A multi-criteria assessment of the implementation of innovative technologies to achieve different levels of microplastics and macroplastics reduction

This paper proposes and applies a multicriteria decision analysis framework tailored to assess measures for reducing the concentration of microplastics and macroplastics in seas, by implementing ground-breaking clean-up technologies and addressing different types of pollutant sources. Environmental, socio-economic and financial impacts are considered to provide a ranking of these measures for better-informed decision making. The data required to evaluate the performance of the technologies in different locations and scales are analyzed to understand the consequences of the different measures in terms of plastic pathways and sites, and the amounts accumulated, using innovative simulation models. The framework is applied to the Mediterranean Sea, providing insights for designing measures to respond to the challenges of cleaning seas and fulfill the EU marine strategy. The results for the best ranked alternatives show that dealing with microplastics is much more expensive (by one order of magnitude) than dealing with macroplastics.

Distribution of dissolved 137Cs, 131I and 238Pu at Eastern Mediterranean Sea in case of hypothetical accident at the Akkuyu Nuclear Power Plant

A coupled hydrodynamic/lagrangian particle drift model was applied to obtain the distribution of key radionuclides that are dispersed at the surface water (upper 100 m) of Eastern Mediterranean Sea, in case of an accident of Nuclear Power Plant at Akkuyu. The model was applied to simulate the dispersion of key artificial radionuclide concentration, in case of a hypothetical accident to assess issues related to sea health and potential hazards. The released radionuclide was found to have a favorable westward direction, following the prevailing currents. The variability of the predicted pattern is interpreted according to the near surface circulation patterns in the study area. The dispersion of key radionuclides (137Cs, 238Pu and 131I) was studied in a spatial and temporal manner at the neighboring coasts of the location of the NPP. Furthermore, the fate of the plume was predicted for each month after the accident date close to the areas of Akkuyu, namely Cyprus, Rhodes Island, North Cretan coast, Cyclades and Syrian Coast. The annual study revealed that the radioactive plume is present with high concentration (maximum values of 1200 Bq m-3 for the long lived isotopes and 600 Bq m-3 for 131I) in the location of the plant for short period of time (1-2 months), while the other areas are affected during the whole year with low level of activity concentration (20-50 Bqm-3). The ERICA Assessment Tool was also used to evaluate dose rates to common marine biota at the studied areas.

Modeling of floating marine litter originated from the Eastern Ionian Sea: Transport, residence time and connectivity

A Lagrangian particle tracking model coupled to a circulation was used to explore the transport, residence time and connectivity of floating litter that originated from the Εastern Ionian Sea during 2011-2014. At the end of simulations, on average 26% of litter was retained within the coastal waters of the Eastern Ionian Sea, whereas 58% was washed into offshore waters without formulating permanent accumulation areas, as the basin-wide surface circulation was characterized by considerable interannual variability. The inflow of litter into the Adriatic and Eastern Mediterranean Seas was moderate, ranging between 9% and 20%, and the beached litter was on average 9.2%, mostly located in the northern subregions. The average residence time of litter particles ranged between 20 and 80 days, implying their temporary retention before drifting offshore. Connectivity patterns depicted an exchange of litter mainly between adjacent subareas and with a northward direction.

Development, application and evaluation of a 1-D full life cycle anchovy and sardine model for the North Aegean Sea (Eastern Mediterranean)

A 1-D full-life-cycle, Individual-based model (IBM), two-way coupled with a hydrodynamic/biogeochemical model, is demonstrated for anchovy and sardine in the N. Aegean Sea (Eastern Mediterranean). The model is stage-specific and includes a 'Wisconsin' type bioenergetics, a diel vertical migration and a population dynamics module, with the incorporation of known differences in biological attributes between the anchovy and sardine stocks. A new energy allocation/egg production algorithm was developed, allowing for breeding pattern to move along the capital-income breeding continuum. Fish growth was calibrated against available size-at-age data by tuning food consumption (the half saturation coefficients) using a genetic algorithm. After a ten-years spin up, the model reproduced well the magnitude of population biomasses and spawning periods of the two species in the N. Aegean Sea. Surprisingly, model simulations revealed that anchovy depends primarily on stored energy for egg production (mostly capital breeder) whereas sardine depends heavily on direct food intake (income breeder). This is related to the peculiar phenology of plankton production in the area, with mesozooplankton concentration exhibiting a sharp decrease from early summer to autumn and a subsequent increase from winter to early summer. Monthly changes in somatic condition of fish collected on board the commercial purse seine fleet followed closely the simulated mesozooplankton concentration. Finally, model simulations showed that, when both the anchovy and sardine stocks are overexploited, the mesozooplankton concentration increases, which may open up ecological space for competing species. The importance of protecting the recruit spawners was highlighted with model simulations testing the effect of changing the timing of the existing 2.5-months closed period. Optimum timing for fishery closure is different for anchovy and sardine because of their opposite spawning and recruitment periods.

Biomass changes and trophic amplification of plankton in a warmer ocean

Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3-D coupled physical-biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate-change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and regional models, imply the need for caution when extending these considerations into higher trophic levels.