Influence of arsanilic acid,Cu<Superscript>2+</Superscript>, PO<Subscript>4</Subscript><Superscript>3–</Superscript> and their interaction on anaerobic digestion of pig manure

Arsanilic acid (ASA), copper ion (Cu²⁺) and phosphate (PO₄ ^3–) are widely used as feed additives for pigs. Most of these three supplemented feed additives were excreted in feces and urine. Anaerobic digestion is often used for the management of pig manure. However, the interaction of ASAwith Cu²⁺ or PO₄ ^3– on anaerobic digestion is still not clear. In this study, the influence of ASA, Cu²⁺, PO₄ ^3– and their interaction on anaerobic digestion of pig manure and the possible mechanisms were investigated. The initial concentrations of ASA, Cu²⁺ and PO₄ ^3– were 0.46 mM, 2 mM and 2 mM in the anaerobic digester, respectively. The methanogenesis was severely inhibited in the assays with only ASA addition, only Cu²⁺ addition and ASA + PO₄ ^3– addition with the inhibition index of 97.8%, 46.6% and 82.6%, respectively, but the methanogenesis inhibition in the assay with ASA + Cu²⁺ addition was mitigated with the inhibition index of 39.4%. PO₄ ^3– had no obvious impacts on the degradation of ASA. However, Cu²⁺ addition inhibited the degradation of ASA, and mitigated the methanogenesis inhibition. The existence of ASA would inhibit methanogenesis and generate more toxic inorganic arsenic compounds during anaerobic digestion, implying the limitation of anaerobic digestion for ASA- contaminated animal manure. However, the co-existence of ASA and Cu²⁺ could mitigate the inhibition. These results could provide useful information for the management of anaerobic digestion of pig manure containing ASA and Cu²⁺.

Open image in new window

     

Impact of solids on biphasic biodegradation of phenanthrene in the presence of hydroxypropyl-<Emphasis Type="Italic">β</Emphasis>-cyclodextrin (HPCD)

The consequence of polycyclic aromatic hydrocarbons (PAHs) in the environment is of great concern. The hydrophobic properties of PAHs significantly impact phase distribution causing limited bioavailability. Enhanced biodegradation has been extensively carried out by surfactants and the redeployment effect was recognized. However, the quantitative relationship concerning the impact of solids was rarely reported. A batch of biphasic tests were carried out by introducing Mycobacterium vanbaalenii PYR-1 and hydroxypropyl-β-cyclodextrin (HPCD) into a mixture of phenanthrene solution and various glass beads (GB37-63, GB105-125, and GB350-500). The comparative results demonstrated that HPCD had little effect on microbial growth and was not degradable by bacterium. A model was proposed to describe the biodegradation process. The regression results indicated that the partition coefficient k _d (1.234, 0.726 and 0.448 L·g^?1) and the degradation rate k (0 mmol·L^?1: 0.055, 0.094, and 0.112; 20 mmol·L^?1: 0.126, 0.141, and 0.156; 40 mmol·L^?1: 0.141, 0.156 and 0.184 d^?1) were positively and negatively correlated with the calculated total surface area (TSA) of solids, respectively. Degradation enhanced in the presence of HPCD, and the enhancing factor f was calculated (20 mmol·L^?1: 15.16, 40.01, and 145.5; 40 mmol·L^?1: 13.29, 37.97, and 138.4), indicating that the impact of solids was significant for the enhancement of biodegradation.     

Efficient oxidation of sulfides into sulfoxides catalyzed by a chitosan–Schiff base complex of Cu(II) supported on supramagnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles

Sulfoxides are versatile synthetic intermediates for the preparation of biological products. Therefore, there is a need for efficient methods to oxidize sulfides into sulfoxides. Such oxidation may be catalyzed by magnetic nanocatalysts due to their good stability, easy synthesis, high surface area, low toxicity and easy separation by magnetic forces. Here we prepared a nanocatalyst by immobilization of the chitosan–Schiff base complex on supramagnetic Fe₃O₄ nanoparticles. The chitosan–Schiff base complex has been previously prepared by functionalization of chitosan with 5-bromosalicylaldehyde and metalation with copper(II) acetate. The catalyst was characterized by Fourier transform infrared, powder X-ray diffraction, transmission electron microscope, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. Results show that the Fe₃O₄ nanoparticles and nanocatalyst were spherical in shape with an average size of 20 nm. Upon the covalently anchoring of chitosan–Schiff base Cu complex on the magnetic Fe₃O₄ nanoparticles, the average size increased to 60 nm. The prepared Fe₃O₄–chitosan–Schiff base Cu complex catalyzed very efficiently the oxidation of sulfides to sulfoxides with 100 % selectivity in all cases under green reaction conditions and excellent yields. Additionally, ease of recovery and reusability up to four cycles without noticeable loss of catalytic activity make the present protocol beneficial from industrial and environmental viewpoint.     

