20
F. A. Khan et al.
in the form of inorganic or organic fertilizers and formulated
feeds were found to dominate the nitrogen biogeochemistry
of aquaculture ponds. Nitrogen application in excess of pond
assimilatory capacity deteriorates water quality (Hargreaves
1998).
2.3.2 Impact of Phosphorus
Phosphorus accelerates freshwater eutrophication and water
quality impairment. Agriculture is regarded as an important
source of P in environment. The loss of P in surface runoff
and subsurface flow originates primarily from small areas
around watershed, where high application of phosphorus
fertilizer or manure coincide with high runoff or erosion potential (Sharpley et al. 2001, Carpenter et al. 1998). In water
bodies phosphorus may be present in various forms. All
forms of phosphorus are not readily available to plants. Total
phosphorus is a measure of all forms of phosphorus (dissolved or suspended) found in any water sample. The soluble
reactive phosphorus (SRP) is a measure of orthophosphate.
The soluble inorganic phosphorus is directly taken up by
plant cells and its concentration indicates the stage of eutrophy and oligotrophy (Hammer 1986). Accelerated eutrophication of surface waters is often caused by high phosphorus
losses from agricultural fields (Schroeder et al. 2004, Djodjic
and Bergstrom 2005, Vadas et al. 2005). In a German lowland
eutrophic river, the clastic sediments acted as P sink in summer when SRP concentrations were relatively high. Organic
river substrates serve as phosphorus source (Schulz and
Herzog 2004). The application of phosphorus fertilizer and
manure increased its transfer potential (Daniel et al. 1998,
Zhang et al. 2004). Agriculture and urban activities are major
sources of phosphorus and nitrogen to aquatic ecosystems.
Nutrient enrichment seriously degrades aquatic ecosystems
and impairs the use of water for drinking, industry, agriculture, recreation and other purposes.
The phosphate is relatively immobile element and may
be carried to streams through soil erosion and storm runoffs
from the excessively fertilized agricultural fields, nurseries, lawns and orchards. Certain synthetic chemicals such
as pesticides, construction materials, flame retardants and
plasticizers are the other sources of phosphate discharges in
freshwater systems (Sharpley 1999). The literature review
revealed that surface water bodies around agriculture land,
nurseries, cities and fertilizer units are prone to nutrient enrichment which promotes excessive algal blooms. Human
interference in up welling and down welling and prevailing
climatic factors govern seasonal variations in the population
dynamics of the aquatic flora and eutophy of surface water
bodies. In the present study, a devastating effect of human
interferences on the existence of a small microcosm of a few
acres near AMU campus has been studied.
2.4 Material and Methods
2.4.1 Description of the Study Site
Lal Diggi pond is a small rainfed pond located very close
on the south of the campus of Aligarh Muslim University,
Aligarh, India. Until last two decades, the human settlement around the pond was sparse but now its eastern side
is densely populated. The western and southern sides have
about 80 and 60 ft wide roads, respectively. In past 20 years,
the roads have been raised, which act as weirs and prevents
the rain water from its northern, southern and western catchments to drain into the pond. It is a rainfed pond and its water
recharging capacity has thus reduced substantially. In 2002,
the margins of this pond were raised again and a bypass drain
constructed around its coastal lines took the rain water of
its catchments away from this pond. The water level consistently reduced during 2002 and 2003. On realizing this
disastrous change, the pond finally dried by May 2004. The
pond was later on refilled and a passage for rain water unloading was reconstructed in 2005. The devastating changes
in the physico-chemical property of the pond and seasonal
variations were studied as described in the following section.
2.5 Results
2.5.1 Monthly Qualitative Studies
April 2003 The water level in the pond at various places
varied between 2 and 4 feet. About 7–8 m wide moist and
marshy northern coastline was occupied by Typha angustata. Eastern marshy coastlines (18–20 ft wide) had relatively
denser population of Typha angustata. A patch of Paspalum
paspaloids occupied 12–15 m wide area of the water body
in the southern margin. South-western side had a patch of
Typha angustata and remaining western side of the pond
was open. Thus, the existing water body was surrounded by
Typha angustata from northern, eastern and south western
sides and by Paspalum paspaloides from the southern side.
The main water body on its eastern margin was covered
with mature water hyacinth ( Eichhornia crassipes) almost
in drying stage. The open area of water body was covered
with duck weeds on the western side and south western side.
The duck weeds were in the mature stage and at places most
of them dried and formed slime body. About 50–100 cm of
water level was recorded at about 5 m inside of the western
coast of this mesocosm.
