bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology and LPS content for the estimation of marine bacterioplankton biomass in the Ionian Sea
Authors: La Ferla Rosabruna , Lo Giudice Angelina , Maimone Giovanna
Published: October 2008

The abundance, morphotypes and biomass of the bacterial assemblages were investigated in the Ionian Sea by using two different methods: the epifluorescent microscopy technique for enumerating and sizing bacterial cells, and the determination of bacterial lipopolysaccharides (LPS). Five bacterial morphotypes were distinguished: cocci, rods, coccobacilli, vibrios and spirillae. The proportions of cocci were higher than those of other morphotypes at every depth, ranging from 39% to 73%. Both rod-shaped bacteria and coccobacilli were homogenously distributed in the water column, while the proportions of vibrios were rather variable. Spirillae occurred only in surface samples and disappeared below 100 m. The two methodologies were compared: LPS concentrations showed a highly significant correlation with the bacterial numbers (P< 0.01; n= 88; r= 0.68), but not with biovolumes, and different ratios between LPS concentrations and bacterial volumes were recorded for the photic and aphotic zones (3.11 ± 1.35 and 0.96 ± 0.37 ng LPS per µm3 respectively). LPS-derived cell carbon content on average was 23 fg C cell-1, similar to the C amount derived by mean cell biovolume (19 fg C cell-1) and the biomass from two highly correlated methods (P< 0.01; n= 95; r= 0.59). Our results confirm that the widely used factor of 20 fg C cell-1 (Lee and Furhman, 1987) should be plausible for studying the biomass of the natural microbial populations in the study area. Nevertheless, the wide variability of the cell size classes, also along the whole water columns, questions the applicability of a constant conversion factor for all the marine ecosystems. Consequently, locally derived biomass estimates of bacteria are essential in order to obtain an accurate evaluation of the bacterial role in biogeochemical cycles.
Tintinnids (Protozoa: Ciliophora) of the Büyükçekmece Bay in the Sea of Marmara
Authors: Balkis Neslíhan
Published: October 2008

This study on the species composition and distribution of tintinnids, which form one of the most abundant ciliate groups in the seas, was carried out in Büyükçekmece Bay in 1998-1999. Plankton samples were collected horizontally from the subsurface (0.5 m) with a 55 µm plankton net at five stations and a 3 l water sampler was used for their quantitative analysis. All tintinnid species were identified according to their lorica shape as the usual important criterion. A total of 14 species were identified. Primary hydrographic conditions such as salinity, temperature and dissolved oxygen were recorded on each sampling occasion. The genera Favella and Eutintinnus were dominant in terms of species and individual numbers. Eutintinnus fraknoi was the most abundant species, with a mean abundance of 0.4x103 ind. l-1. The study shows that the species and individual numbers of tintinnids decreased in winter and early spring when phytoplankton increases. The abundance of tintinnids in Büyükçekmece Bay appears to be correlated with the decrease in abundance of total phytoplankton (rs= -0.57, p= 0.05) and diatoms (rs= -0.65, p< 0.05) and the increase in temperature (rs= 0.61, p< 0.05). Furthermore, phytoplankton abundance was positively correlated to dissolved oxygen (rs= 0.64, p< 0.05). In particular, Favella serrata was more affected by temperature and Eutintinnus lusus-undae by salinity compared to other species.
Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships
Authors: Riaux-Gobin Catherine , Dinet Alain , Dugué Grégory , Vétion Gilles , Maria Eric , Grémare Antoine
Published: October 2008

