Auswahl der wissenschaftlichen Literatur zum Thema „Mediterranean marine ecosystems“

This study is focused on investigating the variation patterns of macroinvertebrate guilds functional structure, in relation to the taxonomic one, across aquatic ecosystem types along the salinity gradient from freshwater to marine and the resulting implications on guild organization and energy flows. Synoptic samplings have been carried out using the leaf-pack technique at 30 sites of the aquatic ecosystems of the Corfu Island (Greece), including freshwater, lagoon, and marine sites. Here, we analyzed the macroinvertebrate guilds of river, lagoon, and marine ecosystems, as: i. taxonomic composition and population abundance ii. trophic guilds composition and relative abundance; and iii. body size spectra and size patterns. The following variation patterns across the three ecosystem types were observed: a. trophic guild composition and body size spectra were more conservative than taxonomic composition within and among ecosystem types, where, trophic guild and size spectra composition were more similar between river and lagoon ecosystem types than with marine ones; b. a dominance on resource exploitation of large species over smaller ones was inferred at all sites; and, c. higher body size-specific density of individuals was consistently observed in lagoon than in freshwater and marine ecosystems. Results extend previous findings suggesting a common hierarchical organization of benthic macroinvertebrate guilds in aquatic ecosystems and showing that lagoon ecosystems have higher energy density transferred to benthic macroinvertebrates than both freshwater and marine ecosystem types.

The status of the Mediterranean Sea fisheries was evaluated across the seven subdivisions of the General Fisheries Commission for the Mediterranean (GFCM), using ecotrophic and catch-based indicators for the period 1970–2017. All indicators confirmed that the fishery resources across the Mediterranean Sea are no longer sustainably exploited and that the structure and function of marine ecosystems has been altered as a result of overexploitation. Although declining catches were a common feature across the Mediterranean Sea, the pattern of exploitation and the state of stocks differed among the subdivisions, with the Levantine Sea and Sardinia having a better status. Although they only include the exploited biological resources of marine ecosystems, catch and ecotrophic indicators can provide insight on ecosystem status and fishing pressure. In the case of southern Mediterranean countries, catch and trophic levels are the only information available, which is extremely valuable in data-poor ecosystems.

Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp . Zostera, P. gemini , or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.

Background Hydrothermal vents, cold seeps, pockmarks and seamounts are widely distributed on the ocean floor. Over the last fifty years, the knowledge about these volcanic-associated marine ecosystems has notably increased, yet available information is still limited, scattered, and unsuitable to support decision-making processes for the conservation and management of the marine environment. Methods Here we searched the Scopus database and the platform Web of Science to collect the scientific information available for these ecosystems in the Mediterranean Sea. The collected literature and the bio-geographic and population variables extracted are provided into a systematic map as an online tool that includes an updated database searchable through a user-friendly R-shiny app. Results The 433 literature items with almost one thousand observations provided evidence of more than 100 different volcanic-associated marine ecosystem sites, mostly distributed in the shallow waters of the Mediterranean Sea. Less than 30% of these sites are currently included in protected or regulated areas. The updated database available in the R-shiny app is a tool that could guide the implementation of more effective protection measures for volcanic-associated marine ecosystems in the Mediterranean Sea within existing management instruments under the EU Habitats Directive. Moreover, the information provided in this study could aid policymakers in defining the priorities for the future protection measures needed to achieve the targets of the UN Agenda 2030.

High-level predators have been depleted in the oceans worldwide following centuries of selective fishing. There is widespread evidence that high-level predators’ extirpation may trigger trophic cascades leading to the degradation of marine ecosystems. Restoration of large carnivores to former levels of abundance might lead to ecosystem recovery, but very few pristine ecosystems are left as baselines for comparison. Marine protected areas (MPAs) can trigger initial rapid increases of high-level predator abundance and biomass. Nevertheless, long term protection is needed before the ecosystem's carrying capacity for large carnivores is approached and indirect effects on lower trophic levels are observed. The Mediterranean is probably very far from its pristine condition, due to a long history of fishing. Today small to medium-sized consumers (e.g. sea breams) are the most abundant predators shaping coastal benthic communities, while historical reconstructions depict abundant populations of large piscivores and sharks inhabiting coastal areas. Mediterranean MPAs are following a promising trajectory of ecosystem recovery, as suggested by a strong gradient of fish biomass increase. Consistent monitoring methods to assess relative variations of high-level predators, together with food-web models aimed at disentangling the indirect effects of their recovery, could be useful tools to help set up appropriate management strategies of MPAs.

Abrupt and rapid ecosystem shifts (where major reorganizations of food-web and community structures occur), commonly termed regime shifts, are changes between contrasting and persisting states of ecosystem structure and function. These shifts have been increasingly reported for exploited marine ecosystems around the world from the North Pacific to the North Atlantic. Understanding the drivers and mechanisms leading to marine ecosystem shifts is crucial in developing adaptive management strategies to achieve sustainable exploitation of marine ecosystems. An international workshop on a comparative approach to analysing these marine ecosystem shifts was held at Hamburg University, Institute for Hydrobiology and Fisheries Science, Germany on 1–3 November 2010. Twenty-seven scientists from 14 countries attended the meeting, representing specialists from seven marine regions, including the Baltic Sea, the North Sea, the Barents Sea, the Black Sea, the Mediterranean Sea, the Bay of Biscay and the Scotian Shelf off the Canadian East coast. The goal of the workshop was to conduct the first large-scale comparison of marine ecosystem regime shifts across multiple regional areas, in order to support the development of ecosystem-based management strategies.

PETRI-MED: Enhancing marine phytoplankton diversity monitoring in the Mediterranean Preserving biodiversity is crucial for sustaining life on Earth. Unfortunately, it is facing growing threats. Marco Talone and the PETRI-MED Team discuss their objectives for the PETRI-MED project and explain why it is urgently necessary. Marine biodiversity is crucial for maintaining healthy and resilient ecosystems. The variety of life forms in our oceans—from microscopic plankton to giant whales—plays a key role in sustaining ecological balance. Each species contributes to ecosystem services such as oxygen production, carbon sequestration, and nutrient cycling, which are vital for the planet’s health. Marine biodiversity also supports the global food web, providing a primary source of protein for over three billion people. Additionally, it contributes to the blue economy through fisheries, tourism, and biotechnology. Lastly, healthy marine ecosystems are better equipped to withstand and recover from environmental changes and human impacts, such as climate change and pollution. Among the various life forms inhabiting our ocean, phytoplankton is one of the most important.

Non-indigenous species (NIS) represent one of the greatest threats to biodiversity and ecosystem functioning, altering invaded habitats, competing with native species, and eventually becoming pests. The Mediterranean Sea is a marine biodiversity hotspot, with its coasts being densely populated and its living resources fished since ancient times. As a result of such a long history of exploitation, the whole basin is exposed to a wide array of human pressures, with their combined effects on marine ecosystems being amplified by ongoing climate change. Caulerpa cylindracea Sonder, 1845, is a non-indigenous invasive seaweed widely distributed in the coastal habitats of the Mediterranean Sea, which ultimately affects marine biodiversity and ecosystem functioning. Here, a systematic literature analysis on the consumption of the NIS Caulerpa cylindracea by Mediterranean native and NIS species is provided, focusing on the benefits and drawbacks for the native biota and human health. The present review aims to synthetise knowledge and provide tools to manage the occurrence of the invasive seaweed C. cylindracea in the Mediterranean Sea, encouraging an ecosystem-based approach to the management of the ecological, economic, and social effects of the successful expansion of this NIS.

The oceans are a vast yet fragile environment, and one of the biggest issues scientists have to tackle today is the conservation of marine biodiversity. In 1975, to try to address the physical, chemical and biological alteration of these delicate ecosystems, 16 Mediterranean States together with the European Union, implemented the Mediterranean Action Plan (MAP). The aim was to safeguard the marine environment and promote its development in the Mediterranean basin.

Abstract. In the western Mediterranean Sea, the RADMED monitoring programme is already conducting several of the evaluations required under the Marine Strategy Framework Directive (MFSD) along the Spanish Mediterranean coast. The different aspects of the ecosystem that are regularly sampled under this monitoring programme are the physical environment and the chemical and biological variables of the water column, together with the planktonic communities, biomass and structure. Moreover, determinations of some anthropogenic stressors on the marine environment, such as contaminants and microplastics, are under development. Data are managed and stored at the Instituto Español de Oceanografía (IEO) Data Centre that works under the SeaDataNet infrastructure, and are also stored in the IBAMar database. In combination with remote sensing data, they are used to address open questions on the ecosystems in the western Mediterranean Sea.

