The paradoxical need for human intervention in the conservation of natural environments in Venice lagoon.

The Venice lagoon-the largest Mediterranean coastal lagoon-is characterized by the presence at its edges of 31 "valli da pesca", types of artificial ecosystems that mime the ecological processes of a transitional aquatic ecosystem. Constituted by a series of regulated lakes bounded by artificial embankments, the valli da pesca were established centuries ago to maximize provisioning Ecosystem Services (ESs), such as fishing and hunting. As time passed, the valli da pesca underwent an intentional isolation process leading to private management. Nonetheless, the valli da pesca are still exchanging energy and matter with the "open' lagoon and today represent an essential element within the context of lagoon conservation. This study aimed to analyze the possible effects of artificial management on both ESs supply and landscape arrangements by assessing 9 ESs (climate regulation, water purification, lifecycle support, aquaculture, waterfowl hunting, wild food, tourism, information for cognitive development, and birdwatching), along with eight landscape indicators. Obtained results suggested that the valli da pesca are today ruled under five different management strategies, according to the maximized ES. Management conditions influence the landscape pattern and achieve a series of "side effects" on the other ESs. The comparison between the managed and abandoned valli da pesca highlights the importance of anthropogenic interventions for conserving these ecosystems, as the abandoned valli da pesca show a loss of ecological gradients, landscape heterogeneity, and provisioning ESs. Nevertheless, the persistence of intrinsic geographical and morphological characteristics still prevails regardless of intentional landscape molding. The result is that the provisioning ESs capacity per unit area is higher in the abandoned valli da pesca than in the open lagoon, emphasizing the importance of these confined areas of the lagoon ecosystem. Considering the spatial distribution of multiple ESs, the provisioning ESs flow that does not occur in the abandoned valli da pesca seems to be replaced by the flow of cultural ESs. Thus, the ESs spatial pattern highlights a balancing effect between different ESs categories. The results are discussed considering the trade-offs generated by private land conservation, anthropogenic interventions, and their relevance for the ecosystem-based management of Venice lagoon.

Effects of first intermediate host density, host size and salinity on trematode infections in mussels of the south-western Baltic Sea.

Trematode prevalence and abundance in hosts are known to be affected by biotic drivers as well as by abiotic drivers. In this study, we used the unique salinity gradient found in the south-western Baltic Sea to: (i) investigate patterns of trematode infections in the first intermediate host, the periwinkle Littorina littorea and in the downstream host, the mussel Mytilus edulis, along a regional salinity gradient (from 13 to 22) and (ii) evaluate the effects of first intermediate host (periwinkle) density, host size and salinity on trematode infections in mussels. Two species dominated the trematode community, Renicola roscovita and Himasthla elongata. Salinity, mussel size and density of infected periwinkles were significantly correlated with R. roscovita, and salinity and density correlated with H. elongata abundance. These results suggest that salinity, first intermediate host density and host size play an important role in determining infection levels in mussels, with salinity being the main major driver. Under expected global change scenarios, the predicted freshening of the Baltic Sea might lead to reduced trematode transmission, which may be further enhanced by a potential decrease in periwinkle density and mussel size.

Cumulative biomass curves describe past and present conditions of Large Marine Ecosystems.

Implementing the Ecosystem Approach in marine ecosystems is moving from preliminary steps-dedicated to defining the optimal features for indicators and developing efficient indicator frameworks-towards an operational phase where multisector marine management decisions are executed using this information. Within this operational context, emergent ecosystem properties are becoming quite promising as they have been demonstrated to be globally widespread and repeatable, and to be quite effective in detecting significant state variations of complex systems. Biomass accumulation across TLs (CumB-TL) combines two important emergent properties of an ecosystem (energy flow, in terms of transfer efficiency, and storage, expressed as biomass), both amenable to detecting rapid ecosystem change. However, for further application, it is crucial to understand which types of drivers an indicator is sensitive to and how robust it is in relation to modifications of the external conditions and/or the system state. Here we address some outstanding questions of these CumB-TL curves related to their sensitivity to various drivers by carrying out a global scale assessment (using data from 62 LMEs) over six decades (1950-2010). We confirm the consistency of the S-pattern across all the LMEs, independent from latitude, ecosystem, environmental conditions, and stress level. The dynamics of the curve shape showed a tendency to stretch (i.e. decrease of steepness), in the presence of external disturbance and conversely to increase in steepness and shift towards higher TL in the case of recovery from stressed conditions. Our results suggest the presence of three main types of ecosystem dynamics, those showing an almost continuous increase in ecological state over time, those showing a continuous decrease in ecological state over time, and finally those showing a mixed behaviour flipping between recovering and degrading phases. These robust patterns suggest that the CumB-TL curve approach has some useful properties for use in further advancing the implementation of the Ecosystem Approach, allowing us to detect the state of a given marine ecosystem based on the dynamics of its curve shape, by using readily available time series data. The value of being able to identify conditions that might require management actions is quite high and, in many respects, represents the main objective in the context of an Ecosystem Approach, with large applications for detecting and responding to global changes in marine ecosystems.

