Digestive carbohydrases from the hepatopancreas of two Antarctic euphausiid species (Euphausia superba and E. crystallorophias)

The hepatopancreatic extracts of Euphausia superba Dana and E. crystallorophias Holt and Tattersall collected from the Antarctic. Ocean during January 1985, are most effective in hydrolysing substrates containing (13)--glucosidic linkages. Three enzymes appear to be involved in the depolymerization of (13)--D-glucans in the euphausiid diet: (1) an exo-(13)--D-glucanase, (2) an endo-(13)--D-glucanase and (3) a -D-glucosidase. The glucanases have a pH optimum of 5.4, a temperature optimum of 50°C and are optimally extracted in bistripropane buffer, pH 7.2. Levels of (13)-D-glucanase in laboratory-cultured E. superba are inversely affected by food availability, and activities double after starvation for 12 d. The increase is due mainly to higher activities of exo-acting glucanases. -Amylase and endo-(14)--D-glucanase (cellulase) activity are also present in the extracts in addition to glycosidase activity against a range of p-nitrophenyl substrates (-and -D-glocose, - and -D-galactose, -D-xylose, - and -D-mannose). Digestive activity against several acidic polysaccharides, including the acidic mucilage polysaccharide of the ice diatom Stauroneis amphioxys, is minimal and is not induced when the polysaccharide is present in the diet of E. superba. These results indicate that some, but not all, components of the algal material in the euphausiid diet can be hydrolyzed and assimilated.     

Testing the ‘agonistic buffering’ hypothesis

Summary Data are presented from a 15-month study on triadic male-infant interactions (agonistic buffering) among wild Barbary macaques, and the agonistic buffering hypothesis reevaluated. The sociometrics of triadic interactions derived from the distribution of 535 interactions among individually known adult and subadult males showed that there were significant individual male differences in the frequency of initating and/or receiving triadic interactions, but there were no such differences between the high and low ranking male subgroups (Tables 2–4).Males did not choose each other equally for triadic encounters. Each male had a different set of three other males (out of 11 possible) that he preferred to approach for a triadic encounter; and each male received triadic approaches essentially from only three males (Tables 4 and 5). Each male showed a specific preference for which infant to select for participation in the triad, and in fact, males who preferred one another for triads also preferred to use the same infant in these encounters. These males that preferred each other and the same infant both had a special care-taking relationship with that preferred infant (Tables 6–7).Possessing an infant per se seemed to be irrelevant in whether a male would approach or be approached for a triad. In 78% of all triads, males separated immediately after termination of the triad. When the agonistic buffering hypothesis is reexamined against the data in this study, it appears that it cannot adequately accommodate the thesis that it serves to regulate dominant/subordinate relations among males. Rather males choose to participate with each other in agonistic buffering because, and by means of, a shared, common, and special care-taking relationship with the same infant. The indiscriminate use of the terminology agonistic buffering to describe multiple-male/infant interactions in this species should be dropped.     

Alternative mating tactics and the law of Diminishing Returns: The Satellite Threshold Model

Summary The mating systems of many species comprise at least 2 alternative male mating tactics — broadly termed Dominant and Satellite tactics here. But, there exists no satisfactory conceptual framework in which to explain their co-occurrence and persistence.A Dominant male's ability to copulate is a positive, but decelerating, function of either his territory's attractiveness or his own attractiveness to females. This Diminishing Returns Effect affords mating opportunities for Satellite males associated with the most attractive sites (or males). A graphical Satellite Threshold Model, analogous to the Polygyny Threshold Model (Orians 1969), is developed to predict quantitatively the presence or absence of Satellite male tactics.Five predictions of the Model are supported quantitatively by data from dragonfly and anuran social systems and, more generally, by evidence from a wide variety of species.The Model should apply both to circumstances in which males are able to alternate between tactics and the instances in which males make an irrevocable tactical decision.     

Sample support and related scale issues in composite sampling

Composite sampling offers the great promise of efficiency and economy in environmental decision making. However, if careful attention is not paid to matching the support of the sample to that required for making the desired decision, the promise is unfulfilled. Obviously this attention must be applied in the design phase of a composite sampling strategy. Less obvious is the potential for alteration of the design sample support during sample collection and assay. The consequences of not paying attention to these aspects of sample design and assay are discussed in this issue paper illustrated with a series of examples taken from the authors consulting experience.     

