Persistence of Gnathostoma hispidum in chronically infected rats

Gnathostomiasis by Gnathostoma hispidum has occurred mainly in southern and western areas of Japan since 1980. In all cases, patients had eaten live loaches, freshwater fish imported from southeast Asia. Chief symptoms were creeping linear skin eruptions and eosinophilia, both of which disappeared in most patients within three months after the onset, and never recurred thereafter. In order to study how gnathostome larvae may survive and behave in humans, rats were infected with gnathostome larvae. Loaches were purchased in city markets in Fukuoka. Gnathostome larvae (G. hispidum) were recovered from the fish and fed to rats. They were killed at intervals of one and six months and one, two and three years postinoculation. Encysted larvae were found in the muscles of all rats and recovered larvae were all viable. A migrating larva was observed in muscle tissue from one rat that was killed three years postinoculation. In histological sections, walls around encysted larva were much thinner in a rat killed three years postinoculation than in a rat killed one month postinoculation.     

Biotic interactions enhance survival and fitness in the caddisfly <Emphasis Type="Italic">Micropterna sequax</Emphasis> (Trichoptera: Limnephilidae)

Fish-based index of biotic integrity (F-IBI) is widely used to assess river ecosystems. With survey data from the Yellow River fishery resources in the 1980s and 2008, fish composition and abundance, vertical distribution, trophic structure, reproductive guilds and tolerance in the river’s upstream, midstream, downstream, and estuary were examined, and F-IBI systems were established for each reach to assess river ecosystem health. Results showed that compared to the 1980s, the number of fish species in 2008 sharply declined in the midstream and downstream reaches, percentage of benthic fish species decreased in upstream and estuary, the number and percentage of omnivorous species decreased in all reaches, and percentage of tolerant fish species increased 15 times in upstream but decreased in midstream and downstream. The F-IBI scores in the four reaches in the 1980s were all higher than those in 2008 and decreased from upstream to estuary; the healthy conditions indicated by F-IBI scores in the 1980s were “good,” “fair,” “poor,” and “fair” from upstream to estuary and “degraded” to “poor” in all the reaches in 2008. This indicated that the river ecosystem has degraded from the 1980s to 2008. This was also shown by variations in water chemistry.     

Ecology and role of zooplankton in the fishery of Lake Naivasha

Taxonomic composition, distribution, community structure and seasonality of Lake Naivasha zooplankton between 1978 and 1980 are described. The ecological status of the zooplankton in relation to prevailing ecological factors and the lakes fishery are discussed. Species composition of the zooplankton community in Lake Naivasha has been remarkably constant since first observations between 1929 and 1931. The community structure and distribution of the zooplankton in the lake varied little from July 1978 to July 1980, however, there was evidence of species succession among the larger zooplankters, especially the cladocerans. In the littoral area zooplankton contribute significantly to the food and production of juvenile fish. There is an absence of fish zooplanktivores in the limnetic area of the lake. Consequently the limnetic zooplankton is not utilised by higher trophic levels.     

IV. Variation in fungicide tolerance: Comparisons between isolates of Erysiphe graminis f. sp. hordei tolerant and sensitive to the fungicide tridemorph

Forty-five single pustule isolates of barley powdery mildew taken at random from tridemorph treated and untreated plants were maintained in culture on leaf segments of barley cv. Golden Promise placed on agar containing benzimidazole. In repeated assays for tridemorph tolerance over a 10 month period, tolerance was found in 25 of 36 isolates from treated plants, and remained stable in all but four of the isolates wherein tolerance was lost after varying lengths of time. A negative correlation was found between pathogenicity and tolerance. The germination of tolerant isolates was less depressed than the sensitive on treated seedlings, but no differences between isolates were found on untreated seedlings. Colony growth of all isolates was slower on treated than untreated seedlings. On plants of several cultivars kept in growth rooms, mildew progressed more rapidly on treated barley when tolerant isolates were used as inoculum. Visible disease symptoms spread most rapidly on isolated, untreated plants, and most slowly on isolated treated plants, irrespective of the isolate. Disease on treated plants progressed more rapidly when untreated plants were adjacent, suggesting that interactions take place between pathogen populations on treated and untreated plants.     