Seasonal variations of transport pathways and potential sources of PM<Subscript>2.5</Subscript> in Chengdu,China (2012–2013)

Seasonal pattern of transport pathways and potential sources of PM_2.5 in Chengdu during 2012–2013 were investigated based on hourly PM_2.5 data, backward trajectories, clustering analysis, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) method. The annual hourly mean PM_2.5 concentration in Chengdu was 97.4 mg·m^–3. 5, 5, 5 and 3 mean clusters were generated in four seasons, respectively. Short-distance air masses, which travelled within the Sichuan Basin with no specific source direction and relatively high PM_2.5 loadings (>80 mg·m^–3) appeared as important pathways in all seasons. These short pathways indicated that emissions from both local and surrounding regions of Chengdu contributed significantly to PM_2.5 pollution. The cities in southern Chengdu were major potential sources with PSCF>0.6 and CWT>90 mg·m^–3. The northeastern pathway prevailed throughout the year with higher frequency in autumn and winter and lower frequency in spring and summer. In spring, long-range transport from southern Xinjiang was a representative dust invasion path to Chengdu, and the CWT values along the path were 30-60 mg·m^–3. Long-range transport was also observed in autumn from southeastern Xinjiang along a northwesterly pathway, and in winter from the Tibetan Plateau along a westerly pathway. In summer, the potential source regions of Chengdu were smaller than those in other seasons, and no long-range transport pathway was observed. Results of PSCF and CWT indicated that regions in Qinghai and Tibet contributed to PM_2.5 pollution in Chengdu as well, and their CWT values increased to above 30 mg·m^–3 in winter.

Open image in new window

     

Variability of competition at scales of 10<Superscript>1</Superscript>, 10<Superscript>3</Superscript>, 10<Superscript>5</Superscript>, and 10<Superscript>6</Superscript> m: encrusting arctic community patterns

Variability in interference competition was studied in benthic marine communities of the arctic and subarctic Atlantic intertidal and shallow subtidal zones. We sampled multiple square-metre quadrats at distances of 10¹, 10³, and 10⁵ m apart around the high polar island of Spitsbergen (Svalbard Archipelago). We also took some similar samples in Iceland and in the Faeroe Islands (10⁶ m apart from Spitsbergen samples). Encrusting fauna were present on high arctic intertidal rocks but we only found competitive interactions on subtidal substrata. On subarctic Icelandic and Faeroese shores, in contrast, spatial competition was common even in the intertidal zone. Analysis of variance of competition intensity data (numbers of interactions per area) revealed multiple factors to be significant influences explaining variability. Amongst the 10¹-, 10³-, and 10⁵-m spatial scales, only the largest emerged as a significant term. Whether intra- or interspecific competition dominated the types of interactions varied greatly between sites: 21–97% of competition was intraspecific. The proportion of competitive encounters resulting in a decided outcome (i.e. a win for one competitor and a loss for the other, rather than a tie or standoff between them) showed little variability at any scale. All the values of competition transitivity (how hierarchical a pecking order is) were very high compared to values reported in the literature from any other (polar or non-polar) locality. Variability in this measure was generally <10% across scales. We conclude from our data that great care must be taken in interpreting patterns of competition between similar taxa in large-scale space or time. Not only did most aspects of competition in our study communities vary significantly at the 10⁵-m scale but different aspects of competition varied at different scales and by hugely different amounts.Communicated by J.P. Thorpe, Port Erin     

Allometry of gill weights,gill surface areas,and foot biomass δ<Superscript>13</Superscript>C values of the chemoautotroph–bivalve symbiosis<Emphasis Type="Italic"> Solemya velum</Emphasis>

