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INSTITUTE OF ZOOLOGY, UNIVERSITY
OF THE PUNJAB LAHORE
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Zulfiqar Shb
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This is one of the first definitions given to the eutrophic process by the OECD
(Organization for Economic Cooperation and Development) in the 70s
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It
is an abnormal growth of algae, a clear manifestation of a process called
eutrophication
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nationalgeographic
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According to the Survey of the State of the
World's Lakes, a project promoted by the International Lake
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lescienze
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CULTURAL EUTROPHICATION:
•All water bodies are subject to a natural and slow eutrophication process, which in recent decades has
undergone a very rapid progression due to the presence of man and his activities (so called cultural
eutrophication)
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e
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These structural changes mainly
depend on 3 factors:

•Fertilizer Use
•Waste Water Discharge
•Reduction in Purification Capacity

FERTILIZERS USE:


Agricultural practices and the use of fertilizers in the soil contribute to the accumulation of
nutrients
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

Example of fertilizer spreading on agricultural land

•

WASTE WATER DISCHARGE:
• Discharge of waste water into water bodies: In various parts of the world, and particularly in
developing countries, waste water is discharged directly into water bodies such as rivers, lakes and
seas
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• In industrialised countries, on the other hand, waste water can be illegally discharged directly into
water bodies
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• Example of discharge of waste water into a reservoir

REDUCTION IN PURIFICATION CAPACITY:
• Reduction of self purification capacity: Over the years, lakes accumulate large quantities of solid material
transported by the water (sediments)
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• Consequently, the accumulation of sediments starts to fill the basin and, increasing the interactions between
water and sediment, the resuspension of nutrients present at the bottom of the basin is facilitated
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• Example of silting of a reservoir
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 When algae start to grow in an uncontrolled manner, an increasingly large biomass is formed which is
destined to degrade
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 An anoxic (oxygen-free) environment is thus created on the lake bottom, with the growth of organisms
capable of living in the absence of oxygen (anaerobic), responsible for the degradation of the biomass
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 The absence of oxygen reduces biodiversity causing, in certain cases, even the death of animal and plant
species
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
An aquatic environment with a limited availability of phosphorus and nitrogen is described as
"oligotrophic" while one with high availability of these elements is called "eutrophic"; a lake with
intermediate availability is called "mesotrophic"
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 The two most acute phenomena of eutrophication are hypoxia in the deep part of the lake (or lack of
oxygen) and algal blooms that produce harmful toxins, processes that can destroy aquatic life in the
affected areas
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e
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• degradation of recreational opportunities, and hypoxia
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S
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2 billion
annually (Dodds et al
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Sampling Lago de Pátzcuaro during a cyanobacterial bloom with Ilyana Berry, Dr
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Fernando
Bernal-Brooks
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

Abundance of inorganic chemicals (i
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

Disappearance or significant reduction of quality fish with very negative effects on fishing (instead of
quality species such as trout undesirable ones such as carp become established)
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) due to the
presence of particular algae
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 In the past, the traditional eutrophication reduction strategies, including the alteration of excess nutrients,
physical mixing of the water, application of powerful herbicides and algaecides, have proven ineffective,
expensive and impractical for large ecosystems (Michael F
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 Today, the main control mechanism of the eutrophic process is based on prevention techniques, namely
removal of the nutrients that are introduced into water bodies from the water
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) of nutrients introduced into the environment
due to human activity
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 Use of alternative practices in animal husbandry to limit the production of waste water
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CONCLUSION:
•Water is not a commercial product like any other but rather a heritage which must be defended and
protected, especially in the presence of a global decline in the availability of drinking water and
increase in its demand
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•The prevention and protection action that countries must adopt to safeguard the quality of surface
water as requested not only by the scientific community and other experts, but to an increasing extent
also by citizens and environmental organizations, is therefore increasingly important
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http://www3
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it/uninsubria/allegati/pagine/5114/eutrofizzazione
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http://algaeanalytics
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http://ec
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eu/environment/water/water-framework/info/intro_en
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http://news
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edu/story/361695/2015/06/25/research/project-reduce-risk-harmful-algal-blooms-ponds-andlakes

vi
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ecologiae
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http://www
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com/list_7346477_harmful-effects-fertilizers-pesticides
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http://www
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it/news/2008/07/22/news/eutrofizzazione_dei_laghi_non_solo_azoto-578799/

ix
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nationalgeographic
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http://www
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org/articoli/anno-2013/laghetti-collinari-e-interrimento/

xi
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unep
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jp/ietc/publications/short_series/lakereservoirs-3/1
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Michael F

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