The deep-sea phytodetritus at the sediment-water interface was investigated in the continental margin, canyons and interfluves from 260 to 2070 m depth in the northwestern Mediterranean in June 1995. Overlying phytoplankton biomass, hydrodynamics and relationships with meiofauna densities were also evaluated. The phytoplankton biomass was low (< 0.2 µg Chl a l-1), with the lowest standing stocks on the eastern part of the Balearic Basin. Two sedimentary entities were identified: 1) the west coast where pigment concentrations were higher, with an average of 0.38 µg Chl a g-1 dry weight and 4.60 Phaeo a g-1 dw on the first half cm of sediments; and 2) the eastern part of the North Balearic basin where pigment concentrations were significantly lower (0.15 µg Chl a g-1 dw). A north to south gradient was observed, with higher pigment amounts on the Rhodanian slope. Differences were found in the different parts of the studied canyons, with a slight increase in the Axis sites. The vertical pigment repartition was a gradual decrease in the Interfluve sites, whereas concentrations decreased sharply below the first cm in the Axis sites, attesting differences in sedimentation, grazing or bioturbation within the different canyon parts. The north to south gradient in the phytoplankton Chl a/Chl b ratio and sedimented phytodetritus attest geographical differences within phytoplankton assemblages (i.e. diatoms are absent in the south). The epifluorescence tests from the interface revealed the presence of living microphytes at the northern sites, associated with aggregates and faeces. No consistent fluff was evidenced anywhere. The revival tests also agree with a north to south trend. The Meiofaunal density was positively related to the quality of the sedimented layer. A PCA, within the major parameters and factors, illustrates these relationships. All results allow two distinct geographical sectors to be discriminated around the frontal zone: the NW and E sides of the NW Mediterranean Basin, following in particular their contrasted hydrodynamics. The results indicated the relationships within phytoplankton input, underlying phytodetritic layer and meiofauna. They confirm the well-documented statement that demonstrates the deep-sea floor chloropigment concentration to be a good proxy for the overlying primary productivity, but also that some pigment ratios representative of plankton assemblages are preserved on surficial deep sediments, even after sedimentation and grazing.
Morphometry, growth and reproduction of an Atlantic population of the razor clam Ensis macha (Molina, 1782)
Authors: Barón Pedro J. , Real Luciano E. , Ciocco Néstor F. , Ré María E.
Published: October 2008

Ensis macha is a razor clam distributed throughout the coasts of southern Argentina and Chile. Even though it represents a valuable fishery resource, the exploitation of its Atlantic populations has begun only in recent years. This study provides the first estimates of growth rate, an interpretation of the reproductive cycle on the coast of the northern Argentine Patagonia and an analysis of the species morphometry. Growth was estimated by direct observation of growth rings on the valves by two observers. The reproductive cycle was interpreted by the analysis of temporal change of oocyte size frequency distributions. Parameter estimations for the von Bertalanffy equations respectively obtained by observers 1 and 2 were 154 and 153.7 mm for L?, 0.25 and 0.20 yr-1 for k, and -0.08 and -0.72 yr for t0. Two spawning peaks were detected: September-November 1999 and May-June 2000. However, mature females were found all year round. An abrupt change in the relationship between shell length and height was detected at 11.2 mm length.
Spatial-temporal changes in dimethyl acetal (octadecanal) levels of Octopus vulgaris (Mollusca, Cephalopoda): relation to feeding ecology
Authors: Rosa Rui , Marques António Manuel , Nunes María Leonor , Bandarra Narcisa , Sousa Reis Carlos
Published: October 2008

The present study aimed to identify and quantify the dimethyl acetal (DMA) levels in the muscle of Octopusvulgaris Cuvier, 1797, and to investigate the possible influence of octopus feeding ecology on their spatial and seasonal variations. The research was performed over one year in three areas of the Portuguese coast: Viana do Castelo, Cascais and Tavira. Significantly higher values of DMA were detected in Tavira (p< 0.05), an area where the importance of bivalves in the octopus’ diet was higher. The biochemical analyses performed in several prey items, belonging to five major taxonomic groups identified in octopus stomachs, revealed significant differences in DMA levels (p< 0.05). The highest values were obtained in bivalves (1.15 mg 100 g-1 dry weight), followed by gastropods (0.74 mg 100g-1 dw), cephalopods (0.67 mg 100 g-1 dw), crustaceans (0.23 mg 100 g-1 dw) and osteichthyes (0.10 mg 100 g-1 dw). Therefore, based on these findings it can be speculated that the higher DMA levels in O. vulgaris obtained in Tavira throughout the year were evidence of its feeding ecology. Since DMAs are derived from ether glycerophospholipids, including plasmalogens (PLMs), the importance and role of this phospholipid class is discussed.
Benthic decapod crustaceans associated with captures of Munida spp. (Decapoda: Anomura) in the Beagle Channel, Argentina
Authors: Pérez Barros Patricia , Tapella Federico , Romero M. Carolina , Calagno Javier A. , Lovrich Gustavo A.
Published: October 2008

