bluuebunny/crossref_metadata_2025 huggingface dataset:
Age and growth of the southern blue whiting Micromesistius australis in the SW Atlantic
Authors: Cassia Maria Cristina
Published: October 2008

Age and growth of southern blue whiting Micromesistius australis are studied. Sagitta otoliths from 3650 specimens were used for age determination. These were taken during research surveys and commercial catches in the South West Atlantic during 1994 and 1995. The size of fishes ranged from 17 to 60 cm total length, corresponding to ages 0 to 23 years. Females attained a greater asymptotic length (L? 59.74 cm) than males (L? 54.72 cm). Comparison of growth curves by the likelihood ratio showed that the differences among females and males were due to the asymptotic length, while the other parameters (K and t0) were not statistically different. The mean weight-at-age, mean length-at-age, and total mortality (Z) were estimated. Growth parameters estimated by sex in the period 1994-95, mean size per age group, and the number of individuals per age in the catches show differences with those calculated when the population was in the early stage of exploitation. A predominance of 2 to 9 year old individuals was observed in the total catches in 1994-1995, whereas in the beginning of the fisheries total catches were basically fish 15 to 19 years old.
The exotic crab Percnon gibbesi (H. Milne Edwards, 1853) (Decapoda, Grapsidae) in the Central Mediterranean
Authors: Relini M. , Orsi L. , Puccio V. , Azzurro E.
Published: October 2008

The grapsid crab Percnon gibbesi (H. Milne Edwards, 1853), not previously recorded in the Mediterranean, has been found by underwater observations in several localities of Linosa, Pelagie Islands, (Italy). This presence increases the list of alien Decapods in the Mediterranean, with a form which can be considered a western migrant.
The reproductive biology of Spondyliosoma cantharus (L.) from the SW Coast of Portugal
Authors: Gonçalves J. M.S. , Erzini K.
Published: October 2008

The study of Spondyliosoma cantharus (L.) reproduction was carried out within the framework of a project on the fisheries resources of the south-west coast of Portugal, and was based on the analysis of the spawning season, gonad maturation, size-at-maturity, fecundity, and hermaphroditism. Spawning took place from February to April, peaking in March. Analysis of the sex ratio by size class and season showed that females were more abundant throughout the year (M/F=0.57) and in the smaller size classes. Overall size at first maturity (L50) was 20.10 cm total length (TL), with a significant difference between males (22.41 cm, TL) and females (19.98 cm, TL). Absolute fecundity (Fa) ranged from 37,506 to 112,074 oocytes, with a mean of 61,396. A power type relationship best described the relationships between absolute fecundity and TL (Fa = 436.27TL1.575), and somatic weight (Fa = 2979.7SW0.585). The number of oocytes/g of female somatic weight ranged from 217 to 549, with a mean of 346. The reproductive strategy of this species is characterised by protogynic hermaphroditism, as indicated by the presence of individuals in transition and of testes with vestiges of preceding ovaries associated with the significant differences in the size frequency distributions of the sexes.
Field calibration of optical sensors for measuring suspended sediment concentration in the western Mediterranean
Authors: Guillén J. , Palanques A. , Puig P. , Durrieu de Madron X. , Nyffeler F.
Published: October 2008

The water turbidity measured with optical methods (transmittance and backscattering) is usually expressed as beam attenuation coefficient (BAC) or formazin turbidity units (FTU). The transformation of these units to volumetric suspended sediment concentration (SSC) units is not straightforward, and accurate calibrations are required in order to obtain valuable information on suspended sediment distributions and fluxes. In this paper, data from field calibrations between BAC, FTU and SSC are presented and best-fit calibration curves are shown. These calibrations represent an average from different marine environments of the western Mediterranean (from estuary to continental slope). However, the general curves can only be applied for descriptive or semi-quantitative purposes. Comparison of turbidity measurements using the same sensor with different calibration ranges shows the advantage of simultaneously combining two instruments calibrated in different ranges when significant changes in suspended sediment concentrations are expected.
Estimating the size of Uca tangeri (Crustacea: Ocypodidae) without massive crab capture
Authors: Lourenço R. , Paula J. , Henriques M.
Published: October 2008

Uca tangeri (Eydoux, 1835) is the only species of fiddler crab that occurs in Portugal, where it mainly inhabits salt marshes in the south and southwest coasts. Individuals spend most of their time on and around their galleries, burrowing structures which they typically create and maintain in muddy substrate. Capturing fiddler crabs in nature is extremely difficult and can be destructive for their habitat. Once disturbed, U. tangeri tend to hide in their burrow, and their capture usually involves the destruction of the upper part of the burrow. In the present study, a method for estimating the carapace length of the fiddler indirectly, using the diameter of the burrow opening, is proposed. Significant sex-specific relationships between the diameter of the burrow opening and the occupant´s length were found. Although the mean length of the carapace was not significantly different between sexes, males were found to be associated with smaller galleries, probably in order to prevent larger males entering their galleries.
The effects of exposure to wave action on the distribution and morphology of the epiphytic hydrozoans Clava multicornis and Dynamena pumila
Authors: Rossi Sergi , Gili Josep Maria , Hugues R. G.
Published: October 2008

