Preliminary observations on the availability of Tor tor (Hamilton) fry in the River Narmada near Hoshangabad, Madhya Pradesh

Collection of mahseer (Tor tor) fry during December to January from three centres of the river Narmada near Hoshangabad, (Joshipur ghat, Dungerwada ghat and Kherra ghat) using a special type of fry collection net is described. The physical features and physico-chemical conditions of the collection sites are also dealt with.

Distribution of planktonic decapods with special reference to Acetes from nearshore waters of Bombay

Distribution and seasonal variation of decapod larvae were studied from 8 stations off Versova and Mahim during Nov. 1979 to Dec. 1980. Decapod larvae were encountered throughout the year contributing 7.27% of total zooplankton. Numerically, they were more to Versova (av. 1766/100 m super(3)) than Mahim (av. 970/100 m super(3)). Acetes) spp. were common along both the transects. They were represented by Acetes indicus, A. siibogae and A. erythraeus. The effect of physico-chemical parameters in the occurrence of decapod larvae is discussed.

Soil quality of Bhilwara District (Rajasthan) in relation to pisciculture

The present paper deals with the physico-chemical data of 13 rainfed and drainable dry bundhs of Bhilwara District (India). All the dry bundhs studied showed a slightly alkaline pH ranging from 7.5 to 8.5. Electrical conductivity ranged from 2 to 8 millimhos/cm. Organic carbon in sediment fluctuated from 0.30 to 0.75%. Nitrogen, phosphate and potassium levels were fairly good, at 30 to 50 and 24 to 36 mg/100 g of soil respectively. Based on these data it was inferred that these dry bundhs were highly productive and suitable for freshwater fish culture.

典型草原土壤性状变化对灌丛化的响应

以草原和稀树草原中木本植物多度的增加为特征的草地灌丛化，是全球范围普遍发生的现象，但灌丛化的生态学效应目前仍存在争议。对灌丛化草地生态系统特征与过程的研究，将有助于我们进一步了解草地生态系统的退化和恢复机理，为退化草原恢复与管理实践提供理论依据。 本研究以位于内蒙古锡林河流域, 一个经23年围封恢复、具有明显灌丛化特征的草原生态系统为研究对象，通过分析小叶锦鸡儿灌丛及其相邻草本群落下的土壤容重、机械组成、土壤有机碳(SOC)、全氮(TN)和无机氮(IN)的差异，确定小叶锦鸡儿灌丛对草原土壤物理化学性状的影响。主要结果如下： （1）小叶锦鸡儿灌丛化增加了表层土壤（0-5 cm）粗粒级颗粒的比例，降低了浅层土壤（0-20 cm）的容重，较大灌丛下10-20 cm土层仍存在这种现象。这至少部分归因于灌丛对凋落物的截获积聚，以及小叶锦鸡儿的根系分泌物在质和量上较之草本植物的不同，促进了土壤团聚体的发育。 （2）小叶锦鸡儿灌丛斑块引起了典型草原生态系统土壤有机碳、全氮和无机氮的空间分布的变化。在浅层土壤中（0-20cm），由灌丛斑块内部向外部SOC、TN和IN均趋于降低。随小叶锦鸡儿灌丛大小（存在时间）的增加，0-20 cm和60-100cm土层SOC和TN均有增加趋势。 （3）除表层（0-5cm）外，小叶锦鸡儿大灌丛与邻近草地土壤C/N比值无显著差异。 总之，小叶锦鸡儿灌丛不仅改变了草原土壤的物理性状，而且提高了灌丛下土壤有机碳和氮的含量，改变了草原生态系统C、N的空间分布格局，表明草原灌丛化明显改变了草原生态系统的碳氮循环。基于草原约占陆地面积的40%以及全球草地灌丛化普遍存在的事实，这种伴随草原灌丛化发生的土壤有机碳和氮的变化可能会对全球碳氮循环和气候有显著影响。

