High CO<Subscript>2</Subscript> absorption of <Emphasis Type="Italic">O</Emphasis>-carboxymethylchitosan synthesised from chitosan

CO₂ absorption by liquid-containing amines to form carbamate and bicarbonates is an effective method of CO₂ mitigation from industrial exhausts, but this process is expensive and requires large quantities of amines. Here we modified chitosan, a naturally occurring biopolymer containing NH₂ functions, to use it for CO₂ absorption in aqueous media. Chitosan was dispersed in 40% aqueous NaOH solution then treated with monochloroacetic acid dissolved in isopropanol, to yield O-carboxymethylchitosan. Results show that the CO₂ absorption capacity of O-carboxymethylchitosan is 0.508 g/g, which is higher than the capacity of conventional amines such as 1-aminoamine, 2-methylpropanolamine and methyldiethanol amine, but lower than the capacity of monoethanolamine. A cyclic study showed that O-carboxymethylchitosan is a stable component for CO₂ absorption and regeneration.     

Characterization of urease activity in three marine phytoplankton species,<Emphasis Type="Italic"> Aureococcus anophagefferens</Emphasis>,<Emphasis Type="Italic"> Prorocentrum minimum</Emphasis>, and<Emphasis Type="Italic"> Thalassiosira weissflogii</Emphasis>

The availability of different forms of nitrogen in coastal and estuarine waters may be important in determining the abundance and productivity of different phytoplankton species. Although urea has been shown to contribute as much as 50% of the nitrogen for phytoplankton nutrition, relatively little is known of the activity and expression of urease in phytoplankton. Using an in vitro enzyme assay, urease activities were examined in laboratory cultures of three species: Aureococcus anophagefferens Hargraves et Sieburth, Prorocentrum minimum (Pavillard) Schiller, and Thalassiosira weissflogii (Grunow) Fryxell et Hasle. Cultures of P. minimum and T. weissflogii were grown on three nitrogen sources (NO₃^m, NH₄⁺, and urea), while A. anophagefferens was grown only on NO₃^m and urea. Urease was found to be constitutive in all cultures, but activity varied with growth rate and assay temperature for the different cultures. For A. anophagefferens, urease activity varied positively with growth rate regardless of the N source, while for P. minimum, urease activity varied positively with growth rate only for cultures grown on urea and NH₄⁺. In contrast, for T. weissflogii, activity did not vary with growth rate for any of the N sources. For all species, urease activity increased with assay temperature, but with different apparent temperature optima. For A. anophagefferens, in vitro activity increased from near 0-30°C, and remained stable to 50°C, while for P. minimum, increased in vitro activity was noted from near 0-20°C, but constant activity was observed between 20°C and 50°C. For T. weissfloggii, while activity also increased from 0°C to 20°C, subsequent decreases were noted when temperature was elevated above 20°C. Urease activity had a half-saturation constant of 120-165 wg atom N l^у in all three species. On both an hourly and daily basis, urease activity in A. anophagefferens exceeded nitrogen demand for growth. In P. minimum, urease activity on an hourly basis matched the nitrogen demand, but was less than the demand on a daily basis. For T. weissflogii, urease activity was always less than the nitrogen demand. These patterns in urease activity in three different species demonstrate that while apparently constitutive, the regulation of activity was substantially different in the diatom. These differences in the physiological regulation of urease activity, as well as other enzymes, may play a role in their ecological success in different environments.     

Patterns of gamete incompatibility between the blue mussels<Emphasis Type="Italic"> Mytilus edulis</Emphasis> and<Emphasis Type="Italic"> M</Emphasis>.<Emphasis Type="Italic"> trossulus</Emphasis>

