Public perception of air pollution sources across Europe

Air pollution is one of the primary concerns of our society for its effect on human health and the environment. Among the policy measures that can be put in place to limit air pollutant emissions, end-of-pipe technologies and/or regulatory instruments may be implemented through legislative acts. Also, equally important are behavioural measures, requiring citizens’ active involvement. The success of any measure to limit pollutant emissions requires the acceptance by the citizens that, in turn, implies a correct perception of the main pollutant emission drivers. We present here the comparison between the public perception of air pollution sources and the real-world situation through a survey carried out in seven European countries and involving 16 101 respondents. Our study shows a dramatic underestimation of the contribution of the agri-food sector to air pollution. This result is common to all respondents in the seven countries examined and only to a small extent depends on gender, age and socio-economic status of the respondents.     

Variation in the trophic structure and species composition of some invertebrate communities in polluted kelp forests in the North Sea

The absence of species from kelp holdfast habitats is used to establish changes in invertebrate community structure in polluted coastal waters along the shores of North Eastern Britain. The study shows the following changes: (1) Approximately 45% of the species complement studied in clean-water habitats are missing from polluted habitats. (2) Rare species are lost and food chains are missing. (3) Dislocations of the marine food web occur: removal of parts of the primary producer to herbivore food chain; suppression of some carnivores; removal of some omnivores and selection of certain suspension feeders. (4) No new species appear in polluted communities. (5) Recombinations of resistant species compensate for the reduction in energy flow through a damaged food web by proportionally increasing the suspension-feeding pathways. (6) The ecological equilibrium of the suspension-feeding groups which are responsible for maintaining the damaged food web are in a delicate state of balance. The further loss of 1 large food chain could result in the collapse of the remaining fragments of a polluted-water invertebrate community food web.     

Advanced age for sexual maturity in the ocean quahog Arctica islandica (Mollusca: Bivalvia)

A study of gonadal state in 39 small specimens of Arctica islandica Linné collected in April 1976 from the Middle Atlantic shelf of North America suggests that sexual maturity is reached at a later age than has been reported for other shelf bivalves. Eight of the specimens had gonads in the undifferentiated state. On the basis of annual internal growth banding in the shells of these immature specimens, age ranged between 4 and 14 years. Average age was 9.38 years (standard deviation, s,= 3.54). Shell length ranged from 24 to 47 mm (average 38.85 mm, s=9.25). Differentiated gonads were found in specimens as young as 6 years. Age of maturity shows a wide range and may be dependent upon growth rate and locality.     

Trophic relations of the cephalopod Martialia hyadesi (Teuthoidea: Ommastrephidae) at the Antarctic Polar Front,Scotia Sea

Samples of the squid Martialia hyadesi were collected aboard two Japanese squid-jigging vessels carrying out commercial fishing trials at the Antarctic Polar Frontal Zone, north Scotia Sea, in February 1989. The dissected stomachs of 61 specimens were classified according to fullness and the contents were examined visually. Identifiable food items included fish sagittal otoliths, crustacean eyes, the lappets on euphausiid first antennule segments and cephalopod sucker rings. The most frequent items in the squid's diet were the myctophid fishes Krefftichthys anderssoni and Electrona carlsbergi, the euphausiid Euphausia superba and a hyperiid amphipod, probably Themisto gaudichaudi. A small proportion of the sample had been feeding cannibalistically. Total lengths of the fish prey were estimated from sagittal otolith size using published relationships. All fish were relatively small; 7 to 35% of squid mantle-length. However, it is possible that some heads of larger fish are discarded by the squid and so are not represented by otoliths in the stomach contents. Over the size range of squid in the sample there was no relationship between size of fish prey and size of squid. Similarly, when the squid sample was divided into groups according to prey categories: crustaceans, crustaceans+fish, fish, cephalopod, there was no evidence that dietary preference was related to squid size. The prevalence of copepod-feeding myctophids in the diet of this squid, which is itself a major prey item of some higher predators in the Scotia Sea, suggests that a previously unrecognised food chain: copepod-myctophid-M. hyadesi-higher predator, may be an important component of the Antarctic oceanic ecosystem.     

Comparisons among species ofAlexandrium (Dinophyceae) grown in nitrogen- or phosphorus-limiting batch culture

Three species of the dinoflagellate genusAlexandrium (Halim)-two strains of toxic.A. minutum, one each of nontoxicA. tamarense andA. affini-were grown in batch culture in either a low-nitrogen or a low-phosphate medium. Maximum carbon-specific growth rates forA. tamarense were lower (at <0.25 d^-1) than for the other strains, which all exceeded 0.38 d^-1. C-quotas (C content per cell) during exponential growth were similar for all strains (2.5 ng C cell^-1), with cells becoming smaller during the N-limiting stationary phase, but enlarging during prolonged P-deprivation. Values of ¹³C during the exponential phase were low (-25to-30), with most cells during the light phase swimming at the surface when nutrient-replete and migrating to the bottom of the flasks when nutrient-deplete with ¹³C rising to around-15. Biomass could not be estimated reliably from pigmentation, but could be estimated from biovolume (r>0.95), although this was complicated in cultures ofA. minutum by the presence of particles comprized of thecal plates of a similar size to intact cells. Alkaline phosphatase activity was not a reliable indicator a P-status. The most toxic strain tested (A. minutum AL1V) contained the highest concentrations of free amino acids, of arginine (a precursor of paralytic shellfish toxins) and of proline, and also had the lowest C:N mass ratio (at 4.3).A. affini contained the lowest concentrations of arginine, andA. tamarense the highest exponential phase C:N (7.8). For all strains, the mole ratio of intracellular glutamine: glutamate (Gln: Glu, which was abnormally high compared to other algae) could only be used to indicate the presence or absence of N-stress rather than the degree of stress. Additions of ammonium and phosphate resulted in increases in Gln: Glu within 20 min in N-stressed cells and also enhanced toxin content inA. minutum (mainly gonyautoxin) 4 over a 24 h period.     