三峡水库蓄水对消落带土壤理化性状的影响

三峡水利枢纽工程的调度运行导致水库水位的涨落，从而在三峡水库周边水陆交错带形成周期性淹没与出露于水面的一段特殊区域，被称为三峡水库消落带。三峡水库消落带生态系统的健康是库岸稳定和水库安全运行的重要保障。土壤养分是三峡库区消落带土壤生态系统的重要组成部分。三峡水库蓄水以来，土壤理化性状发生改变，水土流失日益加剧。土壤是植物的基础，因此，对三峡水库消落带土壤性状的研究对消落带植被恢复有一定的指导意义，也为研究水库消落带水土流失提供依据，为研究水库消落带土壤污染与水体污染提供基础。 本文首先通过对重庆忠县石宝寨水库消落带不同水位、不同时期的表层土壤分析，研究了消落带不同水位土壤容重、酸碱度、有机质、全氮、全磷、全钾、硝态氮、氨态氮、速效磷、速效钾的含量变化。实验结果表明：（1）消落带土壤淹水前各测定指标在不同海拔高程之间的差异均不显著（P>0.05）；（2）三峡水库淹水后消落带土壤由微碱性变为碱性，养分平均含量普遍下降，土壤养分缺乏，淹水易造成养分流失；（3）不同淹水强度下，土壤pH 值、有机质、全氮、全磷、氨态氮、速效钾平均含量差异显著（P＜0.001），经过淹水土壤有机质、全氮、速效钾含量进一步降低；（4）不同淹水时期，土壤全钾、硝态氮、氨态氮平均含量差异显著（P＜0.001），速效氮含量随季节变化较大，与土壤水分有密切关系；（5）干湿交替更容易造成氮、磷解吸释放入水体，从而增加富营养化的风险。 其次，通过对石宝寨消落带5 个时间段6个水位的表层土壤分析，研究了消落带不同时期、不同淹水强度土壤酸碱度及Cu、Zn、Pb、Cr 的含量变化。结果表明（1）淹水土壤pH 显著高于未淹水土壤，长期淹水土壤重金属含量显著高于短期淹水土壤与未淹水土壤，146m 土壤重金属含量最高；（2）经过淹水土壤，pH 先升高后下降，铜含量、锌含量都下降，铬含量先上升后下降，铅含量随着土壤暴露先稍微上升，后又下降，但在08 年9 月达到最大值；（3）各土壤重金属之间均存在显著相关关系，表明三峡消落带土壤存在重金属复合污染隐患；（ 4 ） 以三峡水库土壤背景值为评价标准， 消落带土壤污染程度具有Cu>Pb>Zn>Cr 的特征，其中，铜污染相对最为严重，消落带土壤随着淹水强度的加大与淹水时间的延长，污染程度加重，消落带综合污染指数达到1.24，属于轻度污染级。

Limnology of Chanda beel

A limno-biological investigation was conducted in Chanda beel over a period of 8 months from June ‘95 to January ‘96. The floodplain showed temporal spatial and vertical variation in physico-chemical as well as biological conditions. During study period, physico-chemical parameters were within the suitable range for fish culture. Plankton population was higher in true beel areas. Both phytoplankton and zooplankton showed direct relationship among themselves. Presence of several indication plankton genera showed that the floodplain was eutrophic in nature.

Physiological observations on a diatom Skeletonema costatum (Greville) Cleve

A chain-forming diatom Skeletonema costatum (Greville) Cleve collected from Yatsushiro Sea, Japan was cultured to determine the optimum level of some physico-chemical factors for their growth under laboratory conditions. Filtered and sterilized aged sea water enriched by adding nutrient solution (Provasoli 1968) was used as the culture medium. The plankton could tolerate a wide range of salinities (3-55 ppt). Optimum growth was observed at salinities of 20-35 ppt, temperatures of 20-25°C, light intensities of 80-120µE mˉ² secˉ¹ and pH between 7.5 and 8.0. Growth did not occur at salinities below 3 ppt and at temperatures above 30°C. From the present study, it is concluded that S. costatum was extremely euryhaline and tolerable to very low salinities.