Multivariate morphometric analysis of Pacific herring, <Emphasis Type="Italic">Clupea pallasii</Emphasis> (Clupeiformes: Clupeidae) in Sakhalin waters: Investigation of intraspecific differentiation

In the Pacific herring, Clupea pallasii, eight samples of spawning, mature fish (collected in 1978 and 1981) and six samples of immature fish individuals (collected in 1979, 1980 and 1984) were analyzed. Mature fish were analyzed by 24 conventional morphometric characters or morphometric indices. By means of discriminant and factor analyses (principal component mode) the existence of differentiating groupings of vector scores was found that have obvious biological meaning as local Pacific herring stocks. In concordance with former morphobiological and genetic data, current multivariate observations supported the existence in the surveyed area of Sakhalin waters of at least three stocks. One of them is the Sakhalin-Hokkaido local stock of Pacific herring, which in the past provided the bulk of herring catches in the region and showed a distinct and sharper morphometric differentiation as compared with other herring assemblages.     

Partial recovery of moorland pools from acidification: Indications by chemistry and diatoms

In 1994 the atmospheric deposition on three moorland pools in The Netherlands was only one third of its value in 1980. The effects of this reduction on these moorland pool ecosystems were examined by regular sampling of surface water chemistry and diatoms between 1979 and 1994. Moreover, diatom samples taken at irregular intervals between 1916 and 1978 were studied. In the pools Gerritsfles and Achterste Goorven, the median sulphate concentrations in 1994 were only one third of recorded values in 1980. Peak concentrations of sulphate were found after extremely dry summers. In the pool Kliplo, with an initially low concentration of sulphate, there was 16% increase of the concentration over the same period. Ammonium increased significantly in Kliplo and showed large variations in the other pools. Redundancy analysis showed that sulphate was the most important variable for the distribution of diatoms. As a consequence, the abundance of the acidification indicatorEunotia exigua in 1994 was only 25% of its value in 1980 in Achterste Goorven and 14% in Gerritsfles. Peaks ofE. exigua were found after drought periods. In Kliplo no clear change was observed. In 1994 the diatom assemblages of Achterste Goorven were much more similar to those of 1916–1925 than they were in 1980. In Gerritsfles a new situation, without historical analogue, developed. Overall, the large reduction of SO_x-deposition had very positive consequences for the diatom assemblages.     

The dynamics of a population of roach (Rutilus rutilus (L.)) in a shallow lake: is there a 2-year cycle in recruitment?

Recruitment success of roach varied dramatically between 1978 and 1985 in Alderfen Broad, a small lake in eastern England. All size classes of roach feed to a significant extent upon zooplankton, but the underyearling fish have the greatest effects upon the abundance, species composition and mean size of zooplankton. During years of good recruitment (1979, 1981, 1983 and 1985) when the 0 + age group was abundant, they showed poor growth as a result of the depression of their prey populations. Older fish also tended to grow poorly in these years and may have been less fecund the following year. In years of poor recruitment (1980, 1982 and 1984), with the release of the depressive effect upon the zooplankton exerted by underyearling fish, the older size classes tended to grow well with higher fecundity the following season, giving rise to good recruitment of underyearling fish, even when the number of spawners was low. The evidence indicates that there is a 2-year cycle of roach recruitment in Alderfen and this will be described.     

Succession and soil development in man-made coastal ecosystems at the Baltic Sea

By the creation of Køge Bay Seaside Park in 1978 the opportunity was given to study the establishment of vegetation and primary succession in a man-made coastal area. As the soil consists of marine material from the Baltic Sea, no organic matter or seedbank was present. The first steps of primary succession were followed in 1980, when the initial inventories of flora immigration and soil development were carried out in coastal grasslands and plantings. The surveys were repeated in 1992 and 1993. Except for the planted woody species and a few sown grasses, all other species of plants have reached the area through natural dispersal of diaspores. The total number of species in the permanent plots has increased from 26 in 1980 to 91 in 1993. The results indicate that this number will continue to increase in the coming years until a certain level. Then it will probably decrease as a result of competition from woody species, unless the vegetation is kept in a steady state by disturbances or management. Today the area is very far from the initial situation, and the off-shore barrier has changed towards a landscape dominated by small groves and grasslands of an urban common type.     