Plastic pollution has been recognised as one of the major global threats for marine ecosystems. In the Mediterranean basin, plastic debris are present at concentrations comparable to the subtropical ocean gyres. Microplastics (< 5 mm) also reached the most remote environment on Earth, being reported in Antarctic surface waters and sediments. The limited knowledge on the biological impacts of the smallest fraction of plastic debris, defined as nanoplastics (< 1 μm), is of primary concern, due to their high surface reactivity and nanometric size that allow to easily interact with biological surfaces at the cellular level. Within this thesis, the bioaccumulation and toxicity of nanoplastics in Mediterranean and Antarctic marine organisms have been investigated. Polystyrene nanoparticles (PS NPs), having a nominal diameter of approx. 50 nm and different surface charge, were adopted as nanoplastics as anionic carboxylated (PS-COOH) and cationic amino-modified (PS-NH2). The characterization of their behaviour in natural sea water media was combined with cellular/whole-animal bioassays in order to define uptake, disposition and mechanisms of action under controlled laboratory conditions. The four chapters of the thesis report findings on model organisms including zooplanktonic and benthic species from the Mediterranean Sea and Southern Ocean around Antarctica, as sea urchin embryos (Paracentrotus lividus), green microalga (Dunaliella tertiolecta), brine shrimp (Artemia franciscana) and Antarctic sea urchin (Sterechinus neumayeri) and krill (Euphausia superba) respectively. Overall, we proved that NP surface charge (anionic vs cationic) drives the behaviour of PS NPs in natural sea water in terms of stability and aggregation, which differs in Mediterranean and Antarctic sea waters. Anionic PS-COOH formed large micro-sized aggregates whereas cationic PS-NH2 resulted better dispersed in Mediterranean sea waters. In Antarctic sea waters, such difference in aggregation was reduced, with PS-COOH reaching nano-sized aggregates and PS-NH2 approaching the nominal size. A similar pattern of biodistribution and toxicity was observed in marine organisms from Mediterranean Sea and Antarctica, with respect to NP surface charge. Anionic PS-COOH were mostly ingested, accumulated and excreted with no or limited effect, while PS-NH2 revealed a less clear disposition but cause high toxicity, hinder embryo development and larval growth, disrupt physiology and organism’s survival. For this latter NP, several markers of stress, were identified through up-regulation of apoptotic-related genes (caspase8, hsp60, hsp70 and p-38 mapk) in Mediterranean sea urchin embryos and moulting-related genes (clap, cstb and cb6) in brine shrimp larvae and Antarctic krill juveniles. In Antarctic sea urchin coelomocytes, both PS NPs were able to reduce the cellular phagocytic capacity, with PS-COOH inducing the strongest gene modulation in contrast to a threshold in cell defence ability upon PS-NH2 exposure. Overall, ecotoxicological data constitute a comprehensive baseline on the biological effects of nanoplastics in Mediterranean and Antarctic marine species, motivating future research using more realistic exposure scenarios towards environmental-like conditions and more specific NP-biological interactions (i.e. eco and bio-coronas).

Amb aquest treball es preté comprovar la universalitat de la relació estequiomètrica de Redfield i recercar patrons consistents de les desviacions d'aquesta raó promig en ambients oligotrofics. Per tal de dur a terme aquest propòsit s'han desenvolupat relacions estequiomètriques en el compartiment particulat i dissolt orgànic i inorgànic per el C, N, P i Si.
La estequiometria dels nutrients a l'oceà s'ha examinat al Mar Mediterrani i a l'Oceà Atlàntic subtropical, mentre que la zona costenera del Mar Mediterrani ha servit per estudiar aquestes relacions sota l'influència d'aports terrestres.
En el segon capítol de la tesi es descriuen patrons meridionals del fluxe de nitrogen i fósfor vers la capa biogènica de l'Oceà Atlàntic Central. La raó promig entre el fluxe difusiu del nitrogen inorgànic dissolt (DIN) i del fósfor (DIP) es mostra similar a la raó de Redfield al llarg de l'Oceà Atlàntic Central, però tendeix a valors per sota dels establerts per Redfield a la part sud del trajecte i superiors a la raó de Redfield al centre del gir sudtropical. La raó N:P del fluxe difusiu i la raó N:P dels nutrients dissolts inorgànics en la capa biogènica es troben fortament correlacionats, mentre que no existeix cap correlació amb els valors de la raó N:P de les aigües intermitges. Els resultats trobats en aquest capítol de la tesi indiquen que la recirculació vertical de nutrients a la capa biogènica de l'oceà Atlàntic Central és capaç d'operar amb raons estequimètriques que difereixen de Redfield i per tant els components biogènics i biolítics s'adapten a les variacions locals de la raó de Redfield. La hipòtesis que existeixen raons estequiomètriques previsibles en la reserva oceànica de material dissolt orgànic que es troben en equilibri amb la reserva del material particulat orgànic i dissolt inorgànic, es corrobora en el tercer capítol d'aquesta tesi. La majoria del carboni orgànic present en aigües oligotrofiques del Mediterrani estratificat es troba en forma d'orgànic dissolt, mentre que el POC (carboni orgànic particulat) representa un percentatge menor. El nitrogen i fósfor orgànic dissolt que comprenen el 50-80% del "pool" total de P i N a la capa biogènica, decreix en percentarge a la capa biolítica. S'ha comprovat una distribució uniforme del nitrogen disolt total (TDN). L'increment en el percentatge de N inorgànic disolt i el decreixement en percentatge de N orgànic dissolt amb la fondària, és un indicador clar de l'equilibri dinàmic que existeix entre les reaccions bioquímiques entre les reserves oceàniques. Mitjançant un sistema de balanços, s'estableix un intercanvi de nutrients (exportació-importació) entre els pools dissolt orgànic i dissolt inorgànic en el sistema. S'ha comprovat que el fluxe de nitrogen orgànic dissolt (DON) excedeix al fluxe difusiu de nitrogen inorgànic i per tant els aports atmosfèrics i terrestres són importants en aquesta regió.
En el quart capítol de la tesi es descriu el lligam existent entre el component pelàgic i els component del bentos d'una àrea litoral del Mar Mediterrani, és a dir un compartiment anabolic que produeix matèria orgànica i un de catabolic que actúa com agent oxidant de la reserva de matèria orgànica del sistema. El compartiment pelàgic es mostra heterotrofic. Al mateix temps, existeix una contribució important de material terrestre als sediments. Per contra, el compartiment bentònic és autotrofic on el dèficit en la producció grossa es compensa amb l'excés de producció neta del sistema. Mitjançant la quantificació simultànea dels fluxes anuals de sedimentació per al C, N, P i Si així com dels fluxes sediment-aigua de les espècies orgàniques i inorgàniques dissoltes, s'ha establert un sistema de balanços de matèria del sistema. El compartiment bentonic es configura com a sumider o exportador de matèria orgànica, degut als aports terrestres de carboni en el sistema.
Els patrons de distribució de nutrients derivats dels resultats dels capítols anteriors es comproven mitjançant un experiment d'addició de nutrients. En el capítol cinquè d'aquesta tesi s'estudien els canvis en la distribució de nutrients en les diferents reserves nutricionals d'un sistema quan es troba sotmès a aports controlats de nutrients. S'ha comprovat que, mentre el tamany relatiu de la reserva de nutrients inorgànics dissolts no varia amb l'increment de nutrients en el medi. Hi ha una tendència a l'increment del tamany relatiu de la reserva del material particulat, paral.lela a un decreixement simultani de la reserva de material dissolt orgànic. Aquest experiment contribueix a verificar el paper del DOM (matèria dissolta orgànica) com a principal reserva nutricional en sistemes oliogotròfics.
The stoichiometric ratios are powerful tools to model basic biogeochemical patterns of the sea when the fluxes of a single element are known. It is, therefore essential to understand the full implications of variable stoichiometries to predict the effect of the living components of the ocean on biogeochemical processes. Here, the stoichiometry between C, N, P and Si in different chemical pools (particulate and dissolved organic and dissolved inorganic matter) were examined in contrasting oceanic and littoral ecosystems, and the changes in nutrient partitioning in response to nutrient inputs was tested through experimental research.
In the Central Atlantic Ocean, the average ratio between dissolved inorganic nitrogen and phosphorus in the estimated vertical diffusive fluxes was similar to the Redfield ratio, but tended to be above the Redfield ratio at the center of the South subtropical gyre. The N:P supply ratio and the N:P ratio of dissolved inorganic nutrients in the biogenic layer were strongly correlated, but were not positively correlated to that in the intermediate waters. The vertical nutrient conveyor belt of nutrients in the upper waters operates relatively independently of the underlying waters in the Central Atlantic, so that both the biogenic and the biolythic components should be able to adapt to local variation about the Redfield ratio.
In the stratified NW Mediterranean Sea, the stoichiometry between dissolved inorganic, organic and particulate organic matter pools indicated an excess nitrogen relative to phosphorus, particularly in the biolythic layer, as well as a general silicate deficiency relative to both N and P. Most (> 80 %) of the organic carbon was present as dissolved organic carbon, with POC representing a minor percent of total organic C throughout the water column. The increasing C/N ratio of DOM with depth indicates that N is recycled faster than C in the DOM. There exists a dynamic equilibrium between the biological transformations between these pools with depth, with a dominance of DON production in surface waters and remineralization in the underlying layers, from which dissolved inorganic nitrogen is re-supplied to the biogenic layer.
Alocthonous N inputs must be important in the region since the downward DON flux exceeded the diffusive DIN supply.
The coupling between anabolic and catabolic compartments of a littoral area in the NW Mediterranean Sea are characterized. The pelagic compartment was heterotrophic, supported by significant allochthonous inputs of land material, whereas the benthic compartment was autotrophic, with the excess net benthic community production balancing the deficit in pelagic community production, leading to a system in metabolic equilibrium. Sedimentary inputs of phosphorus and silicon were compensated by sediment release of phosphate and silicate, whereas nitrogen was lost or accumulated in the sediment compartment. Carbon inputs to the benthic compartment also exceeded requirements, due to the allocthonous subsidies to the system, so that the benthic compartment stored or exported organic carbon.
Experimental nutrient additions lead to a parabolic change in C/N and C/P ratios in the dissolved organic matter with increasing nutrient inputs. The relative size of the dissolved inorganic nutrient pools did not vary, but there was a tendency towards an increase in the relative size of the particulate pool at the expense of a decrease in the relative importance of DOM as a reservoir of N, P and C, with increasing nutrient inputs.
The relative importance of different nitrogen pools was examined in relation to the total nutrient stoichiometry of the oligotrophic system. The ratio of dissolved inorganic nutrients reported in the research presented is indicative of a general deficiency in nitrogen compared to the global ratios reported in literature. The dissolved organic matter was highly depleted in P relative to N and C at all locations investigated and the resulting POC:PON ratio (11.7) of this study in the particulate pool deviates greatly from the literature values which approximates Redfield value (5.5-6). The shift of the dominance of DON towards PON at TOC/TN values higher than 20 on the oligothrophic areas of the study, gives evidence of increasing carbon export fluxes in a system dominated by particulate pool and points to the effect of the biota on the gradient-driven export to sinking carbon fluxes in the ocean.