Previous research on gametic incompatibility in marine invertebrates suggests that for highly dispersive marine invertebrate species, barriers to fertilization among closely related taxa are often incomplete and sometimes asymmetric. The nature of these barriers can dramatically affect the patterns of gene flow and genetic differentiation between species, and thus speciation. Blue mussels, in the genus Mytilus, are genetically distinct in allopatry yet hybrids are present wherever any two species within the group co-occur. The present study sampled M. edulis (L.) and M. trossulus (Gould) in May and June 2001 from the East Bay section of Cobscook Bay, Maine, USA (latitude 44°56′30″N; longitude 67°07′50″W), where the two species are sympatric. Gamete incompatibility was investigated in a series of laboratory fertilizations carried out in July 2001. The proportion of fertilized eggs typically exceeded 80% at sperm concentrations of 10³–10⁴ ml^?1 among intraspecific matings (n=18), but was <30% even at sperm concentrations in excess of 10⁵–10⁶ ml^?1 for interspecific matings (n=13). Further analysis indicated that approximately 100- to 700-fold higher sperm concentrations were required to achieve 20% fertilization in interspecific matings relative to intraspecific matings, indicating strong barriers to interspecific fertilization. The proportion of fertilized eggs did not follow this general pattern in all matings, however. The eggs from two (out of five) M. edulis females were almost as receptive to M. trossulus sperm as they were to M. edulis sperm. In contrast, the eggs from all M. trossulus females (n=3) were unreceptive to M. edulis sperm, suggesting that fertilization barriers between these species may be asymmetric. Given the experimental design employed in this study, the results are also consistent with a strong maternal or egg effect on the level of interspecific gamete compatibility in M. edulis.     

Physiological responses of the calcifying rhodophyte, <Emphasis Type="Italic">Corallina officinalis</Emphasis> (L.), to future CO<Subscript>2</Subscript> levels

Future atmospheric CO₂ levels will most likely have complex consequences for marine organisms, particulary photosynthetic calcifying organisms. Corallina officinalis L. is an erect calcifying macroalga found in the inter- and subtidal regions of temperate rocky coastlines and provides important substrate and refugia for marine meiofauna. The main goal of the current study was to determine the physiological responses of C. officinalis to increased CO₂ concentrations expected to occur within the next century and beyond. Our results show that growth and production of inorganic material decreased under high CO₂ levels, while carbonic anhydrase activity was stimulated and negatively correlated to algal inorganic content. Photosynthetic efficiency based on oxygen evolution was also negatively affected by increased CO₂. The results of this study indicate that C. officinalis may become less competitive under future CO₂ levels, which could result in structural changes in future temperate intertidal communities.     

Feeding selectivities of the marine cladocerans<Emphasis Type="Italic"> Penilia avirostris</Emphasis>,<Emphasis Type="Italic"> Podon intermedius</Emphasis> and<Emphasis Type="Italic"> Evadne nordmanni</Emphasis>

We conducted grazing experiments with the three marine cladoceran genera Penilia, Podon and Evadne, with Penilia avirostris feeding on plankton communities from Blanes Bay (NW Mediterranean, Spain), covering a wide range of food concentrations (0.02–8.8 mm³ l^–1, plankton assemblages grown in mesocosms at different nutrient levels), and with Podon intermedius and Evadne nordmanni feeding on the plankton community found in summer in Hopavågen Fjord (NE Atlantic, Norway, 0.4 mm³ l^–1). P. avirostris and P. intermedius showed bell-shaped grazing spectra. Both species reached highest grazing coefficients at similar food sizes, i.e. when the food organisms ranged between 15 and 70 µm and between 7.5 and 70 µm at their longest linear extensions, respectively. E. nordmanni preferred organisms of around 125 µm, but also showed high grazing coefficients for particles of around 10 µm, while grazing coefficients for intermediate food sizes were low. Lower size limits were >2.5 µm, for all cladocerans. P. avirostris showed upper food size limits of 100 µm length (longest linear extension) and of 37.5 µm particle width. Upper size limits for P. intermedius were 135 µm long and 60 µm wide; those for E. nordmanni were 210 µm long and 60 µm wide. Effective food concentration (EFC) followed a domed curve with increasing nutrient enrichment for P. avirostris; maximum values were at intermediate enrichment levels. The EFC was significantly higher for P. intermedius than for E. nordmanni. With increasing food concentrations, the clearance rates of P. avirostris showed a curvilinear response, with a narrow modal range; ingestion rates indicated a rectilinear functional response. Mean clearance rates of P. avirostris, P. intermedius and E. nordmanni were 25.5, 18.0 and 19.3 ml ind.^–1 day^–1, respectively. Ingestion rates at similar food concentrations (0.4 mm³ l^–1) were 0.6, 0.8 and 0.9 g C ind.^–1 day^–1.Communicated by O. Kinne, Oldendorf/Luhe     