Benthic decapod crustacean assemblages in the Beagle Channel are dominated by the galatheid crabs Munidasubrugosa and Munida gregaria. This study deals with the bathymetric and spatial distribution, density and diversity of the assemblage of decapod species that co-occur with Munida spp. in the Beagle Channel. A total of 131 samples were obtained using an epibenthic trawl from February 1999 to December 2000. They were taken monthly from two depth strata separated by the 40 m isobath (range: 4-262 m), and from three different sites: Bahía Lapataia, Ushuaia and Punta Segunda. Sixteen of the 36 recorded species of decapod crustaceans from the Beagle Channel were caught. Munidasubrugosa and M. gregaria contributed 94% to the total decapod material. Of the remaining 6%, Austropandalusgrayi (Caridea) was the most abundant species, constituting 43% of the non-galatheid decapod fraction. Some species, namely Paguruscomptus and Eurypodius spp., were characteristic of shallow waters ( 40 m). The average density and diversity of non-galatheid decapods varied with depth and location. Decapod diversity correlated positively with the density of algae and polychaete tubes. The influence of three-dimensional bottom structure on decapod diversity in the Beagle Channel is discussed.
Feeding ecology of Parapenaeus longirostris (Lucas, 1846) (Decapoda: Penaeidae) from the Ionian Sea (Central and Eastern Mediterranean Sea)
Authors: Kapiris Kostas
Published: October 2008

The purpose of this paper is to investigate the feeding habits of Parapenaeus longirostris1 in the Greek and Italian Ionian Sea. The individuals were caught from September 1999 to July 2000 on a seasonal basis (except winter) in the Greek Ionian Sea, and in August 2000 in the Italian Ionian Sea. A total of 324 males and 309 females of P. longirostris were analysed. A comparative analysis of the diet and feeding activity was made, taking into account sex, season, size classes and study area as factors influencing the feeding habits of the species. Dietary diversity was also estimated. P. longirostris displayed a high feeding preference on a large variety of bathypelagic, benthic and endobenthic preys, mainly polychaetes, crustaceans and molluscs. No clear differentiation in the feeding behaviour between sexes, including diet composition and feeding activity, was observed. The increased feeding activity during spring for males and spring-summer for females could possibly be attributed to metabolic processes. This species undergoes changes in its feeding habits with ontogeny. Larger specimens were more efficient predators than smaller ones, possibly because of their greater swimming ability. The increased feeding activity in the Italian Ionian Sea is possibly related to the different environmental conditions.
Age, growth and mortality of Hake larvae (Merluccius hubbsi) in the north Patagonian shelf
Authors: Brown Daniel Roberto , Leonarduzzi Ezequiel , Machinandiarena Laura
Published: October 2008

Age and growth and mortality rates were estimated in Argentinean hake (Merlucius hubbsi) larvae by counting and measuring otolith daily increments. Larvae were captured with a Bongo net in January and February 2001. Length-at-age data were represented by a linear model whose fitted expression was: L(t) = 0.156 t + 1.7. Slope represented mean the daily growth rate (0.156 mm/day). This value was quite similar to the values recorded by other authors for larvae of other Merluccius species. Individual growth rates were not significantly different between January and February. This homogeneity in the larval growth was coincident with the great thermal homogeneity recorded between months. Statistical analysis of the larval growth rates from different areas did not show significant differences. Daily mortality coefficients derived from the exponential decline models were 0.27 and 0.12 for January and February respectively. The difference between the two mortality coefficients could be attributable to the patchinnes, or larval recruitment pulses of distinct intensity between the two months.
Biology of the Sanzo's goby, Lesueurigobius sanzoi (de Buen, 1918), off Cabo Raso, Portugal
Authors: Martins Cristina Paulo , Lopes Da Cunha Pedro , Raposo de Almeida Pedro
Published: October 2008

The presence of Sanzos's goby, Lesueurigobius sanzoi (de Buen, 1918), off Cabo Raso, Portugal, is recorded for the first time. The biology of this population was studied using 11 samples collected between April 2000 and September 2001 at depths of 70-100 m on muddy and sandy bottoms. The females reach a standard length of 110 mm and the males 103 mm. It attains an age of 24 months, which equals two breeding seasons. The otoliths form two translucent rings each year, which corresponds to the winter growth and the reproduction period. Sanzo's gobies can be classified as prematur and standard individuals, according to whether the first breeding occurs before or after the first winter respectively. Standard individuals, which have an extended first growth, reach a longer length than prematur individuals, whose first growth is much shorter. Although discrete, sexual dimorphism was noticeable even outside the spawning season. The breeding season occurs between May and September/October with more than one spawning. The minimum length for which the maturity stage occurs is 64 mm, at an age of 0+. The feeding activity is quite constant throughout the year, and the diet consists predominantly of small crustacea and molluscs, although polychaets also feature commonly in its diet.
Scope of the Spanish Marine Sciences National Programme from 1995 to 2003
Authors: Morales-Nin Beatriz , Sánchez-Fernández Pilar
Published: October 2008