The spatial distribution patterns of two species of epiphytic hydrozoans, Clava multicornis and Dynamena pumila, on the intertidal alga Ascophyllum nodosum were studied in adjacent wave-sheltered and wave-exposed areas. Clava were more abundant on the wave-sheltered algae than on the wave-exposed fronds, and in both areas occupied the basal and middle sections of the algae. There was no difference in the abundance of Dynamena between the wave-sheltered and wave-exposed areas, but in both areas Dynamena were most abundant on the basal and apical sections of the algae than on the central sections. The number of hydranths per colony of Clava was higher in the sheltered area than in the exposed area. The hydrocauli of Dynamena on the wave-exposed algae bore fewer hydrothecae than those on the sheltered algae. The proportion of Dynamena hydrothecae that contained hydranths was close to 100% in the sheltered area, but only 70% in the exposed area. It was concluded that variations in distribution and morphology could be caused by the direct or indirect effects of one or more variables, including wave action, feeding rates, and exposure to solar radiation. Experiments are required to elucidate the specific effects of these variables.
Additional notes on Clathrozoella drygalskii (Vanhöffen, 1910) (Cnidaria, Hydrozoa)
Authors: Vervoort W.
Published: October 2008

Study of the material of Clathrozoella drygalskii (Vanhöffen, 1910), a hydroid initially referred to the thecate hydroids but probably better classified in athecate hydroids along with such families as Hydractiniidae and Solanderiidae, has been continued with the help of sectioned material. Owing to the conditions of the material available, sectioning proved to be quite difficult; this combined with the poor condition of preservation provided inadequate and inconclusive results, as a result of which the taxonomic position of this enigmatic genus could not be definitely clarified. However, available evidence seems to suggest that the genus Clathrozoella Stechow, 1921, contains at least three species of which one, C. drygalskii, occurs in Antarctic, New Zealand and Australian waters, a second to the south of Stewart Island south of New Zealand, and a third exclusively (so far) in the Antarctic. Histological details of the two additional species are still lacking and information on the cnidome of the three species is still insufficient.
A guideline to nematocyst nomenclature and classification, and some notes on the systematic value of nematocysts
Authors: Östman Carina
Published: October 2008

Cnidocyst nomenclature is based on the structure of the tubule and its armature as viewed in the light microscopy (LM). Investigations utilising optically improved LM and scanning electron microscopy have revealed some errors in the interpretation of the fine structure of tubules and armature of nematocysts. Categories of nematocyst have been modified, therefore, to incorporate observations made with new visualising techniques. Isorhizas are defined as nematocysts whose tubule is of uniform or nearly uniform thickness proximal to the midpoint, while b-mastigophores are nematocysts with a rod-shaped encapsulated shaft and a prominent armature on the everted shaft. The category of amastigophores is retained but redefined as p-amastigophores for the V-shaped notch at the base of encapsulated shaft. The trirhopaloids are found to be similar to the birhopaloids. Mesobasic is redefined as an intermediate length of discharged shafts between micro- and macrobasic. Astomocnidae is redefined as entangling nematocysts and stomocnidae as penetrants.
Total lipid in the broodstock diet did not affect fatty acid composition and quality of eggs of sea bass (Dicentrarchus labrax L.)
Authors: Navas José Mª , Thrush Mark , Zanuy Silvia , Ramos Jesus , Bromage Niall , Carrillo Manuel
Published: October 2008

To determine whether an increase in the quantity of lipids ingested by sea bass (Dicentrarchus labrax) broodstock could improve egg quality, three year-old sea bass were fed three different diets: a natural diet (Control group), and two artificial diets containing 10% or 17% of total lipids. In two consecutive reproductive seasons, the spawning results, the lipid classes and the fatty acid composition of the eggs were studied. No differences in the absolute content of lipids or in the percentage of different lipid classes were observed between the eggs from the three groups. Both experimental groups fed with the artificial diets produced eggs of poor quality, with low percentages of buoyancy and hatching. Those observed in the eggs from the Control Group were significantly higher (p> 0.01) than those of the experimental groups. The higher hatching rate of the eggs from the Control Group was associated with higher DHA:EPA and AA:EPA ratios. The data obtained showed that the fatty acid composition of the eggs was affected by the fatty acid composition of the diets but not by the total quantity of lipids administered to the broodstock.
Spawning of the chilean hake (Merluccius gayi) in the upwelling system off Talcahuano in relation to oceanographic features
Authors: Vargas Cristian A. , Castro Leonardo R.
Published: October 2008

