Effect of temperature on pharmacokinetics of enrofloxacin in mud crab, Scylla serrata (Forssk?l), following oral administration

The study was conducted to evaluate the pharmacokinetics of enrofloxacin following a single oral gavage (10 mg kg(-1)) in mud crab, Scylla serrata, at water temperatures of 19 and 26 degrees C. Enrofloxacin concentration in haemolymph was determined using high-performance liquid chromatography (HPLC). A multiple and repeated haemolymph sampling from the articular cavity of crab periopods was developed. The haemolymph of an individual crab was successfully sampled up to 11 times from the articular cavity. The profile of haemolymph enrofloxacin concentration of an individual crab versus time was thus achieved. The mean haemolymph enrofloxacin concentration versus time was described by a two-compartment model with first-order absorption at two water temperatures. The peak concentrations of haemolymph enrofloxacin at 19 and 26 degrees C were 7.26 and 11.03 mug mL(-1), at 6 and 2 h, respectively. The absorption and distribution half-life time ( and t(1/2alpha)) at 19 degrees C were 3.7 and 4.5 h, respectively, which were markedly larger than the corresponding values (1.1 and 1.5 h) at 26 degrees C; the elimination half-life time (t(1/2beta)) was 79.1 and 56.5 h at 19 and 26 degrees C, respectively. The area under curve (AUC), total body clearance (Cl) and mean residence time (MRT(0-infinity)) at 19 degrees C were 636.0 mg L(-1) h, 0.016 L h(-1) kg(-1) and 102.5 h, respectively; the corresponding values at 26 degrees C were 583.4 mg L(-1) h, 0.018 L h(-1) kg(-1)and 63.7 h. These results indicate that enrofloxacin is absorbed and eliminated more rapidly in mud crab at 26 degrees C than at 19 degrees C.     

Early development of resistance to the salmon louse, Lepeophtheirus salmonis (Krøyer), in juvenile pink salmon, Oncorhynchus gorbuscha (Walbaum)

This study examined the effect of fish weight on the susceptibility of post-emergent pink salmon to Lepeophtheirus salmonis (Krøyer). Three trials were conducted, each with two stocks of pink salmon, Oncorhynchus gorbuscha (Walbaum), at starting weights of c . 0.3, 0.7 and 2.4 g, respectively. In each trial, duplicate tanks of fish were exposed to 0, 25 (only in Trial 1), 50 or 100 copepodids per fish. Mortality in Trial 1 was c . 37%, regardless of stock following exposures to 50 or 100 copepodids. Mortalities occurred up to 26 days after exposure, and more than 80% of the lice on the dead fish were chalimus stages. Infections with adult or preadult lice were observed on c . 35% of fish surviving to 37 days after exposure. Mortality was 5% in Trial 2 and there was no mortality in Trial 3. The abundance of L. salmonis was lower in Trial 3 compared with Trials 1 or 2. Histological changes in the skin coincident with fish growth included a thickening of the epidermis, infiltration of the dermis with fibroblasts by the end of Trial 1 and the first evidence of scales by the end of Trial 2; scales were evident throughout Trial 3. These results showed that the previously reported innate resistance to L. salmonis displayed by pink salmon develops in fish heavier than 0.3 g and appears to be functional by 0.7 g. This resistance coincided with changes to the epidermis and dermis, including the formation of scales. The present results indicate that elevated risk associated with L. salmonis infection among migrating post-emergent pink salmon may occur during a relatively brief period before the fish reaches 0.7 g.     

Marine production mechanisms: M.J. Dunbar (Editor), Cambridge University Press,Cambridge, 1979. International Biological Programme, 20, 338 pp., illus., £25.00, ISBN 0-521-21937-X

A simple mechanical feeding device is described which can volumetrically deliver a preset quantity of pelleted or granulated dry fish feed.     

Regulation of oocyte maturation in the rainbow trout,Salmo gairdneri: role of cyclic AMP in the mechanism of action of the maturation inducing steroid (MIS), 17α-hydroxy, 20β-dihydroprogesterone

In fish, oocyte maturation (resumption of meiosis after completion of vitellogenesis and before ovulation) is triggered by maturation inducing steroids (MIS) which generally appear to be secreted in the ovary in response to stimulation by a pituitary maturational gonadotropin. Converging data from different laboratories show that 17-hydroxy, 20-dihydroprogesterone (17, 20-OH-P) is the principal MIS in salmonoids; but clear identification remains to be done in other taxonomic groups.The experiments reported here in the rainbow troutSalmo gairdneri examine the possible involvement of oocyte cAMP on the mechanism of MIS action. The action of 17, 20-OH-P, on germinal vesicle breakdown (GVBD) in oocytes incubatedin vitro within the follicle, was inhibited by various substances expected to elevate the intraoocyte concentrations of cAMP: cAMP ( 1 mM) or dibutyril cAMP ( 2 mM), phosphodiesterase inhibitors such as theophylline ( 0.2 mM) or 3-isobutyl-1 methylxanthine (IBMX 0.1 mM), adenylate cyclase activators such as cholera toxin (> 100 nM) or forskolin ( 0.03 mM). In fact, the combined action of IBMX (1 mM) and forskolin (0.01 or 0.05 mM)in vitro was to promote accumulation of intraoocyte cAMP within 1 to 5 hours. Oocyte cAMP concentrations exhibited a large variability between different females, depending on the stage of oocyte development; a significant positive correlation between oocyte cAMP concentration and the follicular weight, and a significant negative correlation between oocyte cAMP concentration and the median efficient dose of 17, 20-OH-P for induction of GVBD, were observed. Finally, when intrafollicular oocytes were incubatedin vitro, the addition of a maturation-inducing concentration of 17, 20-OH-P (3×10^–6M) induced a significant decrease of oocyte cAMP within the first 10 hours of incubation. These results show that cAMP appears to play a central role in the regulation of oocyte sensitivity to 17, 20-OH-P and in the intraoocyte mechanisms leading to GVBD in trout.These data are discussed together with the few indications available in fish concerning the mechanism of MIS action which can be compared to some extent with the amphibian model.     