Marine Research in Spain was funded mainly by the National Plans of the Ministry of Science and Technology. These have four-year duration and comprise priority research areas addressed by Research and Development Programmes. Marine Sciences has been identified as a Programme since 1995, and forms part of two National Plans. The Programme made annual invitations to tender with the following objectives: global change, ecosystems, sustainable fisheries, coastal zone, pollution and new technologies. Each objective had several sub-objectives. In the first period (1995-1999) Aquaculture was one of the objectives, and it had its own Programme in the second. The 1995-1999 Programme approved 189 projects (47% of the proposals submitted) with a budget of 9.14 M€ and a participation of 550 persons/year. In the 2000-2003 Programme 175 projects were approved (51% of the proposals submitted) corresponding to €12.42 M and 780 persons/year. The universities were the principal actors (58% of the projects), followed by the Science Council (25% of the projects). Catalonia is the region with the greatest participation both in projects and in funding, followed by Galicia and Andalusia. Considering that in the first period there were five invitations to tender and Aquaculture was the main objective (63 projects and €2.26 M), the increase in participation and funding is considerable. This trend is also confirmed by the increase in success rate (approval of proposals rose from 47% in the first invitation to tender to 51% in the second) and the increase in the mean budget per project (from €48.300 to €70.900 respectively).
Assessment of the behavior of oil in the tanks of the Prestige in the Atlantic deep sea
Authors: Marcos María J. , Agüero Almudena , García-Olivares Antonio , Haupt Bernd J. , De Pablos Jose L.
Published: October 2008

The sinking of the Prestige supertanker off the coast of Spain in November 2002 led to one of the most devastating oil spills ever worldwide. Between 13,800 and 37,500 tons of oil still remain inside the wreckage. The mid-range and long-term behaviour of oil temperature and leaks were analysed to decide whether the oil could be pumped out in the current conditions. Past and present conditions near the wreckage were analysed, considering depth, water pressure, estimated oil behaviour inside the tanks, and possible future hull corrosion. A similar analysis may be useful in the management of future wreckages.
Comparison of the two-dimensional directional wave spectra retrieved from spaceborne synthetic aperture radar images using the MPI scheme against directional buoy measurements
Authors: Violante-Carvalho Nelson , Robinson Ian S.
Published: October 2008

Spaceborne Synthetic Aperture Radar (SAR) is to date the only source of two-dimensional directional wave spectra with continuous and global coverage when operated in the so-called SAR Wave Mode (SWM). Since the launch in 1991 of the first European Remote Sensing Satellite ERS-1, and more recently with ENVISAT, millions of SWM imagettes containing detailed spectral information are now available in quasi-real time. This huge amount of directional wave data has opened up many exciting possibilities for the improvement of our knowledge of the dynamics of ocean waves. However, the retrieval of wave spectra from SAR images is not a trivial exercise due to the nonlinearities involved in the mapping mechanism. In this paper we review the main features of the SAR ocean wave imaging mechanisms and give a detailed description of the Max-Planck Institut (MPI) retrieval algorithm which is running operationally at the European Centre for Medium-Range Weather Forecasts (ECMWF). Some examples of retrieved spectra are compared against directional buoy measurements obtained in deep water in the South Atlantic and against WAM spectra. The main characteristics of the MPI retrieval scheme are discussed and some of its deficiencies and strengths are identified.
Recruitment and post-settlement growth of juvenile Merluccius merluccius on the western Mediterranean shelf
Authors: Morales-Nin Beatriz , Moranta Joan
Published: October 2008

Young-of-the-year European hake (Merluccius merluccius) were sampled during four seasonal cruises between November 1998 and September 1999. The greatest numbers and biomass were found in spring 1999. Some 73% of juvenile fish in terms of number, and 81% in terms of biomass, were caught at depths between 60 and 160 m on the outer western Mediterranean shelf, where the water temperature ranged between 13.5 and 14°C. The length composition of samples showed there to be small hake all year around, with modes between 7 and 11 cm total length depending on the season. Otolith analysis was used to establish age at settlement (62.7 days) and to determine seasonal growth. The monthly growth rates ranged from 1.2 cm month-1 for juvenile hake captured on February 1999 to 2.5 cm month-1 for ones captured in June. The growth rates are related to survival, as was shown by the calculated hatch dates and relative abundances of recruits. This work provides information on the first year of life, recruitment and growth processes in an important species of the Mediterranean demersal ecosystem which is heavily exploited by a recruitment fishery.
Growth of juvenile salema, Sarpa salpa (Teleostei: Sparidae) in the Kornati Archipelago, eastern Adriatic Sea
Authors: Matic-Skoko Sanja , Kraljevic Miro , Dulcic Jakov , Pallaoro Armin
Published: October 2008

