Observations on the histological alterations in various tissues of EUS affected fish, Channa striatus (Bloch)

Histopathological investigations have been made on the skin, liver, kidney and intestine of, (EUS) affected fish, Channa striatus and following anomalies have been observed. Varying degree of degeneration has been observed in the epidermis, dermis, hypodermis and underlying musculature. In all the cases, the skin lost the scales and epidermis completely at the site of infection. The dermis along with hypodermis showed the signs of necrosis. Necrosis also took place in subcutaneous layer underlying the hypodermis. Necrotization and formation of granulomas can clearly be seen in circular and longitudinal muscle layers. The liver exhibited the loosening of tissue and distension in cell bodies. While in case of kidney, shrinkage took place in all the components. Similarly, the intestinal villi got necrotised alongwith their constituent elements.     

Distribution of enzymes of glycolysis and gluconeogenesis in fish tissues

Gluconeogenesis in fishes has been demonstrated in whole animals and liver preparations. However, at present, the relative physiological importance of possible substrates such as lactate, pyruvate and amino-acids or the precise sites of gluconeogenesis are unclear. In mammals, gluconeogenesis takes place in the liver and kidney, and the same could occur in fishes although it has been proposed that fish red muscle is also capable of reconverting lactate (derived from white muscle) to glucose. In this present study, the activities of 3 key glycolytic (hexokinase, phosphofructokinase and pyruvate kinase) and 2 key gluconeogenic (fructose diphosphatase and phosphoenolpyruvate carboxykinase) enzymes were investigated in tissues of the rainbow trout Salmo gairdneri, the cod Gadus morhua, and the plaice Pleuronectes platessa in order to elucidate the relative glycolytic/gluconeogenic capacities of the individual fish tissues. The glycolytic enzymes were found in all tissues, the relative potential being skeletal muscle>heart, brain >kidney, gills>liver. The gluconeogenic enzymes were not present in all tissues, and were mainly concentrated in the liver and kidney. Hence the results indicate that the liver, and to a lesser degree, the kidney are the major sites of gluconeogenesis in fishes, and that the process is unlikely to occur in skeletal muscle.     

Mercury induced architectural alterations in the gill surface of a fresh water fish,Channa punctatus

An air-breathing fresh waterfish Channa punctatus was exposed chronically to sublethal concentrations of mercuric chloride and the respiratory surface was found to exhibit lesions, lifting of lamellar epithelium and increased number of mucus gland openings. The damage increased with increase in the concentrations. The gill surface was studied using scanning electron microscope.     

Mercury bioaccumulation in arthropods from typical community habitats in a zinc-smelting area

This study assessed the enrichment of mercury in the food web from the different community habitats in a zinc-smelting area of China. We used a nitrogen stable isotope technique to analyze trophic level relationships among arthropods and found that the first trophic level consisted of plants in the different community habitats, the second trophic level consisted of herbivores such as locusts and grasshoppers (primary consumers), and the third trophic level included spiders and mantes (secondary consumers). Mercury enrichment in the primary consumers was not evident, but enrichment in arthropods of the third trophic level was significant. The average of enrichment coefficients in spiders and mantes was greater than 1. The δ¹⁵N values indicated that mercury concentrations accumulated from primary producers to top carnivorous arthropods increased. In this zinc-smelting area, the biological amplification of mercury in the food web is significant. It is reasonable to assume that humans, located at the top of the food chain, are exposed to biomagnified levels of mercury.     

第二松花江鱼及蚌汞含量现状及演变规律

为了解第二松花江在彻底切断汞污染源20年后的鱼体汞污染现状，于2003—2004年共采集鱼样10种158条及蚌样28个，测定鱼和蚌中的总汞含量，并搜集20世纪70年代第二松花江鱼样和蚌样的汞污染资料，分析其演变规律。测定表明，各种鱼类的总汞平均含量未达到背景值，有部分样品超标。鱼体汞含量，从上游到中下游，呈增长趋势，之后又向下游递减。该江目前鱼类总汞污染水平主要受沉积汞影响。各种不同鱼类间，底栖鱼类的总汞含量高于生活在水层中上部的鱼类，肉食性鱼类的汞含量高于杂食性和植食性鱼类。在所测定的鱼类中，只有鲫鱼的汞含量与其体长和体质量有相关关系。所测定的鱼样中，有部分鱼样的总汞含量超过了国家食品卫生标准，这说明第二松花江的汞污染还没有完全消除。     