Hydrocarbon (HC) pollution is a worldwide threat to marine natural ecosystems due to the increasing exploitation of underground marine petroleum deposits in several areas and to the high traffic of oil tankers and the presence of submarine pipes that are main transport routes for crude oil and refined products. HCs spread in the marine environment is mainly due to accidental oil spills or inadequate practices and their release affects marine ecosystems causing severe ecological and economical damages. The Mediterranean Sea is particularly endangered by hydrocarbon pollution because of its physical nature – it is an enclosed basin with a slow water exchange – and because it hosts about 20% of the global oil tanker traffic in its waters and tens of oil-related sites along its coastline. The conventional remediation strategies, comprising chemical and physical methods, are extremely expensive and invasive, therefore the development of cheaper and eco-friendly approaches is crucial to preserve human and ecosystem health. In this perspective, bioremediation (i.e. the use of living organisms to remove pollutants from a contaminated area) is a promising technology which, taking advantage of microbes’ metabolic potential to degrade a wide range of pollutants, can both reduce the costs and may represent a permanent solution. Nevertheless, there is still a scarce knowledge of the processes and the microorganisms involved in the clean-up of hydrocarbons from marine environments, hence some problems still exist concerning the in-field application of bioremediation. The aim of the present PhD thesis was to: i) investigate the overall prokaryotic diversity of pristine and oil polluted sites across the whole Mediterranean Sea; ii) depict the phylogenetic and functional diversity of hydrocarbonoclastic bacteria inhabiting pristine and polluted sites; iii) establish a large collection of bacteria showing degrading activities toward hydrocarbon compounds; iv) set up microcosm experiments to investigate the potential of bacterial bioaugmentation in bioremediation processes under laboratory scale conditions, v) test the degrading potential of selected bacterial strains and consortia under different pressure values, simulating different depths along the water column. The diversity of planktonic bacterial communities in the Mediterranean Sea was firstly evaluated on open seawater samples collected at different depths in a transect covering the main oil tanker route across the whole basin, from the Levantine Sea to the Gibraltar strait. Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the microbiome inhabiting deep and surface water samples were sharply separated. Furthermore, the composition of the bacterial communities described in the surface layers of the water columns at different sampling stations has been significantly correlated, beside to their geographical position and depth, to the temperature and salinity values recorded for each sample. Denaturing Gradient Gel Electrophoresis (DGGE) and ARISA fingerprinting were also applied to depict the bacterial composition of highly polluted sediments collected at the Ancona harbor (Italy) and El-Max district (Egypt), showing the significant influence of the different pollutants’ concentration (i.e. hydrocarbons, heavy metals) in the selection of peculiar bacterial assemblages . This molecular approach led to the identification of bacterial species potentially useful for site-tailored bioremediation purposes. A large collection of hydrocarbon degrading bacterial strains was hence established from enrichments using contaminated sediments as inoculum and diesel, crude oil and naphthalene as unique carbon sources. The cultivation approaches adopted to enrich and isolate hydrocarbonoclastic bacteria from chronically polluted area, like the Ancona harbor, permitted to evaluate the influence of different hydrocarbon pollutants used as single carbon source in the selection of specific marine bacteria populations. The results obtained taking advantage of DGGE fingerprinting and 16S rRNA pyrosequencing applied on the enrichments showed that, under laboratory conditions, the supply of different hydrocarbon compounds led to the selection of different, and specialized, bacterial communities. A total of 248 bacterial strains have been isolated from open sea surface water collected along oil tanker routes and the chronically polluted sediments, and have been identified by 16S rRNA gene sequencing. Alcanivorax and Marinobacter, two ubiquitous marine hydrocarbonoclastic genera, were the most abundant within the established collection, representing respectively 67% and 23% of the isolates. Due to the great importance of the Alcanivorax genus for hydrocarbon remediation of marine polluted sites, all the isolates belonging to this genus were investigated at a finer level in terms of phylogenetic and functional diversity. This sub-collection, comprising 179 isolates belonging to the 4 species A. borkumensis, A. jadensis, A. venustensis and A. dieselolei, were genotyped using two different fingerprinting techniques: Internal Transcribed Spacer (ITS)-PCR and BOX-PCR. The combination of the applied techniques allowed the identification of 85 genotypes, distributed among the different sites investigated, showing clear evidence of geographic divergence. The functional diversity of these strains was furthermore investigated through the PCR amplification of the alkB gene, encoding for an alkane monooxigenase involved in the first step of hydrocarbons degradation, and subsequent Restriction Fragment Length Polymorphism (RFLP) analysis of the amplicons, allowing the identification of 16 different polymorphisms. The results demostrated the existence of a high degree of geographical divergence within the Alcanivorax genus, suggesting a potentially high metabolic diversity that could be exploited for site-tailored bioremediation interventions. Recently, the Deepwater Horizon break in the Gulf of Mexico (2010) and the subsequent huge oil spill occurred at a depth of 1500 meters, highlighted the need to get more insight on bioremediation processes occurring at high depth. This accident represents a milestone and shed a light on the importance to investigate the effect of pressure, an environmental parameter that might hamper the activity of oil-degrading strains, on growth and degradation capabilities. The capability of selected hydrocarbonoclastic strains, belonging to the species A. jadensis, A. dieselolei and M. hydrocarbonoclasticus, to adapt and degrade a model alkane molecule (dodecane) at high pressure was therefore tested. The growth of the strains at increasing hydrostatic pressure and their physiologic activities were evaluated, comparing the results with the type strain A. borkumensis SK2. Overall, the results showed a detrimental effect of pressure for all the strains in terms of growth rates, O2 consumption and CO2 production. The potential adaptation of A. borkumensis and A.dieselolei was evaluated also with less recalcitrant carbon source than alkanes (pyruvate), without showing substantial differences, except for the higher consumption of pyruvate by A. borkumensis SK2. This investigation pinpointed that the tested bacteria can survive at high hydrostatic pressures, even though both their growth and degradation capability were mostly inhibited with the increase in hydrostatic pressure. Moreover, aiming to create a baseline for future transcriptomic analyses, the complete genome of this 4 strains was sequenced and annotated: all the strains owned multiple copies of the genes involved in the degradation of hydrocarbons (alkane monoossigenase, alk and cytochrome p450, cyp450), apparently belonging to different families, highlighting the great functional potential of these strains. A second sub-collection of hydrocarbonoclastic bacteria, isolated from chronically polluted sediments, was screened for the presence of functional genes involved in the degradation/detoxification of specific pollutants (alkanes and heavy metals), the ability to grow on different HCs and the ability to produce biosurfactant and from biofilm. The results showed that several isolates, mainly belonging to the Marinobacter genus, were positive for the investigated traits, hence they could be potentially exploited for autochthonous bioaugmentation (ABA) purposes in the sites of provenience. Finally, the bacterial community response in a biodegradation process based on an ex-situ landfarming set-up was evaluated. Landfarming was performed, using a combination of biostimulation and bioaugmentation, to remediate oil-polluted sediment collected at Elefsina bay (Greece). This work was realized to determine the effect of bioaugmentation by four allochthonous oil-degrading bacterial consortia, previously isolated from 4 polluted areas located in the Southern Mediterranean, in relation to the degradation efficiency of the indigenous community. DGGE fingerprinting analysis allowed the characterization of the bacterial community dynamics, evaluating the dominant taxa through time and at each treatment. The results showed that the added allochthonous bacteria quickly perished and were rarely detected, furthermore their addition induced minimal shifts in the community structure. These data, together with the measurement of HC degradation over the experimental time, suggested that, during the landfarming, biodegradation was mostly performed by the autochthonous populations rather than by the allochthonous ones. Furthermore, biostimulation, in contrast to bioaugmentation, was proved to enhance the HCs degradation when compared to the control treatment. To conclude, the results obtained this Ph.D. project emphasized the high bacterial diversity of the Mediterranean Sea in both pristine and polluted sites and the occurrence of distribution patterns which were significantly related to several environmental parameters, including the concentration of hydrocarbons and heavy metals. Moreover, this study confirmed the great potential of the Mediterranean Sea as a source of bacterial strains harbouring degradation capabilities toward different hydrocarbon molecules and, through the ex-situ application of different bioremediation strategies (bioaugmentation and biostimulation), it demonstrated the great importance of autochthonous microbial community in remediating polluted environments.