Growth of juvenile Sarpa salpa from the Kornati Archipelago, eastern middle Adriatic Sea was analysed. A total of 1515 juveniles, ranging in length from 1.6 to 14.2 cm, were caught. Most individuals (94.65%) belonged to the 0+ cohort. The first settlers were aged 1.5-2.0 months, and probably entered shallow coves at the end of November. The relationship between total length and weight indicates positive allometric growth (b = 3.284). The condition factor, as a consequence of length-weight relationship, was CF = 1.41. The parabolic (c = 0.023 mm days-1; R2
Nutrient diffusive fluxes from sediments in the northern Gulf of Aqaba, Red Sea
Authors: Al-Rousan Saber , Rasheed Mohammed , Badran Mohammad
Published: October 2008

Measurements of dissolved inorganic nutrients (NH4+, NO2-+NO3-, HPO4-2 and SiO2) in pore waters (PW) and overlying bottom waters (OBW) were carried out in sediments of two reefs on the Jordanian coast of the Gulf of Aqaba at different water depths down to 30 m. One of the two sites was a marine reserve in front of the Marine Science Station (MSS) and the other hosted an Industrial Complex Zone (ICZ). The PW samples were retrieved using specially designed interstitial water traps. The concentrations in the OBW were within the typical range reported for oligotrophic tropical oceans. They showed minor variations with depth due to a well-mixed water column. Higher nutrient values were found at the ICZ compared to MSS suggested anthropogenic nutrient inputs. Our results showed significantly higher nutrient concentrations in the PW than in the OBW. The average concentrations in PW were about 16, 6, 9 and 5 times higher than the average values reported in the OBW for NH4+, NO2-+NO3-, HPO4-2 and SiO2 respectively. Average fluxes of the dissolved inorganic nutrients were estimated in this study using the pore water gradient concentration across the sediment-water interface. Average diffusion fluxes were in the ranges 1.41-46.44, 2.68-18.25, 0.04-0.60 and 9.68-16.85 ?mol m-2 d-1 for NH4+, NO2-+NO3-, HPO4-2 and SiO2 respectively. Flux of all nutrients was higher at the MSS. This can be attributed to higher sediment organic matter content and high biological activity. The results of this study demonstrate (i) the importance of coral reef sediments in recycling nutrients for coral reef communities and (ii) the effect of pumping cooling water on the nutrient regeneration process.
Active and resting stages of zooplankton and its seasonal evolution in a hypersaline temporary pond of the Mediterranean coast (the Vecchia Salina, SE Italy)
Authors: Moscatello Salvatore , Belmonte Genuario
Published: October 2008

The species composition of zooplankton and its variability were studied with an integrated water-sediment analysis for a period of two years in a hypersaline temporary pond in SE Italy. The basin was affected by extended drought during summer, and even during the wet period the sodium chloride salinity was never below 42.`0. The zooplankton showed the presence of seasonal species (mainly Anostraca), together with not seasonal, but opportunistic ones (mainly Rotifera, and Ciliophora) with a shorter life cycle. Rotifers (mainly Hexarthra fennica and Proales similis), and ciliates (Fabrea salina) attained 99-100% of total planktonic organisms in certain periods. Resting stages were extracted from the upper 6 cm of 14 sediment cores collected during a dry period (August 1998). A total of 24 resting morphotypes (cysts) were listed—more than double the number of the active organisms (11) found in the plankton over the two years. The seasonal succession of species was different in the two years studied. This fact, together with the richness of the cyst bank of the sediment, indicates that in each period the water column shows only a portion of the biodiversity, which the sediment contains unexpressed as resting stages. The study of cyst distribution (both horizontal and vertical) in sediments provided complementary suggestions to understand the space-time distribution of the plankton organisms. Laboratory tests showed that hatching of different cysts generally occurred in a wide range of salinity conditions, and was not synchronous. This allowed us to assume that even the cyst hatching rate could be an adaptation to highly variable extreme environments.
Shrimps of the crangonid genus Paracrangon Dana (Crustacea: Decapoda: Caridea) from the northwestern Pacific: taxonomic review and description of a new species from Japan
Authors: Komai Tomoyuki , Kim Jyung Nyun
Published: October 2008