Comparative life-history study on sympatric hyperiid amphipods (<Emphasis Type="Italic">Themisto pacifica</Emphasis> and <Emphasis Type="Italic">T</Emphasis>. <Emphasis Type="Italic">japonica</Emphasis>) in the Oyashio region,western North Pacific

Life-history features of the sympatric amphipods Themisto pacifica and T. japonica in the western North Pacific were analyzed based on seasonal field samples collected from July 1996 through July 1998, and data from laboratory rearing experiments. T. pacfica occurred throughout the year, with populations peaking from spring to summer. In contrast, T. japonica were rare from autumn to early winter, but became abundant in late winter to spring. Mature T. pacifica females and juveniles occurred together throughout the year, indicating year-round reproduction. Mature T. japonica females were observed only in spring, and juveniles occurred irregularly in small numbers, suggesting limited, early-spring reproduction in this study area. Size composition analysis of T. pacifica identified a total of eight cohorts over the 2 years of the study. Due to the smaller sample size and rarity of mature females (>9.6 mm) and males (>7.1 mm), cohort analyses of T. japonica were not comparable. Laboratory rearing of specimens at 2°C, 5°C, 8°C and 12°C revealed that a linear equation best expressed body length growth by T. pacifica, while a logistic equation best expressed body length growth by T. japoncia. Combining these laboratory-derived growth patterns with maturity sizes of wild specimens, the minimum and maximum generation times of females at a temperature range of 2–12°C were computed as 32 days (12°C) and 224 days (2°C), respectively, for T. pacifica, and 66 days (12°C) and 358 days (2°C), respectively, for T. japonica. The numbers of eggs or juveniles in females marsupia increased with female body length and ranged from 23 to 64 for T. pacifica and from 152 to 601 for T. japonica. Taking into account the number of mature female instars, lifetime fecundities were estimated as 342 eggs for T. pacifica and 1195 eggs for T. japonica. Possible mechanisms for the coexistence of these two amphipods in the Oyashio region are also discussed.Communicated by O. Kinne, Oldendorf/Luhe     

Variation in fertilisation abilities between hemiclonal hybrid and sexual parental males of sympatric water frogs (<Emphasis Type="Italic">Rana lessonae</Emphasis>,<Emphasis Type="Italic"> R. esculenta</Emphasis>,<Emphasis Type="Italic"> R. ridibunda</Emphasis>)

In many species, males and females mate with multiple partners, which gives rise to sperm competition and multiple paternity. The experiments on water frogs presented here demonstrate that such sperm competition can affect the structure and dynamics of mixed-species communities. The hybrid frog Rana esculenta (LR) mates with one of its parental species, usually R. lessonae (LL), although in some areas R. ridibunda (RR), to regain the premeiotically eliminated parental genome ("hybridogenesis"). Mixed LL/LR-populations are stable although hybrid numbers should continuously increase at the expense of parental animals, because of differences in female fecundity and other factors. This would finally lead to the extinction of the sexual host, followed by that of the sexual parasite, unless the reproductive superiority of R. esculenta is reduced by other factors, such as lower hybrid male fertility. Eggs from LL- and LR-females were fertilised in vitro by single- and multi-male sperm suspensions of LL-, LR- and RR-males. In all experiments, the proportion of offspring sired by R. esculenta sperm was significantly lower than that sired by R. lessonae or R. ridibunda sperm. Gonad mass, sperm morphology, sperm swimming velocity, and sperm survival did not explain these differences in fertilisation success; nor did gamete recognition and compatibility. Sperm density was the only trait that paralleled fertilisation success, but it offers no explanation either, because densities were equalised for the in-vitro fertilisations. In natural LL/LR populations, the significantly smaller amount, poorer competitive ability and lower long-term survival of R. esculenta compared to R. lessonae sperm will reduce the initial reproductive superiority of hybrids and contribute to the stabilisation of mixed water-frog populations. Differences in fertilisation ability are also likely to be relevant for the structure and dynamics of several other systems with encounters between eggs and sperm from different genotypes, ecotypes, ploidy levels and/or species.     

