Phosphate treatment of frozen prawns. Pt 2. Frozen storage characteristics of prawn meat treated with polyphosphates

This communication reports the changes in physical, organoleptic and biochemical characteristics of prawn meat dip-treated with alkaline and neutral solutions of polyphosphates during frozen storage. Results are presented on changes in thawed and cooked yields, water extractable nitrogen, non-protein nitrogen, free amino-nitrogen, salt solubility, myosin and moisture in the muscle and loss of soluble nitrogenous constituents in thaw drip during frozen storage up to seven months. The salt solubility remained unchanged during storage in samples treated with neutral polyphosphate solutions and the organoleptic quality was superior to control sample. It is concluded that dip treatment with neutralized solutions of tripolyphosphate not only maintains correct drained weight and improves cooked yield during prolonged frozen storage but also protects the frozen product from denaturation as measured by the salt solubility of the proteins.

Integrated wastewater aquaculture

Utilization of wastewater in fish culture is based on nutrient recycling, which enhances primary productivity, planktonic biomass, macrophytes and benthic organisms which determine fish production. Production of fishes could be enhanced to 10 ton/ha through wastewater recycling by judicial stock manipulation and management. The fallow lands around a sewage fish farm could be utilized for agri-horticultural production by recycling both sludge and sewage water, resulting in a total agro production of about 110 ton/ha through rotational vegetable cropping. The potential for additional production of vegetables not only enhances revenue but also creates employment.

Utilisation of vegetable leaves for carp production

The results of two sets of experiments on mono-culture of grass carp (Ctenopharyngodon idella) and mixed culture of carps (grass carp 50 : catla 20 : rohu 15 : mrigal 15) fed exclusively with vegetable leaves are reported. The experiments were conducted with two replicates each in 0.02 ha ponds of Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara during 1991-93. Monoculture of grass carp stocked at 1000/ha demonstrated an average net production of 21.0 kg/ 0.02 ha/8 months (1501 kg/ha/yr). Mixed culture of carps stocked at 5000 /ha recorded an average net production of 22.5 kg/0.02 ha/8 months (1903.7 kg/ha/yr). Field studies revealed that water bind weed (Ipomoea aquatica) is the most preferred feed of grass carp amongst vegetable leaves followed by amaranths (Amaranthus gangeticus and Amaranthus viridis), cauliflower (Brassica oleracia var. votrytis) and cabbage (Brassica oleracia var. capitata) leaves. Through selection of highly productive leaf vegetables and suitable crop planning on fallow fish pond dykes, round the year feeding programme of grass carp has been explored. Recycling of sewage effluent for vegetable production and utilisation of vegetable leaves for fish production is considered an ideal way of integrated resource management for low cost production.

