The Mediterranean Sea

In this chapter we briefly discussed the main steps of the evolution of the Mediterranean sea, from the Tethys to its closure, until the present days. It is worth highlighting the importance of the physical processes controlling the final shape and bathymetry of the basin, namely the subduction/collision of Africa and Eurasia and associated microplates, and the erosion and sediment dispersal. Both carbonate platforms and organic rich layers (ORL or sapropels) represent the sink of inorganic and organic Carbon, respectively. Therefore, their occurrence and evolution is critical for the carbon cycle, with feedbacks on the global biogeochemical cycle. This chapter highlights how the most interesting geological objects are the result of the interaction between the biological and physical processes.

High-resolution mapping and reflection profiling reveal a depositional fan on the Black Sea SW shelf fed from the Strait of Istanbul (Bosporus). The fan is constructed with an initial deposit of pebbles mixed with glacial and post-glacial shell debris. The pebbles are identical in their composition to quartzite and gabbro recovered in drill cores from the Bosporus Strait. Directly above the pebble layer are mollusks and foraminifera of Mediterranean provenance dated at 6.9 ka bp (uncorrected). Synchronicity between the onset of fan construction and arrival of Mediterranean fauna suggests an origin linked to the connection of the Black Sea’s lake with the global ocean. The volume of the chaotic interior of the fan is comparable in magnitude to the volume excavated from the floor of the Bosporus Strait. We propose that when the exterior ocean breached the sill of this inlet, it transformed into an outburst of saltwater that gained energy as it enlarged the inlet. Torrents stripped the glacial and post-glacial covering from its pathway and scattered entrained debris in sheets and mounds as far away as the edge of the shelf. Even in areas where the pre-existing cover survived, its eroded surface attests to the passage of flooding water.

The aim of this section is to provide a comprehensive overview of the research findings concerning the thermohaline circulation of the Mediterranean Sea. The decadal/inter-decadal variability and long-term evolution of the thermohaline properties of the Mediterranean Basin are extensively discussed. We focus on the major climate transient thermohaline events and their links to atmospheric variability and anthropogenic/environmental changes that dramatically changed the deep hydrology and strongly affected the marine ecosystems of the Mediterranean basin during the last 20 years. This section also includes a synthesis of the results of future projections of the thermohaline circulation derived by climate model simulations of the Mediterranean region covering the twenty-first century. The expected effects of the projected thermohaline circulation changes on the marine ecology are also discussed.

This review summarises the distribution of dissolved nutrients (nitrate, phosphate and silicate) over the period of modern measurements (~30 years) and aspects of the biogeochemical processes which control their distribution in the Eastern Mediterranean Sea (EMS). The levels of nitrate, phosphate and silicic acid (~6 μ mol N kg

−1

, 0.25 μ mol P kg

−1

and 11 μ mol Si kg

−1

in deep water) in the EMS are much lower than all other parts of the ocean due to the unusual anti-estuarine circulation which exports nutrient replete intermediate water at the Straits of Sicily and to the relatively young age of the deep water (τ ≈ 120 years). Dissolved oxygen decrease and nutrients increase eastwards, in the direction of the deep-water circulation with nitrate increasing by ~0.5 μ mol kg

−1

from the Western Ionian to the Eastern Levantine, phosphate by 0.05 μ mol kg

−1

and silicic acid by ~4.5 μ mol kg

−1

representing the amount (rate) of organic matter and biogenic silica (BSi) breakdown over the residence time of Deep Water in the basin. The East Mediterranean Transient interrupted this simple pattern causing lower nutrients in the deep water and upwelled nutrients into the upper layers. The high nitrate/phosphate found in the deep water (25–28:1) is due to a combination of high Nitrate:Phosphate waters advected from the surface of the Adriatic during deep water formation during the P-limited winter bloom and P recycling more efficiently than N from the descending particulate organic matter (POM). High N:P ratios in POM and dissolved organic matter (DOM) show that the entire EMS is P starved. There are seasonal changes in nutrient limitation with conventional P limitation during the winter phytoplankton bloom which becomes N&P co-limitation in early summer and can, under some circumstances, become even N limited in mid-summer in the nutrient starved upper waters. N

2

fixation rates are constantly low in the EMS compared to somewhat higher levels in the western MS. Nutrient budgets have been used to explain that the reason for the unusual N:P ratio in the basin is high N:P ratio in the external inputs combined with low denitrification rates caused by the ultra-oligotrophic status of the basin. However the external nutrient (both riverine and atmospheric) inputs have increased dramatically between 1950 and 2000. Estimates of the pristine flux of nutrients by riverine sources to the EMS are 2.0 × 10

9

moles N/y and 0.095 × 10

9

moles P/y while the atmospheric flux has increased by 85 % for NOx and 65 % for NH3 between 1910 and the end of the twentieth century. It is suggested that climate change may result in dramatic threshold changes in trophic status of the EMS if surface circulation rates decrease as has been predicted.