Genetic analysis of tuna populations,<Emphasis Type="Italic"> Thunnus thynnus thynnus</Emphasis> and<Emphasis Type="Italic"> T</Emphasis>.<Emphasis Type="Italic"> alalunga</Emphasis>

The genetic population structures of Atlantic northern bluefin tuna ( Thunnus thynnus thynnus) and albacore ( T. alalunga) were examined using allozyme analysis. A total of 822 Atlantic northern bluefin tuna from 18 different samples (16 Mediterranean, 1 East Atlantic, 1 West Atlantic) and 188 albacore from 5 samples (4 Mediterranean, 1 East Atlantic) were surveyed for genetic variation in 37 loci. Polymorphism and heterozygosity reveal a moderate level of genetic variability, with only two highly polymorphic loci in both Atlantic northern bluefin tuna ( FH* and SOD- 1*) and albacore ( GPI- 3* and XDH*). The level of population differentiation found for Atlantic northern bluefin tuna and albacore fits the pattern that has generally been observed in tunas, with genetic differences on a broad rather than a more local scale. For Atlantic northern bluefin tuna, no spatial or temporal genetic heterogeneity was observed within the Mediterranean Sea or between the East Atlantic and Mediterranean, indicating the existence of a single genetic grouping on the eastern side of the Atlantic Ocean. Very limited genetic differentiation was found between West Atlantic and East Atlantic/Mediterranean northern bluefin tuna, mainly due to an inversion of SOD- 1* allele frequencies. Regarding albacore, no genetic heterogeneity was observed within the Mediterranean Sea or between Mediterranean and Azores samples, suggesting the existence of a single gene pool in this area.     

Histological investigation of the reproductive cycles of the limpets <Emphasis Type="Italic">Patella </Emphasis><Emphasis Type="Italic">vulgata</Emphasis> and <Emphasis Type="Italic">Patella ulyssiponensis</Emphasis>

This study devised a staging system for, and monitored, the gonad development of the limpet species Patella vulgata and Patella ulyssiponensis on the South West coast of Ireland using histological techniques. Maturation began in the males of both species in January and in the females it began in March. There was no statistical difference in gonad development between sexes and between species. Spawning in the male P. vulgata occurred from September to December 2003 and in September and October 2004. In female P. vulgata spawning occurred from October to December 2003, no spawning of females was observed in 2004. In male P. ulyssiponensis spawning occurred in November and December 2003 and from September 2004 to December 2004. Spawning was observed from November 2003 to January 2004 and in September 2004 in female P. ulyssiponensis. Sex ratios also varied between the species and between months sampled. Nevertheless more males were observed in both species.     

Pt/Mg-Ce-O catalyst for NO/H<Subscript>2</Subscript>/O<Subscript>2</Subscript> lean de-No<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reaction

The NO/H₂/O₂ reaction was studied under oxidizing conditions in the 100-400 °C range over 0.1 wt% Pt supported on various metal oxides such as MgO, CeO₂, SiO₂, La₂O₃, CaO, Y₂O₃ and TiO₂. The Pt/MgO and Pt/CeO₂ catalysts showed good catalytic behaviours. Here, we find that the Pt/Mg-Ce-O catalyst, prepared from MgO and CeO₂ by the sol-gel method, is a very active and selective catalyst towards N₂ formation in the whole 100–400 °C range. This catalyst appears to be the most active, selective and stable one ever reported in the literature for the NO/H₂/O₂ reaction, even in the presence of 5%v H₂O or 20 ppmv of SO₂ in the feed stream.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic.     

