Ambusher fraction Ambusher fraction in detail model 2 main food chains: n, m c A N, (m) C C never dominates m a and m,c A no feeding of C feeding threshold? find observations tune params, sensitivity tests Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 6 / 10
Results 2. Size structure Phyto size structure: trophic levels (TLs)? 3 TLs observations trophic links matter tuning issue? sensitivity tests challenges many parameters to tune (too) basic nutrient dynamics? rigid interactions? Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 7 / 10
Results 2. Size structure Phyto size structure: trophic levels (TLs)? 3 TLs 2 TLs observations trophic links matter tuning issue? sensitivity tests challenges many parameters to tune (too) basic nutrient dynamics? rigid interactions? Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 7 / 10
Results 2. Size structure Phyto size structure: trophic levels (TLs)? 3 TLs 2 TLs trophic links matter tuning issue? sensitivity tests Fi (GEOMAR & DTU Aqua) 2 TLs observations challenges many parameters to tune (too) basic nutrient dynamics? rigid interactions? Zooplankton feeding strategies October 14, 2015 7 / 10
Outlook Flexible interactions Optimal foraging Bei Su, Dynatrait Non-motile Motile φ c I c φ a Respiration R Biomass I a E c E a Foraging Assimilation Excretion I ingestion φ prey capture coefficient E assimilation R respiration A 0 total activity A foraging activity c f foraging cost Pahlow & Prowe 2010 for multiple prey: non-motile prey high A: active (cruise) motile prey low A: ambush find A that maximizes growth = EI R strategy emerges from prey environment Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 8 / 10
Outlook Flexible interactions Optimal foraging Bei Su, Dynatrait Non-motile Motile φ c I c φ a A Respiration A 0 A c f R Biomass I a E c E a Foraging Assimilation Excretion I ingestion φ prey capture coefficient E assimilation R respiration A 0 total activity A foraging activity c f foraging cost Pahlow & Prowe 2010 for multiple prey: non-motile prey high A: active (cruise) motile prey low A: ambush find A that maximizes growth = EI R strategy emerges from prey environment Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 8 / 10
Outlook Flexible interactions model captures switching Bei Su, Dynatrait Ingestion (d 1 ) Clearance (m 3 gc 1 d 1 ) 2.0 1.5 1.0 0.5 40 30 20 10 0 0 100 200 300 400 Diatom concentration (mg C m 3 ) B A copepod feeding on diatoms only diatoms and ciliates fits lab experiments with 2 prey types (Kiørboe et al. 1996) next steps adapt for several trophic levels fit to mesocosm data couple to global model Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 9 / 10
Summary predator-prey encounter model size, motility feeding strategy trade-off: feeding vs. predation risk PFT model, rigid interactions 1 step more complex observations & assessment Ambusher fraction phyto size structure tune model at 1D locations sensitivity studies robustness for testing hypotheses outlook optimal feeding strategy model fitted to lab experiments fit to mesocosm data implement in global model Fi (GEOMAR & DTU Aqua) Zooplankton feeding strategies October 14, 2015 10 / 10