Eutrophication of coastal systems

1. Eutrophication of coastal systems • Our evolving conceptual model of the coastal eutrophication problem; James E.Cloern; 2001 • Submerged aquatic vegetation in relation to different nutrient regimes; Carlos M.Duarte; 1995 • Eutrophication and zoobenthos dynamics; Carlo Heip; 1995

2. Main research question • Phase I • Phase II • Phase III

3. Main research question; How does the anthropogenic nutrient enrichment cause change in the structure or function of nearshore coastal systems.

4. Phase I Model • 1 Signal 1 response • Nutrient loading • more phytoplankton biomass, Primary production, Oxygen concentrations.

5. Phase I Model • Vollenweider-type model

6. Reliability of the model • Limiting nutrients • Sediment traps • Results gathered from temperate latitudes • Weak signal between signal and response

8. Advances beyond Phase I model • Understanding of 1 signal 1 response. • Data gathering (no experiments).

9. Advances beyond Phase I model Responses in the Sediment • Anoxia • Release of phosphate • Inhibition of nitrification

10. Advances beyond Phase I model Responses of fauna • Step wise change from slow growing plants to fast growing algae.

11. Advances beyond Phase I model Responses of fauna • From nutrient limitation to light limitation. • Nutrient availability • Resuspension of the sediment

12. Advances beyond Phase I model Responses of zoo benthos dynamics • Pearson Rosenberg model • Slight increase of biomass. Slight change of species composition • Strong increase of biomass, replacement by opportunistic species • Disappearance of benthic animal species and azoic sediments

13. Advances beyond Phase I model Responses of zoo benthos dynamics • Bioturbation • Nutrient regeneration

14. Advances beyond Phase I model • Importance of more nutrients like P or Si. • Changing redfield ratio • Toxic algal communitities. • Recovery of the ecosystem

16. Advances beyond Phase I model Early responses to enrichment. • Communities changes at species level. • Nutrient cycling. • Change in seasonal timing

17. The Phase II model • The major differences • A more clearer picture of potential responses to nutrient enrichment • Recognition of system attributes acting as a filter for responses to change in nutrient loading • The possibility to reverse some of the direct and indirect responses of increased nutrient loading

18. The Phase II model

19. The Future Problems to solve • Nutrient enrichment is thought as operating as an independent stressor • Limited experimentation and modeling results • Results mostly from highly impacted regions at temperate latitudes

20. A Phase III model

21. A Phase III model • How does the filter work • Tidal currents • Salinity gradients • Horizontal transport processes • Light exposure to submerged plants • Particle filtration by suspension feeders

22. A Phase III model • How does nutrient enrichment interact with other stressors • How are responses to multiple stressors linked • Climatic system • Human manipulation of coastal hydrology • Human translocation of organisms • Interaction between nutrients and toxic contaminants.

23. A Phase III model • How does coastal eutrophication impact the earth systems as a habitat for humanity • Fishery losses • Eating of polluted fish • Methyl bromide or DMS production contributing to ozone depletion and acidification.

24. A Phase III model • What synthetic tools can guide management strategies. • Restore the function of coastal ecosystems • Protection of coastal systems • A model as accurate as possible

25. A Phase III model Things to do • Construction of nutrient budgets • Development of indices to measure sensitivity • Experimentation with representations of coastal systems