ALBERT

Notes: Abstract The feeding behaviour ofClupea harengus L. in the light is dependent primarily on prey concentration. In the laboratory the fish feed by biting at low prey concentrations and by filtering at high concentrations. With the brine shrimpArtemia sp. as prey, the concentration required for the onset of filter-feeding was directly dependent on prey size, but the concentration at which 50% of feeding fish were filtering differed little between three sizes of brine shrimp (nauplii, and 2 and 4 mm larvae). When fed onCalanus finmarchicus, however, 50% of fish fed by filtering at concentrations at least six times lower than on any size of brine shrimp. Filter-feeding thresholds forC. finmarchicus were six to ten times lower than for any size ofArtemia sp. and, on the basis of biomass, approximately eight times lower than for equivalent sizedArtemia sp.

Notes: A field survey of populations of goldsinny wrasse (Ctenolabms rupestris) was undertaken on selected areas of rocky coast of west Scotland. Observations by sub-aqua diving were used to determine distribution, habitat preference, and population density, and their seasonal variations. Availability of the preferred refuge type (crevices on rock faces, or between boulders, where two or more entrances exist) was essential in determining goldsinny presence. Goldsinny were not always present in areas or at depths where the influences of freshwater runoff (low temperatures and salinities) were likely, even if the preferred habitat type was available. In areas remote from these influences, and where there were suitable refuges, depth of water (0–44 m), macroalgal cover and high current speeds (2.1–3.6 ms−1) did not affect goldsinny distribution. Observed densities of goldsinny reached a peak in summer months with a maximum of 4.0 m−2 in areas of shallow boulder scree, but only 1.0 m−2 in shallow areas with little scree, or at deeper study sites. Numbers of goldsinny observed actively swimming decreased after October, with a rapid disappearance in November. A gradual reappearance was recorded in late April, and early May. Changes in activity may be influenced by both water temperature and photoperiod. Young-of-the-year goldsinny were first observed in August in shallow water (0–8 m) areas typified by rock/boulder scree and/or high macroalgal cover. Where adults also inhabited these nursery areas, 0+ fish could make up over 50% of the total population. After their first winter, juvenile goldsinny may migrate away from inshore sites.

Notes: Rates of predation on 0-group plaice, Pleuronectes platessa. in aquaria were compared under four different combinations of conditions to test the hypothesis that the presence of sand in which they may bury affords a refuge from predators. The effect of light and darkness on predation rate was also examined, Two crustaceans, the shrimp, Crangon crangon, and the portunid crab, Liocarcinus holatus, and two fishes, cod, Gadus morhua, and pollack, Pollachius pollachius, were used as predators. Predaton rates were significantly higher in the dark for all predators except pollack. Predation rates in the absence of sand were signifcantly greater only for pollack. The results suggest that predation rates on plaice during their juvenile nursery stage on sandy beaches will be significantly greater during darkness than during the day. Burying in sand appears to provide only a partial refuge from predation, perhaps because natural predators have evolved effective methods of foraging for buried prey.

Notes: Analysis of laboratory video-recordings of herring feeding by biting and filtering on Calanus finmarchicus and three sizes of Artemia enabled the capture rates of the two methods to be estimated at different prey concentrations. At low concentrations the fish feed by selective capture of individual particles, but the capture rate achievable by this method is constrained by the maximum rate at which they can bite. Filter-feeding is not subject to this constraint because capture rate is directly proportional to prey concentration and above a critical prey concentration its capture rate exceeds that of biting. The possession of two feeding methods allows the fish to maximize prey intake over a wide range of concentrations and the phenomenon of switching between feeding methods can be explained by their relative profitabilities at different concentrations. The observation that less than 50% of fish are filtering when capture rates by the two methods are equal suggests that filtering is energetically more costly than biting. Estimates of the energy cost of filtering indicated that it may be from 1.4 to 4.6 times higher than that of biting.

