A new electronic system for the rectangular midwater trawl (RMT)

This paper describes a modified modern version of the original rectangular midwater trawl (RMT) manufactured by the Institute of Oceanographic Sciences (IOS). The shipboard acoustic transducer and the underwater RMT-monitor were replaced by an electronic interface box was while the data transfer, realized by a single-conductor cable. Using frequency shift keying (FSK) signal transmission, a PC-controlled system onboard handles data acquisition and control as well as real time monitoring of the haul. The volume of water filtered by the net is calculated based on the online readings of a net-angle sensor. The new RMT-system was successfully used in the Antarctic during the European Polarstern Study (EPOS) from October 1988 to March 1989. Fifty-seven tows to a maximum depth of 1000 m in open waters and in ice covered areas were performed.     

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 correction to: biological and oceanographic insights from larval labrid (Pisces: Labridae) identification using mtDNA sequences

Previously published mtDNA cytochrome b sequences for Xyrichtys novacula (Linnaeus) and two morphologically distinct types of Xyrichtys larvae (Pisces: Labridae) included human cytochrome b sequence, presumably due to sample contamination and/or poor preservation of sample DNA. Those sequences had been used to identify the two types of Xyrichtys larvae as X. novacula, but owing to the contamination, the identifications are invalid. Fresh specimens were collected: X.␣martinicensis (Cuvier and Valenciennes), X. novacula, X. splendens (Castelnau), and Xyrichtys sp. larvae of each of the two morphotypes (dorsal-forward eye and ventral-forward eye). The cytochrome b fragment was amplified from each specimen using the polymerase chain reaction. Comparison of the sequences with human cytochrome b sequence confirmed that the new sequences were not contaminated. The interspecific differences in Xyrichtys sequences were less than previously reported, but still greater than observed in many fish genera. Distance and parsimony analyses indicated that X. novacula and X. martinicensis were more closely related to each other than to X. splendens. This conclusion differs from our previous conclusion that X. martinicensis and X. splendens were more closely related to each other than to X. novacula. Distance and parsimony analyses also demonstrated that both larval morphotypes were X. novacula and, thus, our previous conclusions regarding larval ecology and oceanographic transport remain unchanged. Received: 12 March 1997 / Accepted: 24 October 1997     

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.     

Synthesis of some novel (2-oxo-3-(arylimino) indolin-1-yl)-N-aryl acetamides and evaluation as antimicrobial agents

A series of sixteen 2-oxo-3-(arylimino) indolin-1-yl)-N-aryl acetamide derivatives were synthesized, characterized by physical and spectral data (IR, ¹H nuclear magnetic resonance (NMR), and mass spectrometry), and evaluated for their antibacterial and antifungal activities against various pathogenic microorganisms. Some of the synthesized compounds showed promising antibacterial and antifungal activities, the best being 2-(3-(4-chlorophenylimino)-2-oxoindolin-1-yl)-N-(3-methoxyphenyl) acetamide.     

A multiple instrument approach to quantifying the movement patterns and habitat use of tiger (Galeocerdo cuvier) and Galapagos sharks (Carcharhinus galapagensis) at French Frigate Shoals, Hawaii

We equipped individual tiger (Galeocerdo cuvier Péron and Lesueur, 1822) and Galapagos (Carcharhinus galapagensis Snodgrass and Heller, 1905) sharks with both acoustic and satellite transmitters to quantify their long-term movements in the Papahanaumokuakea Marine National Monument (Northwestern Hawaiian Islands). Tiger sharks exhibited two broad patterns of behavior. Some individuals were detected at French Frigate Shoals (FFS) year round, whereas others visited FFS atoll in summer to forage on fledging albatross, then swam thousands of kilometers along the Hawaiian chain, or out into open ocean to the North Pacific transition zone chlorophyll front, before returning to FFS in subsequent years. These patterns suggest tiger sharks may use cognitive maps to navigate between distant foraging areas. Different patterns of spatial behavior may arise because cognitive maps are built up through individual exploration, and each tiger shark learns a unique combination of foraging sites. Galapagos shark detections were all associated with FFS, suggesting these sharks may be more resident around oceanic islands. Both Galapagos and tiger sharks primarily used the mixed layer (<100 m depth) and made occasional deeper dives through the thermocline down to 680 m. Results show reef-associated sharks utilize a wide variety of habitats ranging from shallow atoll lagoons to deep reefs and open ocean and may provide important trophic links between these habitats.     

