Movement of common carp, Cyprinus carpio, in a regulated lowland Australian river: implications for management

Abstract  Introduced common carp, Cyprinus carpio L., is the most abundant large fish in the Murray-Darling Basin and past studies have considered it non-migratory. Movement information is, however, important for targeting control efforts to appropriate habitats and spatial scales. Movement patterns of common carp in the Murray River were investigated between November 1999 and August 2001. In total, 3337 common carp were boat electric fished and externally tagged. Of the 293 (8.8%) fish recaptured, up to 1898 days later, the majority (80%) moved <5 km. However, over 7% of the tagged population moved ≥100 km, and the maximum distance was 890 km. Intermediate-sized males moved the greatest distances, usually downstream. Conversely, females and larger males remained close to floodplain spawning areas. For improved management, there is a need to recognise different movement strategies within common carp populations.     

Immunosuppression in rainbow trout, Salmo gairdneri Richardson, caused by the haemoflagellate Cryptobia salmositica Katz, 1951

Abstract. An experimental Cryptobia salmositica infection in rainbow trout, Salmo gairdneri Richardson, produced suppression of the humoral response against sheep red blood cells as measured by direct haemagglutination. Two-month and 5-month infections produced equal suppression. The parasite also produced suppression of the humoral response against a bacterial pathogen, Yersinia ruckeri . Anti- Y. ritckeri titres were significantly lower in most fish infected with C. salmositica than in non-infected fish. Immunosuppression became evident when C. salmositica first appeared in the blood (first 2 weeks of infection), Immunosuppression was confirmed by challenge with Y. ruckeri . Mortality at challenge occurred in 64·3% to 83·3% of the fish already infected with C. salmositica at the time of initial Y. ruckeri exposure. There was no mortality at challenge if fish were not infected with C. salmositica at initial bacterial exposure, nor in those concurrently infected with both pathogens. Antigenic competition may have caused the immunosuppression.     

The immune response of rainbow trout, Salmo gairdneri Richardson, to the haemoflagellate, Cryptobia salmositica Katz, 1951

Abstract. Rainbow trout that recovered from experimental Cryptobia salmositica infection 6 and 10 weeks earlier were protected against multiple intraperitoneal challenges of 50 000 and 10 000 parasites isolated from infected fish. The immunity was non-sterile; low parasitaemias were detected following a larger challenge (112 000 parasites). The indirect haemagglutination test was used to detect C. salmositica -specific agglutimns. Antibody titers increased during the first 18 weeks of infection. The infectivity of cultured C. salmositica was neutralized by incubation in heat-inactivated immune plasma. Infectivity of C, salmositica from infected fish was not neutralized by similar treatment. Complement fixing antibody was detected using the in vitro immune lysis test. Immune lysis occurred when cultured C. salmositica were used. Adoptive transfer of both leucocytes and plasma from immune fish conferred partial protection against the parasite in naive recipients. Complement fixing antibody may be important during early acute infection while phagocytosis may be important during the later chronic phase.     

Goussia auxidis (Dogiel, 1948) (Apicomplexa: Calyptosporidae) from tuna (Pisces: Scombridae) in the South Pacific

Abstract. A coccidian identified as Goussia auxidis (Dogiel, 1948) is recorded for the first time from the liver and spleen of albacore, Thunnus alalunga; the liver of slender tuna, Allothunnus fallai , skipjack tuna, Katsuwonus pelamis and yellowfin tuna, T. albacares: and in the spleen of Scomber australasicus. All host fish were caught in the western and central South Pacific Ocean. Coccidian spores were not found in the liver of southern bluefin tuna, T. maccoyii , or butterfly tuna, Gasterochisma melampus.     

ORNITHOCHOLANIC ACIDS AND CHOLELITHIASIS IN MAN

Ornithocholanic acids and small soft gall stones were found in the bile of patients from which Klebsiella pneumoniae was also isolated. Cholelithiasis may be initiated by metabolic disturbances in the conjugation of bile acids in liver tissue and the subsequent precipitation of cholesterol and bile pigment.     

Laboratory studies on the effect of potassium carbonate solution on the drying of cut forage

The potential drying rate of cut forage grasses and legumes, following treatment with a 2% potassium carbonate (K₂CO₃) solution, were compared with those of untreated crops under laboratory conditions. Material was fully exposed to a flow of conditioned air (20°C; 50% relative humidity). Treatment with K₂CO₃ had little effect on the drying rate of a range of cultivated grass species. The drying of legume species, particularly lucerne was accelerated. The average reduction in lucerne drying time, following K₂CO₃ treatment, was 63% and was similar for a range of varieties. The differential drying of lucerne leaf and stem fractions was reduced following treatment, and reduced further by selective treatment of the stem. Potassium carbonate treatment was superior to traditional mechanical conditioning for accelerating water loss from cut lucerne. The practical implications are discussed.     

The production and persistency of different grass species cut at different heights

The effect of two heights of cutting (5 and 8 cm) on the dry matter harvested and persistency of a range of different grass species and varieties were monitored over a 3-year period (1976 to 1978). Dry matter harvested was measured in the second and third harvest year and persistence of sown grass was assessed at the end of the first and third harvest year. The grasses were managed under a frequent cutting system, i.e. simulated grazing. Results showed that at the low cutting height tetraploid hybrid ryegrasses and diploid Italian ryegrasses in the third harvest year gave lower annual dry matter harvests of sown grass and were less persistent than at the high cutting height, whilst, in contrast, perennial ryegrasses gave higher annual harvests of sown grass but persistency was unaffected. In general at the low cutting height varieties of cocksfoot, meadow fescue and tall fescue gave comparatively higher annual harvests of sown grass in the second harvest year but lower yields of sown grass in the third harvest year. A notable exception was Cambria cocksfoot which in the second harvest year gave higher yields of sown grass and was more persistent at the low cutting height.
However, at 5 cm cutting height, the proportions of weed grasses (mainly Poa spp.) in swards sown to tetraploid hybrid ryegrasses and diploid Italian ryegrasses were generally greater, particularly in mid-season.     

Sward growth under cutting and continuous stocking managements: sward canopy structure, tiller density and leaf turnover

The change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass ( Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.
The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.
There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·20⁴ m^-2 and 6·20³ m^-2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.
Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.