1. BeforeAfter Eutrophication

2. Eutrophication – nutrient enrichment of waters Major nutrients -phosphorus and nitrogen Consequences -increased plant growth -decreased water quality

3. Eutrophication of lakes, reservoirs and rivers ranks as one of the most widespread environmental problems. Eutrophication can have significant negative ecological, health, social and economic impacts on use of a primary and finite resource, water.

4. Decreased water quality Algal blooms –Decreased transparency –DOC and chlorination disinfection products –Toxic cyanobacteria and dinoflagellate Growth of aquatic plants Anoxia

5. Effects of Eutrophication Source: Issues in Ecology #2 (1998)

6. Laguna de Bay, Philippines

7. US East Coast Source: Issues in Ecology #2 (1998)

8. Fish Kills and Anoxia in the Chesapeake

9. Decreased water quality Elevated nitrate concentrations Species changes Increased incidence of water-related diseases

10. Positive features of eutrophication - increased fish yield - increased plant production and nutrient reuse

11. Indicators of eutrophication Secchi disk transparency Chlorophyll concentration Phosphorus concentrations Nitrogen concentrations

12. Chemical Forms – P PO 4 3- (Phosphate) Organic

13. The cycling of Phosphorus Dissolved InorganicParticulate Organic uptake excretion Runoff upwellingsinking decomposition Balance maintained via weathering of rock

14. Chemical Transformations – P Assimilation PO 4 3- → Organic Phytoplankton or other autotrophs Remineralization Organic → PO 4 3- Heterotrophs Excretion Organic → Dissolved Heterotrophs and Autotrophs

15. Experimental Lakes Area Lake 227

16. Lake 226 C, N, P Eutrophic algal blooms C, N

17. Lake 227

19. Effects of Eutrophication Source: Issues in Ecology #2 (1998)

23. Classification of Lakes Source: Principles Env. Sci. & Eng. (Davis & Masten)

24. Probable, not certain… Eutrophic Source: Principles Env. Sci. & Eng. (Davis & Masten)

25. Total P vs. Chlorophyll a Source: Principles Env. Sci. & Eng. (Davis & Masten)

26. Meybeck, 1982

27. N fixation N 2  reactive N –(e.g. NH 3, NH 4 + ) Mostly biological free- living bacteria (asymbiotic) symbiotic

28. Synthetic fertilizer production is considered N fixation takes N 2, reacts it with natural gas, producing NH 3 and CO 2

29. Agriculture…

30. (Townsend et al. Frontiers Ecol. Environ. 2003)

31. (Tilman et al. Nature, 2002)

32. Percent Increase in Nitrogen Fluxes in Rivers Source: Millennium Ecosystem Assessment

34. Gulf of Mexico Dead Zone Source: NOAA

35. US East Coast Source: Issues in Ecology #2 (1998)

36. Fish Kills and Anoxia in the Chesapeake

37. (Townsend et al. Frontiers Ecol. Environ. 2003)

38. Source: Principles Env. Sci. & Eng. (Davis & Masten)

39. Is N or P limiting? – Assessment Concentration ratios Experimental enrichments Supply and recycling ratios Physiological assays

40. Algal bioassays – addition of known quantities of nutrients to algal suspensions and measurement of physiological or ecological responses

41. Watershed factors which moderate degree of eutrophication – * climate * hydrology * biogeochemistry * land use

42. Climatic Variability … rainfall in Goleta Non-El Niño El Niño

43. Hydrologic Response… Arroyo Burro Creek, WY 2001

44. SBC-LTER Study Region… Santa Clara River, 4200 km 2 Santa Barbara Channel (50) Watersheds ranging from 10-50 km 2 Ventura River, 590 km 2 Los Angeles, CA Multi-source Land Cover Data (2002 v1) California Department of Forestry and Fire Protection

45. Parcel Scale… Residential Site Parcel Scale… Residential Site

46. Parcel Scale… Greenhouse Site Parcel Scale… Greenhouse Site

47. Analysis of Cause and Effect Low Nutrient Supply Low N & P conc. in lake Low algae productivity Low chlorophyll a Lake more transparent Greater Secchi disc depth High Nutrient Supply High N & P conc. in lake High algae productivity High chlorophyll a Lake less transparent Smaller Secchi disc depth Gradient of Conditions Toxic inflow High Sediment High Flowrate

48. Within-lake factors which moderate degree of eutrophication * food web structure * sediment regeneration * basin morphology * hydrodynamics

51. Technically effective control of eutrophication is possible but not always economically feasible

52. Solutions… Source Reduction –Eliminate excess fertilization –Wastewater treatment plants In Lake Control: –Mechanical harvesting of aquatic plants –Chemical control (algaecides) –Biological control (increase grazing) –Flow augmentation –Deep water aeration –Selective removal of deep water –Sediment removal