Spatial and temporal variability of phytoplankton biomass,primary production and community structure in the Pontevedra Ria (NW Iberian Peninsula): oceanographic periods and possible response to environmental changes

The spatial distribution of phytoplankton assemblages, chlorophyll, primary production and physical and chemical parameters were studied in the Pontevedra Ria in Galicia (NW Iberian Peninsula) from October 1997 to October 1998. In addition to the usual oceanographic periods described for the Galician Coast, two other periods were observed: a Prebloom or winter bloom, occurring during calm, sunny days in winter and a Continental period, related to the allochthonous intrusion of low salinity water from the Miño River in late spring. The phytoplankton biomass and production in both periods reached values of up to 145 mgChl-a m^?2 and 3.6 gC m^?2 day^?1, respectively, which were similar to those found in summer upwelling blooms. Throughout the year, the phytoplankton biomass and primary production gradients along the ria’s axis were highly dependent on the balance between upwelling and runoff. When the latter prevailed, increased values were measured toward the inner ria, while the opposite pattern was observed during summer upwelling blooms. According to projections derived from climate models and the analysis of wind patterns, temperature and precipitation trends in the area, a drop in the productivity of the ria would be expected as a result of reduced upwelling intensity in summer and decreasing rainfall in spring. In any case the estuarine part of the ria would be the most seriously affected.     

Plasmaproteins and some hematochemical data related to Grampus griseus (Cetacea,Delphinidae) of the Western Mediterranean

The plasmaprotein of a specimen of Grampus griseus G Cuvier, captured in the Western Mediterranean, is studied for the first time and the data obtained are compared with data previously determined by the same method (microelectrophoresis on cellulose acetate gel) for Stenella, Delphinus and Phocaena. Some hematochemical values related to glycemia, azotemia and cholesterolemia (total and fractional) are also given and discussed, together with data on glutamic oxalacetic and glutamic pyruvic transaminases; special reference is made to the theory of Cornelius (1963) on hepatic glutamic pyruvic transaminase.Contributions on Cetacea: XXIV. Prepared with the assistance of the Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen, Forschung (Swiss National Fund for the Promotion of Scientific Research, Grant No. 4606) and the C.N.R.S. (National Centre for Scientific Research), Paris.     

Spermatozoon structure of some North American prosobranchs from the families Lottiidae (Patellogastropoda) and Fissurellidae (Archaeogastropoda)

The spermatozoa of four species of the patellogastropod family Lottiidae (Lottia pelta, L. digitalis, L. strigatella, Tectura scutum) and one species of the archaeogastropod family Fissurellidae (Diodora aspera) were examined in 1990 using transmission electron microscopy. All have primitive or ect-aquasperm, typical of invertebrates using external fertilization. Sperm of the lottiid limpets are characterized by a 5 to 9 m-long head composed of a conical acrosome which constitutes >50% of the head length, and a cylindrical nucleus. The acrosome of all species of lottiids is differentiated internally, and has a posterior invagination 0.9 to 1 m in depth, into which an elongate acrosomal lobe protrudes. Between the posterior acrosomal lobe and the nucleus, the subacrosomal material is aggregated as a fibrous column. The midpiece of the sperm has a ring of 4 to 5 spherical mitochondria of 0.6 m diam, posterior to which is a collar of cytoplasm 1 m long, which sheaths the anterior portion of the axoneme. The size and morphology of the acrosome and large cytoplasmic collar clearly distinguish the spermatozoa of the Lottiidae from other families of Patellogastropoda. The sperm of D. aspera (Fissurellidae) is typical of the family of archaeogastropod; the head has a length to breadth ratio of 4:1, and the cylindrical nucleus is capped by a small acrosome, <25% of the total head length, which is deeply invaginated.     

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.     

SIMCA principal component analysis of fatty acid patterns in Day-1 and Day-8 cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) eggs

Single cod [Gadus Morhua (L.)] and haddock [Melanogrammus aeglefinus (L.)] eggs from the first day and the eighth day after fertilization were acid hydrolised. Fatty acids were liberated and derivatized to methyl esters in a one-step reaction. The non-polar hexane extract was analysed by High Resolution Gas Chromatography (HRGC). Selected peaks, occuring in both types of samples and in all chromatograms, were used to create a matrix for multivariate analysis. HRGC and Mass Spectrometry have been used to identify the fatty acids. The approach is shown to be useful in distinguishing between cod and haddock eggs at both stages and information regarding changes in the fatty acid distributions are obtained. Implications on future possibilities within chemosystematics are discussed.     