The Mediterranean Sea contains a vast spectrum of chemosynthetic habitats from shallow marine to bathyal depths. These habitats (hydrothermal vents, cold seeps, reducing sediment) are home to bacteria and archaea acting as primary producers using the energy obtained by oxidizing reducing compounds in fluids (e.g., H

2

S and hydrocarbons such as CH

4

) to synthesize organic matter. Such sites may make a large microbial biomass available to consumers and promote the development of complex symbiotic relationships between prokaryotes and hosting eukaryotes. Shallow water (<200 m) chemosynthetic niches are pervasive in the Mediterranean where reduced sediment are present (lagoons, seagrass beds, prodeltaic settings etc.) being exploited primarily by sulphur-oxidizing bacteria, some of which are symbiotic with metazoans. Particular cases of shallow chemosynthetic habitats are hydrothermal vents, submarine caves with sulphur springs, cold seeps including active pockmarks and reducing sediments in areas of high organic deposition. Deep-water chemosynthetic habitats (>200 m) with also metazoans with chemoautotrophic symbionts are present at various sites in the Mediterranean, encompassing both cold seeps and hydrothermal vents. Cold seeps are diffuse and geologically diverse, and comprise mud volcanoes, brine pools and active pockmark fields, whose reducing environments are often exploited by endemic chemosymbiotic metazoans, including bivalves and siboglinid polychaetes. Such environments are clustered in the Eastern Mediterranean (Nile Deep Sea Fan, Anaximander mud volcano field, Olimpi mud volcano field, Eratosthenes Seamount, Calabrian Arc, Marmara deep fault systems) but equally occur in the Strait of Sicily, Adriatic, Tyrrhenian and Alboran Seas. Deep hyperhaline anoxic basins occur in the Eastern Mediterranean and even host metazoans that live in anoxic conditions. Deep-water hydrothermal vents characterized by microbial communities and metazoans (siboglinid polychaetes) are documented so far only from some Tyrrhenian seamounts (Marsili, Palinuro) and Aegean submerged volcanic craters (Santorini, Kolumbo). The geo-biological relevance of such complex habitats often situated in the high seas, calls for an international effort towards the implementation of proper protection and sustainable management.

This chapter presents an overview of the diversity, distribution and ecology of major groups of microbial plankton in the Mediterranean Sea, including phytoplankton, viruses, heterotrophic prokaryotes and flagellates, and ciliates. Some protists with hard structures like diatoms, thecate dinoflagellates, coccolithophorids and tintinnids have been relatively well studied from a morphological point of view, but in general microbial diversity is poorly known, in particular with respect to prokaryotes and the smallest eukaryotes. This situation is rapidly changing, in a large part due to the incorporation of molecular techniques. The general oligotrophy of the Mediterranean, which increases from west to east, is reflected in a strong contribution of the picoplankton and the microbial food web. However, a variety of nutrient-enrichment mechanisms, including winter mixing, mesoscale hydrographic structures and land runoff, which operate at various spatio-temporal scales, may enhance primary production and result in the intermittent dominance of diatoms and the herbivorous food web. During the stratification period, a deep chlorophyll maximum is a general feature throughout the basin and plays a substantial role in the fertility of the Mediterranean.

Primary production, the production of organic carbon molecules from carbon dioxide and water by converting sunlight energy to chemical energy through the process of photosynthesis, is the basis of our biosphere. The total Mediterranean Sea primary productivity is 1 % of the global primary productivity (Uitz et al., 2010). The entire Mediterranean Sea as a large marine ecosystem (LME) is characterized as a low-productivity ecosystem, <150 gC m

−2

year

−1

and, as such, is considered a Class III ecosystem (Aquarone et al., 2009). Based on Nixon’s (1995) definition, it is a mesotrophic sea, yet many parts of this LME are oligotrophic, and the Levantine Basin (eastern Mediterranean) is even ultraoligotrophic. Global and local abiotic fluctuations cause variation in the primary-producer communities and their ability to photosynthesize, thus leading to modification of the food web.

The Mediterranean Sea is regarded as the largest and deepest enclosed sea in Earth and represents a marine biodiversity hot spot. The current taxonomic classification of macroalgae in the Mediterranean is well known, with 1,124 species and at least 20 % of endemic species. The origin of these seaweeds is diverse and is a consequence of the geological history of the Mediterranean basin. The present seaweed flora is composed of tropical elements, species coming from the boreal Atlantic Ocean, subtropical Atlantic species, cosmopolitan/panoceanic species, and endemic elements. Analytical biogeography studies based on the deductive-hypothetical approach has allowed exploration of the links between ecological variables and the geographical distribution of selected taxa of Mediterranean seaweeds. This miniature ocean has various sources of disturbances interacting synergistically and therefore, providing an insight into a major question: how resilient are marine ecosystems, and how will their current functioning be modified in the future? Mediterranean is a priority area for studies on climate change, as in this area is documented range shifts and recent appearance of new warm-water species, included tropical macroalgae. The effect of climatic change is difficult to untangle from direct anthropogenic activities. Morphology plasticity and physiological mechanisms determine the capacity to acclimate to global climate change. The conservation efforts made in this ecosystem include the design of a network of Marine Protected Areas that, by definition, higher level of protection than its surrounding areas. Recent national legislation, as the Spanish list of wild species under special protection and the list of threatened species (2011) includes also for the first time 12 species of macroalgae. Additionally, the protection of macroalgae is also enhanced by the protection of particular marine habitats under the Habitat Directive 92/43/EEC. The use of macroalgae for the estimation of the ecological status of coastal and transitional waters of the Mediterranean, in the frame of the Water Framework Directive (2000/60/EC) is a challenging applied subject. It is expected that the monitoring and further management plans for the coast will decrease the probable impact amplification in the coming years and will maintain the ability of the Mediterranean Sea to continue the provision of essential ecological services.

