Marine Mammals in the Mediterranean Sea: An Overview.

Despite being a small part of the world's oceans, the Mediterranean Sea hosts a diverse marine mammal fauna, with a total of 28 different species known to occur, or to have occurred, in the region. Species currently recognised as regular in the Mediterranean-the Mediterranean monk seal (Monachus monachus) and 11 cetaceans (fin whale, Balaenoptera physalus; sperm whale, Physeter macrocephalus; Cuvier's beaked whale, Ziphius cavirostris; short-beaked common dolphin, Delphinus delphis; long-finned pilot whale, Globicephala melas; Risso's dolphin, Grampus griseus; killer whale, Orcinus orca; striped dolphin, Stenella coeruleoalba; rough-toothed dolphin, Steno bredanensis; common bottlenose dolphin, Tursiops truncatus; harbour porpoise, Phocoena phocoena relicta) have adapted well to the region's environmental conditions, but their coexistence with humans is problematic. All the regular species are represented in the Mediterranean by populations genetically distinct from their North Atlantic relatives. Seventeen other species (three pinnipeds and 14 cetaceans) occur or have occurred in the Mediterranean as vagrants from adjacent regions. Impacts on the conservation status of marine mammals in the region deriving from a variety of threats include: (a) mortality caused by deliberate killing (to a large extent resulting from fisheries interactions), naval sonar, ship strikes, epizootics, fisheries bycatch, chemical pollution and ingestion of solid debris; (b) short-term redistribution caused by naval sonar, seismic surveys, vessel disturbance and vessel noise; and (c) long-term redistribution caused by fishery-induced food depletion, coastal development and possibly climate change. Accordingly, seven of the 12 marine mammals regular in the Mediterranean region are listed as Threatened on IUCN's Red List; regrettably, three are Data Deficient and two remain unassessed.

Are Mediterranean Monk Seals, Monachus monachus, Being Left to Save Themselves from Extinction?

Mediterranean monk seals (Monachus monachus), amongst the most endangered marine mammals, are showing localised signs of recovery warranting their recent down-listing, from Critically Endangered to Endangered, on the International Union for the Conservation of Nature (IUCN) Red List. This, however, cannot be taken as a reason for complacency, as the species' condition is still very critical, having been extirpated from most of its historical range. Monk seals within the Mediterranean, a 'unit to conserve' separate from Atlantic conspecifics, were once widely distributed throughout the Mediterranean Sea, with their range also extending into the Sea of Marmara and the Black Sea. Today breeding nuclei persist only in the northeastern portion of the region, in Greek, Turkish and Cypriot waters. The main reasons for their decline include deliberate killing and human encroachment of their critical habitat. Past conservation efforts have mostly failed due to the inability of implementing institutional commitments, lack of coordination and continuity of efforts and insufficient consideration of the socioeconomic implications of conserving monk seals. Yet the small reversal of the species' decline that has been observed in Greece may have resulted from conservation efforts by civil society, combined with ongoing societal change within the local communities coexisting with the seals. The inaccessibility of large portions of monk seal habitat in the Eastern Mediterranean Sea may also have contributed, by offering to the monk seals a refuge from persecution and encroachment. Despite continued threats to monk seals, conservation activities at the local scale that utilise lessons learned from previous failures and successes could secure the survival of the largest Mediterranean colony of monk seals, while also providing a model to support the species' recovery in other portions of its former range.

Biomarkers for endocrine disruptors in three species of Mediterranean large pelagic fish.

The hypothesis that Mediterranean top predator species, such as large pelagic fish, are potentially at risk due to endocrine disrupting chemicals (EDCs), is investigated. The potential estrogenic effects of PHAHs in three fish species of commercial interest, the top predators bluefin tuna (Thunnus thynnus thynnus), swordfish (Xiphias gladius), and Mediterranean spearfish (Tetrapturus belone), were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and mixed function oxidases (EROD, BPMO) as diagnostic tools. High induction of Vtg and Zrp was detected by western blot and ELISA techniques in adult males of X. gladius and T. thynnus thynnus, suggesting that these species are at high toxicological risk in the Mediterranean sea. Comparison of BPMO and EROD activities in the three species indicated, both in male and female, much higher MFO activity in bluefin tuna. This data suggests high exposure of this species to lipophilic xenobiotic contaminants in the Mediterranean environment.

Multi-trial biomarker approach in Meganyctiphanes norvegica: a potential early indicator of health status of the Mediterranean "whale sanctuary.".

