A new multiple rectangular midwater trawl (RMT 1+8M) and some modifications to the institute of oceanographic sciences' RMT 1+8

A new multiple rectangular midwater trawl (the RMT 1+8M) is described. It consists of three 1 m² and three 8 m² mouth area nets combined within the same frame and is based upon the Institute of Oceanographic Sciences RMT 1+8. It is acoustically operated and controlled and has been successfully used to a depth of 4500 m. The condition of the catch is excellent and use of the multiple net has resulted in considerable saving in ship's time. Some modifications to the existing RMT 1+8 are also described.     

Behaviour of the institute of oceanographic science's rectangular midwater trawls: Theoretical aspects and experimental observations

The behaviour of two rectangular midwater trawls, the RMT 1+8 and the RMT 1+8M, is described. The RMT 1+8 consists of a pair of rectangular nets contained within the same frame-a small mouth area RMT 1 of mesh size 320 m and a larger RMT 8 of mesh size 4.5 mm. The RMT 1+8M is a multiple version of the RMT 1+8, combining three RMT 1s and three RMT 8s within the same frame. An expression is developed to describe the dependence of mouth angle on speed for the RMT 1+8 when towed horizontally. Theoretical estimates of the changes in mouth angle with speed agree well with experimental observations. Within normal towing speeds the RMT 1+8 is sensitive to changes in speed; this sensitivity is especially marked in the RMT 1. Between speeds of about 2.6 and 8.0 knots the RMT 8 does not alter its mouth angle with changes in speed; this behaviour is not shown by the RMT 1—at least within a practical speed range. The performance of the RMT 1+8M cannot be completely described by the theory developed for the RMT 1+8 and possible explanations for this are discussed. The multiple net is considerably less sensitive to changes in towing speed; all three nets of each type have similar mouth angles at a constant speed. Variations in warp load with speed for both trawls are described.     

A new environmentally friendly process for the recovery of gold from electronic waste

A new method for the recovery of precious metals, in particular gold, from electronic waste is proposed. This work focused on the research of an easily renewable etching agent, in order to make an environmentally friendly process possible. Two well known hydrometallurgical etching agents, FeCl₃ and CuCl₂, were evaluated in terms of efficiency and kinetics, testing solutions with different concentration of etchant and hydrochloric acid. The recovery of spent etching solutions was evaluated: promising results were found in the case of CuCl₂, which can be completely restored by oxidation of the cuprous chloride formed during the etching using atmospheric oxygen.     

A new source of dimethylsulfide (DMS) for the arctic atmosphere: ice diatoms

We report the first evidence that pennate diatoms growing within the bottom layer of first-year ice in the Arctic produce significant amounts of particulate dimethylsulfoniopropionate (DMSP_p) and dissolved DMSP+DMS. In 1992 in Resolute Passage, a tributary of Barrow Strait, DMSP_p concentrations within the bottom layer of ice reached 1055 mg S m^-3 at the end of the vernal bloom, a value one order of magnitude higher than the maximum value reported in antarctic ice. Bottom-ice concentrations in DMSP_p and DMSP_d+DMS were significantly correlated with the abundance of the dominant pennate diatom Nitzschia frigida. Intracellular concentration in DMSP of ice algae was very low (0.001 pg cell^-1) at the end of April when algae were light-limited and reached 1.17 pg cell^-1 in mid-May following an increase in light and algal growth. We calculate that the rapid release of the dissolved DMSP+DMS from the ice into surface waters following the ice break-up will generate a sea-to-air DMS flux of 0.7 mg S m^-2 d^-1, a pulse ten times higher than the mean arctic summer flux. We estimate that this 1-d pulse represents up to 5% of the annual DMS emission in the Arctic.     

A new towed underwater camera system for wide-range benthic surveys

Following a short review of previous underwater camera systems, a new combined underwater camera system, consisting of a remote controlled TV- and photocamera mounted on a ship-towed steel-tubing sled, is described. The method of using this apparatus for wide-range surveys of the marine littoral benthos, and the techniques used to evaluate and quantify the observations are presented. On the basis of first results obtained in the North Adriatic Sea, the efficiency of the new system is compared with various other instruments and techniques. Advantages and disadvantages, possible improvements, and future prospects are discussed.     