三种萝藦科植物中C21甾类成分的研究

　　本实验对三种萝藦科植物通光散(Marsdenia tenacissima)、黑水藤（Biondia insignis Tsiang）和徐长卿（Cynanchum Paniculatum）中的C21甾体化合物进行了研究。从通光散藤茎乙酸乙酯提取物的水解产物中，分离得到两类八个C21甾类甙元。经光谱鉴定，它们的结构分别为11α-O-(2-甲基)-丁酰基-12β-O-顺芷酰通光藤甙元乙（1），11α-O-乙酰基-12β-O-乙酰基通光藤甙元乙（2），11α-O-（2-甲基）-丁酰基-12β-O-乙酰基通光藤甙元乙(3), 11α-O-苯甲酰基-12β-O-乙酰基通光藤甙元乙(4)， 11α-O-顺芷酰基-12β-O-乙酰基通光藤甙元乙（5）11α-O-顺芷酰基-12β-O-顺芷酰基通光藤甙元乙（6），12β-O-乙酰基通光藤甙元甲（7）和12β-O-顺芷酰基通光藤甙元甲（8）。其中，化合物2和8为新化合物。从黑水藤乙醇提取物的水解产物中，分离得到了两个C21甾体化合物。经1D、2D NMR技术鉴定，分别为（3β，14β，15β，17β）-3, 14-二羟基-15，16-裂-孕甾-5-烯-15-醛-16-半缩醛-20-酮（1）和白前甙元C（2）。其中1为15，16-裂环的新骨架类型的C21甾体化合物，命名为黑水藤甙元甲。从采购于昆明、浙江、湖南三地药材市场的徐长卿的根及根茎中，分离得到了18个化合物（其中昆明徐长卿6个，浙江徐长卿9个，湖南徐长卿3个）。经光谱数据分析，这些化合物被鉴定为：cynapanoside-C (1), cynapanoside-A (2), 白前甙元B 3-O-β-D-磁嘛吡喃糖甙(3)，白前甙元C 3-O-β-D-葡萄吡喃糖基-(1 → 4)-α-L-2-脱氧洋地黄吡喃糖基-（1 → 4）-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-夹竹吡喃糖甙（4），白前甙元C3-O-β-D-葡萄吡喃糖基-(1 → 4)-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙（5），白前甙元C 3-O-β-D-葡萄吡喃糖基-（1 → 4）-β-D-葡萄吡喃糖基-（1 → 4）-α-D-夹竹桃吡喃糖基-（1 → 4）-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-夹竹桃吡喃糖甙（6），cynatratoside-B (7)，cynatratoside-C (8);glaucoside A(9)，新白薇甙元B 3-O-β-L-磁嘛吡喃糖基-（1 → 4）-β-D-洋黄吡喃糖基-（1 → 4）-β-D-夹竹桃吡喃糖甙（10），白前甙元 A 3-O-α-L-磁嘛吡喃糖基-（1 → 4）-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-磁嘛吡喃糖甙（11），白前甙元 B 3-O-α-L-磁糖基吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(12)，白前甙元D 3-O-α-L-磁嘛吡喃糖基（1 → 4）-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-磁嘛吡喃糖甙（13），白前甙元 C 3-O-β-D-葡萄吡喃糖基-（1 → 4）-β-D-葡萄吡喃糖基-（1 → 4）-α-L-2-脱氧洋地黄吡喃糖基-（1 → 4）-β-D-磁嘛吡喃糖基-（1 → 4）-β-D-夹竹桃吡喃糖甙（14），白前甙元 C 3-O-β-D-葡萄吡喃糖基-（1 → 4）-β-D-葡萄吡喃糖基-（1 → 4）-α-L-磁嘛吡喃糖基-（1 → 4）-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-夹竹桃吡喃糖甙（15），白前甙元 B 3-O-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-（1 → 4）-β-D-磁嘛吡喃糖甙（16），白前甙元 D 3-O-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(17)，白前甙元月B 3-O-α-L-磁嘛吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙（18）。其中，化合物3-6，10-18为新化合物，10的甙元为一个新甙元，命名为新白薇甙无B。

Survival of Staphylococci on frozen fish

Using Staphylococcus aureus as the test culture it has been shown that cell injury occurs in two phases during freezing and storage at temperatures below freezing. Certain constituents of fish muscle appear to protect the cells during both phases of injury. The survival of bacteria on fish muscle is not influenced by the rate at which the fish muscle was frozen prior to inoculation. There was no significant difference between growth of bacteria on quick frozen and slow frozen fish muscle after thawing. However there appeared to be a slight tendency for the lag phase of growth to be extended on thawed quick frozen fish muscle when compared with thawed slow frozen muscle.

Chemical analyses of some Ceylon fishes - 2

Sri Lanka is an island surrounded by the Indian Ocean. Many varieties of marine species of fishes are caught in waters surrounding the island. The catches vary from coast to coast with the monsoonal fluctuations. The island is geographically situated in the tropical latitudes of high rainfall. The topographical landscape presents a central cluster of peaks surrounded by vistas of plains. Hence inland water bodies rise and meander in different directions of the country resulting in heterogeneous habitats yielding a host of freshwater fishes. As the different types of marine and freshwater fishes are manifold, an investigation into the nature and constituents of various species from a chemical standpoint was initiated by Lantz and Gunasekera (1957). Their paper was with a view to rendering possible a better commercial utilization of fishes. The present work is an extension of the above with necessary deviations. Lantz and Gunasekera (1957) had published results of 30 species of Sri Lanka fishes. The present paper introduces results of 5 species and investigations are being continued to cover other species. Investigations appearing in this paper were on fish samples obtained from different sales points in Colombo.

Distribution of Cu, Zn, Pb and Cd in some recent molluscan shells from Lake Mariut sediment

Shells and shell fragments were the principal constituents of the core sediment taken from LakeMariut. Their trace metals were studied to assess their contribution to environmental adjustment. The results indicated that the shells of Biomphalaria alexandrina, Mercierella enigmatica and Melanoida tuberculate contain higher amounts of Cu and Zn than the widely distributed shells of Lucina sp. and Cerastoderma edule. The Pb contents found in different types of shells were higher than the other metals. The Cd contents found in different shell types were the most important fraction in comparison to the total Cd in the sediments of the lake. The relationship between the concentrations of trace metals and mineralogical analysis revealed that lead tended to be more concentrated in aragonite than in calcite.