The development of fisheries at Bornholm,Denmark (Baltic Sea) during 1880s–1914

For centuries the abundance of fish in the Baltic Sea has had an important role in the economy of Bornholm, Denmark. This study examines the development of Bornholm fisheries between approximately 1880s and 1914 on the basis of the first officially recorded Danish fisheries data. Several species were caught, but prior to 1914 especially herring, salmon and cod were economically most important. In the late 19th and early 20th century, the catch composition changed fundamentally due to complex interactions between biological, technological and economical factors. During the late 19th century the catches of herring increased, while the catches of salmon and cod decreased. This development coincided with the introduction of new technologies and fishing practices, including motorization of fishing vessels and the exploitation of herring in previously unexploited areas (i.e., expansion of fishing areas). In addition, the salmon fishery diminished after the introduction of driftnets, which caught large numbers of small salmon. The high catches of small salmon, in combination with other factors, probably contributed to the decline in catches of larger salmon. Each of the fisheries for the three species required different types of vessels and gear, and when catches began to drop in the salmon fishery, Bornholm fishermen were faced with two options. They could either specialise in the growing herring fishery, thereby hoping to maintain their income level, or they could pursue a strategy of risk minimization, by acquiring an income outside the fishing industry, while continuing to work part-time in the salmon and cod fisheries. This dual tendency was intensified further as marine engines and new types of vessels were introduced, raising the costs of fishing.     

Oxygen consumption in trilobite larvae of the mangrove horseshoe crab (Carcinoscorpius rotundicauda; Latreille, 1802): effect of temperature,salinity, pH,and light–dark cycle

A set of feeding trials was carried out for different microalgal species and processed diets for the culture of the New Zealand pipi, Paphies australis. Five microalgal species (Isochrysis galbana clone T-ISO, Pavlova lutheri, Tetraselmis suecica, Chaetoceros muelleri, and Thalassiora pseudonana clone 3H) and three formulated diets (baker's yeast, wheat flour, and corn flour) were fed to spat, juvenile, and adult pipi for 21 days. Unfed pipi were used in the control group. The spat and juvenile pipi showed a major shell increase with I. galbana while the greatest wet weight increase was obtained with P. lutheri. The shells of adult pipi grew better with corn flour, and the P. lutheri-fed group obtained the greatest wet weight. Results of proximate analysis in adult pipi revealed that proteins and lipids were accumulated in the tissue for all fed groups, while carbohydrate levels were depleted in all treatments including the control group. It is suggested that the gonads have developed during the experiment.     

Effect of Neguvon® and Nuvan® treatment on crabs (Cancer pagurus,C. maenas), lobster (Homarus gammarus) and blue mussel (Mytilus edulis)

Survival tests were carried out with crabs, lobsters and blue mussels held in tanks of flowing seawater and subjected to Neguvon at 10, 1, 0.5 and 0.1 ppm and to Nuvan at 1, 0.01 ppm. Homarus gammarus was the most susceptible species; the animals died within 24 h at Neguvon levels of 0.5 ppm and higher and at Nuvan levels of 0.1 ppm and higher. The use of these chemicals in salmon farming appears to have deterious effects on marine invertebrate species.     

Inclusion of β-1,3/1,6-glucan in the ornamental fish,Jewel tetra (Hyphessobrycon eques), and its effects on growth,blood glucose,and intestinal histology

The effects of β-1,3/1,6-glucan on Hyphessobrycon eques were assessed after 42 days of feeding diets containing 0 (control group given commercial feed), 0.5, 1, or 2 g β-glucan/kg diet. In total, 180 fish, with an initial weight of 0.43?±?0.03 g, were used. There were 15 fish in each of twelve 42-L aquariums, and there were 3 aquariums of fish for each dietary treatment. The fish were fed until apparent satiety. Performance parameters (final weight, total length, standard length, feed intake, survival rate, weight gain, feed conversion, specific growth rate, and condition factor) and plasma glucose concentration were measured. Histological analysis of the proximal portion of the intestine (width and height of the villi, depth of the crypts, height of the enterocytes, thickness of the muscle layer, and number of goblet cells) was performed. Different levels of the additive did not influence fish performance (for example, final weight: control: 0.63 g, 0.5: 0.60, 1: 0.58, and 2: 0.61). Likewise, there was no influence on the plasma glucose concentration (control: 81.80 mg/dL, 0.5: 75.33, 1: 85.00, and 2: 81.00) and intestinal morphometry of the animals. However, the results showed that 2.0 g/kg of β-1,3/1,6-glucan provided a greater abundance of goblet cells secreting acidic and neutral mucus present in the epithelium (periodic acid-Schiff: 66.67 cells, Alcian blue pH 1.0: 72,67 cells, and Alcian blue pH 2.5: 95.00 cells), showing significant differences when compared to animals in the control group, which may represent better protection of the intestinal epithelium of H. eques.