Quantitative genetic analysis of growth in larval scallops (Placopecten magellanicus)

We estimated the broad-sense heritability of larval size in 20 full-sib families of the giant scallop, Placopecten magellanicus (Gmelin, 1791) grown in laboratory culture in August and September 1991. The goal was to compare scallops with other bivalves which have been shown to have significant heritabilities for larval growth. Secondly, we estimated the lipid content of occytes from female parents, since this is hypothesized to affect larval growth and survival. Finally, we estimated the among-family variation in mortality from 4 to 21 d as a test of possible genetic variation for viability among larval scallops. Significant genetic variation (h²=1.10 to 1.24) was estimated for larval shell length at 4, 14, and 21 d. There was a significant correlation (r=0.66) between larval size at 4 d and lipid content of oocytes, but only when two females with high levels of lipid oocyte^–1 were excluded as outliers. There was no correlation between larval size at 14 and 21 d and lipid content of oocytes. Mortality among families from 4 to 21 d was high (69 to 97%), and was significantly different among families. These results indicate that there is significant heritability for larval growth which is largely independent of the lipid content of the oocytes. A high heritability for larval growth may indicate that this trait is only weakly correlated with fitness.     

Movements of albacore tuna (Thunnus alalunga) in the South Pacific: Evidence from parasites

Parasites were collected from over 400 albacore (Thunnus alalunga) caught by surface trolling and longlining in the south-west Pacific between 1985 and 1988. Parasites found included 1 apicomplexan, 3 nematode species, 4 cestode species, 1 acanthocephalan, 12 digenean species and 3 copepod species. Twelve of these parasite species which could be accurately recognised and counted were used in the subsequent analyses. Parasite data from albacore caught around New Zealand show a decrease in prevalence of three didymozoid parasites with increasing fish length up to a fork length of 70 to 79 cm. The subsequent increase in prevalence of these didymozoids in large longline-caught fish is consistent with fish returning from spawning in tropical waters where re-infection is presumed to occur. Albacore collected at widely separate locations in the south-west Pacific have differences in parasite prevalence, supporting an hypothesis that juvenile albacore move south to New Zealand from the tropics and do not return until the onset of sexual maturity. Albacore appear to move along the subtropical convergence zone, as indicated by a decline in prevalence and abundance ofAnisakis simplex andHepatoxylon trichiuri from New Zealand to the central South Pacific. This is supported by tagging and seasonal movements of the fishery.     

Acceptability and digestion of diets fed to larval stages ofHomarus gammarus and the role of dietary conditioning behaviour

Whilst the role of chemoreception in juvenile crustacean feeding behaviour has received considerable attention, the chemosensory responses of larval planktonic crustacean stages have been neglected. The present study investigated the acceptability of processed, microparticulate and microencapsulated diets and the possible role of chemoattractants for larval and juvenile stages ofHomarus gammarus (Linnaeus) and juvenile stages ofPalaemon elegans (Rathke). Larval and juvenile lobster were obtained from MAFF (Ministry of Agriculture, Fisheries and Food, Conwy, UK), and juvenileP. elegans were collected from the Menai Straits (Gwynedd, UK) during the summer months of 1985/1986. During the larval stages, food capture results from chance encounter, and the role of low molecular-weight chemoattractants appears to be in the determination of the edible from the inedible. Dietary conditioning behaviour in decapod larvae, which has until now not been investigated, enables the larvae to discriminate more rapidly between particles of different digestibilities. The digestibility and assimilation efficiency displayed on artificial diets in the present study suggest that lobster larvae possess limited enzymatic capabilities, although later stages are more efficient and display longer food-retention time. Growth (0.114 mm d^–1) and survival (80.0%) of lobster larvae fed natural diets were significantly better (F=14.8;P=0.001, andF=54.0,P=0.001, respectively) than of individuals fed artificial diets. Although pre-digested artificial diets (ingredients pre-treated with pancreatin) resulted in higher survival (74 and 63%) compared to microencapsulated diets (37%), there was no significant growth difference between the artificial diets tested.     

The mouthparts of the members of the Jaera albifrons group of species (Crustacea: Isopoda)

The mouthparts of Jaera albifrons Leach, Jaera ischiosetosa Forsman, Jaera praehirsuta Forsman and Jaera forsmani Bocquet were examined with the light microscope and the Stereoscan electron microscope, and were found to be identical in all species. The structure of the mouthparts indicate that all four species feed by scouring and abrading algal or bacterial films from rocks or Fucus. Food, therefore, does not seem to be an isolating factor involved in the microdistribution of the four species on a shore.