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Water, Sediment and Macrophyte Quality of Some Shrimp Culture Ponds and Freshwater Ecosystems of Koyra

ABDULLAH HARUN CHOWDHURY
Environmental Science Discipline, Khulna University, Khulna

ROXANA AHMED
Department of Botany, Jahangirnagar University, Savar, Dhaka

Abstract/ Executive Summary:

A total of 29 genera belonging to 24 families of aquatic macrophytes were recorded. Among these, 25 species were recorded from the freshwater aquatic ecosystems, 4 species from both the shrimp culture ponds and freshwater aquatic ecosystems and only one from the shrimp culture ponds. The physicochemical conditions of both the habitats indicate that very poor number of macrophytes can grow in the shrimp culture ponds due to high salinity of water and soil. Low population and abundance indicate that the macrophytes are in alarming condition in Koyra due to increasing salinity.

Keywords: Macrophytes, Shrimp culture ponds, Freshwater ecosystems

Location: KHULNA

Start Date: 01-05-2009

End Date: 30-04-2011

Program Area: Resource Development and Management

Commodity: Shrimp

Objectives:

To study the macrophytes of some shrimp culture ponds and freshwater aquatic ecosystems situated in Koyra. To compare this two habitats investigation was also carried out to know the physicochemical characteristics of water and submerged sediment.

Methodology:

Monthly sampling from 10 permanent stations from each of shrimp culture ponds (SCP) and freshwater aquatic ecosystems was carried out from May, 2009 - April, 2011. The Unions (administrative units at village level) of Koyra holding 10 stations of shrimp culture ponds were: Dakshin Bedkashi 5, Uttar Bedkashi 3 and Maharajpur 2 while the Unions holding 10 stations of freshwater aquatic ecosystems were: Amdi 6, Bagali 3 and Uttar Bedkashi 1. The distance among the stations was 400 - 800 m from each other. Water depth in them ranged from 0.7 - 3.2 m. The stations of shrimp culture ponds had a surface area ranged from 1.3 - 8.5 acre and the surface area of freshwater aquatic ecosystems ranged from 0.6 - 1.7 acre. By using a country boat, the sample of macrophyte was collected by hand (Ambasht 1990). After collection samples were carried to the laboratory under wet condition and later on preserved on herbarium sheet for identification. The populations of aquatic plants in field were measured by following quadrate method (Ambasht 1974). Water from 10 - 25 cm depth was collected for physicochemical analyses (Trivedy 1993). A standard Secchi disc was used to measure the transparency of water while for water temperature a digital thermometer was used (Model No. 950). In situ measurements of total suspended solids (TSS), total dissolved solids (TDS), conductivity, salinity, pH, dissolved oxygen (DO), oxidation reduction potential (Eh) and oxidation reduction index (rH2) were carried out with the help of respective portable field meters. Titrimetric methods were used to determine free CO₂, CO₃ and HCO₃alkalinities (Welch 1948). BOD5, COD and NO₃-N were measured following APHA (1989). Calcium and magnesium were estimated following Mishra et al. (1992). Phosphate and silicate were measured following Gautam (1990). Shovels and large ladders were used to collect the bottom soil samples according to Trivedy (1993). Bottom soil quality was determined in the SRDI laboratory of Khulna following Jackson (1973) and Page et al. (1982). Aquatic macrophytes were identified following Khan and Halim (1987), Fassett (1960) and other relevant literatures. The identification was verified from the Bangladesh National Herbarium, Dhaka.

Source of Information: Bangladesh J. Bot. 41(1): 35-41, 2012 (June)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Utricularia aurea, Nymphaea stellata, Nymphoides cristatum and Oryza rufipogon may become vulnerable in the study area due to degradation of their habitats by increasing salinity. So, it is necessary to conserve the freshwater macrophytes of Koyra. A sustainable management plan such as area demarcation is necessary for the saline water shrimp culture to protect the further degradation of the existing freshwater plant diversity of the study area. The results of this study will be helpful for further study and sustainable management plan of the hydrophytes of saline affected areas.

Knowledge Management: Journal