Bacterial quality and depuration of the green mussel Perna viridis from natural beds

Green mussel (Perna viridis) and sea water from their natural beds on the coastal areas of Porto Novo were studied between April and August 1996 for their bacterial quality. Water samples from the beds were also analysed for their physico-chemical parameters. The total bacterial count of mussels from natural beds as well as bed waters ranged 10³ organisms per gram of mussel meat suspension and per milliliter of sea water. The faecal coliforms were found to be within the permissible limits. Pathogenic bacteria such as Salmonella spp., Streptococcus spp. and Staphylococcus spp. were absent. The variations in pH, temperature, salinity and dissolved oxygen of the seawater samples were insignificant. The mussels were subjected to depuration by different methods among which chlorination was found to be most effective.

Technical report on the environmental monitoring of the cage area at the Source of the Nile (SON) Fish Farm for quarter 1: January-March 2015

Source of the Nile (SON) fish farm is located at Bugungu in Napoleon Gulf, northern Lake Victoria. The proprietors of the farm have a collaborative arrangement with NaFIRRI, a lead agency in fisheries research and innovations, to undertake quarterly environment monitoring surveys at the farm. The agreed areas for monitoring are: selected physico-chemical parameters (i.e. temperature, dissolved oxygen, pH, conductivity, secchi depth); total suspended solids (TSS); nutrient status; BOD5) and biological parameters (i.e. algae, zooplankton, macro-benthos and fish). Water and biological samples as well as field measurements were taken at 3 sites: within the fish cage rows (WIC/experimental), upstream (USC/control) and downstream (DSC) of the fish cages. The key research question was: Does fish cage operations have impacts on the water quality and aquatic biota in and around the SON cage fish farm? The environment monitoring surveys were projected to cover a full calendar year (i.e. from January to December). The first surveys were undertaken in 2011 and have continued on an annual basis since then. The present report presents field observations made for the fourth quarter survey undertaken in November 2014 and provides a scientific interpretation and discussion of the results with reference to possible impacts of the cage facilities to the water environment and the different aquatic biota in and around the fish cage site.

Impact of dead and sunken water hyacinth on biotic communities, the aquatic environment and socio-economic activities

The mobile water hyacinth, which was produced in growth zones, especially Murchison Bay, was mainly exported to three sheltered storage bays (Thruston, Hannington and Waiya). Between 1996 and May 1998, the mobile form of water hyacinth occupied about 800 ha in Thruston Bay, 750 ha in Hannington Bay and 140 ha in Waiya Bay). Biological control weevils and other factors, including localised nutrient depletion, weakened the weed that was confined to the bays and it sunk around October 1998. The settling to the bottom of such huge quantities of organic matter its subsequent decomposition and the debris from this mass was likely to have environmental impacts on biotic communities (e.g. fish and invertebrate), physico-chemical conditions (water quality), and on socio-economic activities (e.g. at fish landings, water abstraction, and hydro-power generation points). Sunken water. hyacinth debris could also affect nutrient levels in the water column and lead to reduction in the content of dissolved oxygen. The changes in nutrient dynamics and oxygen levels could affect algal productivity, invertebrate composition and fish communities. Socio-economic impacts of dead sunken weed were expected from debris deposited along the shoreline especially at fish landings, water abstraction and hydropower generation points. Therefore, environmental impact assessment studies were carried out between 1998 and 2002 in selected representative zones of Lake Victoria to identify the effects of the sunken water hyacinth biomass

Effects of organic manuring (chicken droppings) on growth of Labeo rohita Ham. spawn

An experiment was conducted in six nursery ponds to determine the effect of different doses of organic fertilizer (chicken droppings) on growth and survival of Labeo rohita spawn. Ponds were stocked with four-days old L. rohita spawn at a density of 25 g/decimal and reared for 25 days. Three doses of organic fertilizer viz. 20kg, 10 kg and 5kg per decimal were tried in treatments Tp T2 and T3 respectively with two replication each. Fry were fed twice a day with a mixture of fine mustard oil cake and rice bran at the ratio of 1:1. The highest growth (6.33 em and 3.33 g) and survival rate (72.30%) were observed for the treatment T2. Physico-chemical and biological parameters were found within the productive range for all the treatments.

