Fishing impact and environmental status in European seas: a diagnosis from stock assessments and ecosystem indicators

Stock‐based and ecosystem‐based indicators are used to provide a new diagnosis of the fishing impact and environmental status of European seas. In the seven European marine ecosystems covering the Baltic and the North‐east Atlantic, (i) trends in landings since 1950 were examined; (ii) syntheses of the status and trends in fish stocks were consolidated at the ecosystem level; and (iii) trends in ecosystem indicators based on landings and surveys were analysed. We show that yields began to decrease everywhere (except in the Baltic) from the mid‐1970s, as a result of the over‐exploitation of some major stocks. Fishermen adapted by increasing fishing effort and exploiting a wider part of the ecosystems. This was insufficient to compensate for the decrease in abundance of many stocks, and total landings have halved over the last 30 years. The highest fishing impact took place in the late 1990s, with a clear decrease in stock‐based and ecosystem indicators. In particular, trophic‐based indicators exhibited a continuous decreasing trend in almost all ecosystems. Over the past decade, a decrease in fishing pressure has been observed, the mean fishing mortality rate of assessed stocks being almost halved in all the considered ecosystems, but no clear recovery in the biomass and ecosystem indicators is yet apparent. In addition, the mean recruitment index was shown to decrease by around 50% in all ecosystems (except the Baltic). We conclude that building this kind of diagnosis is a key step on the path to implementing an ecosystem approach to fisheries management.     

Banning of methyl bromide for seed treatment: could Ditylenchus dipsaci again become a major threat to alfalfa production in Europe?

In Europe, the stem and bulb nematode Ditylenchus dipsaci has been listed as a quarantine pest by EPPO: without any control, it may cause complete failure of alfalfa crops. Movement of nematodes associated with seeds is considered to be the highest‐risk pathway for the spread of this pest. Since the 2010 official withdrawal of methyl bromide in Europe, and in the absence of any alternative chemical, fumigation of contaminated seed batches is no longer possible, which makes the production of nematode‐free alfalfa seeds difficult to achieve and leads to unmarketable seed batches. Thermotherapy is being considered as a realistic alternative strategy, but its efficiency still remains to be validated. The combination of the currently available methods (i.e. use of resistant cultivars, seed production according to a certification scheme, mechanical sieving, seed batch inspection) could significantly reduce the likelihood of seed contamination. However, it does not guarantee a total eradication of the nematode. Although it is already widely distributed all over Europe, reclassification of D. dipsaci as a regulated non‐quarantine pest to reduce the possibility of further introductions and the rate of spread of this pest appears to be a risky strategy because of the lack of up‐to‐date documented data to evaluate damage thresholds and determine acceptable tolerance levels. [[ArtCopyrightmsg]]     

A multi-gene analysis of diversity of bartonella detected in fleas from Algeria

We report the molecular detection of several Bartonella species in 44 (21.5%) of 204 fleas from Algeria collected from 26 rodents and 7 hedgehogs. Bartonella elizabethae and B. clarridgeiae were detected in the fleas collected on hedgehogs. Bartonella tribocorum and B. elizabethae were detected in fleas collected from rats and mice, and sequences similar to an unnamed Bartonella sp. detected in rodents from China were detected in rats as well as a genotype of Bartonella closely related to Bartonella rochalimae detected in fleas collected on brown rats (Rattus norvegicus).     

Bartonella and Rickettsia in arthropods from the Lao PDR and from Borneo, Malaysia

Rickettsioses and bartonelloses are arthropod-borne diseases of mammals with widespread geographical distributions. Yet their occurrence in specific regions, their association with different vectors and hosts and the infection rate of arthropod-vectors with these agents remain poorly studied in South-east Asia. We conducted entomological field surveys in the Lao PDR (Laos) and Borneo, Malaysia by surveying fleas, ticks, and lice from domestic dogs and collected additional samples from domestic cows and pigs in Laos. Rickettsia felis was detected by real-time PCR with similar overall flea infection rate in Laos (76.6%, 69/90) and Borneo (74.4%, 268/360). Both of the encountered flea vectors Ctenocephalides orientis and Ctenocephalides felis felis were infected with R. felis. The degrees of similarity of partial gltA and ompA genes with recognized species indicate the rickettsia detected in two Boophilus spp. ticks collected from a cow in Laos may be a new species. Isolation and further characterization will be necessary to specify it as a new species. Bartonella clarridgeiae was detected in 3/90 (3.3%) and 2/360 (0.6%) of examined fleas from Laos and Borneo, respectively. Two fleas collected in Laos and one flea collected in Borneo were co-infected with both R. felis and B. clarridgeiae. Further investigations are needed in order to isolate these agents and to determine their epidemiology and aetiological role in unknown fever in patients from these areas.     

Molecular detection of rickettsial agents in ticks and fleas collected from a European hedgehog (Erinaceus europaeus) in Marseilles, France

The European hedgehog (Erinaceus europaeus) is a synanthropic nocturnal insectivore commonly found in the countryside and in the parks and gardens. Because hedgehogs are already involved in the transmission of a number of zoonoses, including salmonellosis and ringworm, we decided to study their possible role in the epidemiology of the spotted fever group of Rickettsia. We collected ticks and fleas from a hedgehog that was captured in the city of Marseilles in France. Using a genus-specific quantitative PCR (qPCR) analysis followed by a species-specific qPCR analysis for positive samples, we observed that 91.7% (11/12) of the Rhipicephalus sanguineus ticks were positive for Rickettsia massiliae and 99.2% (128/129) of the Archaeopsylla erinacei fleas were positive for Rickettsia felis. Hedgehogs carry infected ectoparasites and then likely ensure the dissemination of spotted fever group Rickettsiae, and their epidemiological role requires further investigation.