A new distribution of Caucasian wingnut (Pterocarya fraxinifolia (Poiret) Spach) in the Kahramanmaras region, Turkey

Caucasian wingnut (Pterocarya fraxinifolia (Poiret) Spach) is a relict tree species having limited natural distribution in Turkey. In this study, a new distribution of this species in the Kahramanmaras region was explained. This distribution occurs in Onsenhopuru and Yavuzlar villages and Yesilyore town of Turkoglu district, at elevations between 600 and 640 m along Orcan stream, and continues about 4 km. In this area, Caucasian wingnut had about 100 trees. This distribution area of the species, quite important for biodiversity, should be protected and the existing individuals should be evaluated as a gene resource. Especially vegetative reproduction of the species should be started and the seedlings obtained should be used at the margins of lakes and streams, parks and large gardens, avenues, boulevards, and streets in the region.     

Lipid compositions,water contents,swimbladder morphologies and buoyancies of nineteen species of midwater fishes (18 myctophids and 1 neoscopelid)

Lipid compositions, water contents, swimbladder morphologies and specific gravities were studied for 19 species of oceanic midwater fishes, chiefly myctophids (lanternfishes) collected offshore from Oregon and California from 1975–1979. Three groups of species were recognizable. The first group had bodies low in both lipid and water content; they were denser than seawater, regardless of swimbladder morphology, which varied from absent through non-inflated to inflated. The second group had bodies low in lipid but high in water content; they were neutrally buoyant, evidently because of their high content of water, although their swimbladders were never inflated. The majority of the members of the aforementioned groups contained higher proportions of triglycerides than wax esters. The third group had bodies with high lipid but low water content; those with high triglyceride content had swimbladders ranging from non-inflated to (less commonly) inflated, were denser than seawater, and the lipid percentage of their body weights varied both with size and season, indicating that triglycerides function mainly as an energy store. The adults of species in the third group with a higher content of wax esters than triglycerides lacked inflated swimbladders, were neutrally buoyant, and the lipid percentage of their body weights was relatively constant with size and season, indicating that wax esters permit these fishes to attain neutral buoyancy in seawater.     

A new fat body associated with the gonad of surgeonfishes (Acanthuridae: Teleostei)

Adults of nine species of surgeonfishes (Acanthuridae) from the Red Sea, Israel and the Eastern Tropical Pacific off Mexico possess previously undescribed fat bodies associated with both male and female gonads. These structures are unique in that they are external to the abdominal cavity, are composed almost entirely of highly-saturated triacylglycerols, and appear to have close circulatory connection with the gonads. In all species except one, the fat bodies rest in triangular pockets between the trunk musculature and skin, which extend posteriorly just above the anal fin base. The composition, arrangement and dynamics of the fat bodies suggest that they support the active gonad during a spawning season that lasts, in one species, from May to September.     

A system dynamics model for the management of the Manila clam, Ruditapes philippinarum (Adams and Reeve, 1850) in the Bay of Arcachon (France)

The Manila clam Ruditapes philippinarum (Adams and Reeve, 1850) is one of the mollusc species that, driven mainly by the shellfish market industry, has extended throughout the world, far beyond the limits of its original habitat. The Manila clam was introduced into France for aquaculture purposes, between 1972 and 1975. In France, this venerid culture became increasingly widespread and, since 1988, this species has colonised most of the embayments along the French Atlantic coast. In 2004, this development resulted in a fishery of ca. 520 t in Arcachon Bay.     

A chromatophore system in the hermatypic,deep-water coral Leptoseris fragilis (Anthozoa: Hexacorallia)

Ultrastructural evidence is presented of a chromatophoresystem in the zooxanthellae containing hermatypic, deep-water coral Leptoseris fragilis (Milne Edwards and Haime). It consists of multilobed cells which mainly occupy the intercellular space of the oral gastrodermis. The cellular processes are filled with electron-dense granules up to 1-m-long and 0.5-m-wide. Within the cytoplasm an elaborate system of microtubules is established. The ramifications of the pigment cells, containing the pigment granules, form a dense and nearly continuous layer close to the overlying zooxanthellae. It is speculated that host pigments may transform the violet portion of the incident light into longer wavelengths, thus increasing the photosynthetic efficiency of the zooxanthellae.     

A new species ofPterygonema (Nematoda: Ceramonematoidea) from sublittoral sand in Liverpool Bay

Pterygonema cambriensis n.sp. is described from sublittoral sand in Liverpool Bay, UK. The species is distinguished by the anterior distension of the cephalic helmet, the shield-shaped cuticular plates on which the amphids are borne, and the presence of 8, well-developed, longitudinal alae.     

