We examined whether escape response performance and mitochondrial capacities could reveal differences created by feeding scallops, Argopecten purpuratus, mono-specific algal diets composed of either Chaetoceros calcitrans or Isochrysis galbana (variety T. iso) hereafter T. iso. Before and after feeding scallops with these diets, we assessed force production in vivo to evaluate escape response performance (initial and repeat). We measured oxidative capacities of mitochondria isolated from the adductor muscle and from the male and female portions of the gonad. Initial escape response performance was reduced more by the C. calcitrans diet than by the T. iso diet. Repeat escape responses, which require aerobic recuperation, were reduced by both treatments. The oxidative capacity of mitochondria isolated from muscle and female gonad was markedly lower in scallops fed C. calcitrans than in those fed T. iso. Flux through complex I–IV and through complex IV was also lower in mitochondria from muscle of scallops fed C. calcitrans than in those fed T. iso. Muscle aerobic capacity, assessed by citrate synthase activity, was lower in scallops fed C. calcitrans than in those fed T. iso. Despite the marked differences in fatty acid (FA) composition of the algal diets, the FA composition of mitochondrial phospholipids differed little between scallops fed C. calcitrans and those fed T. iso. Both escape response behaviour and mitochondrial capacities changed with feeding mono-specific diets. The simplicity of measurements of scallop escape responses suggests this as a practical means of evaluating the status of scallops for the two monoalgal diets tested.

Eight taxa of marine invertebrates, including two new bivalve species, are described from the Low Head Member of the Polonez Cove Formation (latest early Oligocene) cropping out in the Vauréal Peak area, King George Island, West Antarctica. The fossil assemblage includes representatives of Brachiopoda (genera Neothyris sp. and Liothyrella sp.), Bivalvia (Adamussium auristriatum sp. nov., ?Adamussium cf. A. alanbeui Jonkers, and Limatula (Antarctolima) ferraziana sp. nov.), Bryozoa, Polychaeta (serpulid tubes) and Echinodermata. Specimens occur in debris flows deposits of the Low Head Member, as part of a fan delta setting in a high energy, shallow marine environment. Liothyrella sp., Adamussium auristriatum sp. nov. and Limatula ferraziana sp. nov. are among the oldest records for these genera in King George Island. In spite of their restrict number and diversification, bivalves and brachiopods from this study display an overall dispersal pattern that roughly fits in the clockwise circulation of marine currents around Antarctica accomplished in two steps. The first followed the opening of the Tasmanian Gateway at the Eocene/Oligocene boundary, along the eastern margin of Antarctica, and the second took place in post-Palaeogene time, following the Drake Passage opening between Antarctic Peninsula and South America, along the western margin of Antarctica.

A further specimen of the rare allochthonous scallop Chlamys lischkei was found at Schiavonea di Corigliano Calabro, Gulf of Corigliano (Cosenza), while SCUBA diving at a depth of about 30 m on a muddy detritic bottom. This new single record, the third for the entire Mediterranean Sea and the second for the Italian Seas, confirms the sporadic presence, often believed uncertain, of this species in the Mediterranean Sea.

Austrochlamys heardensis (Fleming) is recorded from a boulder of Late Pliocene (3.62–2.5 Ma) volcaniclastic sandstone dredged 70 km east-north-east of Heard Island, the third record of the species. The collection is much larger than the original described by Fleming and includes left valves which are described for the first time. The species is compared with A. anderssoni (Hennig) from Cockburn Island and ‘Chlamys’ mawsoni Fletcher from Îles Kerguelen. The source rock accumulated in fully marine, highly current-affected conditions. The collection is dominated by right valves, possibly because left valves are more susceptible to breakage and the effects of current winnowing. The locality may have subsided some 500 m since deposition. It lies immediately north of a straight, north-east–south-west trending lineament which may mark a major tectonic feature with left-lateral displacement of approximately 50 km, and provides a natural boundary within the Central Province of Kerguelen Plateau.