Eutrophication A Review of Its Process and Ecological Impacts Yang Zhang 12/1/2018

Introduction Previously, 12/1/2018

In the past few decades, 12/1/2018

Definition: The enrichment of water by nutrients, stimulating and array of symptomatic changes including increased production of algae and/or high plants, which can adversely affect the diversity of the biological system, the quality of the water, and the uses to which the water may be put. 12/1/2018

Topics of Discussion Nutrient limitation •CAUSES • PROCESS Nutrient input sources Nutrient loading • PROCESS •ASSOCIATED PHYTOPLANKTONS •CONSEQUENCES 12/1/2018

Causes of Eutrophication Anthropogenic inputs N, P nutrient enrichment Algae bloom Allochthonous C Autochthonous C Organic matter loading 12/1/2018

Nutrient Limitation Basic elements: Macronutrients: C, H, O Macronutrients: Ca, Mg, K, P, N, S, Fe, Si Trace elements: B, Cl, Co, Cu, Mn, Mu, Zn, vitamin 12/1/2018

Nitrogen Phosphorus and Are the key nutrients causing eutrophication problems 12/1/2018

                                                                            Note the bright green color caused by algae stimulated by the experimental addition of phosphorus for the 26th consecutive year. Lake 305 in the background is unfertilized                                                                             Blue green "algae" (Cyanobacteria) were able to "fix" nitrogen that had diffused naturally into the lake from the air, thereby making the nitrogen available for supporting algal growth. 12/1/2018

Nitrogen enrichment not only causes algae blooms, but also… 12/1/2018

Nitrogen formulation can regulate the cell size distribution of phytoplankton communities Smaller species have a higher preference for ammonia uptake over nitrate than larger species Larger species have the capacity for more internal storage of nutrients and become dominant in fluctuating nutrient regimes 12/1/2018

Nutrient Input Sources Nonpoint sources •Run off from farmlands • Run off from lawns and paved areas • Industry • Waste water treatment plants Point sources 12/1/2018

Nutrient Loading P Naturally, --Anthropogenically, Exists as phosphate Sorbed to soil particles Liberated by weathering Not easily leached out --Anthropogenically, Human-caused changes in the global P budget have caused P to accumulate in upland soils, and increasing soil P levels elevate the potential P runoff to aquatic ecosystems. 12/1/2018

N Naturally, Anthropogenically, Many forms of nitrogen, especially fertilizers, are released to the environment Easily leached out of the upper soil layers by rainfall Nitrogen fixation Nitrification Denitrification N2 NH4+ NO3- N2 oxic anoxic Cell mass 12/1/2018

Process of Eutrophication High nutrient release Anaerobic benthic High algal photosynthesis High organic matter 12/1/2018

Algae Associated with Eutrophication “Red tides” Red algae Furcellaria Phycodrys “Green tides” --Green algae Chlorophytes Cryptophytes Cyanobacteria Diatoms Dinoflagellates 12/1/2018

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Consequences of Eutrophication Destroy food chain Algae bloom algae species change block sunlight loss of available food Underwater grasses die Herbivorous die displacement of fish and crabs 12/1/2018

Anoxic water kills fish and crabs High nutrient release Anaerobic benthic High algal photosynthesis High organic matter 12/1/2018

Produce toxic chemicals Toxins produced by cyanobacteria can not be removed by conventional water treatment processes Causing many chronic health problems in humans. 12/1/2018

Thank you!                                            12/1/2018