The protobranch bivalve Solemya velum Say, 1822 has large gills, which harbor chemolithoautotrophic bacteria that supply the majority of the clams organic carbon. A substantial portion of the CO₂, O₂, H₂S, and other nutrients necessary for symbiont autotrophy and host heterotrophy are acquired from the environment through the gills, whose large size may be necessary to facilitate the acquisition of sufficient O₂ from S. velums habitat to meet the combined demands of the host and symbionts. Large gills may also result in an oversupply of CO₂, which may in turn be responsible for the isotopically depleted ¹³C values observed in S. velum biomass (–31 to –34). Alternatively, gill hypertrophy may simply be an adaptation to house a large population of symbionts adjacent to their environmental source of dissolved gases and other nutrients. To better understand gill function in this symbiosis, gill weights, gill surface areas, and foot ¹³C values were measured as a function of total weights. S. velum gill weights were found to be a substantial portion of total clam weight, averaging 38% of wet weight, compared to nonsymbiotic protobranch bivalves Yoldia limatula Say, 1831 (5%) and Nucula proxima Say, 1822 (11%). Gill weights are a smaller percentage of total weight in larger individuals; the allometric equation for gill weight (G) as a function of total weight (M) is G=0.26M^0.85. Dry weights scale similarly. Gill surface areas are immense; the average gill surface area measured was 107 cm² g^–1 total soft tissue wet weight, the highest value for any marine invertebrate. Gill surface area (SA) also scales with size (SA=69.8M^0.85). When gill surface areas were calculated with respect to gill wet weights, they did not scale with size. The ¹³C values do not scale with size either, consistent with high rates of CO₂ supply at all sizes. Extraordinarily high rates of CO₂ supply relative to demand are supported by a model for CO₂ delivery based on Ficks law and the allometric relationship between surface areas and total weight, consistent with a role for large gill surface areas in the generation of isotopically depleted tissue ¹³C values.Communicated by J. P. Grassle, New Brunswick     

Dance precision of <Emphasis Type="Italic">Apis florea</Emphasis>—clues to the evolution of the honeybee dance language?

All honeybee species make use of the waggle dance to communicate the direction and distance to both food sources and potential new nest sites. When foraging, all species face an identical problem: conveying information about profitable floral patches. However, profound differences in nesting biology (some nest in cavities while others nest in the open, often on a branch or a cliff face) may mean that species have different requirements when dancing to advertise new nest sites. In cavity nesting species, nest sites are a precise location in the landscape: usually a small opening leading to a cavity in a hollow tree. Dances for cavities therefore need to be as precise as possible. In contrast, when the potential nest site comprises a tree or perhaps seven a patch of trees, precision is less necessary. Similarly, when a food patch is advertised, dances need not be very precise, as floral patches are often large, unless they are so far away that recruits need more precise information to be able to locate them. In this paper, we study the dance precision of the open-nesting red dwarf bee Apis florea. By comparing the precision of dances for food sources and nest sites, we show that A. florea workers dance with the same imprecision irrespective of context. This is in sharp contrast with the cavity-nesting Apis mellifera that increases the precision of its dance when advertising a potential new home. We suggest that our results are in accordance with the hypothesis that the honeybees’ dance communication initially evolved to convey information about new nest sites and was only later adapted for the context of foraging.     

Catalytic hydrolysis of gaseous HCN over Cu–Ni/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst: parameters and conditions

To decompose efficiently hydrogen cyanide (HCN) in exhaust gas, g-Al₂O₃-supported bimetallicbased Cu–Ni catalyst was prepared by incipient-wetness impregnation method. The effects of the calcination temperature, H₂O/HCN volume ratio, reaction temperature, and the presence of CO or O₂ on the HCN removal efficiency on the Cu–Ni/g-Al₂O₃ catalyst were investigated. To examine further the efficiency of HCN hydrolysis, degradation products were analyzed. The results indicate that the HCN removal efficiency increases and then decreases with increasing calcination temperature and H₂O/HCN volume ratio. On catalyst calcined at 400°C, the efficiency reaches a maximum close to 99% at 480 min at a H₂O/HCN volume ratio of 150. The HCN removal efficiency increases with increasing reaction temperature within the range of 100°C–500°C and reaches a maximum at 500°C. This trend may be attributed to the endothermicity of HCN hydrolysis; increasing the temperature favors HCN hydrolysis. However, the removal efficiencies increases very few at 500°C compared with that at 400°C. To conserve energy in industrial operations, 400°C is deemed as the optimal reaction temperature. The presence of CO facilitates HCN hydrolysis andincreases NH₃ production. O₂ substantially increases the HCN removal efficiency and NO _x production but decreases NH₃ production.