High turnover of inorganic carbon in kelp habitats as a cause of δ13C variability in marine food webs

In a study to assess qualitatively the importance of organic matter derived from kelp production in the Aleutian Islands of subarctic Alaka, replicated samples of autotrophic sources and primary and secondary consumer organisms were sampled for ¹³C among sources, sites, (treatment) islands, and years. Unanticipated variation in the ¹³C of kelps occurred among overtly similar sites at different islands. Variation in the ¹³C of the surface canopy-forming kelp Alaria fistulosa was particularly extreme, ranging from-15.5 to-28.0 compared to the understory kelps, Laminaria spp. A. fistulosa ¹³C varied by as much as 6 to 7 among similar sites at a given island within years, and by as much as 3 to 4 between years at the same sampling site. In serveral cases, ¹³C variation was weakly tracked by some consumer organisms, suggesting that even detritus pathways through the food web can be localized and tightly coupled. Dynamic cycles in the concentration and ¹³C of dissolved inorganic carbon (DIC) and aqueous CO₂ concentration ([CO₂]_aq) were measured at three sites on one island. The ¹³C or organic carbon fixed by A. fistulosa, calculated from diurnal DIC concentration and ¹³C measurements, varied by 15 and varied inversely with [CO₂]_aq concentrations. Local DIC variability, probably resulting from high productivity and decreased turbulence in dense kelp habitats, provides a possible mechanism of variation in kelp ¹³C. The short-term variability in the ¹³C of organic carbon fixed by kelps indicates that sampling methodology and design must assess this potential variation in marine macrophyte ¹³C before making assumptions about the transfer of ¹³C-invariate organic matter to higher trophic levels. On the positive side, a predictable relationship between [CO₂]_aq concentration and kelp ¹³C offers a potentially robust means to assess productivity effects on CO₂ limination in kelps and other complex aquatic macrophyte habitats.     

An advantage to mate choice in the seaweed fly,Coelopa frigida

Summary All natural populations studied of the seaweed fly, Coelopa frigida, are polymorphic for the inversion system on chromosome I. It has previously been shown that heterokaryotypes have superior egg-to-adult survival than either homokaryotype, and that there is non-random mating with respect to inversion genotypes. We have inquired whether the production of fitter progeny in larger numbers is the possible reason for the existence of non-random mating behaviour. We measured the fertility, fecundity and progeny survival of adults that have either been allowed to exercise mate preference, or been given a single, randomly chosen, mate. The fertility (% of females producing progeny) and progeny survival (% of larvae surviving to the late 3rd instar stage) are both significantly greater in choice than nochoice females. There are also significant differences in fertility and progeny survival depending on whether the parents were of similar or dissimilar inversion genotypes. An effect of relative adult size on fertility was also observed. There appear to be no effects of mate choice on fecundity. Indirect evidence is presented that adults are choosing their mates not only on the basis of genotypes but on other criteria as well. It is suggested that the superior reproductive performance of animals allowed a choice of mates may account for the evolutionary origin and continued existence of mate discrimination. Furthermore, since over 25% of the genome of Coelopa is located within inversions, the observed pattern of negative assortative mating may maintain a substantial fraction of the genes in a polymorphic state.     

Dependence of consumers on macroalgal (Laminaria solidungula) carbon in an arctic kelp community: δ13C evidence

Stable carbon isotope measurements (¹³C) were used to assess the importance of kelp carbon (-13.6 to-16.5) versus phytoplankton carbon (-25.5 to-26.5) to resident fauna of an isolated kelp bed community on Alaska's north arctic coast from 1979 to 1983. The predominant kelp, Laminaria solidungula, showed some seasonal variation in ¹³C which was correlated with changes in the carbon content of the tissue. Animals that showed the greatest assimilation of kelp carbon (>=50%) included macroalgal herbivores (gastropods and chitons,-16.9 to-18.2), a nonselective suspension feeder (an ascidian,-19.0) and a predatory gastropod (-17.6). Animals that showed the least incorporation of kelp carbon into body tissues (<=7%) included selective suspension-feeders (hydroids, soft corals and bryozoans,-22.8 to-25.1). Sponges, and polychaete, gastropod and crustacean omnivores exhibited an intermediate dependence on kelp carbon (15 to 40%). Within some taxonomic groups, species exhibited a broad range in isotopic composition which was related to differences in feeding strategies. In the polychaete group alone, ¹³C values identified four major feeding habits: deposit-feeders (-18.0), omnivores (-20.4), predators (-22.2) and microalgal herbivores (-23.0). Distinct seasonal changes in the ¹³C values of several animals indicated an increased dependence on kelp carbon during the dark winter period when phytoplankton were absent. Up to 50% of the body carbon of mysid crustaceans, which are key prey species for birds, fishes and marine mammals, was composed of carbon derived from kelp detritus during the ice-covered period.     

