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e silt with 
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yl-15 
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Avicennia 
cies, (Fig. 
5) and (3) 
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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
  
  
  
  
  
Figure 5: Fringe Mangrove zone showing Rhizophora 
  
  
Figure 6: Peripheral Mangrove zone with mixed 
mangroves with easy access for grazing 
Results and Discussion 
Mangroves have the ability to withstand the action of tides, 
exposure to freshwater, storm, cyclones, diurnal and seasonal 
fluctuation of temperature. Even under the changing 
environment, the physiological processes allow the mangroves 
to sustain. Nevertheless Pichavaram mangroves are considered 
as a critical habitat due to extensive degradation. Many species 
like Kandelia candel and Bruguiera gymnorrhiza reported in 
the past have become extinct now. Sonneratia apetala thrived 
under normal salinity was abundant once and are rare now. 
Another species Bruguiera known to thrive under salinity < 25 
became rare now (Caratini et al., 1973). It is evident from the 
above observation that there was changing scenario of salinity 
which may be due to change in tidal condition or lack of 
427 
  
  
freshwater inflow from upstream or sea level change. 
Considering the fragile nature of the ecosystems, protection 
and conservation of each pocket require scientific basis and it 
would be ideal to identify the cause for each degraded or loss 
parcels in core, fringe and peripheral regions. The GIS overlay 
of the 1970, 1987 and 1998 mangrove distribution reveals that 
the degradation and losses of mangroves were not exclusive for 
a particular zone (Fig. 8). The core mangroves are dominantly 
Avicennia found in the high intertidal region between creeks 
and have tolerance to salinity. The fringe mangroves are 
predominantly Rhizophora and alternatively Suaeda, found 
along the banks of the estuarine creeks, subjected to tidal 
flushing and freshwater mixing. As Suaeda is salt marsh 
species, the succession of Suaeda in fringe region suggested the 
possibility of hypersalinity in the substratum due to lack of 
freshwater mixing from upstream. Experts suggested that 
mangroves with the rainfall of over 2000mm have the best and 
complete succession. The peripheral mangroves found in the 
wetland region on the shoreline were controlled totally by tidal 
inundation and rainfall. The rainfall over 2000mm has been 
unusual in the tropical Indian coasts.Above all over 2000mm 
of rain fall has been unusual in the tropical coasts under the 
changing scenario of global climate. 
ll i 
d Degraded Area” 
  
    
      
   
és 
Bay 
of 
Bengal 
1 7 4 2 A 
  
   
í^. X 
T 
ug. 
Figure 7: Degraded mangrove areas identified from 
satellite data 
  
alti A 
In order to identify the actual cause for mangrove loss and 
degradation, GIS based integration of the water quality, land 
use and land cover changes, estuarine morphology and 
mangrove zonation and socioeconomic data like human 
settlement, population, proximity and social status etc was 
attempted. As a result the losses and degradation of mangroves 
could be attributed to geological and socioeconomic influences. 
The water quality parameters like pH, dissolved oxygen (DO) 
and salinity (Table-1) collected at different sample locations 
(Fig. 7) and other trace element studies did not show any