Notes: Lg records analysis and numerical modelling of Lg propagation are used to find out to what extent this phase can be seen as a marker of unidentified structural anomalies in the crust. This study is based on Lg propagation through the Pyrenean range from earthquakes located in Spain.We have first evaluated the mean value of the S-wave quality factor for central Spain. We have computed simultaneously the seismic station responses and the source functions. The correction for propagation effects, assuming a homogeneous attenuation and the theoretical calculation of the Lg excitation, lead to the seismic moment of each event. The moment magnitude obtained correlates well with the magnitude proposed by the local networks. This gives a confirmation of the Q model in the low-frequency range (1-5 Hz). As we intended to compare traces of different Spanish earthquakes recorded in France at different epicentral distances, we had to make amplitudes independent of propagation and source effects. Therefore, we corrected the spectral amplitudes for geometrical spreading, anelastic attenuation and normalized them to equal seismic moment.We then plotted the records as a function of group velocity, in order to make up a fan profile along the Pyrenean axis. The resulting section reveals that in the central and the eastern parts of the range, neither the North Pyrenean Fault, nor the Moho jump deduced from seismic-refraction experiments and vertical seismics, seem to affect Lg propagation. However, there is an extinction of the Lg phase in the western part of the chain. The lateral extent of this area is correlated with a zone of positive gravity anomaly, probably linked to the presence of dense material of mantle origin. A numerical simulation in the low-frequency band indicates that the Moho topography inferred from deep seismic soundings does not explain the strength of the observed attenuation. Ray-tracing seismograms show that, at high frequency, the conclusion is the same. The attenuation effect due to lateral variation of structure should not be so strong. We, therefore, think that attenuation of guided waves is not due to large-scale geometry effects, but is due to local properties of the crustal materials, possibly apparent attenuation due to scattering on small-scale heterogeneities.

Notes: The sequence of growth of garnet, staurolite and aluminosilicate in Fe-rich metapelitic rocks from the Canigou massif, Pyrenees, is established using evidence of inclusion, reaction and pseudomorphing textures between the different minerals, compositional zoning patterns in garnet and staurolite (that can be related to the KFMASH reaction grid), and the geometric relations between inclusion trails in the porphyroblasts and the matrix microstructures. The evidence indicates that garnet and staurolite commenced growth before aluminosilicate in all cases, even where all three are in textural equilibrium. Interpretation of the reaction textures between the porphyroblasts and of the compositional zoning in garnet and staurolite in terms of the KFMASH reaction grid indicates the importance of continuous reactions in the development of these phases. Some garnet and staurolite porphyroblasts underwent renewed growth during breakdown, producing rims enriched in Mn and Zn respectively. The presence of aluminosilicate in these assemblages (i.e. the absence of a clear andalusite-absent zone in the field) is attributed to a strong pressure-dependence for the aluminosilicate-producing reactions. Porphyroblast-matrix microstructural relations indicate that Hercynian metamorphism in the massif was synchronous with the development of the regional subhorizontal foliation (S3).

Notes: The ability of juvenile plaice (18–190 mm) to bury in sands varying in grain size from 0.062–2 mm was examined. For fish greater than approximately 30 mm in length the relationship between the proportion of the body covered with sand (C), total length (L, mm) and grain size (S, mm) can be estimated from the equation: logit C= 3.250 + 0.069L– 6.771S. Based on their performance in coarser sediments, fish smaller than approximately 30 mm did not bury as well as expected in the finest sediments (0.062 and 0.125 mm).

Notes: Food consumption, gut transit times and assimilation efficiencies of the temperate fishes Lipophrys pholis and Parablennius sanguinolentus (Blenniidae) and Gobius cobitis (Gobiidae. when fed the green alga Ulva lactuca were determined at four temperatures in the laboratory. Food consumption increased and gut transit times decreased with increase in temperature in all three species. Assimilation efficiencies for algal carbon and nitrogen did not vary with temperature in G. cobitis. Carbon but not nitrogen assimilation efficiency varied with temperature in P. sanguinolentus, and both carbon and nitrogen assimilation efficiencies changed broadly with temperature in L. pholis, the most omnivorous of the three fishes. Assimilation efficiencies of all three species were generally within the previously reported ranges for herbivorous marine fishes. These species are thus clearly capable of extracting energy from algal food sources.