Eco-biology of Mastacembelus pancalus (Ham.) and their distribution in different water bodies

The eco-biological of the spiny eel, Mastacembelus pailcalus in the river Padma, adjacent flood plains and ponds were influenced by various physico-chemical factors such as water temperature, water transparency, pH, dissolved oxygen, free carbon dioxide and alkalinity. Flood plain areas are the best habitat for the M. pancalus with maximum abundance.

Impact of Bashundhara Baridhara Housing Project on the status, abundance and species diversity of fish in Bashundhara Housing lake in Dhaka, Bangladesh

A study on the status of fisheries and environmental impact assessment (EIA) was conducted on Bashundhara Baridhara Housing Project (BBHP), Dhaka, Bangladesh for prediction and measure the effects of housing project related development activities that have already been implemented and planned for future implementation. The project is still under development phase and so far allotted 10,000 plots of different sizes. The study shows that the original water bodies and natural fish production there from have greatly declined due to earth filling carried out for development of land for the housing. The physico-chemical parameters of the existing water body within the project area were found to be suitable for fish farming in the estate. A number of economically important fish species are found available in the existing lake. However, the natural fisheries resources of the existing lake is under great stress due to the changes made in the ecosystem, siltation, construction of building and dumping of house building and household waste materials. This has caused some important fish species of the lake to become critically endangered and vulnerable which have been documented in this paper. Appropriate regulatory and mitigating measures with respect to water management, disposal of construction garbage and other biomedical toxic substances far away from the water bodies are required to be taken to keep the water safe and suitable for fish production as well as for multipurpose use of the lake water.

Quantitative and qualitative assessment of plankton: some ecological aspect and water quality parameters of the river Meghna, Bangladesh

Investigation on the seasonal distribution and abundance of various major taxa of phyto and zooplankton and the corresponding physico-chemical characteristics were carried out in four selected stations between the latitude 22°35.494N N-23°23.987 N and longitude 90°35.793 E- 90°49.061 E of the Meghna river system, Bangladesh. Drop count method was followed for the qualitative and quantitative analysis of both phyto- and zooplankton. A total of 41 phytoplankton genera belonging to 17 families and 13 zooplankton genera belonging to 11 families were recorded. Zooplankton growth cycle was noticeably less (3.0%) than the phytoplankton abundance almost throughout the study period. Quantity of plankton registered to increase chronologically from the upper to lower stretches of the river. During summer investigation the load of phytoplankton was recorded maximum (11,300-51,850 No/1). Ratio-wise quantitative difference between zoo- and phytoplankton in composition of the total standing crop fluctuated between 1.0:5.5 and 1:1037. Among the phytoplanktonic groups, Chlorophyceae was found to be dominating (95.0%) in all sampling stations. Protococcus, a single genus of Chlorophyceae played a unique role during summer, contributing the highest density of about 74.0%. The pattern of qualitative and quantitative difference of plankton standing crop in different sampling sites can be attributed to the existing physico-chemical characteristics, mainly water temperature, pH and hardness.

Suitability of sodium lactate as cryoprotectant and its effect on gel forming ability and protein denaturation of croaker fish surimi during frozen storage

The effect of sodium lactate is compared with sucrose + sorbitol + sodium tri-poly phosphate as cryoprotectant on gel forming ability & protein denaturation of croaker surimi during frozen storage at -20±2°C for 90 days was evaluated. The quality of Croaker surimi with 6% (w/v) sodium lactate was examined in terms of biochemical parameters of muscle protein, thaw drip, gel strength and calcium ATPase activity :.omparing with those of surimi added with sucrose/sorbitol & without additive as control. Both the cryoprotectants minimized the negative effects of frozen storage on physico-chemical traits of myofibrillar proteins which was evident from the biochemical and sensory parameters. The residual Ca2+ ATPase activity and gel strength of surimi with sodium lactate were higher than those of control throughout 90 days of storage. Ca2+ A TPase activity and gel strength found a high positive correlation. From the results, it was found that sodium lactate was equally effective in preservation of croaker muscle protein native structure during frozen storage as the sucrose/ sorbitol and also less sweet without any risk of maillard browning.