Coastal marine ecosystems are increasingly subjected to environmental stress and degradation due to pollution. Several research programmes have addressed this problem and produced relevant data sets for specific areas, often including consistent sets of environmental and biological variables. The value of existing information gathered from these types of data can be largely increased by combining them into a common data set to determine globally applicable relationships. To perform this exercise, the Intergovernmental Oceanographic Commission (IOC) of UNESCO has recently formed the Ad hoc Study Group on Benthic Indicators (http://www.ioc.unesco.org/benthicindicators) with the aim of developing robust indicators of benthic health. In this paper, initial products and ongoing activities of this international initiative are described and discussed. An expansion of initial IOC/UNESCO research on benthic fauna-organic carbon relationships is also presented. As part of this follow-up research, the relationship between total organic carbon concentrations of sediment and abundance, biomass and species diversity of benthic macrofauna was evaluated using data sets from 2 different regions of the world comprising 3 different coastal marine environments. The ability of identifying threshold levels in selected variables that could serve as indicators of related adverse environmental conditions leading to stress in the benthos is envisaged within the frame of a larger joint analysis, carried out by the IOC/UNESCO Study Group on Benthic Indicators, of merged data sets from several coastal regions worldwide. 相似文献
Eight pregnancies at risk for cystic fibrosis have been monitored by first-trimester prenatal diagnosis with DNA amplification analysis. The polymerase chain reaction (PCR) was used in all cases to amplify the region detected by KM 19. In two cases, the region detected by CS·7, another DNA probe tightly linked to the CF locus, was also examined. The results of the PCR determinations were confirmed using the Southern blotting procedure, by segregation analysis of restriction fragment length polymorphisms (RFLPs) relative to XV-2c, J3·11, metH, metD, and KM19 probes. 相似文献
Recent large-scale studies have shown that biodiversity-rich regions also tend to be densely populated areas. The most obvious
explanation is that biodiversity and human beings tend to match the distribution of energy availability, environmental stability
and/or habitat heterogeneity. However, the species–people correlation can also be an artefact, as more populated regions could
show more species because of a more thorough sampling. Few studies have tested this sampling bias hypothesis. Using a newly
collated dataset, we studied whether Orthoptera species richness is related to human population size in Italy’s regions (average
area 15,000 km2) and provinces (2,900 km2). As expected, the observed number of species increases significantly with increasing human population size for both grain
sizes, although the proportion of variance explained is minimal at the provincial level. However, variations in observed Orthoptera
species richness are primarily associated with the available number of records, which is in turn well correlated with human
population size (at least at the regional level). Estimated Orthoptera species richness (Chao2 and Jackknife) also increases
with human population size both for regions and provinces. Both for regions and provinces, this increase is not significant
when controlling for variation in area and number of records. Our study confirms the hypothesis that broad-scale human population–biodiversity
correlations can in some cases be artefactual. More systematic sampling of less studied taxa such as invertebrates is necessary
to ascertain whether biogeographical patterns persist when sampling effort is kept constant or included in models. 相似文献
New finds of bones of the Egyptian Mongoose (Herpestes ichneumon), one from Portugal and one from Spain, were directly 14C dated to the first century AD. While the Portuguese specimen was found without connection to the Chalcolithic occupation of the Pedra Furada cave where it was recovered, the Spanish find, collected in the city of Mérida, comes from a ritual pit that also contained three human and 40 dog burials. The finds reported here show that the Egyptian mongoose, contrary to the traditional and predominant view, did not first arrive in the Iberian Peninsula during the Muslim occupation of Iberia. Instead, our findings are consistent with the hypothesis that the species was first introduced by the Romans, or at least sometime during the Roman occupation of Hispania. Therefore, radiocarbon dating of new archaeological finds of bones of the Egyptian Mongoose (Herpestes ichneumon) in the Iberian Peninsula push back the confirmed presence of the species in the region by approximately eight centuries, as the previously oldest dated record is from the ninth century. With these new dates, there are now a total of four 14C dated specimens of Egyptian mongooses from the Iberian Peninsula, and all of these dates fall within the last 2000 years. This offers support for the hypothesis that the presence of the species in Iberia is due to historical introductions and is at odds with a scenario of natural sweepstake dispersal across the Straits of Gibraltar in the Late Pleistocene (126,000–11,700 years ago), recently proposed based on genetic data.