Temporal variation and distribution of trace metals in freshwater and fish from Calabar River, S.E. Nigeria

An investigation on the abundance and distribution of trace metals (Fe, Cu, Zn, Mn, Cr, Cd and Pb) in water, and nine species of fish samples from Calabar river was carried out in 1992. The concentrations of iron (6000–7240gl^–1), zinc (4910–7230gl^–1), and cadmium (3–7gl^–1) showed moderate pollution while those of copper (420–630gl^–1), manganese (23–48gl^–1), chromium (<10–20gl^–1) and lead (<1–10gl^–1) in water were well below WHO permissible levels. Significant seasonal changes (0.001p0.25) were obtained for iron, copper, zinc, manganese and cadmium in water. Furthermore, iron, zinc and cadmium showed statistically significant spatial changes (0.005p0.10). Of the nine fish species studied, no statistically significant relationship between body weight and the concentrations of the metals was observed. The concentrations of the metals per mean total body weight apparently decreases in the order Fe>Zn>Cu>Mn>Pb>Cd=Cr and were within the limits that were safe for consumption.     

Aqua regia extractable trace elements in surface soils of venezuela

Surface soils (0–15 cm) were sampled at 10–20 km intervals along two transects in Venezuela. One (1162 km, 70 samples) ran west to east parallel with the Caribbean coastline, the other (920 km, 92 samples) ran south to north from the frontier with Brazil to the Caribbean shore. Sampling took place in both a wet and a dry season. Trace metals were extracted from dried, sieved (<2 mm) soil with boiling aqua regia followed by analysis by ICP or flame AAS. Metal values did not differ significantly between the two seasons and dates were averaged. Geometric mean values for the west–east transect were: Cr=41.5, Cu 17.9, Cs 3.6, Li=13.9, Mn=294, Ni=21.3, Pb=17.4, Sr=39.4, V=60.4 and Zn = 83.7g g^–1, respectively. Similarly, for the south–north transect Cr=21.3, Cu=4.3, Cs=1.1, Li=2.0, Mn=55.7, Ni=4.4, Pb=6.1, Sr=13.3, V=28.2 and Zn=16.7g g^–1, respectively. A classification of samples by lithology showed surface soil composition to be related to rock composition. Metal values were low in the soils in the south of the country, in the Guyana highlands (Gran Sabana). Low Zn contents were prevalent. Lead contents were affected by roadside fallout from vehicles using leaded petrol except that high Pb contents of soils in the Gran Sabana were of more complex origin.     

Seasonal variation of total dissolved arsenic and arsenic speciation in a polluted surface waterway

Seasonal differences in the dissolved arsenic concentration and speciation in a contaminated urban waterway in northwest England have been determined using a coupled ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS) technique. Waters sampled in the vicinity of an industrial works during relatively dry conditions in April 2000 were found to contain total arsenic concentrations (As) of up to 132 g L^–1, more than an order magnitude greater than the 4 g L^–1 maximum found in December 2000. The difference in As between the April and December sampling periods is speculated to be largely due to the irregular anthropogenic supply of arsenic to the watercourse. For both sampling periods, the dissolved arsenic was exclusively inorganic in nature and had an As(V)/As ratio of between 0.6 and 0.8. Analysis of samples taken downstream of the industrial site, after the confluence with a relatively As-poor stream, revealed that As(III), As(V) and As concentrations were lower than would be expected from conservative mixing. The As(V)/As ratio was also observed to decrease markedly. The loss of arsenic from solution is thought to be due to adsorption on the iron oxyhydroxide-rich sediment observed to coat the riverbed downstream of the confluence. The reduction in the As(V)/As ratio is believed to be due to the more rapid adsorption of As(V) compared to that of As(III). Deviations from conservative behaviour were more marked during the relatively dry April 2000 sampling period and suggest the increased importance of adsorption processes controlling arsenic availability during this time.     

The role of male vs male interactions in maintaining population dialect structure

Summary Nonmigratory populations of Whitecrowned Sparrows in coastal California exhibit dialects in territorial male songs that are stable in space and time. By field playback experiments, we tested a prediction from the hypothesis that male aggressive interactions prohibit mixing of song dialects. Playback of the home dialect Clear song to territorial males singing the Clear dialect resulted in less response than that given to playback of the neighboring Buzzy dialect. Response to both Buzzy and Clear dialect songs by target Clear males, however, was greater than that given to the Bodega dialect recorded 55 km away (Figs. 2 and 3). We conclude that these results are consistent with the hypothesis that male-male aggressive interactions play an important role in reducing dialect mixing.     