A new record of the endosymbiont polychaete Veneriserva (Dorvilleidae), with description of a new sub-species, and relationships with its host Laetmonice producta (Polychaeta: Aphroditidae) in Southern Ocean waters (Antarctica)

A new record of the genus Veneriserva Rossi, 1984 (Polychaeta: Dorvilleidae) is reported, as an endosymbiont in the coelom of the polychaete Laetmonice producta Grube, 1877 (Aphroditidae) in the eastern Weddell Sea and off King George Island (Southern Ocean, Antarctica). The specimens studied were very similar to Veneriserva pygoclava Rossi, 1984; however, due to the greater morphological variability and larger dimensions of our specimens, as well as different host species and geographic locations, a new sub-species, V. pygoclava meridionalis, was erected. A total of 842 specimens of L. producta were examined, 163 of which hosted 209 symbionts (183 in the Weddell Sea samples and 26 in the King George Island samples). Symbiont prevalence was higher in the Weddell Sea samples, and increased with depth (max. 51% at stn 14, 850 m depth). Symbiont intensity was equal to one for 78% and to two for 19.6% of all hosts examined; a maximum of six symbionts per single host was observed. Mean symbiont density was equal to 0.36 and 0.07 for the Weddell Sea and King George Island host populations, respectively. A weak linear relationship was found between symbiont and host size. Eight symbiont specimens (all found at a single station, 850 m depth) were bearing eggs, ranging between 10 and 200 µm in diameter, while 13 specimens were observed in regeneration of the posterior part, suggesting the occurrence of both sexual and asexual reproduction. The way of feeding is still not clear; reduction of the jaw apparatus suggests a parasitic host-symbiont relationship, however, no evident damage was observed in the tissues of the host. These results point out that occurrence of polychaete endoparasites in large aphroditids may be a more frequent and widespread phenomenon than previously believed, and that more attention should be paid to this aspect also in temperate and tropical aphroditid species.     

A refinement of the moult-staging technique for Antarctic krill (Euphasia superba)

The moult-staging technique for euphausiids developed by Buchholz was examined experimentally to obtain estimates of the relative duration of each of the constituent stages. The method entailed removing uropods from indiviually maintainedEuphausia superba Dana on the day of moulting and for each day post-moult, and examining them microscopically to determine the moult stage. The krill were kept alive following uropod removal until the next moult so that the stage observed in the excised uropod could be referenced to both ends of the moult cycle for each individual examined. The proportion of the moult cycle occupied by each stage at 0°C was thereby calculated.     

Mating system of the commensal marine isopod Jaera hopeana (Crustacea)

The commensal marine isopod Jaera hopeana Costa, 1853 was reared in the laboratory through 30 generations in the absence of its host, Sphaeroma serratum, to study its development and reproductive behaviour. It was found that adult males take virtually any opportunity to associate with a young conspecific in manca-I stage (first free-living stage) and carry it around in a characteristic position. This male-manca(I) amplexus ends during the manca's first postmarsupial molt (manca-I to manca-II) at an average age of about 9 d after hatching from the marsupium. Entry into amplexus does not alter a manca's molt timing, the duration of the amplexus thus depending exclusively on the manca's age when it joined by a male. Given a choice, males do not prefer manca-I close to molting over those just hatched. With the first postmarsupial molt, long before sexual maturity, female J. hopeana become receptive to mating. Before a female manca is released from amplexus, it is inseminated by its male partner. Sperm transferred to young immature females are stored within special sperm stores until they are needed for fertilization. The male-manca(I) amplexus seems to be a precopula, wherein males wait for their partners to molt and become sexually receptive. Nevertheless, it is inevitable that every second amplexus on average ends unsuccessfully: although manca-I have already been determined irreversibly (and probably genetically) as males and females in equal numbers, adult males are unable to predict which manca-I are potential mates and which are not. Males accept any manca-I as a precopula partner, and even when given a choice they do not prefer female over male manca-I. From the manca-II stage onward, females are continuously receptive to mating for the rest of their life, and mating can occur immediately upon contact of the partners without any significant investment in energy and time (en passant copulation).     

A new heuristic for capturing the complexity of multimodal signals

Many animal signals are inherently multimodal, engaging more than one of the receiver’s sensory systems simultaneously, and it is the interaction between the two modalities that determines the signal’s function (s) and efficacy. It is hence necessary to quantify the effect of each modality relative to the other in order to fully understand animal communication. We have developed a new heuristic to aid in the identification and interpretation of the many distinct ways in which signals in multiple sensory modalities interact. Our approach represents natural variation in signal production for each modality and uses these to generate three-dimensional receiver response surface plots that map the relationships among the signal components and receiver behavior. We accommodate the extant hypotheses for the interactions between modalities, each of which makes a clear prediction about the shape of the response surface, and extend previous theory by considering new phenomena.     