The northwestern Pacific species of the crangonid genus Paracrangon Dana, 1852 are reviewed. Five species, including one new species, are recognised from the region: P. echinata Dana, 1852 (type species of the genus), P. abei Kubo, 1937, P. furcata Kubo, 1937, P. okutanii Ohé and Takeda, 1986, and P. ostlingos sp. nov. The geographical range of P. okutanii is extended to the northern South China Sea off southwestern Taiwan, representing the first discovery of species of the genus from tropical waters in the western Pacific. These species are diagnosed and illustrated. They are classified into two informal species groups, the P. echinata species group (including P. echinata, P. abei and P. okutanii, and two species from other regions, P. areolata Faxon, 1893 and P. australis Hanamura, Wadley and Taylor, 1999) and the P. furcata species group (P. furcata and P. ostlingos sp. nov.). New findings on the morphology of the genus are presented. The monophyly of Paracrangon is highly corroborated by a number of autapomorphic characters, but its relationship to other crangonid genera remains obscure. A revised key to aid in the identification of the species of Paracrangon is presented.
Human harvesting of Mytilus galloprovincialis Lamarck, 1819, on the central coast of Portugal
Authors: Rius Marc , Cabral Henrique H.
Published: October 2008

The Mediterranean mussel, Mytilus galloprovincialis Lamarck, 1819, has traditionally been removed from the shore by humans in coastal areas to supplement diet, for commerce or for bait. On exposed rocky shores of the central coast of Portugal, humans are an important intertidal predator, especially of mussels and of the pedunculate barnacle Pollicipes pollicipes (Gmelin, 1789). Four rocky shore sites near Cabo Raso with different levels of accessibility were compared in terms of harvesting pressure, substratum cover, density and size structure of M. galloprovincialis. Sampling surveys were conducted from March to September 2002. For substratum cover determinations a 50 cm x 50 cm square was used, while density and size structure were estimated based on scrapings performed on a 10 cm x 10 cm area. A log-linear model was used to evaluate human harvesting according to several factors. Significant differences in the harvesting intensity were related to accessibility, type of day (weekday, weekend or holiday), period of the day, weather and tidal amplitude. The differences relative to zone were not significant. The least accessible site (0.30 person day-1) showed the highest values of substratum cover, and a negative correlation was found between number of harvesters and substratum cover by mussels. Size distribution also varied considerably according to site. The major difference that was noticed was that less accessible sites showed a higher number of large individuals than more accessible areas. Density in the most accessible location showed a clear decline, above all after summer holidays. Over the study period, in the more accessible sites biomass decreased while in the other locations it increased. Long-term studies are necessary to determine the real magnitude and effects of human disturbances in intertidal communities.
Abundance of Octopus vulgaris on soft sediment
Authors: Katsanevakis Stelios , Verriopoulos George
Published: October 2008

Until now the distribution and abundance of Octopus vulgaris had been investigated in the main fishing areas of the species only by fishing surveys. The catching efficiency of fishing gear is variable and depends on several aspects of the animal´s behaviour and life history as well as on the type of the gear and the environmental characteristics of the area surveyed. A good alternative for studying the abundance of octopus is by visual census. The population density of O. vulgaris was measured by visual census with scuba diving. The survey was conducted in coastal areas of Greece and on soft sediment. O. vulgaris density ranged from 0 to 6.88 individuals/1000 m2 and the mean density values of this study were much higher than those mentioned in other papers. Octopus density was significantly associated with season. Densities of octopuses lower than 500 g were higher in coarse sediments than in finer ones. The density of large octopuses (> 500 g) increased with depth. Octopuses larger than 200 g tended to dwell deeper during the period of intense thermocline than during the no-thermocline period.
Temporal patterns of larval fish distribution and abundance in a coastal area of northern Greece
Authors: Koutrakis Emmanuel T. , Kallianiotis Argyris A. , Tsikliras Athanassios C.
Published: October 2008

Species composition, abundance and diversity of fish larvae were assessed in the Strymonikos and Ierissos Gulfs (northern Aegean Sea, Greece). Both gulfs are affected by the freshwater input of the Rivers Strymon and Rihios; water depth does not exceed 80 m. Samples were collected using a bongo net sampler (250 µm mesh size) over a grid of 35 stations in six cruises between June 1997 and May 1998. A total of 48 taxa of fish larvae (36 species, 5 genera and 7 families) were identified. The majority of identified fish larvae taxa consisted of demersal species that included larvae of Bothidae, Gobiidae, Callionymidae, Sparidae and Serranidae. The highest number of species occurred in the warm season (May, June, July, September) and this was attributed to the summer spawners that start their reproduction period during spring/early summer. The European anchovy (Engraulis encrasicolus) was the dominant species between July and September, and the European sardine (Sardina pilchardus) between November and March. Two distinct seasons (warm and cold) were identified by multivariate analysis, highlighting the importance of seasonality in shaping the community structure. The absence of well-defined larval fish associations revealed the importance of depth in the identification of different spatial patterns in an area.
Taxonomic aggregation and redundancy in a tropical macroinfaunal assemblage of the southern Caribbean in the detection of temporal patterns
Authors: Guzmán-Alvis Angela Inés , Carrasco Franklin
Published: October 2008

