Site Suitability for Finfish Marine Aquaculture in the Central Mediterranean Sea

Farm site selection plays a critical role in determining the productivity, environmental impact, and interactions of aquaculture activities with ecosystem services. Satellite Remote Sensing (SRS) provide spatially extensive datasets at high temporal and spatial resolution, which can be useful for aquaculture site selection. In this paper we mapped a finfish aquaculture Suitability Index (SI) applying the Spatial Multi-criteria Evaluation (SMCE) methodology. The robustness of the outcome of the SMCE was investigated using Uncertainty Analysis (UA), and in parallel we evaluate a set of alternative scenarios, aimed at minimizing the subjectivity associated with the decision process. The index is based on the outputs of eco-physiological models, which were forced using time series of sea surface temperature data, and on data concerning Significant Wave Height (SWH), distance to harbor, current sea uses, and cumulative impacts. The methodology was applied to map the suitability for farming of European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) within the Italian Economic Exclusive Zone (EEZ), under three scenarios: Blue Growth, Economic and Environment. Tyrrhenian and Ionian coastal areas were found to be more suitable, compared to the Northern Adriatic and southern Sicilian ones. In the latter, and in the western Sardinia, the index is also affected by higher uncertainty. The application presented suggests that SRS data could play a significant role in designing the Allocated Zones for Aquaculture, assisting policy makers and regulators in including aquaculture within maritime spatial planning

Early Diagenesis in Sediments of the Venice Lagoon (Italy) and Its Relationship to Hypoxia

This work focuses on sediments of a shallow water lagoon, located in a densely populated area undergoing multiple stressors, with the goal of increasing the understanding of the links between diagenetic processes occurring in sediments, the dynamics of dissolved oxygen (DO) in the water column, and potential consequences of hypoxia. Sediment data were collected over three consecutive years, from 2015 to 2017, during spring-summer, at five stations. Measured variables included: sediment porosity, grain size and organic carbon content, porewater microprofiles of O-2, pH and H2S, porewater profiles of dissolved inorganic carbon (DIC), total alkalinity (TA), NH4+, NO3-, dissolved Fe, and SO42-. In addition, long-term time series of oxygen saturations in the water column (years 2005-2017) were utilized in order to identify the occurrence and duration of hypoxic periods. The results show that the median DO saturation value in summer months was below 50% (around 110 mu mol L-1), and that saturation values below 25% (below the hypoxic threshold) can persist for more than 1 week. Sediment stations can be divided in two groups based on their diagenetic intensity: intense and moderate. At these two groups of stations, the average DIC net production rates, estimated trough a steady-state model (Profile) were, respectively, of 2.8 and 1.0 mmol m(-2) d(-1), SO42- consumption rates were respectively 1.6 and 0.4 mmol m(-2) d(-1), while diffusive oxygen uptake fluxes, calculated from the sediment microprofile data, were of 28.5 and 17.5 mmol m(-2) d(-1). At the stations characterized by intense diagenesis, total dissolved sulfide accumulated in porewaters close to the sediment-water interface, reaching values of 0.7 mM at 10 cm. Considering the typical physico-chemical summer conditions, the theoretical time required to consume oxygen down to the hypoxic level by sediment oxygen demand ranges between 5 and 18 days, in absence of mixing and re-oxygenation. This estimation highlights that sediment diagenesis may play a crucial role in triggering and maintaining hypoxia of lagoon waters during the summer season in specific high intensity diagenesis zones. This role of the sediment could be enhanced by changes in regional climate conditions, such as the increase in frequency of summer heat waves

Testing a Model of Pacific Oysters’ (Crassostrea gigas) Growth in the Adriatic Sea: Implications for Aquaculture Spatial Planning

Assessing the potential biomass yield is a key step in aquaculture site selection. This is challenging, especially for shellfish, as the growth rate depends on both trophic status and water temperature. Individual ecophysiological models can be used for mapping potential shellfish growth in coastal areas, using as input spatial time series of remotely sensed SST and chlorophyll-a. This approach was taken here to estimate the potential for developing oyster (Crassostrea gigas) farming in the western Adriatic Sea. Industry relevant indicators (i.e., shell length, total individual weight) and days required to reach marketable size were mapped using a dynamic energy budget model, finetuned on the basis of site-specific morphometric data collected monthly for a year. Spatially scaledup results showed that the faster and more uniform growth in the northern Adriatic coastal area, compared with the southern one, where chlorophyll-a levels are lower and summer temperatures exceed the critical temperature limit for longer periods. These results could be used in planning the identification of allocated zones for aquaculture, (AZA), taking into account also the potential for farming or co-farming C. gigas. In perspective, the methodology could be used for getting insights on changes to the potential productivity indicators due to climatic changes