The aim of this study was to propose a suite of biomarkers (BPMO activity, NADPH-cytocrome c reductase, NADH-ferricyanide reductase. esterases, porphyrins, vitellogenin and zona radiata proteins) and residue levels (organochlorines, PAHs and heavy metals) in the zooplanktonic euphausiid Meganyctiphanes norvegica as a potential multi-disciplinary diagnostic tool for assessment of the health status of the Mediterranean "whale sanctuary". Very little difference in BPMO was detected between sites, with values ranging from 0.75 to 2.68 U.A.F./mg prot/h. On the other hand larger differences between sites were found for reductase activities. Esterases (AChE), porphyrins (Copro-, Uro-, Proto-porphyrins) vitellogenin and zona radiata proteins were also detectable in this zooplanctonic species. Hg showed mean levels of 0.141 ppm d.w., Cd 0.119 ppm d.w. and Pb 0.496 ppm d.w. Total PAHs ranged from 860.7 to 5,037.9 ng/g d.w., carcinogenic PAHs from 40.3 to 141.7 ng/g d.w., HCB from 3.5 to 11.6 ng/g d.w., DDTs from 45.3 to 163.2 ng/g d.w. and the PCBs from 84.6 to 210.2 ng/g d.w.

Do endocrine disrupting chemicals threaten Mediterranean swordfish? Preliminary results of vitellogenin and Zona radiata proteins in Xiphias gladius.

Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fishes. In this research the hypothesis that Mediterranean top predator species (such as large pelagic fish) are potentially at risk due to EDCs is investigated. These marine organisms tend to accumulate high concentrations of EDCs such as polyhalogenated aromatic hydrocarbons (PHAHs). The potential effects of EDCs on a fish species of commercial interest, the top predator Xiphias gladius (swordfish), were investigated using vitellogenin (Vtg) and Zona radiata proteins (Zrp) as diagnostic and prognostic biomarkers. Dramatic induction of typically female proteins (Vtg and Zrp) was detected by ELISA and Western Blot in adult males of the species. These results are the first warning of the potential risk for reproductive function of Mediterranean top predators, and suggest the need for continuous monitoring of this fragile marine environment.

Relationship between organochlorine contaminants and mixed function oxidase activity in skin biopsy specimens of Mediterranean fin whales (Balaenoptera physalus).

The relationship between organochlorine contaminants (PCBs and DDTs) and mixed function oxidase, benzo(a)pyrene monooxigenase activity (BPMO), was investigated in skin biopsy specimens from fin whales (Balaenoptera physalus) of the Mediterranean Sea. Skin biopsy material, sampled by a non invasive technique, is suitable for a wide range of chemical and biomarker analysis. In this study PCBs and DDTs were evaluated in subcutaneous blubber and MFO activity in epidermis. An interesting correlation was found in male specimens between the two variables.

Population genetic structure of North Atlantic, Mediterranean Sea and Sea of Cortez fin whales, Balaenoptera physalus (Linnaeus 1758): analysis of mitochondrial and nuclear loci.

Samples were collected from 407 fin whales, Balaenoptera physalus, at four North Atlantic and one Mediterranean Sea summer feeding area as well as the Sea of Cortez in the Pacific Ocean. For each sample, the sex, the sequence of the first 288 nucleotides of the mitochondrial (mt) control region and the genotype at six microsatellite loci were determined. A significant degree of divergence was detected at all nuclear and mt loci between North Atlantic/Mediterranean Sea and the Sea of Cortez. However, the divergence time estimated from the mt sequences was substantially lower than the time elapsed since the rise of the Panama Isthmus, suggesting occasional gene flow between the North Pacific and North Atlantic ocean after the separation of the two oceans. Within the North Atlantic and Mediterranean Sea, significant levels of heterogeneity were observed in the mtDNA between the Mediterranean Sea, the eastern (Spain) and the western (the Gulf of Maine and the Gulf of St Lawrence) North Atlantic. Samples collected off West Greenland and Iceland could not be unequivocally assigned to either of the two areas. The homogeneity tests performed using the nuclear data revealed significant levels of divergence only between the Mediterranean Sea and the Gulf of St Lawrence or West Greenland. In conclusion, our results suggest the existence of several recently diverged populations in the North Atlantic and Mediterranean Sea, possibly with some limited gene flow between adjacent populations, a population structure which is consistent with earlier population models proposed by Kellogg, Ingebrigtsen, and Sergeant.