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Ocean acidification is predicted to have negative effects on marine biota, resulting in the loss of biodiversity and changes in marine ecosystem structure and function. However, some species and life stages may be capable of thriving in low pH conditions, either due to their natural ability to tolerate stressful low pH-high pC[O.sub.2] conditions and/or alteration of species interactions caused by changes in pH profiles, or due to evolutionary trade-offs. A better understanding of which species may be capable of tolerating ocean acidification can guide future research into the mechanisms for physiological and ecological resilience to future carbon dioxide (C[O.sub.2]) conditions. We investigated the colonization of selected polychaete species along a pH gradient originating from shallow, coastal volcanic C[O.sub.2] vents (Ischia, Italy). Colonization was quantified by exposing artificial invertebrate collectors attached to the substratum for 30 days during different periods of the year (late spring, fall and late winter). Three species, Amphiglena mediterranea, Platynereis dumerilii and Syllis prolifera, were present and abundant along the gradient throughout the year. All three species were significantly more abundant in the most acidified areas, confirming their high tolerance and capacity to cope with very low pH. Abundances of all three species were compared to data previously collected via collectors suspended in the water column. More individuals were found in the collectors attached to the substratum, suggesting that abundances may have previously been underestimated. This is likely due to the close proximity of these collectors with the natural rocky substratum. All three species exhibited similar temporal variability, consistent with their life cycle and reproductive biology. Our results demonstrate high tolerance of the species for low and variable pH and corroborate their use as robust models to explore the capacity to cope with low pH-high pC[O.sub.2] conditions, both in the natural vent systems and in the laboratory., Introduction The increasing concentration of carbon dioxide (C[O.sub.2]) in the atmosphere is one of the most profound environmental threats to marine species and ecosystems (Fabry et al. 2008; Munday et [...]

A new record of the genus Veneriserva Rossi, 1984 (Polychaeta: Dorvilleidae) is reported, as an endosymbiont in the coelom of the polychaete Laetmonice producta Grube, 1877 (Aphroditidae) in the eastern Weddell Sea and off King George Island (Southern Ocean, Antarctica). The specimens studied were very similar to Veneriserva pygoclava Rossi, 1984; however, due to the greater morphological variability and larger dimensions of our specimens, as well as different host species and geographic locations, a new sub-species, V. pygoclava meridionalis, was erected. A total of 842 specimens of L. producta were examined, 163 of which hosted 209 symbionts (183 in the Weddell Sea samples and 26 in the King George Island samples). Symbiont prevalence was higher in the Weddell Sea samples, and increased with depth (max. 51% at stn 14, 850 m depth). Symbiont intensity was equal to one for 78% and to two for 19.6% of all hosts examined; a maximum of six symbionts per single host was observed. Mean symbiont density was equal to 0.36 and 0.07 for the Weddell Sea and King George Island host populations, respectively. A weak linear relationship was found between symbiont and host size. Eight symbiont specimens (all found at a single station, 850 m depth) were bearing eggs, ranging between 10 and 200 [micro]m in diameter, while 13 specimens were observed in regeneration of the posterior part, suggesting the occurrence of both sexual and asexual reproduction. The way of feeding is still not clear; reduction of the jaw apparatus suggests a parasitic host-symbiont relationship, however, no evident damage was observed in the tissues of the host. These results point out that occurrence of polychaete endoparasites in large aphroditids may be a more frequent and widespread phenomenon than previously believed, and that more attention should be paid to this aspect also in temperate and tropical aphroditid species.

