Eutrophication 1 Definition and History Alice Newton University of Algarve

Research Projects  LOICZ (Land-Ocean Interaction in the Coastal Zone)  IMBER (Integrated Marine Biochemistry and Ecosystem Research)  GEOHAB (Global Ecology and Oceanography of Harmful Algal Blooms)  National Estuarine Assessment, NOAA (USA)  EU projects  National INAG/IMAR: Identification of Sensitive Areas and Vulnerable Zones in Four Portuguese Estuaries  Regional MARE (Marine Research on Eutrophication) Programme (funded by the Swedish Foundation for Strategic Research)  European OAERRE

Links Agriculture Fertilizer use Domestic Animal Wastes Atmospheric pollution Photochemical smog Acid Rain Acid Rain Greenhouse effect Water quality impairment impairment OxygenBODHypoxia PhytoplanktonHAB Macrophytes Biodiversity Eutrophication Aquaculture Tourism Fisheries Biogeochemicalcycles

Links to Other Topics  Agriculture Fertilizer use Input of N & P > outputs from crops  Domestic Animal Wastes manure production>>use XS N &P reaches aquatic ecosystem XS N also volatilized  Water quality impairment  Atmospheric pollution  Photochemical smog (Nitric Oxide, NO)  Acid Rain (Nitric Acid)  Greenhouse effect (Nitrous Oxide, N 2 O)  Soil and Erosion  Nitrates leach Ca, Mg & K from soil  Biodiversity

 Biogeochemical cycles: N, P and C. Redfield ratio. Si  Oxygen in the marine environment, Primary Production, Respiration, BOD, Hypoxia  Phytoplankton and harmful algal blooms (HAB) ioc.unesco.org/hab/

Defining Eutrophication

Some etymology…  Eu: Greek prefix “good” and “well”  Troph: Greek “nourishment” “nutrition” “feeding”  Eutrophic: Positive connotation  Eutrophication: Negative connotation

Definition  Eutrophication: nutrient enrichment of natural waters  Natural eutrophication in regions of upwelling: cold, deep, nutrient-rich waters rise to surface eg Chile  Anthropogenic eutrophication is result of nutrient pollution of natural waters eg lakes, rivers, aquifers, estuaries, bays, coastal waters

Scientific definition of Eutrophication…the good?  “Stimulation of algal growth by enrichment of the aquatic environment with mineral nutrients” (Richardson, 1989)  Natural processes are the agents of enrichment: includes naturally eutrophic coastal waters, such as upwelling regions

Variation in the Productivity of the Oceans Primary Productivity using global monthly SeaWiFS data of chlorophyll (Nov 77-Oct 99) and the vertically generalised production model from Behrenfeld & Falkowski (1977) Courtesy of Gay Mitchelson–Jacob Courtesy of Gay Mitchelson–Jacob

Atlantic is much nutrient-rich and more productive than the Mediterranean Mediterranean Chlorophyll CZCS composite Mediterranean Chlorophyll CZCS composite Courtesy of Gay Mitchelson–Jacob

Upwelling regions are especially productive such as the coast of Chile SeaWiFS Chlorophyll, 18 Jan 2000 Chile Courtesy of Gay Mitchelson–Jacob SeaWiFS Chlorophyll, 18 Jan 2000 Chile Courtesy of Gay Mitchelson–Jacob

Coastal Upwelling Chlorophyll Concentrations (CZCS), Cape Verde Islands Courtesy of Gay Mitchelson–Jacob Chlorophyll Concentrations (CZCS), Cape Verde Islands Courtesy of Gay Mitchelson–Jacob Coastal Upwelling off W. Africa

Management definition of Eutrophication… the Bad?  Anthropogenic Eutrophication: mankind is the agent responsible for nutrient enrichment  European Environment Agency definition: “Enhanced primary production due to excess supply of nutrients from human activities, independent of the natural productivity level for the area in question”

UK EA definition “The enrichment of waters by inorganic plant nutrients which results in the stimulation of an array of symptomatic changes. These include the increased production of algae and/or other aquatic plants, affecting the quality of the water and disturbing the balance of organisms present within it. Such changes may be undesirable and interfere with water uses.”

Nutrients & Eutrophication, EEA  The main nutrients causing eutrophication are N in the form of nitrate, nitrite or ammonium and P in the form of ortho- phosphate.  In addition, supply of bioavailable organic P and N cause eutrophication  Silicate is essential for diatom growth, but it is assumed that silicate input is not significantly influenced by human activity.  Enhanced primary productivity may exhaust silicate and change the phytoplankton community from diatoms to flagellates.

Eutrophication process UK EA

Early Eutrophication Model Nutrient loading Responses: Changes in Chlorophyll Primary Production System Metabolism Oxygen Early conceptual models focused on direct responses of coastal waters, such as stimulation of phytoplankton blooms.

Contemporary conceptual model Nutrient loading Filter Direct Responses Chlorophyll Primary Production Macroalgal biomass Sedimentation of O C System Metabolism Phyto. community Si:N N:P Oxygen HAB Indirect Responses Benthic biomass Pelagic biomass Vascular plants Habitat diversity Water transparency O C in sediments Sediment biogeochemistry Bottom-water oxygen Seasonal cycles Mortality Biodiversity Cloern J.E. 2001

Contemporary conceptual model   Growing awareness of the complexity of the problem   Attributes of specific bodies of water create enormous variations in their responses   Cascade of direct and indirect effects   Appropriate management actions to reduce nutrient inputs can reverse some of the degradation caused by enrichment.

History of Eutrophication

History of Fertilizer Historical fertilizer shortage  18 th Century England “mined” battlefields and catacombs  19 th Century USA used bones from buffalo killing fields  Guano deposits mined eg Navassa guano trench

Haber-Bosch Process  Fritz Haber (Nobel prize winner) described chemical process to produce NH 3 from N 2 & CH 4  Carl Bosch (Nobel prize winner) perfected commercial manufacture

Industrial N fixation  N 2 from atmosphere mixed with CH 4 and heated under pressure with a metallic catalizer produces CO 2 and NH 3 (82%N)  Mean plant production is 1.5 million kg ammonia per day

History of Eutrophication  Eutrophication first noticed in lakes where P is the main problem  Also noticed in rivers  Estuaries: eg Chesapeake bay  Bays and coastal waters affected: eg Gulf of Mexico  70 % of world population lives in coastal plains, increasing pressure