Use of crude salt in rearing of freshwater giant prawn, Macrobrachium rosenbergii (de Man) larvae

Three different types of culture media: (i) 100% brine (B 100 ), (ii) 75% brine and 25% crude salt (B 75 CS 25 ), and 50% brine and 50% crude salt (B 50 CS 50) were tested to evaluate the possible use of brackish water reconstituted from the crude salt for the production of M. rosenbergii post-larvae. The production rate of 25.26±0.20 PI/l with a corresponding survival rate of 84.20±0.66% was significantly higher (P<0.05) for the larvae reared on B100 than that of 22.10±0.57 Pl/l with a corresponding survival rate of 73.68±1.89% on B50CS50. Larvae cultured on B75CS25 did not show any significant difference (P<0.05) in production as well as in survival of post-larvae than that on B100. The result shows that, for rearing of prawn larvae, use of brine can be replaced up to 25% without any undue reduction in production of post-larvae. However, the production as well as survival rate of post-larvae with 50% replacement (B50CS50) is also appreciable. It is assumed that the mineral constituents of natural seawater might have some triggering effects on prawn larvae in closing their larval cycle.

Concentration and distribution of heavy metals (lead, cadmium, chromium, copper, nickel, zinc) in Karachi shore and offshore sediments

A study to measure the heavy metal pollution level in the sediment of coastal and offshore area indicates that high concentration of heavy metals were found around Manora channel and eastern coast of Karachi. In comparison with coastal areas, relatively low concentration of heavy metals was recorded in the offshore area. The result shows that sewage and industrial wastes are the main source of heavy metal pollution in the coastal area. The concentration of heavy metals in the sediments is as follows: Chromium 10.4-33.69, nickel 13.3-47.6, lead 10.0-39.04, cadmium 0.08-0.21, zinc 7.4-73.2 and copper 9.44-18.56 mg/kg. In the offshore areas strong correlation was observed between copper and organic carbon, and calcium carbonate and cadmium. In the shore area such correlation has been recorded among nickel, chromium, zinc, and chromium and copper. The Karachi. coast is viewed as moderately polluted when compared to other continental coastal areas.

Hydrographical conditions and benthic assemblages in the Suez Gulf, Egypt

The coastal development and human activities along the Suez Gulf leading to sedimentation, degrade the quality of water, disturbing the natural structure and functions of aquatic communities. The Suez Gulf is a large semi-closed area with a 346 km long coastline on the western beach side. The prevailing physicochemical parameters in shallow intertidal waters were measured seasonally over the year. Benthic faunas in the sampling sites were studied indicating their regional distribution in relation to the impact of different environmental parameters in the intertidal region. The concentration of copper in seawater reached high level at St. IV (4.57 ug/1), which is exposed to sewage and petroleum hydrocarbons. The grain size of the sediment is a determining factor for the organic carbon concentration and the sandy substrate enhances organic matter degradation processes. A large number of oil fields are present along the western coast of the Suez Gulf, therefore, cadmium and organic matter appeared to be high. The values of pH did not vary greatly among the different sampling sites. It was high at EI-Ein, El-Sukhna and Ras-Shukeir due to the disposal of mainly acidic sewage and industrial effluents of the two stations Adabiya and Ras-Gharib respectively. The macrobenthos included 71 species embraced mainly from Mollusca (53.5% Gastropoda and 12.7% Bivalvia) and the other invertebrates included 7 groups namely, Rhizostoma, Polychaeta, Cirripedia, Amphipoda, Isopoda, Decapoda and Echinodermata. The distribution of benthos is affected by the temperature and salinity of seawater. The concentration of organic matter in seawater and in sediments in shallow waters shows high values in the central part of the Gulf of Suez.

Water quality of two semi-closed areas in the United Arab Emirates Coast along the Arabian Gulf:a comparative study