Mitochondrial DNA and electronic tracking reveal population structure of Atlantic bluefin tuna (Thunnus thynnus)

Population subdivision was examined in Atlantic bluefin tuna (Thunnus thynnus) through sequencing of the control region of the mitochondrial genome. A total of 178 samples from the spawning grounds in the Gulf of Mexico, Bahamas and Mediterranean Sea were analyzed. Among the samples from these locations were 36 electronically tagged bluefin tuna that were tagged in the North Atlantic and subsequently traveled to one of these known spawning grounds during the spawning season. Bluefin tuna populations from the Gulf of Mexico and the Mediterranean Sea were found to be genetically distinct based on Φ_st, and sequence nearest neighbor analyses, showing that these two major spawning areas support independent stocks. Sequence nearest neighbor analysis indicated significant population subdivision among the Gulf of Mexico, western Mediterranean and eastern Mediterranean Sea. However, it was not possible to find significant pairwise differences between any sampling areas when using all samples. If only samples that had a high likelihood of assignment to a specific spawning site were used (young of the year, spawning adults), the differentiation increased among all sampling areas and the Western Mediterranean Sea was distinct from the Eastern Mediterranean Sea and the Gulf of Mexico. It was not possible to distinguish samples from the Bahamas from those collected at any of the other sampling sites. These data support tagging results that suggested distinctness of the Gulf of Mexico, Eastern and Western Mediterranean Sea spawning areas. This level of stock differentiation is only possible if Atlantic bluefin tuna show strong natal homing to individual spawning grounds.     

A molecular approach for the identification of meiofaunal turbellarians (Platyhelminthes,Turbellaria)

In the absence of reliable morphological characters, or in conjunction with morphology-based identifications, meiofaunal turbellarians may also be identified using the nucleotide sequence of a portion of the large subunit of the ribosomal RNA (26/28S rRNA). A 284 base pair-long region of the 26/28S rRNA has been identified by isolating genomic DNA from ten species of turbellarians belonging to four orders, namely, the Proseriata, Macrostomida, Prolecithophora and Acoela. The proseriates had been collected from localities in Europe and Israel and were preserved in ethanol. The remaining turbellarians were isolated from intertidal sediment samples collected from two sites on the Maine and New Hampshire coast, USA in 1992. Amplification of the genomic DNA was carried out using two primers designed to match the nucleotide sequence of a portion of the 26/28S rDNA gene of the terrestrial nematode,Caenorhabditis elegans (Maupas 1900). This area consists of a highly variable, about 150 base pair-long region, called the D3 expansion segment, followed by a very conserved stretch of sequence. When folded into its secondary structure, the conserved region will form stem structures that correspond to helices 15 to 18 of theC. elegans structural model. The sequence alignment program PILEUP was used to perform a cluster analysis (unweighted pair group method using arthmetic averages, UPGMA) on the sequences. This analysis revealed that the helices allow for the classification of the turbellarians at the level of families and above, whereas if the D3 expansion segment itself was included in the analysis, intrageneric and intraspecific groupings could be established.     

A new species of Penaeus (Crustacea: Penaeidae) revealed by allozyme and cytochrome oxidase I analyses

 Penaeid shrimps comprise an important portion of the world's industrial fisheries and mariculture. In the Southwest Atlantic, Penaeus (Farfantepenaeus) subtilis, P. (F.) paulensis, P. (F.) brasiliensis and P. (Litopenaeus) schmitti are the most important commercially exploited species. Despite their high commercial value, there is little information available on the different aspects of their biology or genetics and almost no data on stock structure. Also, the taxonomic status of P. subtilis populations in relation to P. paulensis and their geographic ranges have been recently questioned. In this paper we used both nuclear (allozymes) and mitochondrial (cytochrome oxidase subunit 1) data to compare species of south-western Atlantic penaeids and to estimate their phylogenetic relationships. We could readily discriminate among the four main Brazilian penaeid species and detected a fifth, new, species of Penaeus. This new species corresponded to one of the described morphotypes of P. subtilis. Based on these analyses, the geographic ranges of P. subtilis and P. paulensis were clarified. Our data also support the conclusion of Baldwin et al. (1998) that the subgenus Farfantepenaeus is polyphyletic. Received: 6 January 2000 / Accepted: 13 June 2000