The conservation of marine ecosystem structure and functioning is a priority target within the context of the environmental management. This is especially important in oligotrophic systems such as the Balearic Sea, where food availability is a limiting factor. For such a target is fundamental to know the array of predator-prey interactions as a basis to understand the food web trophodynamics. In this Thesis, the trophic structure of the pelagic and benthic habitats off the Balearic Islands and the feeding ecology of three taxonomic groups (cephalopods, elasmobranchs and mesopelagic fishes) playing a key role in marine ecosystems, were investigated A relatively large food web (89 species) encompassing both the pelagic and the benthic habitats were analysed. The food webs extended up to 4 trophic levels in both habitats, and most species occupied intermediate trophic levels. A high partitioning rate of trophic resources was found, which might be related to the reduction of competition for food. The energy link between the pelagic and benthic communities (benthopelagic coupling; BPC) was stronger on the shelf break, where higher hydrodinamism mix the water column and associated nutrients, than on the slope. The geographical variability of oceanographic drivers (i.e. eddies, currents) influenced the strength of the BPC. Regarding species trophic interactions, stomach contents provided evidence of mesopelagic prey coupling pelagic and benthic habitats, especially down the shelf break. Rays from the shelf consumed mainly decapod crustaceans and teleosts, whereas sharks from the slope fed primarily upon mesopelagic prey (i.e myctophids, euphausiids). Sharks and rays variation in diet was driven by species specific ontogenetic stages and habitat use. The diet of the two squid Loligo vulgaris and L. forbesii, examined for the first time in the Mediterranean, showed their highly piscivorous habits. Their prey composition revealed a lack of diet overlap as a result of their bathymetric segregation. Both squids showed shifts in diet related to size and their reproduction period. The squid L. vulgaris feed on small benthic prey until they reach a size threshold and feed on benthopelagic fish thereafter. Seasonal changes in diet in both squid species, likely related to reproduction, might help improving their individual body condition. During this period, L. vulgaris increased the consumption of highly nutritive polychaetes, whereas the adults of L. forbesii carried out movements to deeper waters to feed on lipid-rich mesopelagic prey. Mesopelagic prey are important food resources for demersal species in the Balearic Sea and, as a result of their nycthemeral movements, they have important implications for the transport of mass and energy through the water column. The trophodynamics of this group revealed that food sources (δ13C) varied little over the spatial scales sampled (location and depth) but showed high seasonality, reflecting intra-annual changes in the species composition of the phytoplankton community. By contrast, spatio-temporal variations of mesopelagic trophic interactions (δ15N) were minimal. Important niche segregation was observed between the non-migratory stomiiforms and some of the extensive migratory myctophids. Finally, the comparative analysis of the trophic ecology of deep-sea cephalopods and elasmobranchs showed that they displayed different feeding strategies with a clear resource partitioning between and within taxa. Segregation of the isotopic space indicated a contrasting food source gradient (δ13C) stretching from pelagic (squids and cuttlefishes) to nektobenthic (octopuses and elasmobranchs) sources. However, deep-sea sharks off the Balearic Islands frequently preyed on mesopelagic species, as did squids and cuttlefishes. Cephalopods, in turn, constituted an important food resource for deep-sea sharks. Squid and shark species identified as benthopelagic feeders, play a key role in the transport of energy from midwater regions to the benthic community.

In this thesis, the ecological role of 26 species of abundant, rare and endangered chondrichthyans present in the western Mediterranean has been studied through the study of trophic ecology and main morphological characters. Due to the number of species included, this thesis constitutes the most complete research on the trophic ecology of sharks, rays and chimeras in the Mediterranean Sea. For this purpose, different methodologies such as stomach content analysis, review of available literature and new tools such as stable isotope analysis have been combined. The results reveal the importance of chondrichthyans in the western Mediterranean as mesopredators and top predators. The small sharks Scyliorhinus canicula, Etmopterus spinax and Galeus melastomus act as mesopredators of the ecosystem and, because of their abundance, they could be considered important species in the Mediterranean Sea. S. canicula presents intraspecific changes in relation to its trophic ecology and small individuals feed on different prey than larger individuals. The same occurs with males and females, probably because they feed on different areas of the continental shelf. These three species, along with Dalatias licha, do not present changes in their trophic ecology between areas with different degrees of human impact such as the Catalan Sea and an area restricted to fishing in the Gulf of Lions. This result is probably related to the fact that S. canicula, E. spinax, and G. melastomus are opportunistic species, being able to exploit different resources including part of the fishing discards. In addition, D. licha prey mainly on these opportunistic species. It may also be that the area of the Gulf of Lions has not recovered significantly after its declaration as an area restricted to fishing and does not show substantially different characteristics to the exploited area of the Catalan Sea. Other chondrichthyans that have an ecological role similar to the small demersal sharks are the different species of skates (Rajiformes), species that feed mainly on crustaceans. Other mesopredator rays, such as Mobula mobular and Myliobatis aquila, have a unique trophic role within the studied species: M. mobular is a filter feeding species and M. aquila feeds mainly on bivalves. As top predators are the sharks Alopias vulpinus and Galeorhinus galeus, the ray Gymnura altavela, Torpediniformes, Chimaeriformes and other medium-sized sharks of the orders Carcharhiniformes, Hexanchiformes and Squaliformes. The results present in this thesis have confirmed that the chondrichthyans of the Mediterranean Sea have different ecological roles, being a very important step in the knowledge of the trophic ecology of these organisms. In addition, it has to be emphasized the use of the stable isotope analysis in blood for the first time, a non-lethal technique, for the study of the trophic ecology of the shark S. canicula. This methodology could be very useful for investigating the trophic ecology and the ecological role in sharks and rays that are rare or endangered.
En esta tesis se ha avanzado en el conocimiento del rol ecológico de 26 especies de condrictios abundantes, poco comunes y en peligro de extinción presentes en el Mediterráneo occidental, mediante el estudio de la ecología trófica y de los principales caracteres morfológicos. Por el número de especies incluidas, la presente tesis constituye el trabajo de investigación más completo sobre ecología trófica de tiburones, rayas y quimeras en el Mar Mediterráneo. Para ello se han utilizado de manera combinada diferentes metodologías como el análisis del contenido estomacal, la revisión de la literatura disponible y herramientas novedosas como el análisis de isótopos estables. Los resultados encontrados ponen de manifiesto la importancia de los condrictios en el Mediterráneo occidental como mesodepredadores y depredadores apicales. Los tiburones de pequño tamaño como Scyliorhinus canicula, Etmopterus spinax y Galeus melastomus actúan como mesodepredadores del ecosistema y por su abundancia pueden ser consideradas especies relevantes en el Mar Mediterráneo. S. canicula presenta cambios intraespecíficos en relación con su ecología trófica. Los individuos pequeños de esta especie depredan sobre presas diferentes a los individuos de mayor tamaño. Lo mismo sucede con los machos y las hembras, probablemente porque se alimentan en diferentes zonas de la plataforma continental. S. canicula, E. spinax y G. melastomus, junto a Dalatias licha, no presentan cambios en su ecología trófica entre áreas con diferente grado de impacto antrópico como lo son el Mar Catalán y una zona restringida a la pesca del Golfo de León. Este resultado probablemente está relacionado con el hecho de que S. canicula, E. spinax y G. melastomus son especies oportunistas, pudiendo explotar diferentes recursos, incluidos parte de los descartes pesqueros. Además, D. licha depreda principalmente sobre estas especies de tiburones oportunistas. Puede ser también que la zona del Golfo de León no se haya recuperado significativamente después de su declaración como área restringida a la pesca y no muestre características substancialmente diferentes a la zona explotada del Mar Catalán. Otros condrictios que tienen un rol ecológico similar a los pequeños tiburones demersales son las diferentes especies de rayas del orden Rajiformes, especies que se alimentan principalmente de crustáceos. Otras rayas mesodepredadoras, como Mobula mobular y Myliobatis aquila, tienen un rol trófico único dentro de las especies estudiadas: M. mobular es una especie filtradora y M. aquila se alimenta principalmente de bivalvos. Como depredadores apicales se encuentran los tiburones Alopias vulpinus, Galeorhinus galeus y la raya Gymnura altavela. Otros deprededaores apicales son los Torpediniformes, Chimaeriformes y otros tiburones de tamaño medio de los órdenes Carcharhiniformes, Hexanchiformes y Squaliformes. En esta tesis doctoral se ha confirmado que los condrictios del Mar Mediterráneo tienen diferentes roles ecológicos y se ha dado un paso muy importante en el conocimiento de la ecología trófica de estos organismos. Además cabe resaltar el uso por primera vez del análisis de isótopos estables en sangre, una técnica no letal, para el estudio de la ecología trófica del tiburón S. canicula. Esta metodología puede ser muy útil para estudiar la ecología trófica y el rol ecológico en tiburones y rayas poco abundantes o en peligro de extinción.