Seagrasses are flowering plants that undergo their whole life cycle within shallow coastal habitats. All species share analogous architectural and growth patterns. They are modular plants composed of units arranged by a set of modules: a piece of rhizome, a bundle of leaves (shoot) attached to the rhizome and roots. Four species occur in the Mediterranean bioregion: the endemic

Posidonia oceanica

, the tropical

Cymodocea nodosa

and the temperates

Zostera marina

and

Z. noltii

.

Posidonia oceanica

is the largest one, with very slow growth rates and being considered the climax stage of Mediterranean subtidal bottoms. Meadows extend on 2.5–4.5 millions ha that is close to 25 % of the Mediterranean basin shallower than 50 m.

Cymodocea nodosa

,

Zostera marina

and, particularly,

Z. noltii

are smaller in size but fast growing as typical of the pioneering species. Seagrass meadows are among the most productive ecosystems on earth, providing important ecological services: nursery grounds, biofilters, water cleaners, coastline protectors and carbon sinks. However, despite its paramount importance there is widespread regression of such habitats. Although the four Mediterranean species have been assigned to the “Least Concern” category of the IUCN Red List,

P. oceanica

populations are experiencing the highest rate of decrease. Given the extremely slow growth rate of this species such losses are virtually irreversible. Direct and indirect (i.e., climate change) human activities affecting mostly to physical integrity of habitats, sediment and water quality, coastal sedimentary balance or species composition are argued to be the main drivers of seagrass decline in the Mediterranean Sea. European (and Mediterranean) countries, aware of the key important role that seagrasses play, have established management and conservation plans for these habitats. Thereafter, the aim of the present contribution is to present basic information about the biology and ecology of the Mediterranean seagrasses, the main threats facing these habitats, as well as to provide some information on the main conservation and management strategies.

Nearly 140 alien benthic-algae taxa and one seagrass invader species were reported found in the Mediterranean Sea since the beginning of the twentieth century. Some caused major changes in the community structure and function of marine flora and fauna. Most non-indigenous species reached the Mediterranean due to anthropogenic activities. The opening of the Suez Canal, along with the increase of marine transportation and mariculture, enabled alien invasion from the Atlantic, Indian, and Pacific Oceans. Alien algae from the Atlantic Ocean probably invade the Mediterranean via the Straits of Gibraltar through cargo ships (through ballast water or attached to the hulls). Shellfish transfer is the most important vector for introducing alien seaweed from the Far East into the western Mediterranean. Global warming raised the surface water temperature, especially in the eastern Mediterranean Basin; therefore, it plays an important role in facilitating settlement establishment and the spread of alien algae and seagrasses from the tropical Atlantic, Indian, and Pacific Oceans in the Mediterranean. The control and reduction of marine invasions are also discussed.

The Mediterranean Sea bears one of the longest traditions in the study of zooplankton. Pioneer work focused more on taxonomy to suit the high diversity of zooplankton that inhabits the Mediterranean, and indeed very few ecosystems have such a deep and broad knowledge on zooplankton like the one gathered in the Mediterranean. Further research into ecological aspects encompassed more descriptive studies on distribution and seasonality patterns, to lead in current times to more functional and modelling approaches. In this chapter we present an overview of the seasonality and distribution patterns of zooplankton in the Mediterranean, with special emphasis on the driving mechanisms behind. We will focus essentially on the western basin, and provide an overview on the outcome of the studies conducted by the different schools of marine biologists and oceanographers established in the geographical areas surrounding the Catalan/Balearic Sea, the Ligurian Sea and the Thyrrenian Sea. The latitudinal gradient, the marked seasonality, and the particular productivity patterns in the Mediterranean provide a frame for a zooplankton community in which the succession of species and assemblages occurs with not drastic changes in the whole standing stocks. As in other seas, examples of diel, ontogenetic and seasonal vertical migration can be found in the Mediterranean; however, the presence of a deep chlorophyll maximum during the stratified period drives a distinct vertical distribution of epipelagic zooplankton. Mesoscale singularities such as density fronts and eddies, the presence of submarine canyons which modify the general circulation, and other local phenomena like riverine runoff are responsible for the enhancement of production and favours the aggregation of zooplankton, either by local increase phenomena or by passive accumulation. Finally, current challenges in zooplankton research in the Mediterranean, such as the long-term changes in relation to large-scale atmospheric forcing, the occurrence of gelatinous zooplankton proliferations and the changes in species distribution and presence of non-indigenous ones will be also discussed.