Sabella spallanzanii (Gmelin) is one of the best known and widely distributed Mediterranean polychaetes, but available data on its general biology has been inferred mostly from populations recently introduced to Australia. In the present paper, data on gametogenesis and larval development of a Mediterranean population from the Gulf of Taranto (Ionian Sea, Italy) are reported. Histological and electron microscopical analysis of gametogenesis showed that oogenesis, a long process beginning soon after spawning in February, is of extraovarian type. By contrast spermatogenesis is a very fast process lasting from September to December, when the coelomic cavity is completely packed with mature gametes and almost devoid of coelomocytes. During the period of spawning, some experiments of in vitro fertilisation were performed, always without success, while some of the collected females naturally spawned fertilised eggs (100%). Particularly interesting was the discovery of a small percentage of eggs which appeared fertilised but unspawned within the coelomic cavity of female. Investigation of the S. spallanzanii life cycle, from the naturally spawned fertilised eggs to embryonic and juvenile stages, was performed by daily microscopical observations and by SEM. Despite the presence of large eggs giving rise to a lecithotrophic larva, a long pelagic phase was observed, the longest found among Sabellidae. The larval development pattern is also described. Settlement began after about 2 weeks; metamorphosis occurred 10 d after settlement, when mucus was secreted abundantly and an external tube was formed. The long larval pelagic period and the development pattern, suggesting a high potential for dispersal, support both the introduction and invasive behaviour of the species in Australian waters.

Developmental data and reproductive characteristics such as sperm structure were combined with other morphological data to evaluate the cladistic relationships of the species in genus Amphiglena. Two most-parsimonious cladograms were observed. The monophyly of Amphiglena was indicated by characteristics previously identified as, as well as two features based on sperm morphology. A plesiomorphic larval form cannot be identified for the genus Amphiglena.

The polychaete Sabella spallanzanii (Gmelin) (Sabellidae) is a widely distributed species throughout the Mediterranean where it is commonly found in sheltered shallow areas and up to 30 m depth in more exposed waters. The sedentary habit, the filter-feeding behavior and its capability to colonize disturbed environments such as harbors, suggest the potential utility of this organism as a bioindicator in environmental monitoring programs. The aim of this work was a preliminary characterization of S. spallanzanii, integrating chemical data on trace metal concentrations with the biochemical analysis of antioxidant defenses which play an important role in mediating responses and adaptation to stressful environmental conditions. Organisms were collected in four locations of the Adriatic and Tyrrhenian Sea, characterized by a moderate impact or influenced by organic enrichment or sulphuric emissions. Trace metal concentrations (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were comparable to those of other invertebrate species and quite typical for unpolluted environments. Analyses of individual antioxidants (superoxide dismutase, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase) were integrated with measurement of the total oxyradical scavenging capacity toward specific forms of ROS; the TOSC assay, quantifying the overall capability of a tissue to neutralize specific reactive oxygen species provide a more integrated picture of the balance between prooxidant factors and antioxidant defenses, with important indications about the role of different ROS in appearance of oxidative disease. The antioxidant profile was influenced by the different physiological functions of the analyzed tissues, namely the branchial crown, involved in filtration of large volumes of seawater, and the thorax where digestive processes occur. The analysis of antioxidant defenses revealed significant variations in polychaetes from various sampling sites suggesting the influence of specific environmental conditions like those limiting oxygen availability. Our results confirm the role of antioxidants in adaptation to stressful environmental conditions and their importance in ecotoxicological studies for the sensitivity in revealing the occurrence of biological disturbance. [ABSTRACT FROM AUTHOR]

A new species of Amphiglena Claparede 1864, A. lindae n. sp., is described from Belize having up to five pairs of radioles, eight thoracic chaetigers, and as many as 26 abdominal chaetigers. This species, like other Amphiglena spp., is a simultaneous hermaphrodite with eggs and sperm developing in abdominal chaetigers. However, in A. lindae the gametes are found in the mid-abdominal region rather than the anterior abdomen. It is also unique in having a pair of spermathecae withred pigmentation at the base of the dorsal lips. A redescription of the type species of the genus, A. mediterranea Leydig, 1851, is also provided based on material from Italy. No type material of A. mediterranea was ever deposited but it is thought unnecessary to designate neotypes. The cladistic relationships among the species of Amphiglena are then assessed using an outgroup based on the six genera that are the sister group to the Laononie/Amphiglena clade. Two species of Laonome are included as part of the ingroup. The monophyly of Amphiglenais indicated by features previously identified by Fitzhugh (1989). Asingle most parsimonious cladogram for the various Amphiglena species was found with A. lindae as sister group to a clade comprised of A.pacifica and A. terebro. This clade was then sister group to a cladecomprised of A. mediterranea and A. nathae. [ABSTRACT FROM AUTHOR]