La connectivité, concept vaste et multidimensionnel, joue un rôle essentiel dans la compréhension des interactions au sein des écosystèmes, qu'ils soient terrestres ou marins. Elle fait référence aux flux de matière, d'énergie et d'organismes qui se déplacent et interagissent à travers les habitats, influençant la dynamique des populations et leur résilience face aux perturbations. Cette thèse se concentre sur l'étude de la connectivité dans les écosystèmes marins côtiers méditerranéens, et plus précisément sur la dispersion larvaire des espèces à cycle de vie biphasique. L'objectif principal de ce travail de recherche est de prédire les tendances de dispersion larvaire et de connectivité chez des espèces clés, tout en mettant un accent particulier sur le rôle des îles dans ce processus, grâce à une approche de modélisation biophysique. Ce questionnement vise à mieux comprendre la dynamique des populations et à apporter des réponses cruciales pour la gestion durable des écosystèmes marins méditerranéens. Ces systèmes complexes sont soumis aux activités humaines, qui exercent une pression importante sur les populations naturelles, notamment celles exploitées par les pêcheries. Une étude préliminaire a permis de sélectionner l’outil de modélisation le plus adapté au contexte : Ichthyop, développé par l'équipe du laboratoire MARBEC. Ce logiciel, qui modélise le transport larvaire, a été enrichi au cours de cette thèse avec des fonctionnalités spécifiques aux espèces étudiées, telles que la nage orientée et la variation des proportions de particules dans les zones de lâcher. Le cœur de cette thèse repose sur l'étude de quatre espèces modèles représentatives des écosystèmes côtiers méditerranéens : Paracentrotus lividus (l’oursin comestible), Callinectes sapidus (le crabe bleu invasif), Maja squinado (la grande araignée de mer) et Diplodus sargus (le sar commun). Chaque espèce illustre des dynamiques écologiques spécifiques, influencées par leurs comportements larvaires. Qu'elles soient exploitées ou invasives, ces espèces constituent des enjeux économiques et écologiques majeurs pour la Méditerranée. Pour Paracentrotus lividus, les simulations ont révélé des taux d’autorecrutement élevés, notamment en Corse et en Sardaigne, démontrant une connectivité régulière et durable entre ces habitats rocheux. Le modèle pour Callinectes sapidus a mis en lumière des groupes de connectivité stables dans le temps entre la Corse, la Sardaigne et la Tunisie, contribuant ainsi à la rapide expansion de cette espèce invasive en Méditerranée occidentale. Concernant Maja squinado, les simulations ont montré que sa faible capacité de dispersion larvaire, liée à une courte période larvaire pélagique (PLD), pourrait compromettre la survie des populations locales en cas de mauvaise gestion, soulignant la nécessité d'une surveillance accrue des stocks, en particulier en Corse. Enfin, pour Diplodus sargus, les résultats ont confirmé que la nage orientée des larves joue un rôle clé dans la connectivité et le recrutement, avec une validation par des données de terrain collectées sur plusieurs décennies dans les Pyrénées-Orientales. Ces conclusions soulignent l'intérêt des outils de transport lagrangiens et de la modélisation biophysique en tant que méthodes prédictives pour anticiper les tendances de connectivité. Leur puissance prédictive est, et sera encore, renforcée par leur couplage avec d'autres approches scientifiques et par l'amélioration de la qualité des données qui les alimentent
The concept of connectivity, which is both vast and multidimensional, plays a crucial role in understanding interactions within ecosystems, whether terrestrial or marine. Connectivity refers to the movement of materials, energy, and organisms across habitats, influencing population dynamics and ecosystem resilience to disturbances. This thesis focuses on connectivity in Mediterranean coastal marine ecosystems, emphasizing larval dispersal in species with biphasic life cycles. The primary objective of this research is to predict larval dispersal and connectivity patterns for key species, highlighting particularly the role of islands in this process through a biophysical modelling approach. This research project aims to enhance understanding of population dynamics and provide essential insights for the sustainable management of Mediterranean marine ecosystems. These complex systems are subject to human activities that exert significant pressure on natural populations, particularly those targeted by fisheries. A preliminary study was conducted to select the most suitable modelling tool for this context, identifying Ichthyop, developed by the MARBEC laboratory team. This software, which simulates larval transport, was enhanced during this thesis with specific features tailored to the studied species, including oriented swimming behaviour and varying proportions of particles in release zones. The core of this thesis centers around four model species representative of Mediterranean coastal ecosystems: Paracentrotus lividus (the edible sea urchin), Callinectes sapidus (the invasive blue crab), Maja squinado (the European spider crab), and Diplodus sargus (the white seabream). Each species illustrates distinct ecological dynamics influenced by their larval behaviours. Whether exploited or invasive, these species represent major economic and ecological challenges for the Mediterranean region. Simulation results indicated that Paracentrotus lividus exhibited high self-recruitment rates, notably in Corsica and Sardinia, highlighting consistent and enduring connectivity between these rocky habitats. The model for Callinectes sapidus revealed stable connectivity clusters over time between Corsica, Sardinia, and Tunisia, contributing to the rapid spread of this invasive species in the Western Mediterranean. For Maja squinado, simulations demonstrated that its limited larval dispersal capacity, associated with a short pelagic larval duration (PLD), could jeopardize the survival of local populations under poor management, emphasizing the need for increased stock monitoring, particularly in Corsica. Lastly, results for Diplodus sargus confirmed that oriented larval swimming plays a critical role in connectivity and recruitment, validated by field data collected over several decades along the coastal zones of the Eastern Pyrenees (France). These findings underscore the utility of Lagrangian transport models and biophysical modelling as predictive tools to anticipate connectivity patterns. Their predictive power will continue to be strengthened by coupling with other scientific approaches and by improving the quality of the input data

En esta tesis se revisaron las relaciones que existen entre las poblaciones de dos especies de calamares ommastréfidos Dosidicus gigas y Illex argentinus con las series temporales de la temperatura superficial del mar, clorofila a y las estimaciones de biomasa zooplanctónica, lo que resultó en la comprensión de que la temperatura puede afectar directamente a las poblaciones de organismos productores primarios y a los integrantes del zooplancton, y no así a los organismos juveniles y adultos de ambas especies de calamar. También se observó que en ambas especies la distribución y abundancia de presas potenciales es uno de los principales factores que determinan la localización y en algunos casos migraciones horizontales y verticales en el ecosistema. Para poder entender las relaciones que las especies de calamares guardan en los ecosistemas fue necesario implementar los estudios ecotróficos en los que se determinó la importancia que representan estos calamares en las redes tróficas como depredadores, así como la interacción entre especies semejantes de calamares con las que pueden compartir su hábitat. Para llevar esta investigación se seleccionaron tres áreas de importancia ecológica y comercial, la primera corresponde al océano Atlántico Sur en la plataforma Patagónica y las islas Malvinas/Falkland en las que se identificaron tres especies de calamar I. argentinus, D. gahi y O. ingens, la segunda corresponde al Noroeste del Mar Mediterráneo donde se identificó a I. coindetii y T. sagittatus y la tercera al océano Pacifico en las costas de México y Perú para D. gigas. Los resultados de este trabajo demuestran que la tendencia de las poblaciones de estas especies es afectada directamente por las presas más abundantes y disponibles en el ecosistema, así como el desarrollo de relaciones intrínsecas entre algunas especies presa y su depredador como fue el caso de D. gigas y el pez V. lucetia.
This PhD thesis was focused in the relationships between the ommastrephid squids Dosidicus gigas and Illex argentinus with the time series of sea surface temperature, chlorophyll a and zooplankton biomass. The temperature as factor affected the primary productivity and the abundance of zooplankton, and no effects were found in the populations of juveniles and adult of both squids. In this way the distribution and abundance of squid was related to other factors such as the abundance of prey resources. Then the thesis was complemented with trophic ecology studies performed in the South Atlantic Ocean (Squid species: Doryteuthis gahi, Illex argentinus and Onykia ingens), in the Northwest Mediterranean Sea (Squid species: Todarodes sagittatus and Illex coindetii), and the South Pacific Ocean (Squid Dosidicus gigas). The results showed that the biomass and distribution of squid species are close related to the most abundant and available prey resources, and also it can be found trophic dependencies between some specific prey resources as was observed for Dosidicus gigas and the mesopelagic fish Vinciguerria lucetia .

