Padma Multipurpose Bridge Project

area is no exception of it. Spiders are members of the order Araneae, class Arachnida. In Bangladeshmore than 400 species of spiders have been recorded in 134 genera, and 22 families. Most of theBangladesh spiders belong to Araneidae and Salticidae, followed by Thomisidae, Theridiidae,Tetragnathidae, Clubionidae, Lycosidae and Oxyopidae. Different spider species were observedduring the study.Pierrot ButterflyMothFigure 3-36: Butterflies in the project area3.2.6 Benthos84. In freshwater biology, benthos refers to the organisms found at the bottom of freshwaterbodies of water, such as lakes, Rivers, and streams. These are the organisms which live on, in, ornear the benthic zone. Most organisms in the benthic zone are scavengers or detritivores. Differenttypes of Zoobenthos and Phytobenthos exist in the aquatic part of the study area. Insect larvaeconstitute the most numerous and diverse zoobenthos group. Daphnia, Cypris, Cyclopsand several copepods are important zooplankters in the freshwaters (Figure 3-37), and are the food ofmany fish and other crustaceans.Bellamya bengalensis Lymnaea acuminate Iravadia annandaleiFigure 3-37: Benthos indicator species for fresh water bodies in the Project area.85. These freshwater invertebrates play several important roles in aquatic ecosystem of thePadma River. They are instrumental in cleaning excess living and nonliving organic material fromRiver water column, a service that contributes to the overall quality of the Padma River resources.Water quality degradation of the Padma River due to any reasons adversely impacts the health ofthese aquatic communities including fish and invertebrates. So that these above listed benthicfreshwater invertebrate communities of the Padma River are valuable indicators of water qualitymonitoring in future.3.3 Environmental Quality86. Environmental quality baseline monitoring was conducted in two rounds survey programs tocover both dry and wet seasons. Parameters for baseline quality monitoring are chosen based on therequirements of national air, noise and water quality standards and as well as the expertconsultations. The following parameters are measured: Surface Water Quality: pH, TDS, TSS, EC, Chlorine as Cl - , NH 3 -N 2 , Fe, As, DO, BOD, COD,and oil and grease. Ground Water Quality: pH, Mn, Fe, As, EC, NH3-N2, Total hardness as CaCO 3 , Chlorine asCl- Total Coliforms, Fecal Coliforms3-50