Petri nets for modelling and analysing trophic networks

We consider trophic networks, a kind of networks used in ecology to represent feeding interactions (what-eats-what) in an ecosys- tem. We observe that trophic networks can be naturally modelled as Petri nets and this suggests the possibility of exploiting Petri nets for the analysis and simulation of trophic networks. Some preliminary steps in this directions and some ideas for future development are presented

An R package for simulating growth and organic wastage in aquaculture farms in response to environmental conditions and husbandry practices

A new R software package, RAC, is presented. RAC allows to simulate the rearing cycle of 4 species, finfish and shellfish, highly important in terms of production in the Mediterranean Sea. The package works both at the scale of the individual and of the farmed population. Mathematical models included in RAC were all validated in previous works, and account for growth and metabolism, based on input data characterizing the forcing functions-water temperature, and food quality/quantity. The package provides a demo dataset of forcings for each species, as well as a typical set of husbandry parameters for Mediterranean conditions. The present work illustrates RAC main features, and its current capabilities/limitations. Three test cases are presented as a proof of concept of RAC applicability, and to demonstrate its potential for integrating different open products nowadays provided by remote sensing and operational oceanography

Permanent trawl fishery closures in the Mediterranean Sea: An effective management strategy?

Since June 2010 the Italian government prohibited the trawling activity within three nautical miles from the coast or within the 50 m isobath. This decision was expected to have a great impact on trawl fishing activities, but at the moment no real assessment of the effects on catches and possible ecological implications has been undertaken. In order to fill this gap, an assessment on the North Western Adriatic Sea coast has been performed. Landings per Unit of Effort (kilograms per boat per day) for each trawling fleet segment have been analysed, by comparing on a monthly basis the before (2007-2009) and after ban (2011-2013) period. The comparison was carried out considering total landings and the six main species targeted inside the three miles area (sand smelt, cuttlefish, red mullet, sole, turbot, and mantis shrimp). Within a general reduction of total landings, a differential effect based on the analysed metiers was detected, with small trawlers being more negatively affected than the large and rapido ones, which showed, for some species, positive impacts. From an ecological point of view, though, no positive overall effects were detected, probably due to the fact that the adopted measure is not sufficient to reduce the overexploitation. In any case, all this is affecting the structure of the small-scale fishery in the area, since small trawlers are changing métier, moving towards the artisanal fishery, with deep impacts on the very coastal area that the trawling ban was designated to protect, compromising all possible benefitsSince June 2010 the Italian government prohibited the trawling activity within three nautical miles from the coast or within the 50 m isobath. This decision was expected to have a great impact on trawl fishing activities, but at the moment no real assessment of the effects on catches and possible ecological implications has been undertaken. In order to fill this gap, an assessment on the North Western Adriatic Sea coast has been performed. Landings per Unit of Effort (kilograms per boat per day) for each trawling fleet segment have been analysed, by comparing on a monthly basis the before (2007-2009) and after ban (2011-2013) period. The comparison was carried out considering total landings and the six main species targeted inside the three miles area (sand smelt, cuttlefish, red mullet, sole, turbot, and mantis shrimp). Within a general reduction of total landings, a differential effect based on the analysed m tiers was detected, with small trawlers being more negatively affected than the large and rapido ones, which showed, for some species, positive impacts. From an ecological point of view, though, no positive overall effects were detected, probably due to the fact that the adopted measure is not sufficient to reduce the overexploitation. In any case, all this is affecting the structure of the small-scale fishery in the area, since small trawlers are changing m tier, moving towards the artisanal fishery, with deep impacts on the very coastal area that the trawling ban was designated to protect, compromising all possible benefits. (C) 2015 Elsevier Ltd. All rights reserved

Eco-designing Aquaponics: A Case Study of an Experimental Production System in Belgium

Aquaponics is receiving a growing interest as an emerging technology that combines recirculating aquaculture practices and hydroponics to produce fish and vegetables. However, a proper eco-design is essential to limit the environmental burdens and to enhance the economic profitability. Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) were here combined to estimate the environmental and economic impacts of a designed pilot indoor aquaponic system in Belgium. Results showed that energy consumption, infrastructure and water consumption represent the main critical issues to achieve both the environmental and economic sustainability of this aquaponic system

Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM) degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which was mostly associated with the dynamics of the farming cycle. Sediment trap data at the two sampled stations (inside and outside of the mussel farm) showed average POC background flux of 20.0–24.2 mmol Cm2 d1. The difference of organic carbon (OC) fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol Cm2 d1, and was primarily associated with mussel physiological conditions. Although restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50%decrease in oxygen penetration depth (from 2.3 to 1.4 mm), accompanied by an increase in the O2 influx at the station below the mussel farm (19–31 versus 10–12 mmol O2 m2 d1/ characterised by higher POC flux. Dissolved inorganic carbon (DIC) and NHC 4 concentrations showed similar behaviour, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, of which calibration leads to an estimation of enhanced and shallower bioirrigation underneath the farm: bioirrigation rates of 40 yr1 and irrigation depth of 15 cm were estimated inside the shellfish deposition footprint versus 20 yr1 and 20 cm outside. These findings were confirmed by independent data on macrofauna composition collected at the study site. Early diagenesis model results indicated a larger organic matter mineralisation below the mussel farm (11.1 versus 18.7 mmolm2 d1/, characterised by similar proportions between oxic and anoxic degradation rates at the two stations, with an increase in the absolute values of oxygen consumed by OM degradation and reduced substances re-oxidation underneath the mussel farm

Designing and implementing a multi-scalar approach to Maritime Spatial Planning: The case study of Italy

The Italian coastal and marine space includes areas with remarkable differences in terms of oceanographic characteristics, maritime uses, natural habitats, species distribution, landscape and cultural heritage. In Italy, coastal and marine management competencies are shared among national, regional, and for some aspects even local authorities. This geographic heterogeneity and governance complexity required the adoption of a multiscalar approach to Maritime Spatial Planning (MSP). Such an approach aims at implementing decision-making and spatial planning at multiple and nested scales. In the case of Italy, the multi-scalar approach included the definition of national guidelines and the development of three maritime spatial (MS) plans, one for each maritime area (Adriatic, Ionian and Central Mediterranean, and Tyrrhenian and Western Mediterranean), including subareas and nested planning units. The development of the MS plans involved competent Ministries, the coastal Regions and several researchers. Based on the description of the adopted six-phase methodology and the exemplification of results of the Italian MSP process, this paper discusses the most relevant features and common challenges of multi-scalar MSP (i.e. co-planning, vertical and horizontal integration, multi-level governance, scalability, flexibility, integration of data and knowledge with different resolution, multi-scalar stakeholder engagement). Finally, the paper reflects on some novel aspects of the adopted multi-scalar approach and identifies actions to grant efficacy to this approach during the next phases of the Italian MSP proces

Making space for shellfish farming along the Adriatic coast

This work focuses on the selection of new areas for shellfish farming along the coast of the Northern Adriatic Sea (Italy). Shellfish site suitability was assessed by means of a methodology based on Spatial Multi-Criteria Evaluation (SMCE), which provided the framework to combine mathematical models and operational oceanography products. Intermediate level criteria considered in the analysis included optimal growth conditions, environmental interactions, and socio-economic evaluation (e.g. organic carbon deposition; distance to harbour). Results showed that the whole coastal area comprised within 0 and 3 nm is highly suitable for farming of mussel, while the area comprised between 3 and 12 nm is divided between a highly suitable northern part, and a less suitable southern one. Seven different scenarios of development of shellfish aquaculture industry were explored. The introduction of a new species, and the assessment of the exposure to storm events are specific aspects taken into account in development scenarios. Results show that the degree of suitability for shellfish aquaculture in this area would not change dramatically with the introduction of oyster farming. Furthermore, results highlight that: (i) the growth potential in this area is high; (ii) the space with suitability index >0.5 increases when prioritizing the optimal growth condition criteria, and (iii) the socio-economic is the most restrictive Intermediate Level Criteria. Results were discussed by deriving general lessons concerning the use of SMCE in aquaculture space allocation, from the specific application in the Northern Adriatic Sea. Challenges and opportunities related to the proposed methodological framework, with particular reference to the use of resources provided by remote sensing and operational oceanography by means of mathematical models, were also discussed. Results can support a science-based identification of allocated zones for aquaculture in order to avoid conflicts, and promote sustainable aquaculture in the Mediterranean Sea, where the space for these activities is becoming increasingly limited