Among Mediterranean marine life, benthic communities are possibly the most peculiar in terms of richness and endemic species. The distribution and structure of benthic fauna (sessile and vagile) is driven by environmental gradients that change with season, depth, the type of substrate and the interaction between organisms. The combined action of these multiple factors results in a high variety of assemblages and communities. This chapter focuses on the benthic fauna, with the aim to provide a broad description of the hard and soft bottom communities and the general trends of their characteristics and variability. Special emphasis is given to the ecological strategies of the fauna that inhabit in complex benthic ecosystems. The pressures and impacts on these benthic fauna and ecosystems, from alien species invasions, warming effects, ocean acidification and other direct and indirect human perturbations are also illustrated.

Foraminifera are eukaryotic unicellular microorganisms inhabiting all marine environments.

The study of these protists has huge potential implications and benefits. They are good indicators of global change and are also promising indicators of the environmental health of marine ecosystems. Nevertheless, much remains to be learnt about foraminiferal ecology.

In this chapter we intend to introduce the main issues in the study of foraminifera in the Mediterranean Sea and the state-of-the-art developments in the study of these organisms.

The aims of this chapter are: (

1

) to provide a brief history of the study of foraminifera and (

2

) to review recent developments in the study of modern foraminifera, particularly as they apply to Mediterranean faunas. Our intention is to describe the development of the use of foraminiferal assemblages in Mediterranean applied ecological studies up to their possible use as bio-indicator for the monitoring of marine ecosystems.

Stony corals, especially scleractinians, are a recurrent component of the benthic fauna of the Mediterranean basin and its Mesozoic-to-Cenozoic precursors. Both morphological and geochemical features of coral skeletons place these organisms among the most important natural paleoarchives of the Mediterranean geological history. The present day low diversity of the Mediterranean scleractinian fauna (25 genera and only 33 species) strikingly contrasts with its high diversity in the Early-Middle Miocene (over 80 genera and hundreds of species). The decline in coral richness has occurred since the late Middle Miocene onwards. This impoverishment trend was not linear, but abrupt in shallow-water environments during and immediately after the Late Miocene and more gradual since the Pliocene onwards. At the end of the Miocene, the Mediterranean coral fauna underwent a drastic modification that led to the disappearance of almost all zooxanthellate corals and the well-established shallow-water coral-reef province. However, the generic diversity of azooxanthellate and deep-water corals did not undergo significant modifications, that were instead much stronger at the end of the Pliocene and of the Pleistocene. Indeed, before the Calabrian stage, all remnant Indo-Pacific-like azooxanthellate genera disappeared and a clear NE Atlantic affinity was established, whereas at the Pleistocene – Holocene boundary, there was a clear reduction in psychrospheric deep-water taxa. The causes that led to the impoverishment of the Mediterranean coral fauna diversity are complex and not all fully understood. However, there is a clear link between the coral diversity decrease, the gradual northward shift outside the tropical belt of the Mediterranean region, and the major climate modifications on a global scale during the last 20 million years.

In contrast with the number of studies on tropical species, analyses of the variation of growth parameters with environmental variables in temperate areas are very scarce. The growth of only four species of scleractinians has been analyzed in natural Mediterranean populations:

Cladocora caespitosa

(Family: Faviidae),

Balanophyllia europaea

and

Leptopsammia pruvoti

(Family: Dendrophylliidae), and

Caryophyllia inornata

(Family: Caryophylliidae). Notwithstanding the importance of obtaining information on coral population dynamics, the first study on a Mediterranean scleractinian dates back less than 10 years. To date, field analyses of the relationships between environmental parameters and growth and population dynamics of Mediterranean scleractinians are available only for two solitary dendrophyliid species:

B. europaea

and

L. pruvoti

. Available literature on growth and population dynamics of natural scleractinian populations of the Mediterranean Sea is reviewed in the present work. As general trends, it seems that: (1) solitary species have a definite growth pattern, in contrast with colonial species; and (2) symbiotic species are more sensitive to increasing temperatures and more vulnerable to global warming. Knowledge on the growth and population dynamics of Mediterranean species has significantly increased in the last 20 years, and more effort is still required to gather the necessary information for protecting a hotspot of biodiversity like the Mediterranean Sea from the threats of global environmental change.

The present Mediterranean molluscan biodiversity, comprising more than 2,000 species, was shaped by the multiple events connected with the geodynamic and climatic evolution of this basin in the last million years coupled with the process of biological evolutionary processes on the global scale. Climate, hydrology, basin physiography, and connections via seaways were and are the main forcing factors tuning the type of molluscs making the Mediterranean diversity at any geological instant, resulting in (often cyclical) taxonomic additions and subtractions. However, this basic motif operating in the Mediterranean since its formation as an independent basin over millions of years, has been seriously perturbed by the deliberate or accidental introduction of non-indigenous (alien or non native) species in the last decades. The taxonomic addition of mostly warm-water species is taking place at an unprecedented pace with respect to even the dramatic changes that have marked glacial-interglacial transitions, thus making the present day Mediterranean Sea a planetary biogeographic

unicum

.

The changes in the distribution of two autochthonous molluscs in the Mediterranean Sea are described from the early nineteenth century to date.