Previous studies have shown that the upwelling area off Talcahuano, in central-south Chile, is an important spawning zone for the hake Merluccius gayi. We document the results of a study designed to assess the importance of oceanographic features on the horizontal and vertical distribution of hake eggs and larvae. Ichthyoplankton samples and oceanographic data (CTDO casts, and wind speed and direction) were collected during a cruise carried out off Talcahuano (36º22´S-37º10´S) in early spring (October 1996), which included a grid of 61 stations up to 60 nm offshore. The oceanographic information obtained revealed the presence of an upwelling plume at Lavapie Point (southern zone) extending northward over the shelf, and the presence of a warmer water parcel close to shore in the northern area. Peak egg densities occurred in this northern area over the shelf, in a nucleus located at the shoreward moving deeper layer (40-100 m deep) and associated with the upwelling front about 20-30 nm from shore. The highest larval abundance also occurred in the northern area over the shelf and in the deeper layer but closer to shore than the egg nucleus. Because the timing (early spring) and location of spawning (at depth, over the shelf and in association with frontal structures) are also shared by other hake species in upwelling areas, we propose that they may be part of a more commonly developed strategy to enhance offspring survival in coastal upwelling areas of eastern boundary currents.
Macrobenthic mollusc fauna inhabiting Halopteris spp. subtidal fronds in Sao Miguel Island, Azores
Authors: Costa Ana Cristina , Avila Sergio Paulo
Published: October 2008

The molluscan community structure (species composition, abundance, density and diversity) associated with common brown algae Halopteris spp. at seven subtidal sites on São Miguel island (Azores) wase studied and checked for differences between sites. A total of 8,921 specimens (29 species of Gastropoda, 7 species of Bivalvia) were recorded. Bittium sp., the most common species, representing 85.6% of the total number of molluscs sampled, was present at each site and the number of taxa found at each station ranged from 3 to 17. Four species (Bittium sp., Setia subvaricosa, Tricolia pullus azorica and Rissoa guernei) accounted for 96.6% of all the specimens sampled. The density of the molluscs reached 18,000 specimens/100 g of algal dry weight (ADW). No significant differences in species diversity were found between sites. Further multispecies analysis between sites were conducted with both clustering and ordination techniques, and showed some separation between samples from south and north locations. The species responsible for this separation were the endemic Azorean Rissoids Rissoa guernei and Setia subvaricosa.
Study on the early larval development and growth of the red porgy, Pagrus pagrus with emphasis on the mass mortalities observed during this phase
Authors: Conides Alexis J. , Glamuzina Branko
Published: October 2008

The purpose of this study was to determine the early growth scheme and development stages of the red porgy, Pagrus pagrus larvae through the transition from endogenous and exogenous food sources using as main criterion the body length gained at each development stage. The initial period of the species´ larval life can be divided into three phases: a) an initial phase characterised by no motility (0-24 h time after hatching; TAH); b) a phase characterised by active movement and exploitation of the endogenous food reserves (24 h to 96 TAH); and c) a phase characterised by the transition from endogenous to exogenous food (96 to 168 TAH). It was observed that there does not exist an overlapping period between phases b and c and therefore, there exists a gap of 24-36 hours during which the larvae have exhausted their internal food reserves (oil globule and yolk sac) while the digestive tract is not ready to digest external food items (rotifers). We observed a massive larval mortality reaching almost 85% between days 3 and 7 after hatching.
Spatial distribution of annelids in the intertidal zone in Sao Sebastiao Channel, Brazil
Authors: Rizzo Alexandra E. , Z. Amaral A. Cecilia
Published: October 2008

We studied the spatial distribution of annelids in the intertidal zone of two beaches (Engenho d´Água and São Francisco) in São Sebastião Channel, southeastern Brazil, from August 1995 through July 1996. This region is commonly affected by oil spills and sewage waste. The substratum of the two beaches is composed of a mixture of sand and rock fragments. We established three levels (100 m2) in the intertidal zone of each study site: lower, intermediate, and upper. In general, species richness increased from upper towards lower levels. The distribution of species at Engenho d´Água was more homogeneous than at São Francisco. Only some individual spatial patterns were recognised at São Francisco. The most abundant polychaete species at Engenho d´Água (Nematonereis hebes, Timarete filigera, and Scyphoproctus djiboutiensis) occurred in the intermediate and lower levels. The upper level of São Francisco was characterised by a peak of opportunists, with a large number of individuals but few dominant species (Capitella sp., Scolelepis squamata, Laeonereis acuta, and the oligochaete Tubifex sp).
Gut evacuation rates in Nephrops norvegicus (L., 1758): laboratory and field estimates
Authors: Cristo Margarida
Published: October 2008

Estimates of gut evacuation rates of Nephrops norvegicus (Linnaeus, 1758) (Crustacea, Decapoda) were obtained during laboratory and field experiments. Individuals were collected off the south coast of Portugal in December 1997 and July 1998. Gut evacuation rates (R.h-1) were calculated from the slope of the regression of the natural logarithm of dry stomach content weight versus time, using data obtained by the serial slaughter method. The values obtained during laboratory (R=0.172 h-1) and field experiments (R=0.177 h-1) are compared with gut evacuation rates reported for other marine organisms. The results obtained for both experiments are within the range of the values in the literature, even in the case in which different methodologies were used.
Nivmar: a storm surge forecasting system for Spanish waters
Authors: Álvarez Fanjul Enrique , Pérez Gómez Begoña , Rodríguez Sánchez Arévalo Ignacio
Published: October 2008

