Salinity-induced quiescence in eggs of the calanoid copepod Acartia tonsa (Dana): a simple method for egg storage

We report the effect of salinity and temperature on the viability of stored culture-based subitaneous eggs of the calanoid copepod Acartia tonsa for use of copepods in fish larvae culture. Quiescence induction was recorded at 17 and 25 °C, in salinities from 0 to 30. Quiescence was strongly induced at 0 salinity and partially at 5 in both temperatures. Eggs incubated at 0 salinity for up to 12 days at both temperatures showed a decline in the fraction able to be induced into quiescence by abrupt salinity changes. The hatching success of eggs that were able to enter quiescence stabilized after a 1-day incubation and remained ∼25% viable for 12 days in 17 °C. On the contrary, the 25 °C trial showed a gradual decline in viability until stabilizing ∼10% at day 7 and onwards. Longterm 17 °C incubation for 35 days showed that eggs remained quiescent with a viability of ∼14%. Hence, we recommend salinity storage of A. tonsa subitaneous eggs as a relevant shortterm technique, and a suitable alternative to the recently proposed cold storage of eggs when eggs are to be shipped from the copepod producer to a given fish larvae hatchery.     

Electronic monitoring in fisheries: Lessons from global experiences and future opportunities

Since the beginning of the 21st century, electronic monitoring (EM) has emerged as a cost‐efficient supplement to existing catch monitoring programmes in fisheries. An EM system consists of various activity sensors and cameras positioned on vessels to remotely record fishing activity and catches. The first objective of this review was to describe the state of play of EM in fisheries worldwide and to present the insights gained on this technology based on 100 EM trials and 12 fully implemented programmes. Despite its advantages, and its global use for monitoring, progresses in implementation in some important fishing regions are slow. Within this context, the second objective was to discuss more specifically the European experiences gained through 16 trials. Findings show that the three major benefits of EM were as follows: (a) cost‐efficiency, (b) the potential to provide more representative coverage of the fleet than any observer programme and (c) the enhanced registration of fishing activity and location. Electronic monitoring can incentivize better compliance and discard reduction, but the fishing managers and industry are often reluctant to its uptake. Improved understanding of the fisher's concerns, for example intrusion of privacy, liability and costs, and better exploration of EM benefits, for example increased traceability, sustainability claims and market access, may enhance implementation on a larger scale. In conclusion, EM as a monitoring tool embodies various solid strengths that are not diminished by its weaknesses. Electronic monitoring has the opportunity to be a powerful tool in the future monitoring of fisheries, particularly when integrated within existing monitoring programmes.     

Single-dose pharmacokinetics of flumequine in halibut (Hippoglossus hippoglossus) and turbot (Scophthalmus maximus)

Flumequine was administered to halibut (Hippoglossus hippoglossus) and turbot (Scophthalmus maximus) intravenously (i.v.) and orally (p.o.) at a dose of 10 mg/ kg bodyweight, and as a bath-treatment at a dose of 10 mg/L water for 2 h, using identical experimental designs. The study was performed in seawater with a salinity of 3% and a temperature of 10.3+/-0.4 degrees C (halibut) and 18.0+/-0.3 degrees C (turbot). Pharmacokinetic modelling of the data showed that flumequine had quite similar pharmacokinetic properties in halibut and turbot. Following intravenous administration, the volumes of distribution at steady state (Vss) were 2.99 L/kg (halibut) and 3.75 L/kg (turbot). Plasma clearances (Cl) were 0.12 L/kg (halibut) and 0.17 L/h x kg (turbot) and the elimination half-lives (t(1/2lambdaz)) were calculated to be 32 h (halibut) and 34 h (turbot). Mean residence times (MRT) were 25.1 h (halibut) and 22.2 h (turbot). Following oral administration, the t(1/2lambdaz) were 43 h (halibut) and 42 h (turbot). Maximal plasma concentrations (tmax) were 1.4 mg/L (halibut) and 1.9 mg/L (turbot), and were observed 7 h post administration in both species. The oral bioavailabilities (F) were calculated to 56% (halibut) and 59% (turbot). Following bath administration maximal plasma concentrations were 0.08 mg/L (halibut) and 0.14 mg/ L (turbot), and were observed 0 h (halibut) and 3 h (turbot) after the end of the bath. The bioavailability in halibut following a 2-h bath treatment was 5%.     

Widespread iron limitation of phytoplankton in the south pacific ocean

Diel fluorescence patterns were discovered in phytoplankton sampled over 7000 kilometers of the South Pacific Ocean that appear indicative of iron-limiting growth conditions. These patterns were rapidly lost after in situ iron enrichment and were not observed during a 15,000-kilometer transect in the Atlantic Ocean where iron concentrations are relatively high. Laboratory studies of marine Synechococcus sp. indicated that the patterns in the South Pacific are a unique manifestation of iron limitation on the fluorescence signature of state transitions. Results suggest that primary productivity is iron limited not only throughout the equatorial Pacific but also over much of the vast South Pacific gyre.     

An Outbreak of Newcastle Disease in Free-Living Pheasants (Phasianus colchicus)

The epidemiology of an outbreak of Newcastle disease in a population of approximately 12 000 free-living pheasants (Phasianus colchicus) on the island of Faenø in Denmark in 1996 is described. The mortality during the epizootic was 56 %. The spread of the disease between 7 groups of pheasants could be demonstrated over an observation period of 3 weeks. A total of 70 avian paramyxovirus serotype 1 (APMV-1) isolates was made from the flock. The intra cerebral pathogenicity indices of the 4 isolates tested were in the range 1.78–1.88. By means of immunoperoxidase monolayer assay with murine monoclonal antibodies and sequence analysis of an RT-PCR amplified segment of the F₀ viral protein it was found, that the virus belonged to the highly virulent C1 antigenic group and that the amino acid sequence at the F₀ cleavage site corresponded with the sequences of virulent APMV-1 strains. Based on the epidemiological circumstances it is believed that the virus was transmitted to the pheasants by feral birds.I     

In vitro shoot regeneration ofSolanum tuberosum cultivars: interactions of medium composition and leaf, leaflet, and explant position

Summary Shoot regeneration was investigated on explants from different leaves and leaflets of three potato cultivars Posmo, Folva and Oleva. Explants were excised from glasshouse grown plants and grown for 6 days on callus induction medium with indole-3-acetic acid or 2,4-dichlorophenoxyacetic acid. Explants were then transferred to auxin free shoot regeneration medium with gibberellic acid and 6-benzyladenine or zeatin. By using the optimum combinations and concentrations of plant growth regulators and by excision of explants from particular regions of proximal leaflets from newly unfolded leaves, shoot regeneration frequencies of 97.0% were obtained for cv. Posmo and 32.1% for cv. Folva. Shoot regeneration frequency of cv. Oleva was very low and could not be improved by the different treatments.