The infaunal soft bottom communities of the southern Caribbean are poorly known, partially due to the scarcity of specialised literature and taxonomic expertise for this region. These assemblages might have structurally redundant genera, so it would be possible to study groups of organisms that present a similar pattern to that of the total community. This redundancy can be reflected at higher taxonomic levels. The abundance of the sublittoral infauna of the southern Caribbean was used in multivariate statistical techniques to describe a temporal pattern. This temporal pattern was related to other patterns obtained from a series of genera subsets that were extracted from the total community. These subsets display close relationships (redundancy). Moreover, the total temporal pattern was compared with those obtained from the emphasis of different taxa and by aggregating their abundances at higher taxonomic levels. There is a high structural redundancy that comprises several groups of characteristic, common and dominant genera. Therefore, by emphasising the contributions of common or combinations of common and intermediate taxa, the family level identification appeared to be a good choice to describe the temporal pattern in this region. These results are useful for temporal pattern descriptions of those assemblages in which a high taxonomic uncertainty exists.
Environmental influences on fish assemblage distribution of an estuarine coastal lagoon, Ria de Aveiro (Portugal)
Authors: Pombo L. , Elliott M. , Rebelo J. E.
Published: October 2008

Fish assemblage was examined for patterns in spatial and seasonal structure within an estuarine coastal lagoon, Ria de Aveiro. Two years of variation in abiotic conditions were recorded to identify factors responsible for maintaining the structure of fish assemblages. Nine sites were sampled monthly with a traditional “chincha” beach-seine net between November 1998 and October 2000. Fish abundance and biomass changed significantly between sites. Temperature was found to be the most important abiotic factor affecting the abundance (number of fish) distribution of fish assemblage, which is more related to seasonal migrations than to spatial migrations. Salinity was the most important abiotic factor affecting the fish biomass, with temperature also having a major influence. The other abiotic parameters analysed also showed some influence on the distribution of fish, although, isolated from the other controlled and/or uncontrolled factors, they could not fully explain all the differences between assemblages. Feeding analysis indicates that fish assemblage is mostly dependent on small benthic and pelagic crustaceans and/or detritus, although they can feed opportunistically on other prey. The low spatial segregation of fish in relation to feeding preference indicates that, in a food-rich lagoon such as Ria de Aveiro, the environmental-biological interactions appear to have a greater effect on fish distribution than do biological interactions.
Phytoplankton functional groups and harmful algae species in anthropogenically impacted waters of the NW Mediterranean Sea
Authors: Vila Magda , Masó Mercedes
Published: October 2008

Phytoplankton assemblages were analysed by multivariate analysis techniques in highly modified waterbodies (harbours) of the northwestern Mediterranean Sea over an annual cycle. The phytoplankton functional groups that characterise these anthropogenically impacted waters were identified and related to HAB events. Four functional groups can be distinguished from the analysis: (1) bloom-forming dinoflagellates, (2) winter diatoms, (3) summer-autumn diatoms, and (4) large dinoflagellates and elongated diatoms. The species that characterise these functional groups occurred at all sampling stations. Potentially harmful species are distributed through all the clusters. However, bloom-forming dinoflagellates occur particularly in large harbours and during summer months. The results indicate that: (1) functional groups indicate where and when there is a high risk of blooms, but they cannot determine the risk of a toxic or fish-killing event; and (2) large harbours in tideless seas must be considered as areas with a high risk of high-biomass bloom occurrences.
Spawn and larval development of Pleuroploca aurantiaca (Lamarck, 1816) (Gastropoda: Fasciolariidae) from Northeast Brazil
Authors: Meirelles Carlos A. O. , Mattews-Cascon Helena
Published: October 2008