In this paper, a storm surge prediction system for the Spanish Waters is presented. The system, named Nivmar, is based on the ocean circulation Hamsom model and on the harmonical prediction of tides computed from data measured by the tide gauge network Redmar, managed by Puertos del Estado. Nivmar is executed twice a day, running Hamsom forced by meteorological fields derived from the INM (Instituto Nacional de Meteorología) operational application of Hirlam atmospheric model. Data from Redmar tide gauges is used to to forecast the tidal elevations, to validate the system and to perform data assimilation, correcting systematic errors in the mean sea level due to physicals processes that are not included in the ocean model (i. e. steric height). The forecast horizon is 48 hours. In order to validate the system with measured data from Redmar a very stormy 5 months period was selected. Results from this test (November 95 to March 96) are presented. Data from this experiment shown that Nivmar is able to correctly predict sea level in the region. A simple data assimilation scheme for sea level is described and results from its application are studied. Finally, special focus is made in future plans and potential developments and applications of the system.
Water masses, circulation and transport in the eastern boundary current of the North Atlantic subtropical gyre
Authors: Hernández-Guerra Alonso , López-Laatzen Federico , Machín Francisco , De Armas Demetrio , Pelegrí J. L.
Published: October 2008

CTD sections carried out in September 1998 are used to describe the water masses, geostrophic circulation and mass transport in the easternmost branch of the Canary Current. The surface water mass (< 600 m) consists of North Atlantic Central Water (NACW) flowing south with a net mass transport of 2.3 x 109 kg s-1. A tongue of relatively fresh water, consisting of Antarctic Intermediate Water (AAIW), was found approximately in the 600-1100 m depth layer. This tongue was 200 km wide, stretching from the African coast almost to Gran Canaria Island, and transported a net mass of 1.1 x 109 kg s-1 northward. This system of currents is what constitutes the real eastern boundary current of the North Atlantic Subtropical Gyre.
Residual circulation and thermohaline distribution of the Ría de Vigo: A 3-D hydrodynamical model
Authors: Torres López S. , Varela R. A. , Delhez E.
Published: October 2008

A three-dimensional, non-linear, baroclinic model is described and tested for the first time to study the residual circulation and the thermohaline distribution of the Ría de Vigo (NW Spain) at short time scales and under different wind stress regimes. Two markedly different realistic scenarios were chosen: northerly upwelling-favourable winds and southerly downwelling-favourable winds. The numerical experiments carried out indicate that the hydrodynamic regime of the Ría de Vigo is mostly a consequence of wind events. As could be expected, moderately strong North winds reinforce the normal (positive) Ría circulation, while winds blowing from the South, when sufficiently strong, reverse the typical circulation pattern and reduce the characteristic outgoing velocities and the flushing time inside the Ría. The temperature and salinity fields generated by the model in both situations were compared with observations and found to be in qualitatively good agreement, supporting the 3D velocity field distribution.
Phytoplanktonic biomass synthesis: application to deviations from Redfield stoichiometry
Authors: Fraga Fernando
Published: October 2008

During biomass formation as a result of phytoplankton photosynthesis, CO2 and the nutrients NO3 and PO4 are consumed and O2 produced in fixed proportions known as the Redfield ratio. Broecker’s tracers, i.e., “NO” = O2+RN·NO3, “PO” =O2+RP·PO4, and “CO” = O2+RC·CO2, remain constant during photosynthesis, because nutrients consumed are offset by O2 formation. When one or several nutrients become depleted, the Redfield ratio no longer holds, and the tracers cease to remain constant. The main causes are formation of excess carbohydrates or lipids, N2 fixation, or production of CaCO3 plates by phytoplanktonic populations that have developed different strategies for obtaining the nutrients they need. This paper presents new tracers that remain constant, irrespective of whether or not Redfield stoichiometry is satisfied. Differences between the values of the new tracers and the values of the conventional tracers reveal the presence of anomalies in biomass production. They also allow quantification of any such anomalies, both globally and by depth stratum, and assessment of each individual anomaly separately, even when more than one anomaly occur simultaneously.
The top layers of water bodies, a most important although relatively neglected piece of the biosphere plumbing
Authors: Margalef Ramón
Published: October 2008

Reducing power from light is used by plant life in ways that shift along ecological succession. When nutrients are non limiting, growth prevails; when essential nutrients (in the first place P) become scarce, reducing power is applied somehow and otherwise, often, as in red tides, in the synthesis of toxics. On land, the same reducing capacity results in the production of wood, terpenes, essences, cork or rubber. In water bodies, reduction of nitrate at least adds nitrite to the environment. Very likely this explains the common presence of nitrite-enriched layers around the levels of twilight. A large fraction of the generating capacity might be expected to come from the small prokaryota of phytoplankton, which almost global ubiquity and capacity to persist alive in a state of forced minimal activity are known. The result might be a kind of one-way plankton surface valve, that isolates partially and in some chemical aspects the deeper ocean from the top layers. One could perhaps speak of a surface valve with a planetary role.
Karyotypes of three species of toadfish (Batrachoididae: Teleostei) from Venezuela
Authors: Nirchio M. , Turner B. J. , Pérez J. E. , Gaviria J. I. , Cequea H.
Published: October 2008