Open image in new window

     

Where are larvae of the vermetid gastropod <Emphasis Type="Italic">Dendropoma maximum</Emphasis> on the continuum of larval nutritional strategies?

This study evaluated whether larvae of the Indo-Pacific vermetid gastropod Dendropoma maximum are obligate planktotrophs, or whether they exhibit an intermediate feeding strategy. Experiments were conducted in Moorea, French Polynesia (149°50′W, 17°30′S), Sep–Oct 2009, to examine D. maximum larval growth and metamorphic responses to different diets and amounts of food. Dendropoma maximum larvae required particulate food to undergo metamorphosis, but were able to survive and grow in the absence of food for up to 20 days. Larvae in Low and Unfed food treatments exhibited phenotypic plasticity by growing a larger velum (the larval feeding structure) compared with those in high food. Unfed D. maximum larvae had a slower initial growth rate; however, by 11-day post-hatch fed and unfed larvae had converged on the same mean shell height (553 μm), which was only 10% larger than the initial size at hatching. Therefore, although the nutritional strategy of D. maximum larvae is best described as obligate planktotrophy, it appears to approach an intermediate feeding strategy.     

Removal of chelated copper from wastewaters by Fe<Superscript>2+</Superscript>-based replacement–precipitation

We studied the removal mechanism and affecting factors of Fe²⁺-based replacement–precipitation process for treating CuEDTA-containing wastewaters. Since Fe²⁺ was easily oxidized to Fe³⁺ in the presence of oxygen, the chelated copper was removed by the synergetic effect of Fe³⁺ replacement and NaOH precipitation. Our experiments showed that the copper removal efficiency was considerably dependant on pH conditions of the solution and molar ratio of Fe²⁺/Cu²⁺.     

Review of total suspended particles (TSP) and PM<Subscript>2.5</Subscript> concentration variations in Asia during the years of 1998–2015

In Asian countries such as China, Malaysia, Pakistan, India, Taiwan, Korea, Japan and Hong Kong, ambient air total suspended particulates and PM_2.5 concentration data were collected and discussed during the years of 1998–2015 in this study. The aim of the present study was to (1) investigate and collect ambient air total suspended particulates (TSP) and PM_2.5 concentrations for Asian countries during the past two decades. (2) Discuss, analyze and compare those particulates (TSP and PM_2.5) annual concentration distribution trends among those Asian countries during the past two decades. (3) Test the mean concentration differences in TSP and PM_2.5 among the Asian countries during the past decades. The results indicated that the mean TSP concentration order was shown as China > Malaysia > Pakistan > India > Taiwan > Korea > Japan. In addition, the mean PM_2.5 concentration order was shown as Vietnam > India > China > Hong Kong > Mongolia > Korea > Taiwan > Japan and the average percentages of PM_2.5 concentrations for Taiwan, China, Japan, Korea, Hong Kong, Mongolia and Other (India and Vietnam) were 8, 21, 6, 8, 14, 13 and 30%, respectively, during the past two decades. Moreover, t test results revealed that there were significant mean TSP and PM_2.5 concentration differences for either China or India to any of the countries such as Taiwan, Korea and Japan in Asia during the past two decades for this study. Noteworthy, China and India are both occupied more than 60% of the TSP and PM_2.5 particulates concentrations out of all the Asia countries. As for Taiwan, the average PM_2.5 concentration displayed increasing trend in the years of 1998–1999. However, it showed decreasing trend in the years of 2000–2010. As for Korea, the average PM_2.5 concentrations showed decreasing trend during the years of 2001–2013. Finally, the average PM_2.5 concentrations for Mongolia displayed increasing trend in the years of 2004–2013.     

