ALBERT

Description: Four research surveys of Falkland Island waters were carried out to determine the distribution and abundance of the early life-history stages of Loligo gahi (d'Orbigny, 1835) in the austral winter of 1988 and the austral springs of 1990, 1991 and 1992. Juveniles were caught during three of the four surveys in both Bongo nets and an RMT8 net. In each case, greatest numbers were consistently caught in waters of ≤100 m to the south and east of East Falkland. The use of an opening/closing net in 1992 showed that most L. gahi juveniles aggregate close to the sea floor and are more available to the sampling gear by night than by day. Limited temperature data for the 1991 and 1992 surveys suggest that distribution on the coastal shelf may be associated with water-column structure. In 1992 when temperature data implied a mixed water column, juveniles were caught in deeper water than in 1991 when the water column was stratified. The results suggest that the spawning grounds of L. gahi are probably situated to the south and east of the Falkland Islands, at least for squid hatched in the austral winter/spring.

Description: A total of 40 (29 female and 11 male) Ross seals were sampled in January over three years. Seals were weighed, measured and age determined by counting dentine lines in teeth. Stomach contents were identified against reference material and species of helminths were determined using standard techniques. Asymptotes in body mass and length are reached at some nine years of age. Age class varied from 2–20 years. Antarctic silverfish Pleurogrammma antarcticum was the only fish species identified. Psychroteuthis glacialis dominated the squid component. Fish was dominant in three samples, squid was the exclusive component in two samples and a minor component in another two. Glandicephalus antarcticus, Diphyllobothrium wilsoni and Contracaecum spp were the dominant helminths present. The high proportion of empty or nearly empty stomachs conforms with the knowledge that this species moults and consequently fasts in January.

Description: Geographic variation in the squid Loligo forbesi was investigated using multivariate analysis of morphometric and meristic characters in samples of squid taken from 13 localities in the Northeast Atlantic Ocean. Two character sets, body morphometrics and beak morphometrics, indicated similar patterns of variation, with squid from the Azores differing markedly from those on the continental shelf. No consistent pattern was apparent in meristic data. Partial Mantel tests indicated that similarity matrices for morphological data were significantly correlated with distance matrices for (a) geographic proximity, (b) whether the capture site was on the continental shelf or the Azorean bank, and (c) (beak data only) average seasurface temperature at site of capture. Partial Mantel tests on allozyme data for the same individuals support hypothesis (b). The results suggest that L. forbesi in the Azores may reasonably be regarded as a distinct stock, differing significantly from L. forbesi on the continental shelf.

Description: Abralia trigonura is a small squid that is an important member of the mesopelagic boundary community around Hawaii. Squids were aged by examining statolith growth increments, and various reproductive parameters were measured. Female longevity is ∼6 mo, and they become sexually mature at ∼3.5 mo. Male longevity is the same, but they become sexually mature at ∼2.5 mo. This species appears to be a multiple spawner, and peculiarities in the number of eggs found in the oviducts suggests that they spawn every few days. Possible advantages of this reproductive mode are examined.

Description: The home range system of the coelacanth Latimeria chalumnae was investigated along 11 km coastline at Grande Comore, Western Indian Ocean, between 1987 and 1991. 67 individuals were identified on individual white dot patterns. The home range consisted of daytime caves where fish aggregated in groups of up to 14 individuals while at night individuals moved singly downwards to a depth of 250 to 300 m in search of food. Site fidelity of at least 5 yr was found. The coelacanths used several caves within their home ranges. Cave size, cave occupation rate, average and maximum group size and cave preferences were studied. Tracking experiments with ultrasonic transmitters revealed horizontal home ranges of at least 8 km width. Population estimates of 200 to 230 individuals at Grande Comore confirm earlier counts. Large home ranges and highly mobility in a topographically narrow habitat apparently favoured inbreeding of the small local island population.

Description: Eleven fish species from the Weddell Sea (Antarctic) were examined for infestation with anisakid nematodes. Two species of the genus Contracaecum and the sealworm Pseudoterranova decipiens were isolated from the liver and the body cavity of fish affected. Only two specimens of P. decipiens (1.4%) partly invaded the belly flaps. The following fish species were infested by P. decipiens at the given prevalences: Cygnodraco mawsoni (74.4%), Trematomus scotti (23.2%), Pagetopsis maculatus (10.0%), Cryodraco antarcticus (7.1%), Trematomus lepidorhinus (3.0%), and Dolloidraco longedorsalis (2.7%). All of these, except Trematomus scotti, are new host records. Chaenodraco wilsoni, Chionodraco myersi, Gerlachea australis, Racovitzia glacialis and T. eulepidotus were not infested. The reasons for low prevalence and intensity of infestation are seen in the difficulties of P. decipiens in completing its benthic life cycle in the Weddell Sea environment, in the absence of shallow coastal waters due to the floating shelf-ice. Cygnodraco mawsoni is a crucial intermediate host, without which completion of the parasite life cycle might not be possible. In order to clarify the taxonomical position of Antarctic Pseudoterranova, morphological comparisons with specimens of P. decipiens from the German and Norwegian coast were made using scanning electron microscopy. Results revealed no differences; hence, all specimens studied belong to the same species P. decipiens.

Description: Coupling of physical, biological and chemical processes associated with particle resuspension and seston flux was investigated at three sites in the North Sea with contrasting water column (mixed/stratified) and seabed (cohesive/non-cohesive) characteristics.

Description: RNA/DNA ratios in individual herring (Clupea harengus) larvae (collected from Kiel Bay, Baltic Sea, in 1989) were measured and proved suitable for determining nutritional status. Significant differences between fed and starving larvae appeared after 3 to 4 d of food deprivation in larvae older than 10 d after hatching. The RNA/DNA ratio showed an increase with age or length of the larvae and was less pronounced in starving larvae compared to fed larvae. The individual variability of RNA/DNA ratios in relation to larval length of fed larvae and of larvae deprived of food for intervals of 6 to 9 d is presented. Based on the length dependency and the individual variability found within the RNA/DNA ratios, a laboratory calibration is given to determine whether a larva caught in the field has been starving or not. An example for a field application is shown.

Description: A hierarchy of ENSO (El Niño/Southern Oscillation) prediction schemes has been developed which includes statistical schemes and physical models. The statistical models are, in general, based on advanced statistical techniques and can be classified into models which use either low-frequency variations in the atmosphere (sea level pressure or surface wind) or upper ocean heat content as predictors. The physical models consist of coupled ocean-atmosphere models of varying degrees of complexity, ranging from simplified coupled models of the lsquoshallow waterrsquo-type to coupled general circulation models. All models, statistical and physical, perform considerably better than the persistence forecast on predicting typical indices of ENSO on lead times of 6 to 12 months. The most successful prediction schemes, the fully physical coupled ocean-atmosphere models, show significant prediction abilities at lead times exceeding one year period. We therefore conclude that ENSO is predictable at least one year in advance. However, all of this applies to gross indices of ENSO such as the Southern Oscillation Index. Despite the demonstrated predictability, little is known about the predictability of specific features known to be associated with ENSO (e.g. Indian Monsoon rainfall, Southern African drought, or even off-equatorial sea surface temperature). Nor has the relative importance for prediction of different regional anomalies or different physical processes yet been established. A seasonal dependence in predictability is well established, but the processes responsible for it are not fully understood.