1. Exploring the effects of plastic ingestion on the energy budget
Effects of plastic ingestion on the life cycle of an endangered sea turtle
Exploring the effects of plastic ingestion on the energy budget
Nina Marn, Marko Jusup, Tarzan Legović, ‘Bas’ Kooijman, Tin Klanjšček
Ruđer Bošković Institute, Zagreb, Croatia
Tromsø, 01st June 2017

2. Motivation yearly production of plastic: 230 mil.tons
yearly consumption: 100kg/capita – > 140kg/c (2015)
growth in plastic production
source: P. Kershaw, S. Katsuhiko, S. Lee, J. Samseth, D. Woodring. UNEP year book 2011,
Maarten Vanden Eynde

3. Motivation 100 milions tons of plastics in the ocean
around 80% marine debris is plastic

4. almost 300 marine species affected
Motivation ?
almost 300 marine species affected

5. Loggerhead sea turtles
long lived, migratory
hard to study; vulnerable to environmental and anthropogenic pressures
endangered

6. Loggerhead sea turtles
long lived, migratory
hard to study; vulnerable to environmental and anthropogenic pressures
endangered

7. Loggerhead sea turtles
long lived, migratory
hard to study; vulnerable to environmental and anthropogenic pressures
endangered

8. Dynamic Energy Budget (DEB) theory
Making best use of existing data
knowledge about the species (data)
knowledge about processes (theory)
pars estimat.
Parameter estimates
Model predictions
Marn et al., (2017) Mar. Environ. Res.

9. Plastic ingestion Synthesizing units (SUs)  Assimilation units (AUs)
Kooijman (1998), Biophys. Chem.

10. Plastic ingestion Synthesizing units (SUs)  Assimilation units (AUs)
Busy or free

12. Plastic ingestion Synthesizing units (SUs)  Assimilation units (AUs)
Busy or free

14. Plastic ingestion

15. Plastic lowers the scaled functional response
Plastic ingestion
Plastic lowers the scaled functional response

16. Plastic dilutes the food

17. More plastic, or plastic staying longer
f =0.81
f =0.81
f =0.75
f =0.61
f =0.61
f =0.75

18. Same pattern as lower food availability
slower maturation and lower reproduction quantified
slower growth and smaller size of adults quantified

19. How much plastic? Depends on the amount and residence time
at 14 % reproduction not likely

20. How much plastic? Depends on the amount and residence time
at 14 % reproduction not likely
Longer residence time = more plastic
at 3 % puberty not reached

21. Conclusions mechanistic models plastic waste
lower food availability could lead to population decline
both residence time and amount of plastics in the gut need to be taken into account
education and better waste management necessary
Hawaii photo by: Rick Loomis

22. Thank you! Questions?