Echinolittorina punctata

(Gastropoda: Littorinidae) had until the end of the twentieth century a distribution limited to the western Mediterranean (southern Spain and from Morocco to northern Tunisia, a few localities in southern Sicilia) and to the eastern Mediterranean (from Egypt to Syria). At the end of the twentieth century the range started to expand to all along the coast of Sicilia and northward along the Italian peninsula. Today, the species is found north of Roma.

Eastonia rugosa

(Bivalvia: Mactridae) used to have a distribution limited to the western Mediterranean, not exceeding the Siculo-Tunisian sill. During the end of the twentieth century and in the 2000s, the species was recorded from the Gulf of Gabès and from progressively northern localities in Italy. Today the species is found north of Livorno, in Toscana. The distributional changes of a few more Mediterranean molluscs is described in less detail, but wishes to highlight potential further descriptors of change of the biodiversity of the Mediterranean Sea.

Mussels

Mytilus galloprovincialis

have been used as model bivalves to study the impacts of global warming on their physiological performance in Themaikos Gulf, North Greece. The studies have been conducted under laboratory and field conditions for more than 6 years and focused on the biochemical, metabolic, physiological and energetic responses of

M. galloprovincialis

to increases in the ambient temperature. Here we summarize the findings concerning the responses of

mussels

to environmental temperature, present an integrated model of their physiological performance during thermal stress and discuss these findings in the light of the predicted temperature changes in the Thermaikos Gulf from the regional climate trends and the mean global temperature projections for the period 1990–2100 based on IS92 emission scenarios of the Intergovernmental Panel for Climate Change (IPCC). Our findings indicate that mussels in Themaikos Gulf currently face the temperatures close to their upper thermal limits, especially during the summer, and thus are likely vulnerably to any further increase in the temperature such as expected during the global warming.

A short introduction is given to the systematics and morphology of pelagic Gastropoda (Mollusca: Heteropoda and Pteropoda), also explaining some details of the animals’ particular way of life. The fossil record of these invertebrates is discussed briefly, followed by an overview of existing literature, focussing on the Mediterranean Basin. Developments during the Mediterranean Cenozoic are explained stage by stage and the numerical occurrences of species within the basin are correlated with palaeo-temperatures, generally with very good results. In the same context illustrations are added of index species or otherwise interesting taxa. The very intensively studied Quaternary occurrences are referred to briefly, citing other papers recently published. A preliminary Mediterranean biozonation scheme, recently developed and based on fossil Pteropoda, is referred to and schematically included in one of the illustrations. In the last part, we discuss possible future developments of holoplanktonic molluscs, resulting on the one hand from increased knowledge of the systematics, phylogeny and biogeography due to recent interest in this group and the application of modern powerful morphometric and molecular techniques. On the other hand, there exist major concerns about the future of this group resulting from the (combined) effects of global warming and ocean acidification.

Continuously-increasing concentrations of atmospheric carbon dioxide CO

2

, primarily through the burning of fossil fuels, are rapidly increasing the oceanic concentrations of CO

2

and leading to the phenomenon of ocean acidification. Evidence to date on the effects of altered seawater chemistry on the biota is growing, yet is in its infancy. Evidence of effects is limited mostly to fish, molluscs and echinoderms, yet there is a growing body of evidence of effects of ocean acidification on the Crustacea. Our predictive ability on physiological effects and the potential ecosystem level effects is currently limited. By posing fundamental questions, the answers may lie in implementing mechanistic-level studies in order to elucidate organism physiological limits and species’ potential to adapt to future oceanic conditions.

Bryozoans in the Mediterranean Sea are recognized as bioconstructional framework builders, both primary builders that construct frameworks alone or in combination with other organisms, or secondary builders that play various functional roles. Ten bryozoan species or complexes of species in the Mediterranean are responsible for providing habitats for diverse species and assemblages, thus playing important roles in promoting biodiversity and habitat heterogeneity. Four habitat-forming bryozoans respond to climatic changes (global warming and ocean acidification) by altering their colony growth, zooidal morphology and development, skeletal mineralogy and geochemistry. Under conditions of reduced pH, these species reallocate energy resources within the colony by regulating zooid size, proportion of polymorphs, number of zooidal generations, colony growth rate, and investment in the organic components involved in biomineralizational processes. Mediterranean ‘bryo-constructions’ are suitable ‘ecosystem models’ to be monitored in the context of climate change, especially ocean acidification and warming.

This chapter summarizes and presents an overall view of the various aspects of the native Mediterranean fish diversity. The Mediterranean Sea is a land-locked sea, comprising ca. 0.7 % of the hydrosphere area hosting ca. 5 % of the world’s marine fish species and supplies ca. 1 % of the global marine catch. Eight percent of the fish species in the Mediterranean have been categorized as regionally threatened.

The total number of native marine fish species in the Mediterranean (May 2012) is 580 belonging to 151 families. The classes Myxini and Holocephali are represented in the Mediterranean by a single family and a single species each; The Cephalaspidomorphi by a single family and with two species; the Elasmobranchii (cartilaginous fish) by 24 families and 81 species; the Actinopterygii (bony fishes) is represented in the Mediterranean by 124 families and 495 species.

The total number of reported deep-sea fishes (below 1,000 m) is 60, belonging to 33 families.