Lysozyme and chitinase in blood and lymphomyeloid tissues of marine fish

The enzyme lysozyme (muramidase) has a degrading effect on chitin, but chitinase is more effective in this respect. Both enzymes occur in fish, but their distribution and function are poorly known. Activities of lysozyme and chitinase were measured in body fluids and tissues of marine fish. Lysozyme was estimated by a plate method, chitinase by a viscosimetric method with glycol chitin as substrate. pH optima and other characteristics were studied. Lysozyme was found in lymphomyeloid (haematopoietic) tissues of chondrichtyan fish (rays, shark, Chimaera monstrosa) and in the plasma and lymph of certain teleosts. Chitinase occurred in lymphomyeloid tissues (except thymus) of chondrichthyans and teleosts, and in the plasma and lymph of teleosts. The results indicate that these enzymes are normal components of fish blood. Probably they are produced by the granulocytes, white blood corpuscles rich in lysosomes. The enzymes might have defence functions in fish blood. Lysozyme is bacteriolytically active while chitinase possibly offers protection against chitincontaining parasites. Very high chitinase activity was found in the pancreas of C. monstrosa. The pancreatic enzyme probably has a digestive function.     

Mercury concentrations in the surface sediments of the intertidal area along the west coast of Peninsular Malaysia

Total mercury (Hg) levels in the intertidal surface sediments along the west coast of Peninsular Malaysia were analysed by using heat vaporization method. Total Hg levels in these sediments ranged from 3.00 to 201?µg?kg^?1 dry weight with a mean concentration of 60.0?µg?kg^?1 dry weight. More than 90% of the samples studied have the total Hg concentrations less than 150?µg?kg^?1 dry weight. Compare with the regional data and sediment quality guidelines, the Hg contamination in the intertidal area along the west coast of Peninsular Malaysia was not serious, except for a few sites that might have received anthropogenic Hg in the samples collected between 1999 and 2000. It is suggested that a similar study of heavy metals in the sediments of the west coast of Peninsular Malaysia be conducted regularly.     

Removal of Mercury from Polluted Waters by the Water Hyacinth (Eichhornia crassipes)

The uptake of mercury by water hyacinth (Eichhornia crassipes) was studied in an outdoor experiment for 25 days at different metal concentrations. the removal of mercury from the water and uptake by plants was very effective during the first hours and decreased rapidly thereafter. the uptake of mercury was directly proportional to the initial concentration in the water. the highest concentrations were found in plant roots. According to the results, water hyacinth could be used for treatment of mercurial waste waters.     

Removal of Mercury from Polluted Waters by the Water Hyacinth (Eichhornia crassipes)

The uptake of mercury by water hyacinth (Eichhornia crassipes) was studied in an outdoor experiment for 25 days at different metal concentrations. the removal of mercury from the water and uptake by plants was very effective during the first hours and decreased rapidly thereafter. the uptake of mercury was directly proportional to the initial concentration in the water. the highest concentrations were found in plant roots. According to the results, water hyacinth could be used for treatment of mercurial waste waters.     

A better method for standardizing vitellogenin content of fish tissues

Vitellogenin (vtg) concentrations were measured in plasma and liver samples from 12 hybrid Tilapia oreochromis niloticus x O. aureus to compare concentrations in these tissues. The results were calculated under two different normalizations: volume per gram of sample used (similar to normalization usually published in the literature and typically used for ELISA) and volume per total protein (similar to normalization used in polyacrylamide gel electrophoresis; PAGE). It was observed that the normalization procedure used in PAGE (per gram total protein) minimized the method detection limit by about 1000 and 2500 times in plasma and liver respectively, compared to the normalization usually reported in the literature. It was also observed that normalizing per gram total protein makes it possible to eliminate a potential problem of accidental dilution of plasma samples during sample collection. Moreover, the normalization on a per gram of total protein makes it possible even to compare results from the two different methods namely PAGE and ELISA. It also allows comparison between different tissues. Using the normalization procedures as used in PAGE (per gram total protein) for liver and the normalization method as reported in literature for ELISA (per volume of sample used), it was observed that liver samples had higher vtg levels (mean: 62 microg vtg/g) compared to the corresponding plasma samples (mean: 0.24 microg vtg/ml). However, when both results were normalized per gram total protein all but one liver sample were lower (62 microg vtg/g) than the corresponding plasma concentrations (mean = 246 microg vtg/g).     

Inbreeding avoidance in a poeciliid fish (Heterandria formosa)

Polyandry is hypothesized to give females an opportunity to avoid inbreeding through postcopulatory selection mechanisms if precopulatory inbreeding avoidance is not possible, for example, because of forced matings. Here, we report a postcopulatory, prefertilization, inbreeding avoidance mechanism in the least killifish, Heterandria formosa, a species in which males can force matings. Females had 50% less sperm in their oviducts and ovarian cavities after mating with a sibling compared to a mating with a nonsibling male. Neither sex showed inbreeding avoidance in a dichotomous precopulatory mate choice test or during mating trials. Females in this species invest substantially in each offspring after fertilization (matrotrophy), whereas males invest little more than sperm. Based on theory, females should therefore be more likely than males to avoid inbreeding in this species. We suggest that females do this by reducing the amount of sibling sperm in their reproductive system. However, the possibility that males invested more sperm to nonsiblings could not be ruled out. In a fertilization success experiment, the first male to mate with a female sired all the offspring in most cases, even if it was a sibling. However, large females were more likely to carry offspring of multiple males. Possibly female sperm storage sites were filled by the first male, and only large females had space for the second male's sperm.     