Mortality of pre-smolt Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., caused by fluctuating water levels in the regulated River Nidelva, central Norway

The river Nidelva, situated in central Norway, is regulated for production of electricity. Water discharge may vary from 150 to 30 m3 s -1 over a period of 10 min at the outlet of the power stations. The water level then sinks 50 cm during the next 30 min. The Nidelva produces both salmon and trout. Water fluctuations were found responsible for large losses of O+ salmon and trout. The recruitment of salmon was concluded as satisfactory, while recruitment of trout was reduced as a result of stranding.     

The composition of the coastal fish fauna around Elephant Island (South Shetland Islands, Antarctica)

The composition of the coastal fish fauna around Elephant Island (northern South Shetland Islands) was investigated during seven bottom trawl surveys of FRV “Walther Herwig”, FV “Polarstern” and FRV “Yuzhmorgeologiya” from 1981 to 1998. Low-Antarctic (or lesser or peri-Antarctic) fish species were the predominant element of the coastal fish fauna. Large-scale fishing from 1978 to 1981 reduced stock sizes of the most abundant species Champsocephalus gunnari and Notothenia rossii to the extent that only a small fraction of the initial stock remained. After the period of intensive fishing, Gobionotothen gibberifrons became the most abundant species around the island. The by-catch species, which had probably been less affected by harvesting, recovered by the end of the 1980s/beginning of the 1990s. Fish biomass was highest in the 100- to 400-m depth range. An MDS plot revealed the existence of five groups of species that overlapped in their distribution to some extent. One important factor that separated the five groups was depth. Other factors that might have been important in structuring the vertical distribution of the fish fauna, such as bottom topography and sediment type, could not be investigated. Species composition was dominated by a few abundant low-Antarctic species. In four of the five groups, G. gibberifrons was by far the most abundant species, after C. gunnari and N. rossii had been largely eliminated due to fishing. Only in the 100- to 200-m depth range was C. gunnari more abundant than G. gibberifrons. In the 400- to 500-m depth stratum, a high-Antarctic species, Chionodraco rastrospinosus, and Lepidonotothen squamifrons, a species of Patagonian origin which lacks antifreeze glycopeptides, gained some importance. Species richness showed a positive trend with increasing depth. Evenness and Hill's N1 index were highest in the shallowest and deepest depth strata. Hill's N2 index was lowest in depth strata 3 and 4, which had the most even distribution of the abundant fish species. Accepted: 21 May 2000     

1980—2007年大亚湾鱼类物种多样性、区系特征和数量变化

根据2004—2005年大亚湾海域底拖网鱼类调查数据,并结合1980—2007年的历史资料,分析了该海域鱼类的种类组成、区系特征、多样性、优势种和数量变化趋势.结果表明： 2004—2005年,大亚湾海域共记录鱼类107种,分属13目50科,以中下层鱼类的种类最多,为48种,其次是中上层和底层种类,分别为37种和21种.大亚湾鱼类区系具热带和亚热带特性,以暖水性种类占绝对优势,为97种,暖温性种类为10种.多样性指数以夏季最高（3.82）,其次是冬季（3.37）和秋季（3.00）,春季最低（2.40）.Pielou均匀度指数的季节变化情况与多样性指数相似.1980—2007年大亚湾海域鱼类群落特征发生了明显的变化：鱼类种类数减少,优势种更替明显.鱼类种类数由1980年的157种减少至1990年的110种,2004—2005年继续减少至107种;鱼类优势种由1980年以带鱼和银鲳等优质鱼为主,更替为以小型和低值的小沙丁鱼、小公鱼和二长棘鲷幼鱼为主.用包含年际变化趋势和季节性周期变化的回归模型模拟1980—2007大亚湾鱼类资源密度的变化,鱼类资源密度在1980—1999年和1990—2007年两个时期均呈下降趋势,但1990—2007年间下降幅度比1980—1999年间大;1980—1999年鱼类资源密度的季节波动幅度较平缓（振幅为0.099）,而1990—2007年的季节波动较大（振幅为0.420）,说明1990—2007年阶段大亚湾鱼类数量的季节变化更为显著.     