Intermittent rivers and ephemeral streams (IRES) are watercourses that naturally and periodically cease to flow. They represent more than half of the global river network and are expanding due to global change. In this thesis, I investigate the mechanisms linking flow intermittence with biodiversity and ecosystem functioning, which sustain biogeochemical cycles and energy transfer in the system. Chapter 1 analyzes the effects of hydrology, micro-habitat (surface and subsurface zones) and biotic features on organic matter decomposition and fungal biomass, in 20 streams. In Chapter 2, I assess the effect of different flow intermittence metrics (i.e., annual intermittence regime and recent aquatic status) on aquatic biodiversity, including both taxonomic and functional-trait-based metrics, in 33 streams. Chapter 3 analyzes how aquatic hyphomycete richness and composition (beta diversity and its turnover and nestedness components) are affected by a flow intermittence gradient and how these community changes affect organic matter decomposition, in 15 streams and in a microcosm approach. Finally, in Chapter 4, I explore how changes in both leaf litter quality and quantity determine the feeding preferences and growth of an invertebrate shredder. The results of Chapter 1 show that the subsurface zone contributes to maintaining microbial decomposition during non-flow periods in IRES, mainly because of the levels of fungal biomass present in the subsurface zone. In Chapter 2, I conclude that a combination of flow intermittence metrics are needed to explain the high dynamism of the invertebrate community in IRES and potentially ecosystem functioning. Moreover, this chapter shows that hydrological variables outweigh non-hydrological factors in explaining invertebrate community variation, thereby supporting the use of the former in IRES classification and bio-monitoring routines. Chapter 3 reveals that the reduction of aquatic hyphomycete richness and species turnover as a result of flow intermittence, could have negative effects on organic matter decomposition. Finally, in Chapter 4, I provide evidence on how flow intermittence reduces the quality of leaf litter, in terms of fungal richness and composition, fungal biomass and lipid content. These changes in food quality influence the consumption rates and growth of shredders, which are able to feed selectively on higher quality leaves, even though its availability is lower. Taken together, these results will help to improve the biomonitoring and management of IRES and to a better prediction of ecosystem trajectories in response to global change.

The development of offshore wind farms and marine renewable energy devices in the Mediterranean is central to both national, and international, energy strategies for countries bordering the Mediterranean Sea. The ecological impacts of marine renewable energy development in the Mediterranean region, although essential for policy makers, are as yet unknown. The Northern Adriatic is identified as a plausible site for offshore wind farm development. Using the wider region (Adriatic and Northern Ionian) as a case study, this thesis examines the likely impact to the marine environment if an offshore wind farm is established. Site suitability, based on wind speed, bathymetry, and larvae connectivity levels are investigated along with the plausibility of the turbines operating as artificial reefs in the area. As offshore wind farms may alter the larval connectivity and supply dynamics of benthic populations, a connectivity map was constructed to identify areas of high and low connectivity in the Adriatic Sea. The Puglia coast of Italy is a likely larval sink, and displays some of the highest connectivity within the region, suggesting potential inputs of genetic materials from surrounding populations. Considering offshore wind farms could operate as artificial reefs, an in-situ pilot project was established to simulate the presence of wind turbines. Macroinvertebrates colonized the new substrata within the first few months but were lower in abundance when compared to a natural hard substrata environment. Time, turbine location, and the material used for turbine construction all affected the macro-invertebrate communities. In addition, fish abundances, and diversity were lower around the simulated OWF foundations in comparison to a natural hard substrata environment, and no increases in fish abundance occurred around the simulated turbines when compared to reference sites of soft substrata. This observation was validated with the use of an ecosystem modelling software (Ecopath with Ecosim), which simulated the overall ecosystem level impacts that would occur if 50 offshore monopile wind turbines were introduced to the Northern Ionian and colonized by macroinvertebrate communities. When compared to the baseline scenario (no simulated introduction of an OWF), the introduction of new habitat had no discernible impacts to the structure or functioning of the marine ecosystem. Noticeable changes to the ecosystem were only apparent if fishing restrictions were enforced in parallel with the simulated offshore wind farm; the ecosystem appears to become more structured by top down predation. In addition seabirds are also impacted by the reduction of fishing discards as a food source. These results are the first attempt to quantify the suspected benefits of offshore wind farms operating as de-facto marine protected areas.

