Lack of genetic structure in the jellyfish Pelagia noctiluca (Cnidaria: Scyphozoa: Semaeostomeae) across European seas.

The genetic structure of the holopelagic scyphozoan Pelagia noctiluca was inferred based on the study of 144 adult medusae. The areas of study were five geographic regions in two European seas (Eastern Atlantic and Mediterranean Sea). A 655-bp sequence of mitochondrial cytochrome c oxidase subunit I (COI), and a 645-bp sequence of two nuclear internal transcribed spacers (ITS1 and ITS2) were analyzed. The protein coding COI gene showed a higher level of divergence than the combined nuclear ITS fragment (haplotype diversity 0.962 vs. 0.723, nucleotide diversity 1.16% vs. 0.31%). Phylogeographic analysis on COI gene revealed two clades, the larger consisting of specimens from all sampling sites, and the smaller mostly formed of specimens from the Mediterranean Sea. Haplotype diversity was very high throughout the sampled area, and within sample diversity was higher than diversity among geographical regions. No strongly supported genetically or geographically distinct groups of P. noctiluca were found. The results - long distance dispersal, insignificant F(ST) values, lack of isolation by distance - pointed toward an admixture among Mediterranean and East Atlantic populations.

Reflection of hydrocarbon pollution on hepatic EROD activity in the black goby (Gobius niger).

Hepatic ethoxyresorufin-O-deethylase (EROD) activity was measured in black gobies (Gobius niger) collected from seven sampling sites along the Slovenian coast during spawning and non-spawning periods. Sediments from the same sites were tested for their toxicity and for total polycyclic aromatic hydrocarbon (PAH) content. EROD activity was significantly higher during the non-spawning period in winter than during the spawning period in spring and generally correlated well with increased total PAH content in sediments and with sediment toxicity. An 11-fold increase of EROD activity was induced 48h after injecting 10µgg(-1) weight of benzo(a)pyrene into black gobies. On the basis of these results and of its ecological characteristics, the black goby is proposed as a suitable candidate for future biomonitoring programmes.