Comparison of five methods for estimating growth of <Emphasis Type="Italic">Calanus helgolandicus</Emphasis> later developmental stages (CV–CVI)

The activity of the enzymes aminoacyl-tRNA synthetases (AARS) in adult females and males and copepodites stage V of Calanus helgolandicus was studied at the L4 time-series station in the English Channel from June 2002 to December 2003. AARS activity was explored as an index of somatic growth in the laboratory as well as in the field by comparison with other methods of measuring growth: (1) the direct method (Heinle in Chesapeake Sci 7:59–74, 1966), (2) the weight increment (WI) method, (3) the Hirst and Bunker (HB) equation (Limnol Oceanogr 48(5):1988–2010, 2003) and (4) the egg production (EPR) method. AARS activity showed a significant correlation with the direct measurement of growth in the laboratory (R ²=0.55). However, the correlation was lower for growth assessed either with the WI or the HB approaches in the field (R ²=0.05–0.17). Female AARS activity showed a positive correlation with specific EPR during the reproductive season (R ²=0.40) but no relationship was found during the non-reproductive period.     

Analysis of insecticide “Toxaphene”; in fish products

The gaschromatographic determination of Toxaphene in the presence of other chlorinated hydrocarbons with similar retention times is often difficult. The practibility of a new method, based on photodehalogenation of the interfering substances, is shown during the analytical determination of Toxaphene residues in selected environmental samples, especially in fish and fish products. Irradiation of the extracts after clean‐up procedures with wavelengths at 254 nm lead directly to photodechlorination products of interfering substances with shorter retention times and makes it possible to determine the Toxaphene components quantitatively, which are mostly stable under the same experimental conditions.     

Stable isotope analysis in two sympatric populations of bottlenose dolphins <Emphasis Type="Italic">Tursiops truncatus</Emphasis>: evidence of resource partitioning?

Skin and muscle from 43 bottlenose dolphins (38 juveniles/adults, 5 calves) stranded in NW Spain were analysed to determine whether stable isotope ratios (δ¹³C and δ¹⁵N) could be used to assess dietary variation, habitat segregation and population substructure. Results were compared with published stomach contents data. Stable isotope ratios from 17 known prey species were also determined. Isotope ratios of the main prey (blue whiting, hake) varied significantly in relation to fish body size. Dolphin calves showed significant heavy isotope enrichments compared to adult females. Excluding calves, δ¹⁵N decreased with increasing dolphin body size, probably related to an ontogenetic shift in diet towards species at lower trophic levels, e.g. on blue whiting as suggested by stomach content results. Bottlenose dolphins were divided into two putative populations (North, South) based on previous genetic studies, and values of δ¹³C and δ¹⁵N differed significantly between these two groups, confirming the existence of population structuring.     

Photodegradation of Ibuprofen,Cetirizine, and Naproxen by PAN-MWCNT/TiO<Subscript>2</Subscript>–NH<Subscript>2</Subscript> nanofiber membrane under UV light irradiation

Background

In this study, the photodegradation of three pharmaceuticals, namely Ibuprofen (IBP), Naproxen (NPX), and Cetirizine (CIZ) in aqueous media was investigated under UV irradiation. The photocatalyst used in this work consists of surface functionalized titanium dioxide (TiO₂–NH₂) nanoparticles grafted into Polyacrylonitrile (PAN)/multi-walled carbon nanotube composite nanofibers. Surface modification of the fabricated composite nanofibers was illustrated using XRD, FTIR, and SEM analyses.

Results

Sets of experiments were performed to study the effect of pharmaceuticals initial concentration (5–50 mg/L), solution pH (2–9), and irradiation time on the degradation efficiency. The results demonstrated that more than 99% degradation efficiency was obtained for IBP, CIZ, and NPX within 120, 40, and 25 min, respectively.

Conclusions

Comparatively, the photocatalytic degradation of pharmaceuticals using PAN-CNT/TiO₂–NH₂ composite nanofibers was much more efficient than with PAN/TiO₂–NH₂ composite nanofibers.