Oogenesis and spawn-formation in the pigmy lion fish Dendrochirus brachypterus (Pteroidae)

Dendrochirus brachypterus possesses a special type of ovary in which the germinative epithelium surrounds a spongy stroma hanging in the lumen. The inner side of the ovarian wall is covered by a special type of epithelium that produces a gelatinous envelope around the gametes (spawn) during reproduction. In general, oogenesis in the lion fish resembles that of other teleosts, the characteristic difference being in the formation of ovigerous peduncles-protrusions of the spongy stroma, each of which bears a single oocyte. During oogenesis the oocytes rise above the germinal epithelium, enveloped in their follicular epithelia. The larger the oocyte the greater the length of its peduncles and the further its position from the germinal layer (Fig. 3). During this phase of development, a marked multiplication of yolk granules occurs; they increase their diameter and finally homogenize at ovulation. Under favorable thermal conditions, oogenesis continues all year round. The peduncular growth of oocytes enables the growing egg cells to move away from the egg-producing surface, thus making space available for the ovary to produce more eggs. This ability should have a survival value for these fish if we take into consideration that the most vulnerable stage in their life history is that of planktonic larvae (Fishelson, 1975).     

松花江沉积物中总汞及汞形态的演化

为进一步掌握松花江汞污染的动态,通过2005年的样品采集与分析,结合有关历史数据,研究了松花江表层沉积物中汞的分布与变化.结果表明,在切断汞的主要污染源之后,第二松花江和松花江干流沉积物中汞含量均呈明显下降趋势;松花江18个断面沉积物中总汞质量含量较低,平均为0.172 mg·kg-1,除哈达湾、哨口和白旗江段外,大部分江段已处于背景水平.各江段沉积物中汞的形态分布差别较大,第二松花江沉积物中汞以过氧化氢溶态和王水溶态为主,而干流江段则以酸溶态和过氧化氢溶态为主;与20世纪80年代相比,除了王水溶态汞以外,2005年哈达湾、哨口和白旗3个代表性断面酸溶态、碱溶态及过氧化氢溶态汞含量均大幅下降.说明经过多年的环境治理以及水体的自然净化作用,松花江的汞污染已经得到了有效控制.     

Analysis of the mutual attraction in the association of the fish Cryptocentrus cryptocentrus (Gobiidae) and the shrimp Alpheus djiboutensis (Alpheidae)

The mutual attraction between the fish Cryptocentrus cryptocentrus and the shrimp Alpheus djiboutensis has been investigated experimentally. The fish is attracted to its partner visually, the shrimp is attracted chemically. The mutual attraction is reinforced by the strong negative phototactic reaction of both partners, orienting them towards the burrow.     

Associative behavior of the fish Cryptocentrus cryptocentrus (Gobiidae) and the pistol shrimp Alpheus djiboutensis (Alpheidae) in artificial burrows

Observations and experiments on the associative behavior of the fish Cryptocentrus cryptocentrus (Valenoiennes) and the shrimp Alpheus djiboutensis De Man from the Red Sea were carried out in artificial burrows. A signal system, bringing about correlated behavior in fish and shrimp, consisted of antennal contact of the shrimp with the fish, tail undulations by the fish and, finally, emergence of the shrimp. The shrimp emerged from the burrow only in the presence of the fish. A constant antennal contact was maintained by the partners while the shrimp was outside the burrow. Emerging from the burrow, the shrimp pushed the fish towards the entrance. Following visual stimulation, the shrimp always retreated back into the burrow with the fish. However, the further back the shrimp was located inside the burrow, the less intense was its retreat with the fish. In the absence of the fish, visual stimulation of the shrimp had no effect. Cleaning of fish by shrimp was observed within the burrow.     

