Effects of enhanced loads of nutrients on epiphytes on leaves and rhizomes of Posidonia oceanica

The increase of anthropogenic activities has severely altered both terrestrial and aquatic systems. Urbanisation, excessive use of agricultural fertilisers, organic runoff and climate change have caused an increase of nutrients in coastal waters, altering the diversity and food-web structure of benthic assemblages. The aims of the present paper were to text if an experimentally increased availability of nutrients, primarily nitrogen and phosphorous, in an oligotrophic basin, would affect epiphytic assemblages on leaves and rhizomes of P. oceanica and whether this could change rates of consumption of the plant by herbivores. In particular, we tested the hypothesis i) that changes to species composition and abundance of epiphytic assemblages generated by nutrients enrichment would vary between leaves and rhizomes and that ii) alterations to epiphytic assemblages on leaves might, in turn, modify feeding rates of herbivorous fish. After two years, the structure of both leaf and rhizome epiphytic assemblages responded to changes in nutrient concentrations before the occurrence of drastic alterations to the host plant, but only the former showed significant changes in terms of species composition. Moreover, a larger intensity of grazing on P. oceanica leaves was documented in experimentally enriched areas than in controls. The present findings and conclusions are applicable to other systems where patterns of biodiversity depend on changes in the availability of nutrients due to natural or anthropogenic events, likely interacting with biological processes, such as competition and grazing.     

Capacity and economic efficiency in small-scale fisheries: Evidence from the Mediterranean Sea

To design an effective capacity management plan for small-scale fisheries one must understand what one is measuring and define its capacity. As recognized by some authors, overcapacity is a problem that generally affects small-scale fisheries just as much as it does other types of fishing. This study aims to estimate fishing capacity, technical efficiency, scale efficiency and capacity utilization in a particular small-scale fishery in the Mediterranean, i.e., the Northwest Sardinian fleet in Italy. A non-parametric approach using a data envelopment analysis (DEA) model was applied to a sample of trawls in order to estimate their economic capacity, and related measurements were taken. The capacity and efficiency with reference to two different alternative scenarios were also calculated.     

Hard coastal-defence structures as habitats for native and exotic rocky-bottom species

The use of hard coastal-defence structures, like breakwaters and seawalls, is rapidly increasing to prevent coastal erosion. We compared low-shore assemblages between wave-protected and wave-exposed habitats on breakwaters along a sandy shore of Tuscany (North-Western Mediterranean). Assemblages were generally characterized by a low diversity of taxa, with space monopolized by Mytilus galloprovincialis and Corallina elongata on the seaward side of breakwaters and by filamentous algae on the landward side. Assemblages in wave-protected habitats were characterized by greater temporal stability than those in exposed habitats and supported non-indigenous macroalgae such as Caulerpa racemosa and Codium fragile ssp. tomentosoides. Hence, the introduction of hard coastal-defence structures in otherwise soft-bottom dominated areas, attracting native and exotic rocky-bottom species, should be of great concern for the conservation of marine biodiversity at local and regional scales and for the management of biological invasions.     

Unpacking some of the linkages between uncertainties in observational data and the simulation of different hydrological processes using the Pitman model in the data scarce Zambezi River basin

The main objective of this study was to use an uncertainty version of a widely used monthly time step, semi-distributed model (the Pitman model) to explore the equifinalities in the way in which the main hydrological processes are simulated and any identifiable linkages with uncertainties in the available observational data. The study area is the Zambezi River basin and 17 gauged sub-basins have been included in the analyses. Unfortunately, it is not generally possible to quantify some of the observational uncertainties in such a data scarce area and mostly we are limited to identifying where these data are clearly deficient (i.e., erroneous or non-representative). The overall conclusion is that the equifinalities in the model are hugely dominant in terms of the uncertainties in the relative occurrence of different runoff generating processes, although water use uncertainties in the semi-arid parts of the basin can contribute to these uncertainties. The identification of landscape features that suggest the occurrence of saturation excess surface runoff provides some information to constrain the model. Improved independent estimates of groundwater recharge is also identified as a key source of observational data that would help a great deal in constraining the model parameter space and therefore reducing some of the model equifinality.     

The Imaclim-R model: infrastructures, technical inertia and the costs of low carbon futures under imperfect foresight

This paper analyzes the transition costs of moving towards a low carbon society when the second-best nature of the economy is accounted for. We emphasize the consequences on mitigation costs of considering the interplay between a) technical systems inertia, including slow infrastructure turnover in transportation and construction; and b) imperfect foresight influencing investment decisions. To this end, the hybrid general equilibrium modeling framework Imaclim-R is employed as it allows for transitory partial adjustments of the economy and captures their impact on the dynamics of economic growth. The modeling exercise quantitatively emphasizes the a) specific risks that the interplay between inertia and imperfect foresight leads to high macroeconomic costs of carbon abatement measures; b) opportunities of co-benefits from climate policies permitted by the correction of sub-optimalities in the reference scenarios. The article draws insights for the framing of future climate architectures by studying the role of measures that act complementarily to carbon pricing in the transport sector. In particular, reallocating public investment towards low-carbon transport infrastructure significantly reduces the overall macroeconomic costs of a given GHG stabilization target and even creates the room for long-term net economic benefits from climate policies.     