A Petri net modeling approach to explore the temporal dynamics of the provision of multiple ecosystem services.

The representation of the temporal dynamics of ecosystem services (ES) is a crucial research frontier in the field of ES modeling. In fact, most current ES models focus on static ES assessments, that need to be repeated with different inputs per time step to explore potential changes in ES. Here, we present a new approach for the dynamic modeling of multiple ES, based on the Petri Net modeling framework. The key features are: (i) multiple ES are modeled together as a single network, using a social-ecological systems (SES) perspective; (ii) the model accounts for the interactions occurring among ES, by distinguishing between the ES whose provision is mediated by some type of human input, which can produce some side-effects on the system, and those that are generated directly through ecosystem functions and do not generate side-effects; (iii) the model can reproduce the effects of changing drivers on the elements of the SES. These features allow to use the model to explore how ES can evolve over time under different "what-if" scenarios. The importance of considering the ES interactions is tested, showing that failing to include them in the model remarkably affects the results. Due to its complexity, the model should be used as an exploratory tool, focusing on the analysis of the general trends of multiple ES provision, rather than on the generation of quantitative projections. A first conceptual application to the Venice lagoon, Italy, is presented, in which the trends of 13 different ES are simulated. This application shows the potential of the model in exploring the development produced by climate change and socio-economic pressures, and the effects of a set of possible management actions. This modeling approach can contribute to generate new perspectives on the dynamic modeling of multiple ES and on the integrated management of SES.

Emergent Properties Delineate Marine Ecosystem Perturbation and Recovery.

Whether there are common and emergent patterns from marine ecosystems remains an important question because marine ecosystems provide billions of dollars of ecosystem services to the global community, but face many perturbations with significant consequences. Here, we develop cumulative trophic patterns for marine ecosystems, featuring sigmoidal cumulative biomass (cumB)-trophic level (TL) and 'hockey-stick' production (cumP)-cumB curves. The patterns have a trophodynamic theoretical basis and capitalize on emergent, fundamental, and invariant features of marine ecosystems. These patterns have strong global support, being observed in over 120 marine ecosystems. Parameters from these curves elucidate the direction and magnitude of marine ecosystem perturbation or recovery; if biomass and productivity can be monitored effectively over time, such relations may prove to be broadly useful. Curve parameters are proposed as possible ecosystem thresholds, perhaps to better manage the marine ecosystems of the world.

Ecosystem overfishing in the ocean.

Fisheries catches represent a net export of mass and energy that can no longer be used by trophic levels higher than those fished. Thus, exploitation implies a depletion of secondary production of higher trophic levels (here the production of mass and energy by herbivores and carnivores in the ecosystem) due to the removal of prey. The depletion of secondary production due to the export of biomass and energy through catches was recently formulated as a proxy for evaluating the ecosystem impacts of fishing-i.e., the level of ecosystem overfishing. Here we evaluate the historical and current risk of ecosystem overfishing at a global scale by quantifying the depletion of secondary production using the best available fisheries and ecological data (i.e., catch and primary production). Our results highlight an increasing trend in the number of unsustainable fisheries (i.e., an increase in the risk of ecosystem overfishing) from the 1950s to the 2000s, and illustrate the worldwide geographic expansion of overfishing. These results enable to assess when and where fishing became unsustainable at the ecosystem level. At present, total catch per capita from Large Marine Ecosystems is at least twice the value estimated to ensure fishing at moderate sustainable levels.

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.