Notes: Summary A commercially available mouse monoclonal antibody to human platelet glycoprotein IIIa was used to demonstrate sequestration of platelets in hepatic biopsies obtained from baboons following intravenous infusion of echistatin, a novel fibrinogen receptor antagonist derived from the venom of the snake Echis carinatus. Biopsies of liver and spleen were taken prior to administration of echistatin. The hepatic biopsies were either snap-frozen in Freon-22/liquid nitrogen or fixed in 10% neutral buffered formalin. Biopsies of spleen were snapfrozen. During infusion of echistatin (2.3 µg/kg/min), circulating platelet counts decreased from 331000/mm3 to 167000/mm3. Selective sequestration within the liver was confirmed using whole body gamma camera imaging to demonstrate 111Indium-oxine labeled platelet accumulation within the liver during the thrombocytopenic episode. Hepatic biopsies were again taken and either snap-frozen in Freon-22/liquid nitrogen or fixed in 10% neutral buffered formalin. Biopsies of spleen and inguinal lymph node were also snap-frozen. Platelet rich plasma smears, included as positive controls, dewaxed paraffin sections, and cryosections of liver, spleen, and lymph node were stained with monoclonal mouse anti-human platelet glycoprotein IIIa using an avidin biotinylated peroxidase complex (ABC) technique. Prior to infusion of echistatin, platelet staining within the liver was minimal. After echistatin infusion, hepatic cryosections showed prominent platelet staining within hepatic sinusoids. No localization was shown in lymph node, however, the spleen showed prominent platelet staining both before and after echistatin infusion. Platelet rich plasma smears were intensely positive. No prominent platelet staining was observed in formalin-fixed, paraffin-embedded material. Thus, this immunocytochemical technique may help localize platelets in cryosections of tissues from baboons and other primate species.

Notes: Summary Fluvial salmonids have evolved to use the diversity of habitats in natural streams for different life history stages and at different seasons. Required freshwater habitat of Atlantic salmon can be classified generally as that suitable (i) for spawning, (ii) for feeding during the major growing period, and (iii) for overwintering. Spawning habitat of salmon is usually in rapid water at the tail of pools on the upstream edge of a gravel bar, ideally with depths about 25 cm, in mean water velocities of about 30–45 cm s-1, with maximum velocities about 2 body lengths s-1, and with a substrate of irregularly shaped stones of cobble, pebble, and gravel. Underyearling salmon (〈7 cm TL) are most common in shallow (〈15 cm) pebbly riffles, whereas older and larger parr (〉7 cm TL) are usually in riffles deeper than 20 cm with a coarse substrate. Depth preference increases with size. Multiple linear regression models quantifying parr habitat have identified substrate as an important variable, with a positive relationship to an index of coarseness. Negative relationships were found with mean stream width, range of discharge, and overhanging cover. Water chemistry, especially alkalinity, nitrates, and phosphates, are important regulators of production. Although similar variables had importance, coefficients among rivers differed. Interactions occur among variables. Further studies are required to quantify productive capacity of habitat for parr. Results suggest that useful models can be derived and if a river system is mapped, and stratified by habitat, then smolt yield could be predicted and the required egg deposition could be estimated. In winter, young salmon shelter among coarse substrate or move to pools, but continue feeding, with larger parr being more active. Feeding is in general opportunistic. Food consists mainly of insects, taken primarily in the water column, but also from the surface and at the bottom. Young salmon in flowing water are highly territorial but are less so in slow or still waters. In fast water, parr use their large pectoral fins to apply themselves to the substrate, allowing them to occupy this type of habitat with little expenditure of energy. Height above the substrate decreases with water velocity, but increases with temperature and social status. Although riffles are preferred habitat, and are relatively more productive, lentic waters can be occupied where there are few predators or severe competitors and may provide significant smolt yield in some systems. Selective segregation minimizes competition between salmon and brook charr or brown trout, but brook charr and brown trout may have negative effects on underyearling salmon, and on parr in pools, whereas salmon have negative effects on small brook charr and brown trout in riffles and flats. Competition by both interference and exploitation results in interactive segregation when the resource, mainly food, becomes limiting. Limited downstream movement of underyearling salmon may occur during the summer. Older juveniles may make upstream movements, but generally migrate downstream, with most movements in the spring, and a lesser peak of activity in the autumn. Dispersal tends to be mainly downstream, indicating that for full distribution, spawning areas are best located upstream. High densities of yearling parr may have negative effects on growth and survival of underyearlings in some river systems, but apparently not in others, so that future research is required in this regard. Density-dependent growth is evident where food is limiting, and can provide an indicator of densities of cohorts so that if a quantitative relationship has been derived, mean size from a sample can give an estimate of the density at that station, with minimum size occurring at carrying capacity. Such regressions vary between habitats with differing productive capabilities, so that future research could provide useful models for assessing productive capacity of a habitat, and optimum densities. Life history strategies can change with changes in density-dependent growth rates. Present stock-recruitment functions do not take environmental variables into consideration, and have limited applicability. Further research is required to determine optimum spawning requirements for salmon in different types of river systems in different geographical areas.