Geochemical Characteristics of the Acid Mine Drainage in the Water System in the Vicinity of the Dogye Coal Mine in Korea

This study investigated geochemical characteristics of the acid mine drainage (AMD) discharged from the abandoned mine adits in the vicinity of the Dogye coal mine in Korea. Acid mine drainage discharged from Jeoncha pit adit of the Dogye coal mine, which is the main source of the AMD in the study area, had a pH value of 3.0 and concentrations of 2148mg SO₄ ^2– L^–1, 229mg Fe L^–1, 71mg A1 L^–1 and 11mg Mn L^–1. The reduction of some metal concentrations downstream from the discharge point could be explained on the basis of dilution and precipitation. The order of removal of metal ions downstream from the discharge point was Fe>A1, Cu>Zn, Mn. Acidity could be used as a good determining factor offering comprehensive and quantitative values for the polluting extent of acid mine drainage. The acidities existing in all acidic water samples in the Gunahan district originated primarily from mineral acidity, especially in the upper Nahan Creek from dissolved Fe and Al and in the middle and down Nahan Creek from dissolved Al. From the application of the WATEQ4F program, it was determined that predominant species of dissolved Fe in all water samples was Fe²⁺, and those of dissolved Al were AlSO₄ ⁺ and Al³⁺ except for IW2 sample which was associated with white precipitates. The species of dissolved Al in IW2 sample include also AlOH²⁺ and Al(OH)₂ ⁺. The saturation indices of goethite and haematite were positive in the water samples associated with ochrous precipitates (usually called Yellow Boy), therefore these solids might be precipitated. For the IW2 sample, the saturation indices of amorphous Al(OH)₃ and gibbsite were positive, so theoretically these solids might also be precipitated. By XRD analysis, it was found that goethite occurs in ochrous precipitates, and gibbsite in white precipitates.     

Populational distribution I: The digital simulation

This paper presents a method of investigating the distributional pattern of a biological population, using a technique of simulation. The method consists of the comparison of the empirical frequency curve of a population, obtained using the Method of Quadrats, with a simulated one, since the pattern of the simulated curve depends on the simulated distribution. An example is given.     

The evolution of cheating and selfish behavior

Summary We examine the necessary conditions for the spread of genes that determine selfish and cheating behaviors and the rate of spread of these genes through structured populations, in order to address the question of the invadability of altruistic systems by anti-social mutations. We find that, although cheaters always have a higher relative fitness than altruists within groups, population structures which permit the evolution of altruism also preclude invasion by anti-social mutations. These results are related to a discussion by Hamilton (1971) concerning the limits to the evolution of altruistic and selfish behaviors.     

Studies on the nutrition of marine flatfish. The effect of dietary fatty acids on the tissue fatty-acids of the plaice Pleuronectes platessa

The ratios of polyunsaturated fatty acids in the lipids of hatchery-reared plaice [Pleuronectes platessa (L.)] maintained on a diet containing corn oil and freeze-dried cod muscle accurately reflect ratios of polyunsaturated fatty acids in the diet. Such plaice have much greater levels of triglycerides in both their livers and extrahepatic tissues than wild plaice of comparable size; the total amount of 22:6 3 acid in triglycerides of the two groups is, however, very similar. Transfer of experimental plaice to a fat-free diet caused a marked depletion of triglycerides from both livers and extrahepatic tissues with almost all fatty acids being reduced in amount. Addition of 12:0 and 14:0 ethyl esters (4% of each) to the fat-free diet caused some accumulation of triglycerides in extrahepatic tissues. Further addition of 18:2 6 and 18:3 3 acids (both at levels of 0.4%) to the diet caused an accumulation of triglycerides in the liver. These triglycerides had increased levels of saturated and monounsaturated fatty acids up to C 18 but the levels of higher polyunsaturated fatty acids were not inereased. There was relatively little change in the fatty acids of phospholipids throughout these experimental dietary regimes. The levels of phospholipids were constant and very similar to those of wild plaice. The results indicate: (1) plaice fed a diet relatively low in 22:6 3 acid may accumulate relatively large amounts of triglyceride in order to store adequate amounts of 22:6 3 acid; (2) plaice are capable of synthesising saturated and mono-unsaturated fatty acids up to C 18 in the presence of dietary 12:0 and 14:0 acids; (3) 18:2 6 and 18:3 3 acids in the diet do not undergo chain elongation and further desaturation in plaice with the dietary regimes we used.     