May 2003 The duckweeds on the western side of the pond
dried almost completely. The water level in this area of the
pond was maintained between 50 and100 cm. The water hyacinth on eastern side completely dried. The Typha angustata
F. A. Khan et al.
in the form of inorganic or organic fertilizers and formulated
feeds were found to dominate the nitrogen biogeochemistry
of aquaculture ponds. Nitrogen application in excess of pond
assimilatory capacity deteriorates water quality (Hargreaves
1998).
2.3.2 Impact of Phosphorus
Phosphorus accelerates freshwater eutrophication and water
quality impairment. Agriculture is regarded as an important
source of P in environment. The loss of P in surface runoff
and subsurface flow originates primarily from small areas
around watershed, where high application of phosphorus
fertilizer or manure coincide with high runoff or erosion potential (Sharpley et al. 2001, Carpenter et al. 1998). In water
bodies phosphorus may be present in various forms. All
forms of phosphorus are not readily available to plants. Total
phosphorus is a measure of all forms of phosphorus (dissolved or suspended) found in any water sample. The soluble
reactive phosphorus (SRP) is a measure of orthophosphate.
The soluble inorganic phosphorus is directly taken up by
plant cells and its concentration indicates the stage of eutrophy and oligotrophy (Hammer 1986). Accelerated eutrophication of surface waters is often caused by high phosphorus
losses from agricultural fields (Schroeder et al. 2004, Djodjic
and Bergstrom 2005, Vadas et al. 2005). In a German lowland
eutrophic river, the clastic sediments acted as P sink in summer when SRP concentrations were relatively high. Organic
river substrates serve as phosphorus source (Schulz and
Herzog 2004). The application of phosphorus fertilizer and
manure increased its transfer potential (Daniel et al. 1998,
Zhang et al. 2004). Agriculture and urban activities are major
sources of phosphorus and nitrogen to aquatic ecosystems.
Nutrient enrichment seriously degrades aquatic ecosystems
and impairs the use of water for drinking, industry, agriculture, recreation and other purposes.
The phosphate is relatively immobile element and may
be carried to streams through soil erosion and storm runoffs
from the excessively fertilized agricultural fields, nurseries, lawns and orchards. Certain synthetic chemicals such
as pesticides, construction materials, flame retardants and
plasticizers are the other sources of phosphate discharges in
freshwater systems (Sharpley 1999). The literature review
revealed that surface water bodies around agriculture land,
nurseries, cities and fertilizer units are prone to nutrient enrichment which promotes excessive algal blooms. Human
interference in up welling and down welling and prevailing
climatic factors govern seasonal variations in the population
dynamics of the aquatic flora and eutophy of surface water
bodies. In the present study, a devastating effect of human
interferences on the existence of a small microcosm of a few
acres near AMU campus has been studied.
2.4 Material and Methods
2.4.1 Description of the Study Site
Lal Diggi pond is a small rainfed pond located very close
on the south of the campus of Aligarh Muslim University,
Aligarh, India. Until last two decades, the human settlement around the pond was sparse but now its eastern side
is densely populated. The western and southern sides have
about 80 and 60 ft wide roads, respectively. In past 20 years,
the roads have been raised, which act as weirs and prevents
the rain water from its northern, southern and western catchments to drain into the pond. It is a rainfed pond and its water
recharging capacity has thus reduced substantially. In 2002,
the margins of this pond were raised again and a bypass drain
constructed around its coastal lines took the rain water of
its catchments away from this pond. The water level consistently reduced during 2002 and 2003. On realizing this
disastrous change, the pond finally dried by May 2004. The
pond was later on refilled and a passage for rain water unloading was reconstructed in 2005. The devastating changes
in the physico-chemical property of the pond and seasonal
variations were studied as described in the following section.
2.5 Results
2.5.1 Monthly Qualitative Studies
April 2003 The water level in the pond at various places
varied between 2 and 4 feet. About 7–8 m wide moist and
marshy northern coastline was occupied by Typha angustata. Eastern marshy coastlines (18–20 ft wide) had relatively
denser population of Typha angustata. A patch of Paspalum
paspaloids occupied 12–15 m wide area of the water body
in the southern margin. South-western side had a patch of
Typha angustata and remaining western side of the pond
was open. Thus, the existing water body was surrounded by
Typha angustata from northern, eastern and south western
sides and by Paspalum paspaloides from the southern side.
The main water body on its eastern margin was covered
with mature water hyacinth ( Eichhornia crassipes) almost
in drying stage. The open area of water body was covered
with duck weeds on the western side and south western side.
The duck weeds were in the mature stage and at places most
of them dried and formed slime body. About 50–100 cm of
water level was recorded at about 5 m inside of the western
coast of this mesocosm.
May 2003 The duckweeds on the western side of the pond
dried almost completely. The water level in this area of the
pond was maintained between 50 and100 cm. The water hyacinth on eastern side completely dried. The Typha angustata