Karyotypes of three species of toadfish (Amphichthys cryptocentrus, Batrachoides manglae and Thalassophryne maculosa), reported here for the first time revealed diploid complements of 46 chromosomes. Karyo-evolutionary trend of these species is discussed. Based on differences in arm number, we suggest that T. maculosa possesses the most evolved karyotype among the three species, hence it would be the more recent one, followed by B. manglae and A. cryptocentrus.
SEM study of Anisakis brevispiculata Dollfus, 1966 and Pseudoterranova ceticola (Deardoff and Overstreet, 1981) (Nematoda: Anisakidae), parasites of the pygmy sperm whale Kogia breviceps
Authors: Abollo Elvira , Pascual Santiago
Published: October 2008

Scanning Electron Microscopy (SEM) was used to study different topo-morphological characteristics of the architecture (cuticle, excretory pore, lips and adjacent structures, number and distribution patterns of caudal papillae and papillae-like structures) of the anisakid nematodes Anisakis brevispiculata and Pseudoterranova ceticola, parasites in the stomach of the pygmy sperm whale Kogia breviceps. SEM micrographs herein help to accurately define the above surface topographical features by adding a more adequate 3-D picture to the original descriptions of both parasitic species. In A. brevispiculata the entire body cuticle structure, well-differentiated paracloacal papillae and the wrinkle cuticle of the papillae are clear examples that enhance the above differentiation of structures as seen by LM or SEM. Similarly, in P. ceticola the cuticle striations, bulky cloacal lips, rectangular distribution pattern of distal papillae and the absence of a groove separating paracloacal papillae which are obliquely arranged are all different to those features previously described.
A new species of Austrofilius (Crustacea, Isopoda, Janiridae) from Western Mediterranean
Authors: Castelló José
Published: October 2008

A new species of janiridean isopod, Austrofilius mediterraneus sp. nov., from the Columbretes Islands (Castellón de la Plana), Mediterranean coast of the Iberian Peninsula, is described, given it is the first record of the genus in the Northern Hemisphere. It is mainly distinguished from the other two species of the genus by the male pleopod 1, which is wider at the apex and with hooked lateral lobes, curved and nearly surpassing medial lobes. Furthermore, the female operculum shows only four distolateral setae. The rostrum of Austrofilius mediterraneus sp. nov. is extended into single frontolateral tips but is shorter than in A. furcatus Hodgson, 1910.
The feeding behaviour of some demersal fish species in response to artificial discarding
Authors: Olaso Ignacio , Sánchez Francisco , Rodríguez-Cabello Cristina , Velasco Francisco
Published: October 2008

In an attempt to detect changes in the diet and the feeding intensity of demersal fish caused by fishery discarding, two hauls were carried out 22 h apart at a depth of 90 m in an area of the Cantabrian Sea closed to trawling. Before the second haul, dead fauna that were not common in the sampling area under natural conditions, such as Micromesistius poutassou and squat lobster (Munida spp.), which are both usually discarded by the fleet and mainly found in deeper water, were thrown overboard. A total of 319 stomach contents from 12 demersal fish species caught in both hauls were analysed. The percentage emptiness decreased in the second haul (32%) with respect to the first (43%), and at the same time the feeding intensity of scavenger species such as Trachinus draco, Pagellus acarne, Scyliorhinus canicula, Raja montagui and Leucoraja naevus increased. Discards of M. poutassou was actually found in the stomach of a typically planktophagous species, Pagellus bogaraveo. Observed changes in trophic structure of the species analysed as a response to discards are discussed.
The Indo-Pacific striped eel catfish, Plotosus lineatus (Thunberg, 1787), (Osteichtyes: Siluriformes), a new record from the Mediterranean
Authors: Golani Daniel
Published: October 2008

The striped eel catfish, Plotosus lineatus (Thunberg, 1787), is recorded for the first time from the eastern Mediterranean coast of Israel. Seventeen specimens of this highly-venomous fish were caught by a commercial trawler at depths of 20 m. This species´ occurrence in the Mediterranean is the result of migration from the Red Sea via the Suez Canal (Lessepsian migration).
The status of three rare siphonophores (Cnidaria, Hydrozoa) described by Tamiji Kawamura: Bathyphysa japonica, Athorybia longifolia and Forskalia misakiensis
Authors: Pagès Francesc
Published: October 2008

The holotypes of three species inquirendae siphonophores collected in Japanese waters and described by Tamiji Kawamura were re-examined. It is considered that Bathyphysa japonica is not a valid species because there are no characters that distinguish it from other Bathyphysa species; Athorybia longifolia is an incorrectly described specimen of A. rosacea; and Forskalia misakiensis is a wrongly described and badly preserved specimen, probably of F. edwardsi.
Gill net and long-line catch comparisons in a hake fishery: the case of southern Portugal
Authors: Santos Miguel N. , Gaspar Miguel B. , Monteiro Carlos C. , Vasconcelos Paulo
Published: October 2008

