No abstract

Infectious salmon anemia vlrus (ISAV) was isolated at a marine grow-out site in New Brunswick. Canada, from Atlantic salmon Salmo salar which experienced mortalities due to hemorrhagic kidney syndrome (HKS). Of 20 fish sampled in this study, 14 showed histologically various degrees of interstitial hemorrhaging, tubular epithelia1 degeneration and necrosis, and tubular casts in the posterior kidney, typical of HKS. Posterior kidney and spleen homogenates produced a cytopathic effect on chinook salmon embryo (CHSE-214) cells 10 to 14 d after inoculation. Pleomorphic virus particles in the size range 80 to 120 nm were seen by electron microscopy. The virus was confirmed as ISAV using reverse transcriptase-polymerase chain reaction (RT-PCR) This is a systematic diagnostic study of the isolation of ISAV on the North American continent and the first description of the growth of ISAV on the CHSE-214 cell line.

Ctenodiscus crlspat~ls is a non-selective deposit feeder on organically-rich (9.7 O/o of sediment dry weight) oxidized clayey-silt in the Gulf of Maine, USA. The mud star's lack of selectivity is attributed to the thorough mix~ng and very fine particle size of the habitat sediment, in which 90 % of the particlt.5 are less than 4 @ (62.5 lim) in diameter These sediments are easily disturbed and present problems in maintaining unimpa~red gas-exchange surfaces. C. crispatus has adapted to this by establiah~ng a temporary burrow and using its extensible epiproctal cone to nlalntaln connectron w~t h the water column. The burrow is irrigated by ciliary currents which, based on laboratory observations of burrowed mud stars, provide a continuous respiratory flow with a min~mum of disturbance to the flocculent surface sediment. Particles incidentally drawn into the burrow are trapped in cleansing mucus which is ingested, likely accounting for the enrichment in organlc content of stomach contents relative to habitat sediment. The low convection requirement (1.69 1 of water pumped per m1 of 0, removed from the current) reflects the respiratory, as opposed to nutnt~onal, ndture of the current. Thc cribriforrn organs not only create the driving force for the lcspiratory current, but themselves provide a large surface area (11 cm' in a 1.5 g individual), and ddditionally are r~chly supplied with microvilli. Both the extensive ciliation and anatom~cal arranger~lcnt of the cribriform lamellaeeliminate unstirred I<~yrrs at tht.11 ,lirfc~c.c> and account for low K, values tor tl~zzolved amino acid uptake, which despite a low concentrat~on ( L I L .~I .~( J~ 4.4 pM) in ~nterstitial water rn the hdbitat prov~de a net income in the ~~ninlal's c.ncrgv butlyel. The biology of the eurybathic C, crispatus I S d~scussed wrth relerence to that 01 thc r r Ik,tcd Porc~,llanasteritiae, a group of truly deep-sea d~p o s i t feedlng astero~ds.

Abstract. Information on the diet, feeding behavior, and surface morphology was obtained for Astrotoma agassizii, a large, simple-armed

Labidiaster annulatus is a large, multi-armed sea star common in moderate depths along the Antarctic Peninsula and off the islands of the Scotia Arc. Analyses by frequency of occurrence and several volumetric methods of stomach contents from 194 individuals from South Georgia, the South Sandwich Islands, and the Antarctic Peninsula show L. annulatus is an active and opportunistic predator and scavenger on prey from at least 10 phyla. Most common prey are euphausiids and amphipods which are caught initially by large, crossed, toothed pedicellariae arranged in wreaths on annuli along the arms and subsequently retained and passed to the oral surface and along the ambulacral groove to the mouth by the action of flexible arms and tube feet. L. annulatus obtains food, including activelyswimming crustaceans and small fish, directly from the water column, and to a lesser degree from within and on the substrate. Patterns of surface ciliation suggest that no methods of feeding involving cilia are utilized. Differences in the size and function of crossed pedicellariae, sources and types of prey and methods of prey capture now suggest that L. annulatus is not an ecological equivalent of Pycnopodia helianthoides from western North America.