Can a highly invasive species re-invade its native community? The paradox of the red shiner

Red shiners (Cyprinella lutrensis) are among the most widespread, ecologically general, and environmentally tolerant fish species in North America, and are highly invasive where they have been introduced outside their native range. However, long-term data on fish assemblages showed that red shiners gradually (1980s to 2006) disappeared from creeks that are direct tributaries of Lake Texoma (Oklahoma, USA) where they are native and historically had been numerically dominant. Following a major flood in 2007, red shiners were detected anew in some of these creeks, but repeatedly disappeared and re-appeared through November 2009. Given their invasive abilities where they are not native, their failure to become re-established prompted us to examine factors that affect their apparent inability to re-invade their native habitat. We established assemblages of five common fish taxa native to Brier Creek in 12 large, outdoor mesocosm stream units. Subsequently, we introduced red shiners at two densities of 10 or 30 per unit, six replicates each, to examine potential effects of propagule pressure on establishment success. Approximately six months later, we ended the experiment and recovered all fish. Red shiners failed to become established in the experimental units, regardless of initial stocking density. They also exhibited much lower survival than other species in the native community, which not only survived well but exhibited some recruitment. Red shiner survival was significantly negatively related to the number of sunfish (Lepomis spp.) that grew to adult size in experimental units, suggesting that predation can inhibit early stages of invasion by red shiners.     

Biomanipulation development in Norway

Since 1974 several studies have been carried out in Norway to investigate the interactions between planktivorous fish, zooplankton, phytoplankton and water chemistry. Since 1978 a long-term national research program has been conducted by the Norwegian Council for Scientific and Industrial Research (NTNF). In this program several whole lake manipulations of the fish stocks have been performed to test hypotheses about trophic interactions. It was predicted that manipulations of planktivorous fish populations, might also improve water quality in lakes undergoing eutrophication. Two examples are given to illustrate the achieved results. I: Whole lake fertilization experiment (1974–1978) carried out by Langeland and Reinertsen. The results revealed the importance of top-down effects in the lake ecosystem. When cladocerans dominated, the zooplankton community was able to maintain a more or less constant phytoplankton biomass and a rather low phytoplankton production even when nutrient levels were increased. During years with rotifer dominance, algal biomass and productivity increased, despite the low amounts of added nutrients. II: Experiment performed by Reinertsen, Jensen, Koksvik, Langeland and Olsen in the eutrophic Lake Haugatjern, total elimination of the fish populations by rotenone in late 1980, resulted in a 4-fold decrease in the algal biomass. The species composition changed from the dominance of large-sizedAnabaena flos-aquae andStaurastrum luetkemuelleri to smaller, fastgrowing species and gelatinous green algae. The results are discussed in relation to management of inland waters by combined techniques of biomanipulation and reduced external nutrient supply which increase food-chain efficiency.     

国内鱼类病毒病研究进展

病毒性疾病是危害水生动物最严重的一类疾病,是水产养殖业发展的重大障碍。近年来,中国水生动物病毒病的研究取得了一定成就,但是还有许多方面的研究有待加强,有很多未知领域需要进行探索与研究。本文综述了近年来国内鱼类病毒病的研究进展,主要介绍了草鱼出血病、传染性胰脏坏死病、淋巴囊肿病、传染性脾肾坏死病、鳗鲡病毒病、真鲷病毒病等不同鱼类病毒病的临床症状、流行病学、检测手段、致病机理、防治措施以及引起该病的病原体的形态结构、理化性质等,旨在为鱼类病毒病的防治提供参考。     

Development of anthelmintic resistance in nematodes from sheep in Australia subjected to different treatment frequencies

Development of anthclmintic resistance in nematodes from sheep in Australia subjected to different treatment frequencies. International Journal for Parasitology13: 125–132. In a three year (1978, 1979, 1980) field experiment in south-eastern Australia Merino weaner sheep were exposed to one of four worm control programmes. Sheep were treated either 50–51 times, 9–12 times, 3–6 times or 1–3 times annually with anthelmintic. Thiabendazole (TBZ) was used throughout 1978 and for the initial dose in 1980, levamisole (LEV) throughout 1979 and 1980. Sheep were replaced annually each December.During 1978 in vitro egg hatch tests indicated that populations of Haemonchus contenus with resistance factors to TBZ of 10·7, 10·0, 2.5 and 1·8 respectively were selected by these treatment frequencies. No resistance to LEV was detected in 1979 but during 1980 in vivo egg count reduction tests showed that highly resistant populations of Ostertagia spp. were selected in sheep dosed either 49 or 11 times. This was confirmed by an in vitro larval paralysis test. Partial resistance occurred where sheep were dosed 5 times but not where one dose was given. The only population of H. conlortus still present at the end of 1980 in sufficient numbers to allow eggs to be tested in vitro was from the sheep dosed once. This had retained its resistance to TBZ.     