A comparative study was carried out between the two biggest creeks along the Arabian Gulf coast of the United Arab Emirates to evaluate impacts of sewage and industrial effluents on their hydrochemical characteristics. Surface and bottom water samples were collected from Abu Dhabi and Dubai creeks during the period from October 1994 to September 1995. The hydrochemical parameters studied were: temperature (21.10-34.00°C), salinity (37.37-47.09%), transparency (0.50-10.0 m), pH (7.97-8.83), dissolved oxygen (1.78-13.93 mg/l) and nutrients ammonia (ND- 13.12,ug-at N/1), nitrite (ND-6.66 ,ug-at N/1), nitrate (ND- 41.18 ,ug-at N/1), phosphate (ND- 13.06 ,ug-at P/1), silicate (0.68-32.50 ,ug-at Si/1), total phosphorus (0.26- 21.48 ,ug-at P/1), and total silicon (0.95- 40.32 ,ug-at Si/1). The present study indicates clearly that seawater of Abu-Dhabi Creek was warmer (28.l2°C) than Dubai (27.56°C) resulting in a higher rate of evaporation. Owing to more evaporation, salinity levels showed higher levels at Abu Dhabi (43.33%) compared to Dubai (39.03%) seawater. The study also revealed higher secchi disc readings at Abu Dhabi Creek (4.68 m) as compared to Dubai Creek (2.60 m) suggesting more transparency at Abu Dhabi Creek. Whereas, seawater of Dubai exhibited higher levels of pH (1.03 times), and dissolved oxygen (1.05 times) than Abu Dhabi seawater due to an increase in productivity. Meantime, seawater of Dubai showed higher tendency to accumulate ammonia (8.22 times), nitrite (10.93 times), nitrate (5.85 times), phosphate (10.64 times), silicate (1.60 times), total phosphorus (3.19 times), and total silicon (1.54 times) compared to Abu Dhabi seawater due to the enrichment of seawater at Dubai with domestic sewage waters which has distinctly elevated the levels of the nutrient salts particularly in inner-most parts of the creek leading to eutrophication signs. The changes occurred in the receiving creek water of Dubai as a result of waste-water disposal that have also reflected on the atomic ratios of nit: Effect of pollution rogen: phosphorus: silicon.

Heavy metals in certain commercially important finfish off Mahim in Mumbai coastal waters

The coastal water of the metropolitan city of Mumbai has deteriorated due to the indiscriminate discharge of untreated sewage and industrial waste in huge quantities. Mahim creek is one such locality surrounded by a large number of industrial units discharging heavy metals. The accumulation of the heavy metals Cu, Cd, Zn and Pb in finfishes (Coilia dussumeri, Lepturacanthus savala, Harpodon nehereus and Johnieops elongates) from this locality along with that in the sediment was studied. The rate of accumulation of Cu was high compared to Cd, Zn and Pb. A gradual increase in the bioaccumulation of heavy metals was noticed in fishes with increase in average body weight and length, perhaps due to biomagnification. A declining trend in concentration of heavy metals horizontally from inshore to offshore was observed in these fishes.

Diversity indices of selected macrobenthos in Karanja Creek (District-Raigad), Maharashtra, west coast of India

The diversity indices can be used as a good measure for studying the effect of industrial pollution because industrial wastes and sewage almost always reduce the diversity of natural systems into which they are discharged. A measurement of diversity often provides a better index of pollution than a direct measurement of pollutants. The assessment of macrobenthos diversity with respect to diversity indices reflects the marine population and habitat disturbance, and also serves as an important indicator of environmental conditions. The present study was designed to investigate the diversity indices of selected macrobenthos at two ecologically distinct locations on the Karanja creek (District - Raigad), Maharashtra, west coast of India. Results on various diversity indices like Index of Frequency (F) or Importance Probability (Pi), Index of Dominance (c), Rarity Index (R), Shannon's Index of General Diversity (H¹) Margaf’s Richness Index (R sub(1)) and Evenness Index (e) did not vary significantly. This demonstrates that at present, Karanja creek harbours varied forms of macrobenthic community showing no effect of human disturbance, but in future, measures must be taken for the protection and conservation of macrobenthic community of the creek.

Ice storage characteristics of fresh and brined shark fillets

Ice storage characteristics of fresh and brined fillets from fresh shark (Carcharias melanopterus) were studied in and out of contact with ice for more than two weeks. Changes occurring in biochemical constituents, physical qualities and bacterial counts of the fillets are reported. Shelf life of brined fillets out of contact with ice was considerably longer than that of control samples tinder similar conditions. Icing of shark fillets is suggested as a method for the removal of urea on a commercial scale.

Seasonal changes in the biochemical composition of liver in Garra mullya (Sykes)

Seasonal changes taking place in the biochemical constituents of liver of G. mullya are reported. An inverse relationship was noticed in the variation of fat and water. Maximum fat contents were observed during june-july. Reserve fat was utilized through gluconeogenesis during the spawning months. Protein and glycogen percentages were comparatively higher in liver than in the muscles and gonads. Decline in the glycogen content was associated with spawning during July to November. Nutritive values have shown more energy contents in the liver during pre-spawning months.