During 1998, a study of the European hake (Merluccius merluccius) static gear fishery was undertaken in southern Portugal. This study aimed to compare long-line and gill net catches within the same area in terms of catch composition, fishing yield, by-catch and discards, and specifically for hake, catch size frequency distribution and quality of the fished product. At least 35 species of fish and invertebrates were caught, with hake dominating the catches in terms of both weight and number. The by-catch represented 23% and 15% of the catch in weight for long-lines and gill nets respectively. No illegal sized hake (under 27 cm total length) were caught in either gear during the study period. Discards of non-commercial species were similar for both gears and considered to be negligible (< 3% by weight). Hake discards were significantly different between gears (7% for long-lines and 42% for gill nets, by weight), due to fish deterioration related to soaking time. Higher daily yields were obtained for long-lines (258.37 kg / 9,000 hooks) compared with those for gill nets (127.12 kg / 10 km net). These findings will help to improve the management and conservation of this valuable hake fishery.
Larval condition and growth of Sardinella brasiliensis (Steindachner, 1879): preliminary results from laboratory studies
Authors: Del Bianco Rossi-Wongtschow Carmen Lúcia , Clemmesen Catriona , Ueberschär Bernd , Ferraz Dias June
Published: October 2008

Brazilian sardine, the most important resource along the southeastern Brazilian coast, presented great variations and declines in its stocks. The main factors contributing to this are: oceanographic structure changes; recruitment failures; excessive catches of juveniles and increase in fishery effort. In spite of this, no alterations in the density-dependent parameters were detected. Consequently, methods analysing the condition of the larvae coupled with methods determining growth using sagittae otolith increment width were applied to evaluate growth under experimental conditions. The results of the readings on the sagittae were compared with the age of the laboratory-reared sardine larvae and confirmed that increments are formed on a daily basis. Under poor feeding conditions, sardine larvae showed a low growth expressed by dry weight, RNA/DNA ratio and tryptic enzyme activity and by the narrow and low contrast increments in the otoliths. The results of the biochemical indices showed an unexpected decline in the feeding group coupled with a decrease in width of increment numbers 8 and 10. Other factors than food availability were affecting the condition of the larvae and might be indicative of physiological processes and ontogenetic changes occurring in sardine larvae.
Variations in planktonic bacterial biomass and production and phytoplankton blooms off A Coruña (NW Spain)
Authors: Valencia Joaquín , Abalde Julio , Bode Antonio , Cid Angeles , Fernández Emilio , González Nicolás , Lorenzo Jorge , Teira Eva , Varela Manuel
Published: October 2008

Bacterial abundance, biomass and heterotrophic activity, along with hydrographic and phytoplankton variables, were measured from February 1998 to September 1999 at two coastal stations off A Coruña (Galicia, NW Spain). Bacterial abundance varied from 0.1 to 1.8 x 106 cells ml-1 and water-column integrated bacterial production ranged from 34 to 1132 mg C m-2 d-1. Two annual maxima of bacterial abundance and production were observed, in spring and summer, although relatively high abundance values remained until autumn. In autumn and winter production values were low with the exception of the results obtained in November 1998, when the highest values of bacterial production of the whole study were observed at both stations. Bacterial biomass constituted a significant, but low, fraction of particulate organic carbon (4-21 %) and was always lower than phytoplankton biomass (up to 40% of phytoplankton carbon). Also, bacterial production was generally < 30% of primary production, but in some situations (as in early spring or in autumn) bacterial production exceeded primary production, suggesting a delayed response of bacterial activity after a phytoplankton bloom.
Two unknown species of Mollusca Gastropoda from the Archipelago Fernando de Noronha (Brazil), with description of a new species belonging to the genus Phidiana Gray, 1850 and a new record of Dendrodoris senegalensis Bouchet, 1975
Authors: García Francisco J. , Troncoso Jesús S.
Published: October 2008

The Brazilian Archipelago of Fernando de Noronha lies off Cape Sao Roque, State of Rio Grande do Norte, about 195 nautical miles offshore. Only a few faunistic lists of this tropical archipelago have been published, and only four species of Gastropoda Opisthobranchia were cited. In this paper two species of Opisthobranchia Nudibranchia are recorded from this Archipelago. Dendrodoris senegalensis Bouchet 1975, known from Cape Verde and Senegal, amplifies its extension range toward the Western Atlantic. The brazilian specimens differ from the African specimens, in the presence of a completely white branchial tuft. Phidiana riosi sp nov clearly differs from other co-generic species in its colour pattern, having a red ground colour, with numerous white spots scattered on the dorsum. The rhinophores are orange and the cerata white with the cnidosac orange. Internally, this species has jaws with a single row of denticles, and the radular teeth have a central cusp with 7-8 denticles each side. The penis is armed with a black spine and the seminal receptacle connects with two independent ducts, the oviduct and the vaginal duct. Both species are compared with other similar taxa.
Otolith morphology and body size relationships for juvenile Sciaenidae in the Río de la Plata estuary (35-36°S)
Authors: Waessle Juan A. , Lasta Carlos A. , Favero Marco
Published: October 2008