Does reduced feeding prior to release improve the marine migration of hatchery brown trout Salmo trutta smolts?

The aim of this study was to test the hypothesis that hatchery brown trout Salmo trutta smolts, with 50% reduced or no feeding over the last 5 months before release, were more likely to migrate to the sea than individuals with standard feeding ratios. The juvenile fish were divided into three groups 176 days before release: (A) with no feeding, (B) with 50% and (C) with 100% feeding. To study their seaward migration, 40 fish from each feeding group were tagged with acoustic transmitters and tracked by automatic listening stations in the River Nidelva, Trondheim, Norway, its estuary and in the nearest marine environment. At the time of release, mean condition factor was significantly lower in group A and the fish from groups A and B had higher levels of Na+, K+‐ATPase. Significantly more fish from group A migrated to the sea, but the rate of downstream progression from release to the estuary did not differ between the three groups. In conclusion, the S. trutta smolts with no access to food in the last 176 day before release were more likely to migrate to the sea. Fish from all three feeding groups, however, appeared to smoltify and had the same rate of downstream progression to the estuary. This indicates that differences in migratory behaviour between individuals from the three feeding groups begin from the time when the fish reach saline waters. It is suggested that feeding in hatcheries has to be greatly reduced (by 50% or more) over several months to have a pronounced effect on the migratory behaviour in S. trutta.     

Neutrophil activity affects Oreochromis mossambicus (Peters, 1852) antibody production against heat‐killed Aeromonas hydrophila vaccine

Aeromonas hydrophila is one of the important and most common pathogens of warm water fish. Prophylactic and therapeutic measures against A. hydrophila infection are essential to prevent loss of fish production in aquaculture. A heat‐killed vaccine was developed against three strains of A. hydrophila, namely O21, O26 and O28, and analysed for their comparative immunogenicity in Oreochromis mossambicus (Peters, 1852). Studied were the neutrophil activity and specific antibody response of the host against the vaccines, which showed that neutrophil activity was highest for the heat‐killed O21, but that the heat‐killed O28 produced the highest antibody titres. The antibody cross‐reactivity tests indicated that the antibody raised against O28 was pan‐reactive whereas it was less cross‐reactive in O21. Thus strain O28 may be used as a vaccine candidate for a pan‐protection of fish from various strains of A. hydrophila infections. However, further rigorous studies with different fish species and bacterial strains are needed to confirm these results.     

Report of a large fish kill resulting from natural acid water conditions in Australia

A large natural fish kill which resulted in the deaths of a total of more than 3400 fish comprising eight different species occurred in a freshwater billabong (lagoon or small permanent waterbody) on the Magela Creek in the subtropical Northern Territory of Australia in January, 1980. The fish deaths were assessed to be the result of a combination of natural acid water runoff into the billabong and resultant elevated aquatic biotoxic aluminium levels. Details of water quality changes which occurred during the event and analytical data for the fish killed are provided, together with some explanation of the sequences of occurrence of the fish kill.     

Effects of dietary trimethylamine on free amino acid and nonprotein nitrogen levels in muscle of the guppy, Poecilia reticulata, in relation to seawater adaptation

Guppies Poecilia reticulata acclimated to 100% seawater (SW) had lower taurine and alanine levels in muscle than fish kept in freshwater (FW). The glycine level, in contrast, was higher in SW fish than in FW fish. Levels of other free amino acids (FAA) were comparatively low and little different between fish adapted in FW and in SW. In both FW and SW fish almost all of muscle FAA showed little difference in levels between fish kept on diets containing three different levels of trimethylamine (TMA) (0, 223, and 334 mumol TMA/kg dry weight of diet). Total FAA and nonprotein nitrogen levels in muscle were unaffected by the difference in either the diet species or the ambient salinities. Muscle trimethylamine oxide levels were higher in SW fish than in FW fish. In both salinities, muscle trimethylamine oxide levels in fish on the diets containing 223 and 334 mumol TMA/kg were slightly greater than the level in fish on the TMA-free diet.