Classification of juvenile rockfish,<Emphasis Type="Italic"> Sebastes inermis</Emphasis>, to<Emphasis Type="Italic"> Zostera</Emphasis> and<Emphasis Type="Italic"> Sargassum</Emphasis> beds,using the macrostructure and chemistry of otoliths

Young-of-the-year (YOY) Sebastes inermis use Zostera and Sargassum beds as nursery grounds, although it is not known which habitat YOY prefer. In this study, YOY S. inermis were accurately assigned to Zostera or Sargassum beds by two approaches: the width and length of the otolith nucleus and the composition of trace elements in otoliths. The otolith nucleus was initially opaque and then showed a marked shift to hyaline deposition once YOY settled in the nursery grounds. The first hyaline zone (FHZ) was deposited earlier in Zostera beds (from mid-May to early June) than in Sargassum beds (around mid-summer). Likewise, irrespective of settlement year, the FHZ was formed at both significantly younger ages and shorter back-calculated sizes (total length, TL) in the Zostera bed (overall mean: 131±3 days; 2.5±1.7 mm TL) than in the Sargassum bed (overall mean: 158±12 days; 61.3±1.00 mm TL). YOY collected in the Zostera bed were born earlier (mainly in January) than YOY from the Sargassum bed (mainly in February). In addition, a significant linear relationship was found between the age at formation of the FHZ and nucleus dimensions, suggesting that nucleus dimensions were a reliable macroscopic indicator of the time of formation of the FHZ and, consequently, also an indicator of the nursery where YOY grew. Linear discriminant function analysis (LDFA) based on the width and length of the otolith nucleus could distinguish juveniles from Zostera (88–96%) and Sargassum (96–97%) beds with a high degree of accuracy. In the other approach, six detectable trace elements (Li, Mn, Ni, Cu, Zn, and Ba) in otoliths of YOY collected in the nursery grounds were measured by high-resolution, inductively coupled mass spectrometry. LDFA based on the trace elemental composition separated YOY from three nurseries with 100% of accuracy. Findings suggest that both the trace elemental composition and nucleus dimensions of otoliths can be used as natural tags of the nursery grounds of S. inermis, offering a considerable potential for answering questions on habitat use and the contribution of nursery grounds to the adult stock.Communicated by T. Ikeda, Hakodate     

Geographical genetic structure and phylogeography of the <Emphasis Type="Italic">Sargassum horneri</Emphasis>/<Emphasis Type="Italic">filicinum</Emphasis> complex in Japan,based on the mitochondrial <Emphasis Type="Italic">cox3</Emphasis> haplotype

The genetic structure and phylogeography of the brown seaweed Sargassum horneri/filicinum complex in Japan were studied based on the mitochondrial cox3 haplotype. The cox3 haplotypes found were divided into three clades in a statistical parsimony network, among which there were large numbers of steps. Contrary to the reported large amount of drifting S. horneri along the Japanese coast, the three clades were dividedly distributed on the Japanese coast: the northern Pacific, the central Pacific, and western Japan. The western Japan S. horneri had haplotypes that were phylogenetically closer to those of S. filicinum than to the northern and central Pacific S. horneri populations. The S. filicinum populations were included within the western Japan clade and grouped together with the S. horneri samples from western Japan. Taken together with the unstable morphological diagnosis, this result suggests that S. filicinum should be reduced into a synonymy of S. horneri. The TMRCA analysis suggested that the divergence time of each clade may go back to the last interglacial period and a skyline plot suggested that the last glacial maximum had only a small effect on the population size of S. horneri. The geographic subdivision of the three groups, in spite of a large amount of drifting mats, suggests a limited contribution of drifting mats to gene flow on a large geographic scale. On a small geographic scale, a small number of haplotypes were shared between S. horneri-type and S. filicinum-type populations. This result suggests that populations of these two types are partially, though not completely, isolated from each other, possibly by selfing in S. filicinum-type populations or by a difference in peak reproduction.     

Ground gleaning in horseshoe bats: comparative evidence from<Emphasis Type="Italic"> Rhinolophus blasii</Emphasis>,<Emphasis Type="Italic"> R. euryale</Emphasis> and<Emphasis Type="Italic"> R. mehelyi</Emphasis>

