Pollution Characteristics and Risk Assessment of Heavy Metal Elements in Sediment in the West Lake of Hengshui Lake

21 sampling points were set in the West Lake of Hengshui Lake including 20 fish ponds and 1 natural pond to analyze the contents distribution of heavy metal elements including Cr, Zn, Pb, Cu, Cd, Hg, As, and Sb in sediment. The degree of heavy metal pollution was evaluated by the geoaccumulation index (Igeo) method. The results showed that the concentrations of Cr, Zn, Pb, Cu, Cd, and Hg at in all sampling points of the fish ponds were lower than soil risk screening values of agricultural land in soil environmental quality: risk control standard for soil contamination of agricultural land (trial) (GB 15618-2018). The concentrations of As at 5 sampling points were higher than soil risk screening values and lower than soil risk control values of agricultural land in GB 15618-2018. The concentrations of Sb were lower than soil risk screening values of construction land in soil environmental quality: risk control standard for soil contamination of development land (trial) (GB 36600-2018). The evaluation results of the geoaccumulation index method showed that the pollution degrees of Cd, Pb, and Hg were moderately contaminated in general, the pollution degree of Cu was uncontaminated to moderately contaminated in general, the pollution degrees of Cr and As were uncontaminated to moderately contaminated in some sampling points, and Zn and Sb could be regarded as uncontaminated in sediment of the fish ponds in the West Lake of Hengshui Lake. Otherwise, the average contents of other heavy metal elements in sediment of the fish ponds in the West Lake of Hengshui Lake were higher than the background value of soil in Hebei Province (BVSH) except for Zn and Sb. The average contents of seven heavy metal elements in sediment of the natural pond in the West Lake of Hengshui Lake were lower than BVSH except for Cr. The result can be regarded as no pollution in the natural pond because the values of Igeo were all lower than 0. The heavy metal pollution in the sediment of the West Lake of Hengshui Lake may be due to the introduction of feeding. The water environment of the West Lake of Hengshui Lake can be effectively improved by cleaning up the sediment of fish ponds and “returning fishing to wetland.”

Production performance of Pabda (Ompok pabda) and Gulsha (Mystus cavasius) with Rohu (Labeo rohita) in natural pond conditions

The study was carried out infourselected farmer’s pond in Netrokona sadarand Barhatta upazillas(sub district) under Netrokona district during April to September 2019 having average pond area of 0.14 haeach. The ponds were prepared by removing aquatic vegetation and unwanted fish and other animals, andapplying with lime at the rate of 250 kg/ha. Five days after liming, water was supplied from shallow tubewell to the ponds and filled up to the depth of 1.5 m. The fry of Pabda (Ompok pabda) and Gulsha (Mystuscavasius) with Rohu (Labeo rohita) were stocked at the rate of 175000; 87,500 and 2000/ha, respectively.After stocking, fish were fed at a rate of 5-12% of body weight with supplementary feed (30% crudeprotein). Fish sampling were done at monthly interval to know the fish growth status and also to adjust feedration. After six months rearing, fish were harvested by repeated seine netting. Total bulk weight and numberof fish from each pond was recorded. Survival and gross production of fish of each pond were estimated. Theharvesting weight of pabda ranged from 33 to 36g. While the harvesting weight of Gulsha and Rohu rangedfrom 26-27g and 591-614g, respectively. Based on the number of fish harvested at the end of the experiment,survival ranged from 75 to 88%.Total production of Pabda (O. pabda) and Gulsha (M. cavasius) with Rohuwas estimated at 5202, 1772 and 1066 kg/ha, respectively. The total production of fish as recorded in trialponds were 8043 kg/ha

The current state of natural ponds of North Unguja, Zanzibar: The alteration due to climate change and anthropogenic events

Natural ponds are a biologically important habitat type for their specialized collection and the considerable numbers of rare and endemic species they support and play critical role in maintaining biodiversity. Continued increases in anthropogenic behavior and climate change, act in concert to cause alteration to pond and pond perimeter. In Zanzibar, there are several ponds that impound rainfall runoff; however, there is slight concern in conservation in spite of it great support to ecosystem and livelihood. This paper aimed to determine the current changes within the natural pond perimeter of both natural and anthropogenic events, in north region of Unguja, Zanzibar. A mixed method approach was employed to collect data from 113 respondents that are community members around the six ponds (Vuga, Kichungwani, Mbiji, Muwanda, Kinyasini, and Ketwa) were involved in the study. The qualitative data collected through observations based on checklist made around the ponds was analyzed using atlas Ti software, whereas quantitative data collected through questionnaires and measurement were analyzed using SPSS software version 20. The study findings revealed that in the northern Unguja ponds, there is a greater decrease in Area size, changing in condition of water, settlement encroachment and change in vegetation cover which alter the ecosystem composition and human livelihood. These findings highlight the fundamental importance to raise awareness of the alteration trend of the northern Unguja pond and Zanzibar in general. Keywords: Natural ponds, climate, changes (alteration), anthropogenic, freshwater.

Population and reproductive traits of a freshwater amphipod (Crustacea, Peracarida, Hyalellidae) from northwest of the state of Rio Grande do Sul, Brazil

The study of population and reproductive traits provides information about the ecological structure of natural populations. This study aimed to characterize dynamics and reproductive traits of Hyalella palmeirensis from a natural pond from southern Brazil. The amphipods were sampled monthly (August 2012 to July 2013) by a person with the aid of a hand net for 20 minutes. Ovigerous females and pre-copulatory pairs were individualized in the field. A total of 12,325 individuals were sampled, being 1,421 males, 6,983 females (including 215 ovigerous females) and 3,921 juveniles. Paired and unpaired males were significantly greater in size than females. There was a positive correlation between body size (CL) of paired males and females. Males and females showed bimodal distribution. Total sex ratio favored females, and these were more frequent in almost all months. Ovigerous females and precopulatory pairs were found throughout the year, but with high frequency in winter and autumn, respectively, characterizing a seasonal reproduction. Juveniles were sampled throughout the year, with greater intensity in the spring. The mean fecundity was 19.6 ± 4.34 eggs. No reduction in the number of eggs was observed during embryonic development. The results observed in H. palmeirensis demonstrate that this species has a population and reproductive dynamics very similar to other species of Hyalella already analyzed in southern Brazil. Moreover, it can be seen that although the H. palmeirensis occurs in an environment with anthropic influence (soy cultivation,) the population is managing to remain in the area, with reproduction and recruitment in most months of year.

A new species of freshwater amphipod (Crustacea, Amphipoda, Hyalellidae) from state of Rio Grande do Sul, Southern Brazil

The current study describes a new species of Hyalella found in a natural pond at the municipality of Palmeira das Missões, located in the northwestern region of state of Rio Grande do Sul, southern Brazil. The new species differs from other species found in state of Rio Grande do Sul (Hyalella bonariensis, H. castroi, H. kaigang, H. imbya, H. georginae, H. gauchensis, H. montenegrinae and H. pampeana) in the type and number of setae on uropods, on telson and on the inner face of gnathopod 1. Besides, Hyalella palmeirensis is morphologically similar to H. curvispina, especially in the shape and number of setae of uropods. However, H. palmeirensis differs from H. curvispina in having only two simple setae on telson, the inner face of gnathopod 1 with five serrate setae and only the posterior distal margin with denticles in comb-scales, and especially by the tubular sternal gills, present on segments 3 to 7. These new records increase from 11 to 12 the number of species known from state of Rio Grande do Sul.