Seven species of the family Sciaenidae have been reported inhabiting bottom waters of the Río de la Plata estuary. Of these juvenile stripped weakfish (Cynoscion guatucupa), king weakfish (Macrodon ancylodon), whitemouth croaker (Micropogonias furnieri) and banded ground drum (Paralonchurus brasiliensis) are by far the most abundant. These species are also important prey of several top-predator species among large fishes, seabirds and mammals. In this study we provide new information regarding otolith morphology and body size relationships of juvenile sciaenid fish. The sagittae morphology of juvenile sciaenids showed strong changes in the course of their development (e.g. in overall shape and development of concrescences on the outer surface). Analysing the morphometric relationships, we concluded that otolith length and otolith mass are good indicators of fish standard length and fish weight in all species. If otolith length or mass is used to estimate fish length, the regression explained more than 97% of the variation in all species. All equations relating fish standard length and fish weight for juvenile stages of the species studied explained a very large proportion of the variance in the data. These data will help researchers studying food habits of top predators to determine size and weight of usually juvenile fish-prey from length, broad and/or weight of recovered otoliths.
Patterns of paralytic shellfish toxicity in the St. Lawrence region in relationship with the abundance and distribution of Alexandrium tamarense
Authors: Blasco Dolors , Levasseur Maurice , Bonneau Esther , Gelinas Roger , Packard T. T.
Published: October 2008

Shellfish toxin data from 11 years and Alexandrium tamarense abundance during 6 of those years are analysed. Comparison of PSP toxicity in Mytilus edulis with PSP toxicity in Mya arenaria shows a significant correlation (r2=0.61), with M. edulis being five times more toxic. The results support using M. edulis as a sentinel species for shellfish toxicity in the St. Lawrence region. High interannual variability was found in the PSP and A. tamarense data, but no trends were manifest. Correlation analysis revealed clearly defined geographical station groups. These groups were characterised by seasonal distributions and outbreak times, and were associated with the surface seawater circulation. The results indicate blooms spreading from the open Gulf, upstream toward the Estuary. Since the spring bloom also spreads upstream, we hypothesise that the A. tamarense bloom is just one of the steps in the traditional phytoplankton succession diatoms-dinoflagellates-small flagellates, which is controlled by the classic oceanographic processes of nutrient depletion and water column stratification. A. tamarense distribution over the entire sampled area was similar to the PSP toxicity in M. edulis. In 1993, 59% of PSP variability was explained by A. tamarense. Furthermore, mussel toxin rises with increasing A. tamarense concentration. Shellfish contamination starts as soon as A. tamarense is present in the water. In addition, detoxification starts when A. tamarense decreases below the level of detection. However, the most important finding of this study is that only 1000 A. tamarense cells per litre are sufficient to raise the toxin in the mussels to the level (80 µg STX eq/100 g tissue) at which the closure of shellfish harvesting activities is obligatory.
Biffarius pacificus, a new species of the Callianassidae (Crustacea: Decapoda: Thalassinidea) from northern Chile
Authors: Guzman Guillermo L. , Thatje Sven
Published: October 2008

Nine specimens of Biffarius pacificus sp. nov. were collected with a "van Veen" grab at two sublittoral stations off the northern coast of Chile (Iquique, 22º12´S; Patache, 22º45´S) at depths ranging from 17 to 30 m. This is the first record of the genus Biffarius from the southeastern Pacific Ocean off South America. Biffarius pacificus sp. nov. is closely allied to B. poorei from Tasmanian waters. A detailed differentiation of both species is provided.
Grazing by Diadema antillarum (Philippi) upon algal communities on rocky substrates
Authors: Alves Filipe M.A. , Chícharo Luis M. , Serrao Ester , Abreu António D.
Published: October 2008

Grazing by Diadema antillarum sea urchins is well documented for coral reefs, although information is scarce for the eastern part of the Atlantic Ocean, where rocky substrate dominates the sea bottom. This study analysed grazing activity by D. antillarum upon the algal communities living on rock substrates, and its possible impact on the subtidal communities. Controlled feeding experiments using exclusion cages were performed between May and September 1998 at Madeira Island (NE Atlantic). Three experimental treatments were used: (1) closed cages to exclude sea urchins, (2) open cage controls, and (3) uncaged controls (nine replicates in each treatment). After four months, in September 1998, the percentage algal cover was quantified. One-way analysis of variance followed by Post Hoc Tukey (HSD) tests showed significant differences between algal abundance in the presence (uncaged and open cage controls) or absence (closed cages) of sea urchins. In the areas where D. antillarum was excluded (closed cages), algal abundance increased by about 10% in the four-month period. Diadema antillarum thus effectively reduces algal abundance, and this may have important consequences in determining the algal community structure of rocky substrate.
Quantifying the roles of competing static gears: comparative selectivity of longlines and monofilament gill nets in a multi-species fishery of the Algarve (southern Portugal)
Authors: Erzini Karim , Gonçalves Jorge M.S. , Bentes Luís , Lino Pedro G. , Ribeiro Joaquim , Stergiou Konstantinos I.
Published: October 2008