The 71 species of horseshoe bat (genus Rhinolophus) use echolocation calls with long constant-frequency (CF) components to detect and localize fluttering insects which they seize in aerial captures or glean from foliage. Here we describe ground-gleaning as an additional prey-capture strategy for horseshoe bats. This study presents the first record and experimental evidence for ground-gleaning in the little-studied Blasius horseshoe bat (Rhinolophus blasii). The gleaning bouts in a flight tent included landing, quadrupedal walking and take-off from the ground. The bats emitted echolocation calls continuously during all phases of prey capture. Both spontaneously and in a choice experiment, all six individuals attacked only fluttering insects and never motionless prey. These data suggest that R. blasii performs ground-gleaning largely by relying on the same prey-detection strategy and echolocation behaviour that it and other horseshoe bats use for aerial hawking.We also studied the Mediterranean horseshoe bat (R. euryale) in the flight tent. All four individuals never gleaned prey from the ground, though they appeared to be well able to detect fluttering moths on the ground. It is not known yet whether ground-gleaning plays a role in Mehelys horseshoe bat (R. mehelyi). In a performance test, we measured the ability of these three European species of middle-sized horseshoe bats (R. euryale, R. mehelyi and R. blasii) to take-off from the ground. All were able to take flight even in a confined space; i.e. the willingness to ground-glean in R. blasii is not related to a superior take-off performance. In contrast to ground-gleaning bats of other phylogenetic lineages, R. blasii appears not to be a specialist, but rather shows a remarkable behavioural flexibility in prey-capture strategies and abilities. We suggest that the key innovation of CF echolocation paired with behavioural flexibility in foraging strategies might explain the evolutionary success of Rhinolophus as the second largest genus of bat.Communicated by T. Czeschlik     

Heart rate reflects osmostic stress levels in two introduced colonial ascidians <Emphasis Type="Italic">Botryllus schlosseri</Emphasis> and <Emphasis Type="Italic">Botrylloides</Emphasis><Emphasis Type="Italic">violaceus</Emphasis>

The influence of abiotic factors on the establishment and success of invasive species is often difficult to determine for most marine ecosystems. However, examining this relationship is critical for predicting the spread of invasive species and predicting which habitats will be most vulnerable to invasion. Here we examine the mortality and physiological sensitivity to salinity of adult colonies of the colonial ascidians Botryllus schlosseri and Botrylloides violaceus. Adult colonies of each species were exposed to abrupt changes in salinity (5, 10, 15, 20, 25, 30 psu) in the laboratory. Salinity ranges used in the laboratory corresponded with those of the field distributions of B. violaceus and B. schlosseri in the Great Bay Estuary, NH. Heart rate was used as a proxy for health to assess the condition of individual colonies. Heart rates were monitored daily for approximately 2 weeks. Results revealed that both species experienced 100% mortality after 1 day at 5 psu and that their heart rates declined with decreasing salinity. Heart rates of B. schlosseri remained consistent between 15 and 30 psu and slowed at 10 psu. Heart rates of B. violaceus remained constant between 20 and 30 psu, but slowed at 15 psu. These laboratory results corresponded to the distribution of these species in estuaries, indicating salinity is a key factor in the distribution and dominance of B. schlosseri and B. violaceus among coastal and estuarine sites. Furthermore, physiological differences to salinity were found between colonies of B. schlosseri in the Venetian Lagoon and colonies in Portsmouth Harbor, suggesting adaptation to environmental variables.     

NO oxidation over Co-La catalysts and NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reduction in compact SCR

A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO₂ resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH = 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO₂ (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO₂ adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h^–1 when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR.

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Genetic evidence fails to discriminate between <Emphasis Type="Italic">Macroramphosus gracilis</Emphasis> Lowe 1839 and <Emphasis Type="Italic">Macroramphosus</Emphasis><Emphasis Type="Italic">scolopax</Emphasis> Linnaeus 1758 in Portuguese waters

Fish belonging to the genus Macroramphosus are distributed throughout the Atlantic, Indian and Pacific oceans. Some authors consider this genus monotypic, Macroramphosus scolopax being the only valid species. Other authors consider (based on several morphological and ecological characters) that another species (Macroramphosus gracilis) exists and occurs frequently in sympatry with the first one. Intermediate forms are also reported in literature. In this paper, using the mitochondrial control region and the nuclear first S7 intron markers, we failed to find genetic differences between individuals considered to belong to both species as well as the intermediate forms. Our results suggest that in the northeastern Atlantic, Macroramphosus is represented by a single species, M. scolopax, with different morphotypes interbreeding in the sampling areas.