Lead-based paint in dwellings: The potential for contamination of the home environment during renovation

The quantity and particle size characteristics of lead in dust released during three different paint removal techniques was determined under controlled conditions and in situ in a dwelling. Air-lead and deposited dust-lead levels were highest after sanding but burning-off and hot-air removal methods also produced significant contamination. The importance of dust particle-size and lead is discussed in relation to the potential hazard to home renovators via inhalation and to children via the hand-to-mouth route.This paper is also being published in Proceedings of the Conference on Lead in the Home Environment and is one of several selected from SEGH sponsored conferences for simultaneous publication in this journal.     

Residues of Organochlorinated Pesticides in Eggs of Water Birds from Tai Lake in China

The levels of organochlorine compounds in eggs of water birds from the colony on Tai Lake in China were studied. The eggs were collected in 2000 and belonged to the following species: 65 samples of black-crowned night heron (Nycticorax nycticorax), 36 samples of little egret (Egretta garzetta), 26 samples of cattle egret (Bubulcus ibis) from 13 clutches and 43 samples of Chinese pond heron (Ardeola bacchus) from 17 clutches. Dichlorodiphenyltrichloroethane (DDT) and its derivates (DDE and DDD), hexachlorocyclohexane (HCH) and its isomers (-HCH, -HCH, -HCH, -HCH), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, -endosulfan, -endosulfan, and endosulfan sulfate were determined in the laboratory by gas chromatography. The data showed that DDE had the highest levels in all the samples, followed by -HCH. The mean levels of DDE among the water bird species were in the order as follows: black-crowned night heron (5464.26ng/g, dry weight) > Chinese pond heron (2791.12ng/g, dry weight) > little egret (1979.97ng/g, dry weight) > cattle egret (660.11ng/g, dry weight). DDT and its metabolites accounted for 90% of the total organochlorines, except that it was only 73% for cattle egret. The differences of the residue among the bird species were statistically significant and could be attributed to their variations in prey and habitat. Although the DDE burdens in Tai Lake were much lower than 8 g/g (wet weight) which are thought to have significant adverse effects on black-crowned night herons, they would be expected to increase the risk of adverse effects on survival of chicks of herons and egrets, particularly black-crowned night heron, based on the critical value of 1 g/g (wet weight) DDE. The burdens of HCHs in this study were higher and the cyclodienes were lower than those found elsewhere.     

Effects of monospecific algal diets of varying biochemical composition on the growth and survival of Pacific oyster (Crassostrea gigas) larvae

Using monospecific diets of Thalassiosira pseudonana cells grown under different steady-state conditions, it was determined that higher growth rates of larval Crassostrea gigas Thunberg were obtained when fed T. pseudonana cells grown under high light. High light grown T. pseudonana cells consistently contained relatively more of the saturated fatty acids 14:0 and 16:0. Considered over three independent experiments, high light grown T. pseudonana cells were lower in protein and higher in carbohydrate than low light grown cells. Higher growth rates of larval C. gigas were obtained on diets with more of the essential fatty acid (EFA) 22:63, and less of the other EFA, 20:53. The relative requirements of C. gigas larvae for the essential fatty acids 20:53 and 22:63 are discussed. Faster growing larvae contained higher percentages of the fatty acids 14:0 and 16:0, and lower percentages of 22:2j. Oyster growth rates were correlated with their content of the fatty acids: 14:0, 16:0 and 22:2j in two experiments utilizing separately spawned batches of larvae. Fatty acid profiles are proposed as a technique for assessing larval condition. C. gigas larvae contained ten times the percent composition of the FAs 16:43, 18:17, 20:17 and 22:2j compared with their diet. Correlation analysis suggests that the dietary source of 18:17, 20:17 and 22:2j was 16:17. It is concluded that T. pseudonana cells grown under high light are a superior diet for C. gigas larvae in comparison with low light grown cells of the same species.     

Transformation of progesterone by marine bacteria

The progesterone transforming ability of marine bacteria has been determined. 20 of the 53 marine cultures tested were found capable of transforming progesterone to 6-hydroxyprogesterone and/or to 11,17-dihydroxyprogesterone.     

Song as an attractant for male and female European starlings,and the influence of song complexity on their response

Summary We tested the hypothesis that song attracts females and repels males in the European starling. We broadcast recorded song from speakers attached to nestboxes, while paired boxes with silent speakers served as controls. As predicted, females were attracted to the song boxes. Contrary to prediction, males were also attracted to the `song' boxes. Singing by male starlings may be costly because it attracts competitors for limited nesting sites, but the cost cannot be avoided due to the need to attract a mate. In a second experiment simple song (composed of 20 different phrase types) and complex song (40 phrase types) were played simultaneously. More males were captured at boxes where simple song was played. Song complexity may function as an indicator of male quality and be used by male starlings to assess potential competitors.