The near-shore regions along the European coast, from Spain to Italy (including the Adriatic Sea), are the richest parts of the sea with 360–460 fish species. The near-shore poorest parts are most of Egyptian and eastern Libyan coasts with 200–270 species.

According to climatic models, the Mediterranean basin will be one of the regions most affected by the ongoing warming trend and increase in extreme events. The Mediterranean is already one of the most impacted seas in the world, where climate change interacts with many other stressors. Coastal lagoons, in particular, represent critical areas for their importance in terms of land use, economic relevance and anthropogenic pressure, and are the main objects of our analysis. A concept emerged in recent studies on climate changes, suggesting that the only environmental signals that matter to an organism are those that the organism experiences. Thus, animal responses may be very different from those expected at a large-scale, and the impacts of climate change can be different according to a number of local/organismal conditions. The present contribution is focused on the effects of climate change-driven factors on animal physiology, considering that physiology bridges the gap between mechanistic molecular understanding and the larger scale ecosystem responses. Indeed, adaptive responses to large-scale perturbations, such as climate change, affect all biological levels but they initially take place at the cellular and individual levels, and are then integrated and translated to upper levels of biological organization. The geochemical features that may influence animals responses are also addressed.

The Mediterranean is a sea rich with many kinds of diversity. It is a hotspot of marine biodiversity which covers many habitats and environmental conditions, and is surrounded by three continents characterized by different cultures and degrees of socio-economic development, whose coastal human activities exert multiple pressures on the marine environment. Yet, surprisingly, the diversity in the structure and functioning of Mediterranean marine ecosystems has not been analyzed rigorously, especially on large spatial scales. Such information are critical to implement an Ecosystem Approach to the management of the Mediterranean Sea. To fill this gap, a comparative analysis of the South Catalan, the Northern-Central Adriatic, the Northern Adriatic and the North Aegean Seas was performed. Trophic network models of the marine pelagic environment in each system were assembled with Ecopath software, based on published datasets. To facilitate the comparison, models were constructed with the same number and kind of trophic groups. Multiple indicators from ecological network analysis were calculated and consistently highlighted similarities and differences among Mediterranean pelagic food webs. Shared traits included the key role of intermediate-trophic level species, the low overall impact exerted by large predators, and inefficiencies in the exploitation of phytoplankton and detritus production giving rise to high export flows fuelling the benthic compartment. Primary productivity markedly influenced food web properties, but additional differences in the global structure of trophic flows emerged, highlighting a great ecosystem diversity. The systems could be ranked in a clear order of development and maturity (from high to low): South Catalan, Northern-Central Adriatic, North Aegean, Northern Adriatic Sea.

In the Mediterranean Sea, most important habitat formers are bioconstructors. Bioconstructors provide habitats for a large variety of organisms and these organisms rely on bioconstructors as a source of food and shelter. Marine bioconstructors in temperate seas have been recognized to have a structural and functional role of marine biodiversity (as a habitat formers and ecosystem engineers), the same as coral reefs in tropical regions. Bioconstructors are ranging from coralligenous formations (formed usually by coralline algae, sponges, cnidarians, and bryozoans) to vermetid reefs, deep-sea white corals and oyster banks. Some habitats like coral banks formed by shallow-water coral

Cladocora caespitosa

od deep-water coral

Lophelia pertusa

, together with coralligenous buildups and maerl beds are of special interest for scientists and people involving with nature protection. Habitat degradation, destruction, fragmentation and loss are the most dramatic consequences of anthropogenic pressures on natural ecosystems and marine bioconstructors as a part of that. Under the present climate warming trend, together with marine acidification, new mass mortality events may occur in the near future, possibly driving a major biodiversity crisis in the Mediterranean Sea, especially in Mediterranean bioconstructors.

Research conducted in the Mediterranean significantly contributed to our understanding of bioerosion, providing faunistic records and key information about the succession that occurs when fresh substrate is colonized by eroding biota. Bioeroders that have a substantial role in the Mediterranean are microendoliths, sponges, boring mollusks and various grazers. A multitude of environmental factors controls their abundances, diversities and eroding capacities. With ongoing climate change, several of these factors are likely to magnify the effects of bioerosion in the Mediterranean and worldwide. We regard eutrophication as the most important in the Mediterranean, but climate change, especially ocean acidification, will also have an important effect. Should bioerosion levels change, characteristic limestone coasts will be impacted, as will be community and sediment compositions, enigmatic cold-water coral ecosystems, mollusk aquaculture and man-made materials that are submerged. Understudied topics in Mediterranean bioerosion include rates, interactions at community level, as well as direct effects of climate change.

Six hundred and eighty alien marine multicellular species have been recorded in the Mediterranean Sea, with many establishing viable populations and dispersing along its coastline. A brief history of bioinvasions research in the Mediterranean Sea is presented. Particular attention is paid to gelatinous invasive species: the temporal and spatial spread of four alien scyphozoans and two alien ctenophores is outlined. We highlight few of the discernible, and sometimes dramatic, physical alterations to habitats associated with invasive aliens in the Mediterranean littoral, as well as food web interactions of alien and native fish. The propagule pressure driving the Erythraean invasion is powerful in the establishment and spread of alien species in the eastern and central Mediterranean. The implications of the enlargement of Suez Canal, reflecting patterns in global trade and economy, are briefly discussed.