Firstly, I reviewed modelling approaches that were used to assess the impact of invasive alien species (IAS) in aquatic ecosystems. According to the review, multispecies/ecosystem mechanistic models dominated the applications, with dynamic and non-spatial models being the most prevalent. Most of the models included an additional human stressor, mainly fisheries, climate change and/or nutrient loading. I summarised the main features of these applications and analysed their capabilities and limitations. Based on my conclusions, I reflected on future directions of development and applications of suitable modelling tools. The review showed that the Ecopath with Ecosim (EwE) modelling approach was frequently used to assess the impacts of already established IAS and highlighted its capabilities to forecast existing, emerging and potential new IAS. As a second step, I developed two static Ecopath ecosystem models using the EwE approach and representing the food web of the Israeli Mediterranean coast in 1990s and 2010s. I characterized the structure and functioning of the ecosystem and assessed past and current impacts of IAS and fishing. I then used the time-dynamic Ecosim module of EwE to fit the 1990s model to available time series of observations between both periods and to explore the historical dynamics of the ecosystem considering the effects of IAS, fishing dynamics and sea warming. Finally, the time-dynamic ecosystem model was used to analyse alternative future simulations of ecosystem change. Particularly, and after interacting with key stakeholders, I assessed the future effects of a new set of fishing regulations currently being implemented in Israel, future changes in sea temperature following IPCC (Intergovernmental Panel on Climate Change) scenario projections and the potential increases in IAS biomass. I investigated the impacts of the stressors separately, and then I combined them to evaluate their cumulative effects. Results from the static Ecopath models highlighted that the Israeli marine ecosystem, despite productivity differences, shared some structural and functional traits with other Mediterranean ecosystems such as the dominance of the pelagic domain in term of flows, the important role of detritus through low trophic levels and the importance of the benthic-pelagic coupling. In both time periods investigated, the same keystone groups were identified with the exception of European hake in 2010s, which showed a decline in its keystone role. This may indicate that hake lost its ecological role due to population declines. Most of the functional groups identified as keystone species were previously identified as keystones in other Mediterranean ecosystems, such as dolphins, large pelagic fishes, sharks and squids. The temporal dynamic Ecosim model indicated that trophic interactions, ocean warming and fishing were important drivers of the ecosystem dynamics. In general, temporal biomass trends revealed that native demersal predators and native medium trophic level fishes largely declined over time, while an increase over time of alien species was observed. Results from ecological indicators suggested a degradation pattern of the ecosystem over time. Future scenarios using the temporal dynamic Ecosim model showed overall potential benefits of fishing effort reductions in the future, and detrimental impacts of increasing sea temperature and increasing biomass of alien species. Cumulative scenarios highlighted that the beneficial effects of fisheries reduction could be dampened by the impact of increasing sea temperature and alien species when acting together. These results support the need for reducing local and regional stressors, such as fishing and biological invasions, to retain marine ecosystems within a “safe operating space” and ensure ecosystem resilience in an ongoing warming and impacted sea.
Los ecosistemas marinos del Mediterráneo oriental han sufrido cambios ecológicos importantes debido a múltiples presiones antropogénicas, incluido el impacto de especies invasoras, la sobrepesca y el calentamiento del mar. En primer lugar, he revisado los modelos que se han utilizado para evaluar el impacto de las especies invasoras en los ecosistemas acuáticos. De acuerdo con esta revisión, predominan los modelos mecanísticos de carácter multiespecífico/ecosistémico, siendo los modelos dinámicos y no espaciales los más frecuentes. La mayoría de los modelos incluyen un impacto antropogénico adicional, principalmente la pesca, el cambio climático y el aporte de nutrientes. Además, he resumido las principales características de estos modelos y he analizado sus capacidades y limitaciones. En base a las conclusiones de esta revisión, se han mostrado posibles direcciones para futuros desarrollos de los modelos y la aplicación de modelos adecuados. En esta revisión, he observado que el modelo Ecopath with Ecosim (EwE) ha sido utilizado frecuentemente para evaluar los impactos de las especies invasoras ya establecidas. Además, la revisión ha destacado las capacidades de EwE de pronosticar los futuros impactos de las especies invasoras establecidas, emergentes y potenciales. Otras revisiones disponibles en la literatura han demostrado las capacidades de EwE para evaluar los impactos de la pesca y el cambio climático. Por lo tanto, he desarrollado dos modelos estáticos Ecopath que representan la red trófica de la costa Mediterránea de Israel en los años 1990 y 2010 para caracterizar la estructura y funcionamiento del ecosistema y evaluar los impactos de las especies invasoras y la pesca en el pasado y en el presente. Después he utilizado el módulo dinámico-temporal Ecosim para ajustar el modelo de 1990 a series temporales de datos disponibles entre ambos periodos y para explorar la dinámica histórica del ecosistema considerando el efecto de las especies invasoras, la dinámica de la flota pesquera y el calentamiento del mar. Finalmente, el módulo dinámico-temporal ha sido utilizado para realizar simulaciones futuras de cambios en el ecosistema. En particular, he evaluado los efectos de un nuevo conjunto de regulaciones de pesca que se están implementando actualmente en Israel, futuros cambios en la temperatura del mar siguiendo las proyecciones del Panel Intergubernamental sobre el Cambio Climático (IPCC por sus siglas en inglés) y posibles aumentos de la biomasa de las especies invasoras. Primero he investigado los diferentes impactos por separado y, luego, los he combinado para evaluar sus efectos acumulativos. Los resultados de los modelos estáticos Ecopath han destacado que el ecosistema marino israelí, a pesar de un patrón de productividad diferente, comparte algunas características estructurales y funcionales con otros ecosistemas mediterráneos como el dominio del hábitat pelágico en términos de flujos tróficos, el importante papel del detritus a través de niveles tróficos bajos y la importancia del acoplamiento bentónicopelágico. Los mismos grupos funcionales clave fueron identificados en ambos periodos investigados, a excepción de la merluza en 2010, lo que puede indicar que la merluza ha perdido su papel ecológico debido al declive de su población. La mayoría de los grupos funcionales identificados como especies clave ya han sido identificados previamente como tales en otros ecosistemas mediterráneos como por ejemplo los delfines, los grandes peces pelágicos, los tiburones y los calamares. El módulo dinámico-temporal Ecosim indicó que las interacciones tróficas, el aumento de la temperatura del mar y la pesca jugaron un papel clave en la dinámica del ecosistema. En general, las tendencias temporales de la biomasa revelaron que los depredadores demersales nativos (por ejemplo, la merluza) y los peces demersal nativos de nivel trófico medio (por ejemplo, los salmonetes) disminuyeron en gran medida con el tiempo, mientras que se observó un aumento de las especies invasoras con el tiempo. Los resultados de los indicadores ecológicos sugirieron un patrón de degradación del ecosistema con el tiempo. Los escenarios futuros utilizando el módulo dinámico-temporal Ecosim mostraron los beneficios potenciales generales de las reducciones del esfuerzo pesquero y los impactos negativos del aumento de la temperatura del mar y el aumento de la biomasa de las especies invasoras. Los escenarios acumulativos resaltaron que los efectos beneficiosos de la reducción de la pesca pueden verse disminuidos por el impacto del aumento de la temperatura del mar y las especies invasoras cuando actúan al mismo tiempo. Estos resultados respaldan la necesidad de reducir los impactos antropogénicos locales y regionales como la pesca y las especies invasoras, para mantener los ecosistemas marinos dentro de un “espacio operativo seguro (SOS por sus siglas en inglés)” y promover la resiliencia de los ecosistemas en un mar en continuo calentamiento y altamente impactado.
Els ecosistemes marins de la Mediterrànea oriental han patit canvis ecológics importants a causa de múltiples pressions antropogèniques, inclòs l’impacte d’especies invasores, la sobrepesca i el calentament del mar. En primer lloc, he revisat els models que s’han utilitzat per avaluar l’impacte de les espècies invasores en ecosistemes aquàtics. D’acord amb aquesta revisió, predominen els models mecanístics de caràcter multiespecífic/ecosistèmic, sent els models dinàmics i no espacials els més freqüents. La majoria dels models inclouen un impacte antropogènic adicional, principalment la pesca, el canvi climàtic i l’aport de nutrients. A més, he resumit les principals característiques d’aquest models i he analitzat les seves capacitats i limitacions. En base a les conclusions d’aquesta revisió, s’han exposat possibles direccions per futurs desenvolupaments dels models i l’aplicació de models adecuats. En aquesta revisió he observat que el model Ecopath with Ecosim (EwE) ha estat utilitzat freqüentment per avaluar els impactes de les espècies invasores ja establertes. A més, la revisió ha destacat les capacitats d’EwE de pronosticar els futurs impactes de les espècies establertes, emergents i potencials. Altres revisions disponibles a la literatura han demostrat les capacitats d’EwE per avaluar els impactes de la pesca i el canvi climàtic. Per tant, he desencolupat dos models estàtics Ecopath que representen la xarxa tròfica de la costa Mediterrànea d’Israel en els anys 1990 y 2010 per caracteritzar l’estructura i funcionament de l’ecosistema i avaluar els impactes de les espècies invasores i la pesca en el passat i el present. Després he utilitzat el mòdul dinàmic-temporal per ajustar el model de 1990 a sèries temporals de dades disponibles considerant l’efecte de les espècies invasores, la dinàmica de la flota pesquera i l’escalfament del mar. Finalment, el mòdul dinamic-temporal ha estat utilitzat per realitzar simulacions futures de canvis en l’ecosistema. En particular, he avaluat els efectes d’un nou conjunt de regulacions de pesca que s’estan implementant actualment a Israel, canvis en la temperatura del mar seguint les projeccions del panell intergovernamental sobre el Canvi Climàtic (IPCC per les seves sigles en anglès) i possibles augments de la biomass de les espècies invasores. Primer he investigat els diferents impactes per separat i, després, els he combinat per avaluar els seus efectes acumulatius. Els resultats dels models estàtics Ecopath han destacat que l’ecostema marí d’Israel, malgrat un patró de productivitat diferent, comparteix algunes característiques estructurals i de funcionals amd altres ecosistemes marins mediterrànis com el domini de l’hàbitat pelàgic en termes de fluxes tròfics, l’important paper del detritus a través de nivells tròfics baixos i la importància de l’acoplament bentònic-pelàgic. Els mateixos grups funcionals clau van ser identificats en els dos períodes investigats, a excepció del lluç en el 2010, que pot indicar que el lluç ha perdut el seus paper ecològic a causa del declivi de la seva població. La majoria del grups funcionals identificats com a espècies claus ja han estat identificats com a tals en altres ecosistemes mediterranis com ara els dofins, els gran peixos pelàgics, els taurons i els calamars. El mòdul dinàmic-temporal Ecosim ha indicat que les interaccions tròfiques, l’augment de la temperatura del mar i la pesca van jugar un paper clau en la dinàmic de l’ecosistema. En general, les tendències temporals de la biomasa van revelar que els depredadors demersals natius (per exemple, el lluç) i els peixos dersals natius de nivell tròfic mitjà (per exemple, els rogers) van disminuir en gran mesura amb el temps, mentre que es va observar un augment de les espècies invasores amb el temps. Els resultats dels indicadors ecològics van suggerir un patrò de degradació de l’ecosistema amb el temps. Els escenaris futurs van mostrar els beneficis potencials generals de les reduccions de l’esforç pesquer i els impactes negatius de l’augment de la temperatura del mar i ’augment de la biomasa de les espècies invasores. Els escenaris acumulatius van ressaltar que els efectes beneficiosos de la reducció de la pesca poden ser reduïts per l’impacte de l’augment de la temperatura del mar i les espècies invasores quan actuen al mateix temps. Aquests resultats recolzen la necessitat de reduir els impactes antropogènics locals i regionals com la pesca i les espècies invasores, per mantenir els ecosistems marins dins d’un “espai operatiu segur (SOS per les seves sigles en anglès)” i promoure la resiliència dels ecosistemes en un mar en continu escalfament i altament impactat.