Fishing trials with monofilament gill nets and longlines using small hooks were carried out in Algarve waters (southern Portugal) over a one-year period. Four hook sizes of "Mustad" brand, round bent, flatted sea hooks (Quality 2316 DT, numbers 15, 13, 12 and 11) and four mesh sizes of 25, 30, 35 and 40 mm (bar length) monofilament gill nets were used. Commercially valuable sea breams dominated the longline catches while small pelagics were relatively more important in the gill nets. Significant differences in the catch size frequency distributions of the two gears were found for all the most important species caught by both gears (Boops boops, Diplodus bellottii, Diplodus vulgaris, Pagellus acarne, Pagellus erythrinus, Spondyliosoma cantharus, Scomber japonicus and Scorpaena notata), with longlines catching larger fish and a wider size range than nets. Whereas longline catch size frequency distributions for most species for the different hook sizes were generally highly overlapped, suggesting little or no differences in size selectivity, gill net catch size frequency distributions clearly showed size selection. A variety of models were fitted to the gill net and hook data using the SELECT method, while the parameters of the logistic model were estimated by maximum likelihood for the longline data. The bi-normal model gave the best fits for most of the species caught with gill nets, while the logistic model adequately described hook selectivity. The results of this study show that the two static gears compete for many of the same species and have different impacts in terms of catch composition and size selectivity. This information will be useful for the improved management of these small-scale fisheries in which many different gears compete for scarce resources.
Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain
Authors: Bischof Kai , Janknegt Paul J. , Buma Anita G.J. , Rijstenbil Jan W. , Peralta Gloria , Breeman Anneke M.
Published: October 2008

The generation of reactive oxygen species (ROS) and scavenging of the superoxide radical by superoxide dismutase (SOD) was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the canopy and on radiation conditions. Samples exposed to the full solar spectrum were most affected, whereas samples either exposed to photosynthetically active radiation (PAR) alone or UV radiation without PAR exhibited fewer peroxidation products. The activity of SOD appeared to be controlled by the impinging UV-A and UV-B radiation and also increased in response to oxidative stress. The results provide evidence for additive effects of high PAR and UV-B under field conditions and support the previously proposed hypothesis that UV-B effects are mediated by an inhibition of the xanthophyll cycle, which increases ROS production and, consequently, causes oxidative damage to components of the photosynthetic machinery, such as proteins and pigments.
The effect of food on the respiration rates of Daphnia magna using a flow-through system
Authors: Schmoker Claire , Hernández-León Santiago
Published: October 2008

Respiration rates and gut fluorescence of the cladoceran Daphnia magna were studied using a flow-through system. This open system has the advantage of introducing food or producing a starvation effect during the course of the experiment. Severe variations in respiratory rates were observed in relation to the presence or absence of food, indicating short-term variability. Organisms kept starved or at low food for a long period (15-20 h) responded to a sudden increase in food by increasing their respiration rates three- to four-fold in parallel with their gut content. A significant relationship between gut fluorescence and respiration rates was observed, suggesting that feeding and the related swimming activity were responsible for the observed metabolic variability.
Reproduction, gonad histology and fecundity of Aidablennius sphynx (Pisces: Blenniidae) of the Catalan Sea (North-Western Mediterranean)
Authors: Carrassón Maite , Bau Marina
Published: October 2008

The reproductive biology of the Mediterranean blenny fish Aidablennius sphinx was studied on the basis of microscopic and macroscopic analysis. A. sphynx is a resident species of the shallow waters of this region, lays demersal eggs and provides parental care to the developing embryos. Mature male gonads occur between March and July, whereas mature females appear between April and August. Male gonads are composed of the testis and the testicular gland. Spermatids are released into the testicular gland. The testicular gland is relatively more prominent than the testis after the reproductive season. Six stages of oocyte development (included atretic ones) are considered. Seasonal variations of gonads of both males and females are illustrated. Low fecundity was recorded, as the ovaries may contain 432 to 1682 oocytes according to female size. Equations describing the relationship between gonad weight and length and weight of males and females are presented. Equations describing the relationship between absolute individual fecundity and length and weight of females are also presented.
Attendance of scavenging seabirds at trawler discards off Galicia, Spain
Authors: Valeiras Julio
Published: October 2008

The occurrence of scavenger seabirds at fishing trawlers was studied off Galicia, Spain. A total of 9,368 seabirds of 23 species were recorded during 92 fishing operations in 1998 and 1999. The most common species were the yellow-legged and lesser black-backed gull (Larus cachinnans and L. fuscus), Sabine´s gull (L. sabini), the northern gannet (Morus bassanus), the great shearwater (Puffinus gravis), sooty shearwater (P. griseus), the Manx and Balearic shearwater (P. puffinus and P. mauretanicus), the great skua (Catharacta skua) and terns (mainly Sterna hirundo and S. paradisaea). Other species occurred in small numbers: Leach´s petrel (Oceanodroma leucorhoa), the storm petrel (Hydrobates pelagicus), the little shearwater (Puffinus assimilis), Cory´s shearwater (Calonectris diomedea), the parasitic skua (Stercorarius parasiticus), the pomarine skua (S. pomarinus), the black-headed gull (Larus ridibundus), the glaucous gull (L. hyperboreus), the kittiwake (Rissa tridactyla), the sandwich tern (Sterna sandvicensis), the black tern (Chlidonias niger), the guillemot (Uria aalge) and the little auk (Alle alle). The maximum number of seabirds recorded at a haul was 320. The maximum number of a particular species ranged from 120 great shearwaters to 250 yellow-legged/lesser black-backed gulls during a single haul. The differences in ship-follower species abundance are related to migratory movements but fisheries could also have a strong influence at a smaller scale on the distribution of seabirds off Galicia. The degree to which seabirds rely on fishery discards as food was not quantified, but may be important for several species.