This chapter focuses on analysing the current biodiversity of the Mediterranean Sea and the changes that are taking place on a human time scale (decades). Some of the changes observed may be sometimes interpreted as natural changes (cyclical, episodic or catastrophic), but most of them are of human origin. Each of the main anthropogenic impacts (habitat fragmentation and loss, overfishing and exploitation of living resources, pollution, species introductions and others) are analysed separately, although it is noted that predictions of how all the impacts interact synergistically are necessary. Furthermore, the effects of the so called “global change” (including both global warming and ocean acidification) on Mediterranean biodiversity are highlighted. It also deals about some episodic events (mass mortalities, jellyfish blooms, noxious algal blooms, proliferation of mucilages) caused by a combination of different impacts. Finally, some predictions are done about the near future of marine biodiversity in the Mediterranean Sea and some suggestions to address the problem are given.

Marine ecosystems are facing unprecedented pressures for instance rising water temperatures, changing current patterns and ocean acidification. Coastal systems in particular are also challenged with additional anthropogenic pressures caused by accelerating rates of human settlement near the coast. This trend places increasing strains on the delivery of ecosystem services associated with recreation but also coastal fisheries. Here we introduce the concepts related to ecosystem stability and ecosystem services and review the evidence for regime shifts in the world’s ecosystems with particular reference to the Mediterranean, before reviewing mechanisms for ecosystem valuations, ending with recommendations for increasing the practical relevance of future ecosystem evaluations. We stress the need for regional approaches, taking into account the views and needs of local populations, which might differ greatly geographically even for the same issue being considered.

This chapter illustrates the main trends of interlaced forces acting on the development of the Mediterranean landscape during the Holocene. The mosaic of habitats distributed in the Mediterranean basin has been continuously transformed by climatic changes occurring at a global scale during the early, mid and late Holocene. In the meantime, the environment has been exploited and the landscape shaped by different civilizations. Climate changes and human activities are observed through the lens of pollen found in terrestrial and marine sediment cores and in archaeological layers. Joint actions of increasing dryness, climate oscillations, and human impact are hard to disentangle, and this becomes particularly true after the mid-Holocene onset of Bronze Age cultures. Regional differences and similarities are reported for eastern, central and western Mediterranean, and for northern Africa and Sahara. The mixing of cultures accelerated the exchanges of ideas, technologies, raw materials and people along the coasts of this ‘great lake’, making the different civilizations linked between them as one network of regions belonging to the ‘Mediterranean culture’.

The Mediterranean Sea has long been one of the most important and crowded natural hubs for the expansion of human genes and cultures, representing a tri-continental crossroads for human migrations since the first dispersals of anatomically modern humans out of Africa. Both its ancient and modern history, with its amazing chronicle of biological and cultural transitions, has substantially influenced the current patchwork of anthropological types existing within this area. For a deep dissection of this patchwork, Anthropological Genetics combines information related to the population dynamics able to shape the genetic structure of human populations (i.e. geographical constraints, language, cultural, social and political barriers) to those provided by the powerful tools of molecular biology and population genetics. This comprehensive approach allows to trace genetic profiles of Mediterranean populations into the past to discover and reconstruct their origins and demographic histories, as well as their evolutionary relationships. Nevertheless, the genetic landscape of Mediterranean populations is far from being exhaustively drawn. Several Anthropological Genetics projects, basing on an even deeper genetic characterization of dense and accurately selected geographic samples, have been just launched and promise to shed new light on the pivotal role of the Mediterranean basin as a genetic barrier and/or a bridge between human groups characterized by different African, Near Eastern or European cultural backgrounds.

The Mediterranean was the great sea of Antiquity. And its waters, symbol of a changing world, allowed many men – Egyptians, Phoenicians, Greeks, etc. – to find and to recognize themselves in their particularities. Later, Rome, which in just three centuries redesigned the world, ensured that the messages of the early times – of Egyptian, Phoenician and Greek spaces – penetrated this world. It added others – law and religion – and thus it was shaped Western civilization, which is Roman and Greek, but it is also African and Oriental, via a river whose waters “drew” the history of the world.

The eastern Mediterranean coast was the center of the dyeing industry in the ancient world. Royal purple, the most famous indigoid dye of antiquity, was derived from hypobranchial-gland extracts of various marine gastropod mollusks. Extensive marine biological surveys have revealed that the only snails in the Mediterranean that produce stable dyes are those of the murex family. The dye obtained from the common snail

Murex trunculus

is very stable and steadfast. The extracts were processed in a lengthy, elaborate procedure, according to the Roman writer of the first century AD, Pliny the Elder; other, more cursory texts are known from the Classical Greek period up until Byzantine times. Purple dyeing was also discovered by cultures on the western and eastern shores of the Pacific Ocean in China and Peru, respectively, apparently with no connection to the Canaanites or Phoenicians. We describe here the history of this dye from its earliest traces, through its role in Jewish rituals, its rise to Roman regal attire, and its subsequent decline and final replacement by synthetic products.