     

What did Lotka really say? A critical reassessment of the “maximum power principle”

This paper presents a critical discussion of the so-called “maximum power principle”, often quoted in studies about the energy balance of living systems and also known in the emergy literature as “maximum em-power principle”. Several authors consider this principle highly relevant and some even proposed it as a “fourth law of thermodynamics”. A critical analysis of the original source, namely Alfred Lotka's 1921-22 papers, conducted both in an historical perspective (the connection between Lotka's writings and the ongoing debate at his time) and in a more modern context, leads to a more detailed and less biased assessment. It turns out that in spite of Lotka's very anticipatory and incredibly sharp vision of the possible interconnections between the second law of thermodynamics and evolutionism, doubts arise about the general applicability of his “maximum power principle”. From an accurate analysis of his writings, it can be concluded that: (a) Lotka explicitly and consistently addressed the “optimal use” of the flow of exergy (available energy), and therefore the quantity defined as “em-power” is an incorrect interpretation of Lotka's constrained maximum power principle; (b) “Lotka's principle” can be reformulated within Ziegler's “maximum entropy production” or Prigogine “minimum entropy generation” paradigm only under two different respective sets of rather stringent additional conditions which Lotka was probably already aware of but never explicitly stated.     

Does the presence of non-breeders enhance the fitness of breeders? An experimental analysis in the clown anemonefish<Emphasis Type="Italic"> Amphiprion percula</Emphasis>

The stability of animal societies depends on individuals decisions about whether to tolerate or evict others and about whether to stay or leave. These decisions, in turn, depend on individuals costs and benefits of living in the group. The clown anemonefish, Amphiprion percula, lives in groups composed of a breeding pair and zero to four non-breeders. To determine why breeders accept the presence of non-breeders in this species I investigated the effect of non-breeders on multiple components of the breeders fitness. Non-breeders did not assist breeders in any obvious way. Experimental removal of non-breeders had no significant effect on the survival, growth, or reproductive success of breeders. Experimental removal of one of the breeding pair showed that non-breeders had little effect on the time taken for a widowed breeder to recommence breeding. The results indicate that the presence of non-breeders neither enhances, nor reduces, the fitness of breeders in A. percula. I suggest that non-breeders might modulate their effect on the fitness of breeders, either by reducing the costs they inflict or by increasing the benefits they provide, such that it just pays breeders to tolerate, rather than to evict, them. This study illustrates that animal societies can be stable even when some individuals gain nothing from the association.Communicated by M. Abrahams     

Preparation and characterization of <Emphasis Type="Italic">β</Emphasis>-FeOOH-coated sand and its adsorption of Cr(VI) from aqueous solutions

Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180 minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of ΔG ⁰ and the positive value of ΔH ⁰ showed that the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.     

Temporal and spatial variation in the δ<Superscript>15</Superscript>N and δ<Superscript>13</Superscript>C values of fish and squid from Alaskan waters

To test the hypothesis that stable isotope ratios from marine organisms vary, the δ¹⁵N and δ¹³C values from fish and squid collected in Alaskan waters were measured across years (1997, 2000, and 2005), seasons, geographic locations, and different size/age classes, and between muscle tissue and whole animals. Temporal, geographic, and ontogenetic differences in stable isotope ratios ranged from 0.5–2.5‰ (δ¹⁵N) to 0.5–2.0‰ (δ¹³C). Twenty-one comparisons of stable isotope values between whole organisms and muscle tissue revealed only four small differences each for δ¹⁵N and δ¹³C, making costly and space prohibitive collection of whole animals unnecessary. The data from this study indicate that significant variations of stable isotope values from animals in marine systems necessitates collection of prey and predator tissues from the same time and place for best interpretation of stable isotope analysis in foraging ecology studies.     

“Decision-making” in conflicts of wild chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>): an extension of the Relational Model

>We examined the "decision-making" process of aggressive interactions within a community of wild chimpanzees (Pan troglodytes verus) in the Taï National Park, Côte d'Ivoire (West Africa). Costs and benefits were investigated for 876 dyadic aggressive interactions among 18 adults (including 4 independent adolescents) of either sex. An extended version of the Relational Model was developed to describe the dynamics of the "decision-making" process in Taï chimpanzees, which suggests that the net benefit determines the occurrence of conflicts. Both sexes fought more frequently for the resources that were most important to them, food for females and social contexts for males. Individuals used two different strategies according to their likelihood of winning the aggressive interaction, determined by the dominance relationship of the conflict partners. Dominant initiators had longer and more intense aggressive interactions, but they limited their social disadvantages by fighting non-cooperative partners. Subordinate initiators had shorter and less intense aggressive interactions, but risked more social costs, which they could reduce afterwards by reconciliation. Both strategies included a positive overall net benefit. The extended Relational Model fits the complexity of wild chimpanzee conflicts and allows for more flexibility in the "decision-making" compared to the original version.Communicated by E. Sterck