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Detailed Ecological Assessment Report 2008 – Keenjhar Lake
invertebrates, float on the slightest breeze. These tiny invertebrates form clouds
of aerial plankton that drift unseen through the skies. (Hawking, J.H et al 2006)
Aquatic invertebrates are an important source of food for birds, mammals,
amphibians, reptiles, fish, and other invertebrates. Changes in terrestrial and
aquatic habitats lead to changes in invertebrate assemblages, which in turn
increase, decrease, or change food supplies for other animals. As impacts occur
in a stream, species richness (number of species) decreases but the population
size of some species may increase. Further, large-sized species are usually
replaced by small species (e.g., Wallace and Gurtz 1986). Conversely, when the
stream condition improves, larger invertebrate species replace small species
(Grubaugh and Wallace 1995). Such changes can have critical impacts on
species that depend on invertebrates for a food supply.
Aquatic benthic invertebrates are a diverse group of relatively long-lived
sedimentary species that often react robustly and mostly predictable due to
human disturbance of aquatic systems. This capability to demonstrate a strong
reaction makes them a cost-effective and comprehensive tool for the monitoring
of stream water quality. Benthic invertebrates are therefore among the most
common group of organisms used to assess water quality in a good number of
wetlands worldwide.
A taxonomic investigation of aquatic invertebrates is essential to assess the
status of biodiversity in any area. Monitoring of invertebrates at a higher
taxonomic level (genus, family, order) can be useful in indicating changes in
invertebrate assemblages in response to some impact if proper controls are
established, but such monitoring usually cannot determine loss of species.
The Indus Delta comprises more than of 95% of the total mangrove areas of
Pakistan and has the seventh largest mangrove forest in the world. This area has
been famous for its mangrove forests and some 129,000 hectares of mangrove.
These mangrove forests form a habitat of a large number of migratory and
residential bird species and serve as a huge nursery of various fish species. Keti
Bunder is part of the Indus delta and is located in the mouth opening of the Indus
in the Province of Sindh, Pakistan. It consists of main River Indus, various creeks,
estuaries, mud, sand, salt flats, mangrove habitat, marshes, riverine forests, fresh
and salt-water lakes, riverbanks and channels. It falls under largely arid and semiarid
climatic conditions and is characterized by river discharge and moderate
tides. Mangroves cover in the Delta has decreased by about 70% over the last
thirty years (although recently stabilized), which must be reflected in the declining
stocks of key coastal/marine species, which are also over hunted, in any case,
especially prawn.
1.2.7.2 Objectives of the study
The study was formulated to provide a comprehensive ecological and systematic
account of the Invertebrate fauna of Keti Bunder, Keenjhar Lake, Chotiari
Reservoir, Pai forest and Keti Shah. The prime objectives of the study were to:
a. Collect and review secondary data on the invertebrates of the abovementioned
area, with the help of available literature and local community.
b. Collect data from the field on species occurrence, abundance and
diversity in the study areas.
c. Prepare a taxonomical checklist of the invertebrate groups found in the
desired reservoir
WWF Pakistan – Indus for All Programme Page 14 of 165