In the present chapter we qualitatively survey the impacts of changes in Mediterranean Ecosystem on human wellbeing via three economic indicators: the fishery sector, tourism industry and human migration. The indicators selected cover impacts on different dimensions of human being needs: labor and welfare, living, and leisure.

The commercial sponge industry is a fascinating cultural heritage of several Mediterranean countries, where it continues to represent an important economic activity. Mediterranean bath sponges are of the highest quality and the commercial demand for them is still significant, however, sponges are suffering from environmental disturbances that seem to be occurring more frequently in recent decades. Here we present some general data about commercial sponges of the Mediterranean Sea, and examine probable consequences of both overfishing, which has been occurring for many centuries on most sponge beds, and the effects of climatic change, which appears to be responsible for increased disease outbreaks and mass mortality events. Together these disturbances may alter the species distribution. We also examine the potential future of sponge cultivation under these conditions.

Current projections for the twenty-first century show that global warming will accelerate, with stronger storms, extreme precipitation, dry spells and rising sea levels as the primary symptoms. Such changes will have implications in seafood production, security, and safety, as well as in human health, due to the increase in the frequency of harmful algal blooms, levels and bioaccumulation of several chemical contaminants, prevalence and virulence of common foodborne pathogenic microorganisms. The Mediterranean will be particularly affected by climate change due to water scarcity in the region. Assuring seafood safety in such scenario requires the active involvement of all stakeholders to elaborate and implement adaptation and mitigation plans. In this context, the current chapter aims to provide an overview of the potential effects of climate change in the Mediterranean seafood safety and human health, taking into account chemical and biological contaminants, and to discuss potential adaptation and mitigation measures.

The semi-enclosed Mediterranean Sea is the biggest marginal sea of the Earth, and it is at the centre of the life of several millions of people. Seafood is widely consumed in this region, with an average of 16.5 Kg/capita/year, and one fourth of the seafood supply comes from aquaculture activities. The Mediterranean aquaculture sector has expanded over the last decades. It increased 77 % over the last decade reaching circa 1.3 million tons in 2009. The value ranged around 3.700 millions US dollars, representing 3.4 % of the global aquaculture value. The growth of seafood demand in the Mediterranean is expected to increase in the future, especially in southern countries. Yet, during the 21st century, the Mediterranean basin is expected to observe: (i) an increase in air temperature between 2.2 °C to 5.1 °C, (ii) a significant decrease in rainfall (ranging between −4 and −27), (iii) an increase in drought periods related to high frequency of days during which the temperature would exceed 30 °C, (iv) an increase of the sea level (around 35 cm) and saline intrusion. Moreover, extreme events, such as heat waves, droughts or floods, are also likely to be more frequent and violent. Here, we review the present status of the Mediterranean aquaculture (e.g. production trends, main farmed species, production systems, major producing countries), the most relevant impacts of climate change to this sector (e.g. temperature, eutrophication, harmful algae blooms, water stress, sea level rise, acidification and diseases), and provide a wide range of adaptation and mitigation strategies that can be implemented to minimize such climatic effects.

Since the 1970s an increase in temperatures has been observed, and future climate predictions suggest an increase in the frequency and intensity of extreme weather events. Conversely to other environmental risks, climate change is a global phenomenon which will have an impact on the population’s health at the global scale. In recent years, many studies have documented the impact of extreme events and climate variability on health as well as estimating the potential future risks under different climate change scenarios. An overview of the potential effects of climate change on health in the Mediterranean region is presented focussing on the increase in health burden associated with heat waves and extreme events, floods and droughts, air pollution episodes and, to the rise in the indirect health effects of infectious disease.

Global warming poses a significant challenge for the Mediterranean region (Southern Europe, North Africa and Middle East). The assessment starts from a description of the physical effects of climate change, including variations in temperature, precipitation, weather extremes and sea-level, that affect soil erosion, desertification, river flows, coastal zones, rural and urban areas. The vulnerability of the region is analysed in various dimensions, including water, food, migration and energy. Climate hotspots are discussed which are particularly vulnerable, including North Africa and the Nile River basin. The potential consequences of these developments for population, economy and societal stability as well as human security and violent conflict in the region are considered. Finally, we investigate policy responses and institutional frameworks for climate adaptation, conflict resolution and cooperation, with a particular focus on renewable energy collaboration across the Mediterranean region.

Man’s ability to exploit marine resources has improved in recent decades and as expected, efforts of exploitation have intensified. To avoid conflicts and support ecosystem-based principles, determination of pro-active marine policy based on an understanding of current and future uses of the marine environment is essential. This chapter highlights major uses of the marine and near shore environment of Israel. I relate trends in marine uses in this part of the Mediterranean Sea to corresponding past policy developments in coastal and near-shore management. Current policies fail to address new and increasing uses, especially those that are exclusively marine and/or beyond the country’s territorial waters. The lack of marine policy in Israel is particularly worrisome when one considers the value of the country’s offshore resources and the pressures on its terrestrial resources. Approaches such as marine ecosystem based management, integrated coastal zone management and mechanisms for the pro-active mediation of develop and conservation interests, such as marine spatial planning, are discussed in terms of their potential contribution for the management of evolving and emerging uses of the sea.