Detection of health hazard insecticide dichlorodiphenyltrichloroethane (DDT) in some common marine dry fish samples from Bangladesh

Objectives: The general purpose of this study is to detection and determination of the concentration level of dichlorodiphenyltrichloroethane (DDT) in some commercially available marine dry fishes and to investigate the contamination status of dichlorodiphenyltrichloroethane (DDT) of these dry fishes. Methods: Samples were collected from six largest dry fish markets (three from Chittagong district and three from Cox’s Bazar district) and four types of dry fishes were taken in this study are Ribbon fish (Lepturacanthus savala), Sin Croaker (Johnius dussumieri), Bombay duck (Harpodon nehereus) and Shrimp (mixed species). Total numbers of samples were 24 that were analyzed in the laboratory. Results: The results of the study show that the mean concentrations of dichlorodiphenyltrichloroethane (DDT) in the samples of Ribbon fish, Bombay duck and Sin croaker were ranged between 130.85 - 153.47ppb, 125.21 - 181.4ppb and 119.86 – 208.65ppb respectively. The mean concentrations of dichlorodiphenyltrichloroethane (DDT) were found at a lower amount in shrimp sp. than the other. Conclusions: This result indicates that the concentration of dichlorodiphenyltrichloroethane (DDT) in dry fish samples from Bangladesh are higher and may causes chronic disease and potential long-term risk for human health.

A simple and inexpensive method for muddy shore profiling

There are several well-established methods for obtaining beach profiles, and more accurate and precise high-tech methods are emerging. Traditional low-cost methods requiring minimal user skill or training are still popular among professionals, scientists, and coastal zone management practitioners. Simple methods are being developed with a primary focus on sand and gravel beaches. This paper describes a simple, low-cost, manual field method for measuring profiles of beaches, which is particularly suitable for muddy shores. The equipment is a type of flexible U-tube manometer that uses liquid columns in vertical tubes to measure differences in elevation; the supporting frame is constructed from wooden poles with base disks, which hold measuring scales and a PVC tube. The structure was trialed on a mudflat characterized by a 20~0-cm-thick surface layer of silt and clay, located at the Kutubdia Island, Bangladesh. The study results are discussed with notes on the method＇s applicability, advantages and limitations, and several optional modifications for different scenarios for routine profiling of muddy shores. The equipment can be used by one person or two people, and the accuracy of the method is comparable to those in other methods. The equipment can also be used on sandy or gravel beaches.

Grain Size Analysis of a Growing Sand Bar at Sonadia Island, Bangladesh

Sonadia is one of the most important islands of Bangladesh. South-eastern shore of the island, which is a growing sand bar, has to encounter continuous and rapid morphological changes. So study of the sediment characteristics of this Sand Bar is very important. In the present study, grain size analysis of this Sand Bar has been done on the basis of laboratory analysis. Sediment samples were collected from 9 (Nine) stations and texture analysis of sediment was completed following a standard procedure of sieve analysis of sand samples. The average value of median (MD), mean (M), standard deviation (s), skewness (SK) and kurtosis (K) of sediment of the Sand Bar of Sonadia Island was 1.93, 1.87, 0.44, 0.11 and 1.88 respectively. Highest median, mean, standard deviation, skewness and kurtosis of Sand Bar of Sonadia Island was 2.98 (Station 2, Lower Shore), 2.68 (Station 1, Lower Shore), 0.83 (Station 1, Middle Shore and Station 2, Lower Shore), 0.65 (Station 2, Lower Shore) and 3.59 (Station 1, Lower Shore) respectively. Lowest median, mean, standard deviation, skewness and kurtosis of Sand Bar of Sonadia Island was 1.42 (Station 9, Middle Shore), 1.45 (Station 9, Middle Shore), 0.30 (Station 5, Lower Shore and Station 8, Lower Shore), 0.04 (Station 5, Upper Shore) and 0.94 (Station 6, Upper Shore) respectively.

The Relation between the Coefficient of Friction and Pressure Drop by Using the Different Reynolds Number in a Circular Tube

This study explains the relationship between friction coefficient and pressure change at a range of Reynolds (21,056 - 28,574) and (0 - 1.4) solid loading ratio of two-phase flow (gas-solid) inside a circular copper pipe by using laboratory apparatus and solving the equations mathematically. An experimentally relationship of friction coefficient and pressure change with Reynolds number and flow velocity obtained also the relationship between the Solid loading ratio with friction coefficient and pressure change has been done for a Limit range of Reynolds number. It was noticed that the increase in friction coefficient and pressure change for two-phase flow was occurred when solid loading ratio increased. Also the relationship between pressure change and Reynolds number was direct proportion while the relationship between friction coefficient and Reynolds Number was inversely related.

Captures and Diet of Three Sharks Species in the Veracruz Reef System

During July to November of 2008, the artisanal fisheries captured juvenile sharks belonging to the Carcharhinus and Sphyrnidae family in the Veracruz Reef System (south western Gulf of Mexico). The three most abundant organisms were of the species Sphyrna lewini, Carcharhinus brevipinna and Rhizoprionodon terraenovae. Local fisherman recognized five captured areas of sharks as a direct way or bycatch. Some of these areas are located near to eddies formations and river discharges (high productivity areas). These top predators fed on benthic and demersal prey of coastal and reef habits had been the Teleost group the most important item in its diet. However it is possible to observe differences in its feeding tendency.

Biological responses of small yellow croaker(Larimichthys polyactis) to multiple stressors: a case study in the Yellow Sea, China

Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k（growth coefficient） and t_0（zero-length age） gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞（body length）sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r（inflexion age） decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as： fishing vessel power〉feeding grade〉sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.

Social-ecological dynamics of the small scale fisheries in Sundarban Mangrove Forest, Bangladesh

The Sundarban Mangrove Forest(SMF)is an intricate ecosystem containing the most varied and profuse natural resources of Bangladesh.This study presents empirical research,based on primary and secondary data,regarding the social-ecological system(SES),social-ecological dynamics,different stakeholders and relevant management policies of small-scale or artisanal fisheries such as the SMF;showing how,despite extensive diversification,the livelihood activities of the artisanal fishers in the SMF all depend on the forest itself.Regardless of this critical importance of mangroves,however,deforestation continues due to immature death of mangroves,illegal logging,increased salinity,natural disasters and significant household consumption of mangrove wood by local people.As the mangroves are destroyed fish stocks,and other fishery resources are reduced,leading to moves of desperation among those whose livelihood has traditionally been fishing.The present study also considers several risks and shock factors in the fishers'livelihood:attacks by wild animals(especially tigers)and local bandits,illness,natural disasters,river bank erosion,and the cost of paying off corrupt officials.The artisanal fishers of the SMF have adopted different strategies for coping with these problems:developing partnerships,violating the fisheries management laws and regulations,migrating,placing greater responsibility on women,and bartering fishing knowledge and information.This study shows how the social component(human),the ecological component(mangrove resources)and the interphase aspects(local ecological knowledge,stakeholder's interest,and money lenders or middle man roles)of the SMF as an SES are linked in mutual interaction.It furthermore considers how the social-ecological dynamics of the SMF have negative impacts on artisanal fishermen's livelihoods.Hence there is an urgency to update existing policies and management issues for the sustainable utilization of the SMF resources,eventually contributing to the improvement of the artisanal fishers'livelihoods.