Eutrophication:
Download
1 / 19

Defining Eutrophication - PowerPoint PPT Presentation


  • 123 Views
  • Uploaded on

Eutrophication: managing a growing problem in aquatic systems Laurence Mee Professor of Marine and Coastal Policy, Plymouth University. Defining Eutrophication. Most limnologists consider eutrophication as an increase in the rate of supply of organic matter to an ecosystem.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Defining Eutrophication' - nova


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Defining eutrophication
Eutrophication:managing a growing problem in aquatic systemsLaurence MeeProfessor of Marine and Coastal Policy, Plymouth University


Defining eutrophication
Defining Eutrophication

Most limnologists consider eutrophication as an increase in the rate of supply of organic matter to an ecosystem.

For marine scientists, eutrophication (GESAMP, 1990) is “used simply to mean ‘enhanced nourishment’ and refers to the stimulation of aquatic plant growth by mineral nutrients, particularly the combined forms of phosphorus or nitrogen”.

Link to lecture notes


Defining eutrophication

  • There are over 600 small lakes in Northern Ireland. Research on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

  • (source: redrawn from Anderson, J. Freshwater. Biol. 38, 427-440, Fig. 9)


  • Defining eutrophication

    How is eutrophication manifested in the sea? on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    Here are some of the impacts of eutrophication. The consequences of each of these impacts will be explained in the lecture:

    • Decrease in the transparency of water.

    • Decrease in the average size of phytoplankton cells.

    • Increased demand for oxygen below the photic zone.

    • Change in phytoplankton speciation.

    • Change in the aesthetic value of the water body.


    Defining eutrophication

    Case Study: The Black Sea on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    Link to lecture notes


    Defining eutrophication

    Evolution of the NW Shelf ‘Dead Zone’ on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    1974

    1973

    1990

    1978


    Defining eutrophication

    Decline in the Phyllophora beds on the NW Shelf on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    1980s

    1970s

    1950s

    1960s


    Defining eutrophication

    Distribution and migration of Turbot prior to 1980 on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    Spawning

    Feeding


    A causal chain for eutrophication
    A causal chain for eutrophication on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.


    Defining eutrophication

    PRESSURE-STATE-RESPONSE MODEL FOR EUTROPHICATION on the sediments in six of these has reconstructed a remarkable record of changes in total phosphorus concentration over the past 150 years that appears to be typical of lakes in most developed countries. The data shown above is for three lakes that have no point sources (e.g. sewage) draining into them, only the inputs from surrounding agriculture. Each of the lakes shows an increase in phosphorus, initially as a result of land clearances (ploughing releases phosphorus) and then a more pronounced increase since the 1950s. This recent large change is due to land drainage, fertiliser use and the indirect impact of rural sanitation. Impacts of these activities are accelerating the demise of the lakes. Each of the lakes is affected in a slightly different manner according to the characteristics of the particular drainage basin. Recent decreases may reflect more prudent use of fertilisers.

    Environmental impacts

    Eutrophication

    Socio-economic impacts

    Transboundary consequences

    Response

    Immediate causes

    Secondary causes

    Uncertainties

    Barriers for overcoming the problem

    Tertiary causes

    Socio-economic root causes


    Defining eutrophication

    This figure is taken from Sala et al. ‘Global Biodiversity Scenarios for the year 2100’ to appear shortly in Science.


    Defining eutrophication

    Appendix: Scenarios for the year 2100’ to appear shortly in Science

    Managing lakes to reduce eutrophication.

    Follow the hyperlink to a draft World Bank Guideline. Please note that this document should not be cited - it is still a draft under review but gives a useful summary for those of you that are unfamiliar with limnology

    Link


    Defining eutrophication

    Further reading: Scenarios for the year 2100’ to appear shortly in Science

    Two key articles are priority reading:

    Smil, Vaclav (1997) Global population and the nitrogen cycle. Scientific American, July 1997, 76-81

    Vitousek, P. et al. (1997) Human alterations of the Global Nitrogen Cycle: sources and consequences. Ecological applications 7(3): 737-750

    Get a subscription (free) to the web based peer reviewed Journal of Conservation Ecology (www.consecol.org)