Assessment of the impact of climate change on the olive flowering in Calabria (southern Italy)

In phenological studies, plant development and its relationship with meteorological conditions are considered in order to investigate the influence of climatic changes on the characteristics of many crop species. In this work, the impact of climate change on the flowering of the olive tree (Olea europaea L.) in Calabria, southern Italy, has been studied. Olive is one of the most important plant species in the Mediterranean area and, at the same time, Calabria is one of the most representative regions of this area, both geographically and climatically. The work is divided into two main research activities. First, the behaviour of olive tree in Calabria and the influence of temperature on phenological phases of this crop are investigated. An aerobiological method is used to determine the olive flowering dates through the analysis of pollen data collected in three experimental fields for an 11-year study period (1999–2009). Second, the study of climate change in Calabria at high spatial and temporal resolution is performed. A dynamical downscaling procedure is applied for the regionalization of large-scale climate analysis derived from general circulation models for two representative climatic periods (1981–2000 and 2081–2100); the A2 IPCC scenario is used for future climate projections. The final part of this work is the integration of the results of the two research activities to predict the olive flowering variation for the future climatic conditions. In agreement with our previous works, we found a significant correlation between the phenological phases and temperature. For the twenty-first century, an advance of pollen season in Calabria of about 9?days, on average, is expected for each degree of temperature rise. From phenological model results, on the basis of future climate predictions over Calabria, an anticipation of maximum olive flowering between 10 and 34?days is expected, depending on the area. The results of this work are useful for adaptation and mitigation strategies, and for making concrete assessments about biological and environmental changes.     

Application of biotic indices and relationship with structural and functional features of macrobenthic community in the lagoon of Venice: an example over a long time series of data

In the context of the application of WFD, a scientific debate is growing about the applicability of biotic indices in coastal and transitional waters. In the present work, the question about the discriminating power of different biotic indices and the relationships with the structure and functioning of the macrobenthic community in a transitional environment is discussed. A time series of samples collected during the last 70 years in the lagoon of Venice, reflecting different environmental conditions (a sort of 'pristine state' in 1935, the distrophic crisis in 1988 and subsequent modifications in 1990, the invasion by an alien species and the developing of high impacting fishery in 1999) has been used. The comparison of results obtained by applying different biotic indices, such as AMBI, Bentix and BOPA, shows differences in the discriminating power of indices and a general overestimation of environmental conditions. Discrepancies between environmental status as indicated by biotic indices and the structure and functioning of the benthic community have been highlighted.     

Atmospheric response to the North Atlantic Ocean variability on seasonal to decadal time scales

The NCEP twentieth century reanalyis and a 500-year control simulation with the IPSL-CM5 climate model are used to assess the influence of ocean-atmosphere coupling in the North Atlantic region at seasonal to decadal time scales. At the seasonal scale, the air-sea interaction patterns are similar in the model and observations. In both, a statistically significant summer sea surface temperature (SST) anomaly with a horseshoe shape leads an atmospheric signal that resembles the North Atlantic Oscillation (NAO) during the winter. The air-sea interactions in the model thus seem realistic, although the amplitude of the atmospheric signal is half that observed, and it is detected throughout the cold season, while it is significant only in late fall and early winter in the observations. In both model and observations, the North Atlantic horseshoe SST anomaly pattern is in part generated by the spring and summer internal atmospheric variability. In the model, the influence of the ocean dynamics can be assessed and is found to contribute to the SST anomaly, in particular at the decadal scale. Indeed, the North Atlantic SST anomalies that follow an intensification of the Atlantic meridional overturning circulation (AMOC) by about 9 years, or an intensification of a clockwise intergyre gyre in the Atlantic Ocean by 6 years, resemble the horseshoe pattern, and are also similar to the model Atlantic Multidecadal Oscillation (AMO). As the AMOC is shown to have a significant impact on the winter NAO, most strongly when it leads by 9 years, the decadal interactions in the model are consistent with the seasonal analysis. In the observations, there is also a strong correlation between the AMO and the SST horseshoe pattern that influences the NAO. The analogy with the coupled model suggests that the natural variability of the AMOC and the gyre circulation might influence the climate of the North Atlantic region at the decadal scale.