Comparison of heavy metal concentrations in fish samples from three fish farms (Eastern Mediterranean) utilizing antifouling paints

Although aquaculture is considered the fastest growing food production industry, nevertheless there is little information regarding pollutant levels in cultured fish. Samples of cultured sea bass – Dicentrarchus labrax (Linnaeus, 1758), sea bream – Sparus aurata (Linnaeus, 1758), and sharpsnout sea bream – Diplodus puntazzo (Walbaum, 1792) from three fish farms located in the Eastern Mediterranean which utilized antifouling paints on the nets were analyzed for quantitative determination of zinc (Zn), chrome (Cr), and copper (Cu) in the gills, the liver, and the muscle separately for each tissue and fish. The results show that the highest levels of zinc (up to 29.6 mg kg^?1 dry wt) were found in the gills of all samples of sea bream and sharpsnout sea bream while in the samples of sea bass, the highest levels of zinc and chrome were found in the liver (up to 39.3 and 13.8 mg kg^?1 dry wt, respectively). Insofar, as copper is concerned the highest exposure was found in the liver of sharpsnout sea bream (up to 5.49 mg kg^?1 dry wt). The results indicate that the use of antifouling paints in aquaculture practices are a significant source of chemical pollution in cultured fish and poses a risk to the exposed organisms.     

Mercury in surface waters of a macrotidal urban estuary (River Adour, south-west France)

Surface waters were collected in the River Adour estuary (south-western France) during different sampling periods from 1998 to 2001 in order to investigate the phase distribution and speciation of methylmercury (MeHg⁺). Although a high variability is observed, significant higher average concentrations of total MeHg⁺ (dissolved and particulate) are measured during the warm seasons, at 4.40±8.18 pM and 3.90±1.87 pM for July 1998 and September 1999, compared with the winter seasons, with concentrations at 0.99±2.85 pM and 1.00±1.75 pM for February 1998 and February 2001, respectively (one-tailed t-test, P=0.01). The seasonal variations are explained with enhanced bacterial activity during summer and sedimentation/resuspension phenomena. Additionally, signi-ficant longitudinal variations of the MeHg⁺ concentrations are observed. The highest levels in both dissolved and particulate fractions are found within the downstream urban estuarine area. This can be explained by the high methylation potential of the sediments, but direct anthropogenic inputs of MeHg⁺ from specific discharge points cannot be neglected. Biogeochemical factors like phytoplankton biomass and salinity also show a relationship with MeHg⁺ partitioning in the surface waters of the Adour estuary.     

Nearshore distributional gradients of larval fish (15 taxa) and planktonic crustaceans (6 Taxa) in Hawaii

Fifteen taxa of fish larvae (most identified to species) and 6 taxa of crustaceans (most identified to species) were studied in zooplankton samples collected 0.2, 0.5, 1.0 and 3.0 km off the leeward coast of Oahu, Hawaii in May and July 1975. The following distributional patterns were elucidated: inshore (2 spp); inshore-neritic (2 spp); neritic (7 spp); and offshore-neritic (7 spp). Three of these 18 species had age-related differences in behaviour that led to age-dependent distributional patterns, and 4 further species had a random distribution. All abundant types of fish larvae were either oceanic as adults or were hatches from the demersal or brooded eggs of reef species. The larvae of reef fishes with pelagic eggs were not abundant in the nearshore region sampled and were probably to be found more than 3 km offshore. The offshore-neritic distributional pattern evidently resulted from relatively passive movement with currents. In contrast, maintenance of inshore and neritic patterns probably required relatively active swimming by the animals. The current regime, including a tidal eddy and possible nearshore upwelling, probably helped maintain the inshore and neritic patterns of such animals. The limited area occupied by these inshore coastal plankton communities could make them particularly vulnerable to environmental changes, including anthrogenic ones.     

Biogeochemical characterization of surface waters in the Aljustrel mining area (South Portugal)

Aljustrel mining area (South Portugal) is a part of the Iberian Pyrite Belt and encloses six sulfide mineral masses. This mine is classified of high environmental risk due to the large tailings’ volume and acid mine drainage (AMD)-affected waters generated by sulfides’ oxidation. The use of biological indicators (e.g., diatoms) revealed to be an important tool to address the degree of AMD contamination in waters. Multivariate analysis has been used as a relevant approach for the characterization of AMD processes. Cluster analysis was used to integrate the significant amount and diversity of variables (physicochemical and biological), discriminating the different types of waters, characterized by the high complexity occurring in this region. The distinction of two main marked phenomena was achieved: (1) the circumneutral-Na-Cl water type (sites DA, PF, BX, BF, RO, CB), expressing the geological contributions of the Cenozoic sediments of Sado river basin, with high diatom diversity (predominating brackish diatoms as Entomoneis alata); and (2) the acid–metal-sulfated water type (sites BM, JU, RJ, AA, MR, BE, PC, AF), reflecting both the AMD contamination and the dissolution of minerals (e.g., silicates) from the hosting rocks, potentiated by the extremely low pH. This last group of sites showed lower diatom diversity but with typical diatoms from acid- and metal-contaminated waters (e.g., Pinnularia aljustrelica). In addition to these two water types, this hierarchical classification method also allowed to distinguish individual cases in subclusters, for example, treated dams (DC, DD), with alkaline substances (lime/limestone), that changed the physicochemical dynamics of the contaminated waters.