Nowadays, remote sensing techniques play an important role in the rapid acquisition of a large amount of spatial environmental data. The development of sensors in the last decade has led to the development of Earth observation satellite missions, e.g., Sentinel, PlanetScope. Numerous machine learning and deep learning methods are used in nowadays research to classify satellite imagery to enable rapid environmental mapping (e.g., land cover and land use, water bodies). Posidonia oceanica is considered the most important and best-studied seagrass species in the Mediterranean Sea. The objective of this preliminary research is to test the applicability of machine learning image classification methods for rapid seagrass mapping based on Sentinel-2 imagery. The research was conducted in the study area located in the north part of Dugi Otok in the central Adriatic in Croatia. Accuracy assessment of the mapped seagrass emphasises that Cart, Random Forest (RF), and Support vector machine (SVM) overperformed Naive Bayes (NB) method. Further, detailed visual analysis of seagrass map and accuracy assessment shows that RF and Cart give the best results. This research was done as part of the project Climate HIDROLAB (KK.01.1.1.04.0053) � Integrated hydrographic system for sustainable development of the marine ecosystem.

While originally developed for weather forecasting, the Extreme Forecast index (EFI) concept has found utility in diverse fields. This study marks the inaugural application of EFI principles to numerical ocean forecasting. EFI offers a metric to gauge the forecast's deviation from historical norms specific to the location and time of year. A heightened EFI value signifies that the forecast falls beyond the usual range of variability, signifying a higher probability of extreme conditions. This novel use of EFI stands to benefit oceanographers by identifying significant oceanic events, aiding decision-making, and supporting early warning systems, particularly for extreme marine conditions. It enhances comprehension of forecast uncertainties and facilitates clearer communication of potential risks to the public and stakeholders. Such insights are invaluable for preparedness, coastal management, and mitigating the impact of marine extremes on communities and ecosystems. EFI indices for the Mediterranean Sea are computed using a first implementation of a forecast ensemble system that is being developed for the Mediterranean Sea Monitoring and Forecasting Center of the Copernicus Marine Environment Service. This deliverable report presents the first-ever application of the EFI approach to the Mediterranean Sea. After presenting the EFI definition adopted in this study, we discuss its application to sea surface temperature (SST) and sea surface height (SSH) extremes. A case studies using ensemble forecasts for the year 2021 are presented and discussed. (EuroSea Deliverable, D4.11)

Description: Shipping is responsible for a range of different pressures affecting air quality, climate, and the marine environment. Most social and economic analyses of shipping have focused on air pollution assessment and how shipping may impact climate change and human health. This risks that policies may be biased towards air pollution and climate change, whilst impacts on the marine environment are not as well known. One example is the sulfur regulation introduced in January 2020, which requires shipowners to use a compliant fuel with a sulfur content of 0.5% (0.1% in SECA regions) or use alternative compliance options (Exhaust Gas Cleaning Systems, EGCS) that are effective in reducing sulfur oxide (SOx) emissions to the atmosphere. The EGCS cleaning process results in large volumes of discharged water that includes a wide range of contaminants. Although regulations target SOx removal, other pollutants such as polycyclic aromatic hydrocarbons (PAHs), metals and combustion particles are removed from the exhaust to the wash water and subsequently discharged to the marine environment. Based on dilution series of the Whole Effluent Testing (WET), the impact of the EGCS effluent on marine invertebrate species and on phytoplankton was found to vary between taxonomic groups, and between different stages of the invertebrate life cycle. Invertebrates were more affected than phytoplankton, and the most sensitive endpoint detected in the present project was the fertilisation of sea urchin eggs, which were negatively affected at a sample dilution of 1 : 1,000,000. Dilutions of 1: 100,000 were harmful to early development of several of the tested species, including mussels, polychaetes, and crustaceans. The observed effects at these low concentrations of EGCS effluent were reduced egg production, and deformations and abnormal development of the larvae of the species. The ecotoxicological data produced in the EMERGE project were used to derive Predicted No Effect Concentration values. Corresponding modelling studies revealed that the EGCS effluent can be considered as a single entity for 2-10 days from the time of discharge, depending on the environmental conditions like sea currents, winds, and temperature. Area 10-30 km outside the shipping lanes will be prone to contaminant concentrations corresponding to 1 : 1,000,000 dilution which was deemed harmful for most sensitive endpoints of WET experiments. Studies for the Saronikos Gulf (Aegean Sea) revealed that the EGCS effluent dilution rate exceeded the 1 : 1,000,000 ratio 70% of the time at a distance of about 10 km from the port. This was also observed for 15% of the time within a band of 10 km wide along the shipping lane extending 500 km away from the port of Piraeus. When mortality of adult specimens of one of the species (copepod Acartia tonsa) was used as an endpoint it was found to be 3-4 orders of magnitude less sensitive to EGCS effluent than early life stage endpoints like fertilisation of eggs and larval development. Mortality of Acartia tonsa is commonly used in standard protocols for ecotoxicological studies, but our data hence shows that it seriously underestimates the ecologically relevant toxicity of the effluent. The same is true for two other commonly used and recommended endpoints, phytoplankton growth and inhibition of bioluminescence in marine bacteria. Significant toxic effects were reached only after addition of 20-40% effluent. A marine environmental risk assessment was performed for the Öresund region for baseline year 2018, where Predicted Environmental Concentrations (PECs) of open loop effluent discharge water were compared to the PNEC value. The results showed modelled concentrations of open loop effluent in large areas to be two to three orders of magnitude higher than the derived PNEC value, yielding a Risk Characterisation Ratio of 500-5000, which indicates significant environmental risk. Further, it should be noted that between 2018-2022 the number of EGCS vessels more than quadrupled in the area from 178 to 781. In this work, the EGCS discharges of the fleet in the Baltic Sea, North Sea, the English Channel, and the Mediterranean Sea area were studied in detail. The assessments of impacts described in this document were performed using a baseline year 2018 and future scenarios. These were made for the year 2050, based on different projections of transport volumes, also considering the fuel efficiency requirements and ship size developments. From the eight scenarios developed, two extremes were chosen for impact studies which illustrate the differences between a very high EGCS usage and a future without the need for EGCS while still compliant to IMO initial GHG strategy. The scenario without EGCS leads to 50% reduction of GHG emissions using low sulfur fuels, LNG, and methanol. For the high EGCS adoption scenario in 2050, about a third of the fleet sailing the studied sea areas would use EGCS and effluent discharge volumes would be increased tenfold for the Baltic Sea and hundredfold for the Mediterranean Sea when compared to 2018 baseline discharges. Some of the tested species, mainly the copepods, have a central position in pelagic food webs as they feed on phytoplankton and are themselves the main staple food for most fish larvae and for some species of adult fish, e.g., herring. The direct effect of the EGSE on invertebrates will therefore have an important indirect effect on the fish feeding on them. Effects are greatest in and near shipping lanes. Many important shipping lanes run close to shore and archipelago areas, and this also puts the sensitive shallow water coastal ecosystems at risk. It should be noted that no studies on sub-lethal effects of early 19 life stages in fish were included in the EMERGE project, nor are there any available data on this in the scientific literature. The direct toxic effects on fish at the expected concentrations of EGCS effluent are therefore largely unknown. According to the regional modelling studies, some of the contaminants will end up in sediments along the coastlines and archipelagos. The documentation of the complex chemical composition of EGCS effluent is in sharp contrast to the present legislation on threshold levels for content in EGCS effluent discharged from ships, which includes but a few PAHs, pH, and turbidity. Traditional assessments of PAHs in environmental and marine samples focus only on the U.S. Environmental Protection Agency (EPA) list of 16 priority PAHs, which includes only parent PAHs. Considering the complex PAHs assemblages and the importance of other related compounds, it is important to extend the EPA list to include alkyl-PAHs to obtain a representative monitoring of EGCS effluent and to assess the impact of its discharges into the marine environment. An economic evaluation of the installation and operational costs of EGCS was conducted noting the historical fuel price differences of high and low sulfur fuels. Equipment types, installation dates and annual fuel consumption from global simulations indicated that 51% of the global EGCS fleet had already reached break-even by the end of 2022, resulting in a summarised profit of 4.7 billion €2019. Within five years after the initial installation, more than 95% of the ships with open loop EGCS reach break-even. The pollutant loads from shipping come both through atmospheric deposition and direct discharges. This underlines the need of minimising the release of contaminants by using fuels which reduce the air emissions of harmful components without creating new pollution loads through discharges. Continued use of EGCS and high sulfur fossil fuels will delay the transition to more sustainable options. The investments made on EGCS enable ships to continue using fossil fuels instead of transitioning away from them as soon as possible as agreed in the 2023 Dubai Climate Change conference. Continued carriage of residual fuels also increases the risk of dire environmental consequences whenever accidental releases of oil to the sea occur.