Gonadosomatic and hepatosomatic indices of the freshwater fish Notopterus notopterus (Pallas) in response to some heavy metal exposure

Area wise, the measurement of LC50 for pollutants is of great value in predicting the safe concentration dose of the contaminant in the environment on different aquatic species. The lethality of toxic substances including heavy metals to the aquatic organisms are usually assessed by following static bio-assay or continuous flow methods. The toxicity tests for mercuric chloride (HgCl2), cadmium chloride (CdCl2) and their mixture on Notopterus notopterus was determined by using 96h LC50 concentration on fish N. notopterus which indicated that cadmium chloride (CdCl2) was less toxic and mercuric chloride (HgCl2) was most highly toxic. The order of toxicity is mercuric chloride > mixture > cadmium chloride. On the basis of gonadosomatic index the reproductive cycle of N. notopterus can be categorised into immature, developing, maturing, mature, ripe and spent stages. Liver forms important organ of the body, which has a role in the ovarian development. On exposure to heavy metals at sublethal concentration both GSI (gonadosomatic index) and HSI (hepatosomatic index) are reduced.     

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 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.     

Impaired behavior and changes in some biochemical markers of bivalve (Ruditapes decussatus) due to zinc toxicity

Susceptibility and response of bivalves, the clam Ruditapes decussatus, to zinc (Zn) were studied by monitoring behavior using valve movement and some biochemical parameters. The LC₅₀ was 4.1 mg L^?1 at 7 days. Depuration of Zn from their tissues was also followed. Accumulation of Zn increased with concentration and duration of exposure. After 20 days, Zn caused impairment of valve movement as well as the antioxidant system, decreasing glutathione and protein levels and increasing the lipid peroxidation which is indicative of oxidative damage. Results suggested that behavior and biochemical parameters of clam R. decussatus were sensitive and suitable responses for assessing the effects of Zn on the aquatic ecosystems. It could be concluded that there is a time–dose–response relationship of Zn with behavior and oxidative stress of R. decussatus.     

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.     

Sperm competition in the damselfly Enallagma hageni Walsh (Odonata: Coenagrionidae): benefits of multiple mating to males and females

Summary Sperm competition was investigated in the non-territorial damselfly, Enallagma hageni. Using irradiated (sterile) male techniques, the last male to mate was found to fertilize up to 95% of the eggs of the first clutch laid after mating. Dissection of females collected before, during, and after copula showed that a male removes a maximum of 87% of the sperm by volume of a previous mate. These data verify an earlier estimate of lifetime reproductive success in this species which was based on mating success, and suggest that indirect dissection methods offer minimum estimates of sperm precedence. Male E. hageni have ample opportunity to benefit from sperm precedence, since at least 10% of the receptive females encountered had already mated once that day, but still contained complete or partial clutches of eggs. Female E. hageni benefit directly from high sperm precedence because it allows them to exchange matings for guarding service by males during oviposition bouts under water.     

A proteomic approach to the study of the marine mussels Mytilus edulis and M. galloprovincialis

In this study, a proteomic approach was applied for the generation of reference maps and subsequently to detect, quantify and compare the global protein expression between two related species of marine mussels, Mytilus edulis and Mytilus galloprovincialis, growing in their own geographical habitats. A comparative study of the protein profiles generated from analytical two-dimensional electrophoresis gels was performed, and changes in protein expression were analysed quantitatively by computer analysis. An average of 1,278 spots per gel was detected in 16 individuals (8 M. edulis and 8 M. galloprovincialis); however, not all spots were included in the study. Expression of 420 spots was compared, and significant differences in the intensity levels were detected in 37 protein spots (8.8%). Fifteen proteins showed higher expression in M. edulis, and 22 proteins, in M. galloprovincialis. The technique of peptide mass fingerprinting using MALDI-TOF (matrix-assisted laser desorption ionisation/time-of-flight) and/or nanoelectrospray double subfragmentation mass spectrometry enabled the unambiguous identification of 15 of these 37 differentially expressed proteins. Most of the identified proteins can be grouped basically into four broad functional classes: cytoskeletal and myofibrillar proteins, proteins associated with stress response, proteins associated with the storage or production of energy, and proteins related to rearrangement in the synthesis of native structures. These results expand our understanding of the molecular differentiation of the two mussel taxa and serve as a useful base for future ecological, physiological and genetic studies.     

Variation in strength of attachment to the substrate explains differential mortality in hybrid mussel (Mytilus galloprovincialis and M. edulis) populations

Mussel samples were collected from a hybrid mussel (Mytilus galloprovincialis and M. edulis) Population at Croyde, southwest England, in January, March and May 1990. The strength of attachment of each mussel to the substrate was measured with a spring balance. A number of diagnostic characters were also recorded. These are shell lengh, width and height, mantle colour and genotype at two allozyme loci, esterase-D and octopine dehydrogenase. Multiple-regression analysis was used to assess the effect of the diagnostic characters on strength of attachment as dependent variable. Mussels possessing the relatively high shells and darker mantle colouration characteristic of M. galloprovincialis had higher values, on average, for strength of attachment than mussels resembling M. edulis. Phenotypically intermediate mussels had intermediate values for strength of attachment. The results suggest an adaptive difference which can account for reports of differential mortality acting in favour of M. galloprovincialiis.