Spawn and larval development stages of Pleuroploca aurantiaca from northeast Brazil are described. The reproductive period lasted from August to December, with a peak in November. Spawn masses were composed of 29 ± 3 vase-shaped capsules which measured 9 ± 1 mm (n = 30) in length and 4.5 ± 0.5 mm (n = 30) in width. The exit plug was located on the apical area and measured 2.5 ± 0.5 mm (n = 30) in diameter. Each capsule had 353 ± 59 (n = 10) eggs that measured 240 ± 1 µm (n = 15) in diameter. On the tenth day, the intracapsular veliger stage was observed. The intracapsular pediveliger stage was observed on the twenty first day, when the individuals had a functional foot and a reduced velum. Hatching occurred on the thirtieth day, when the early juvenile measured 3 to 5 mm in length and there was no remaining velum. Only 1% of the eggs developed to the hatching stage. The rest were nurse eggs used by embryos as a food resource. Pleuroploca aurantiaca has an intracapsular metamorphosis development type.
Egg masses of Sepietta oweniana (Cephalopoda: Sepiolidae) collected in the Catalan Sea
Authors: Deickert Adrianne , Bello Giambattista
Published: October 2008

Examination of 89 egg masses of Sepietta oweniana collected in the Catalan Sea (western Mediterranean) showed that 15.8% of them were composed of eggs at different developmental stages laid in more than one spawning bout; 6.7% of them were polyspecific and contained eggs of other sepioline species in addition to S. oweniana. The egg mass size, or number of eggs per egg mass, does not necessarily correspond to the spawning batch size, i.e. the number of eggs laid by a female in one spawning event. Furthermore the egg mass size appears to vary depending on the season.
Vanadium, rubidium and potassium in Octopus vulgaris (Mollusca: Cephalopoda)
Authors: Seixas Sónia , Pierce Graham
Published: October 2008

The levels of vanadium, rubidium and potassium were determined in Octopus vulgaris caught during commercial fishing activities at three locations (Cascais, Santa Luzia and Viana do Castelo) in Portugal in autumn and spring. We determined the concentration of these elements in digestive gland, branchial heart, gills, mantle and arms in males and females. At least five males and five females were assessed for each season/location combination. Elemental concentrations were determined by Particle Induced X-ray Emission (PIXE). Vanadium was detectable only in digestive gland and branchial heart samples. Its concentration was not correlated with total weight, total length or mantle length. There were no differences in concentrations of V, Rb and K between sexes. There were significant differences in vanadium concentrations in branchial hearts in autumn between samples from Viana do Castelo and those from the other two sites. We found a significant positive relationship between the concentration of vanadium and those of potassium and rubidium in branchial hearts. Branchial hearts appear to play an important role in decontamination of V.
Age and growth rate of juvenile bluefin tuna Thunnus thynnus from the Mediterranean sea (Sicily, Italy)
Authors: La Mesa Mario , Sinopoli Mauro , Andaloro Franco
Published: October 2008

The microstructural analysis of the sagittal otoliths of juvenile Atlantic bluefin tuna, Thunnus thynnus, can be used to estimate the age and growth rate of young-of-the-year individuals born in the Mediterranean. Samples of juvenile bluefin tuna, obtained as by-catch of the local small-scale pelagic fishery for Atlantic bonito and dolphinfish, were collected off the northern coast of Sicily between late August and early November 2002. Otolith age readings were carried out on 56 specimens ranging between 195 and 400 mm fork length and between 112 and 1266 g total weight. Based on microincrement analysis along a counting path from the otolith core to the antirostrum, juvenile fishes were found to be between 77 days and 153 days old. The estimated growth rate was practically linear over the whole size range, accounting for about 2.0-2.37 mm/day. Derived from the length-weight relationship and the estimated length-at-age data, the mean weight-at-age was 168, 429 and 813 g for 2, 3 and 4 month-old juveniles respectively. Furthermore, the hatching date distribution of bluefin tuna, obtained by means of the back-calculation of ageing data, indicated a spawning period of at least two months, namely from mid-May to mid-July, with a peak in mid-June. Our data indicate that juvenile bluefin tuna have a very high growth rate in the first part of their life, reaching a weight of more than 1 kg in four months.
Larval development and growth of the European hake Merluccius merluccius in the northwestern Mediterranean
Authors: Palomera Isabel , Olivar M. Pilar , Morales-Nin Beatriz
Published: October 2008

The larval growth and development of the European hake, Merluccius merluccius, was studied from field larvae. Larvae were collected in the northwestern Mediterranean on three cruises carried out during the peak spawning months (November 1998, September 1999 and November 1999). Like other species of the genus, these larvae are characterised by a well-developed anterior part of the body, head and trunk region. Nevertheless, yolk sac larvae are much more slender than larvae at notochordal flexion stages. In the present study we analysed the allometric relationships between several body measurements and body length. This is the first attempt to infer larval growth of Merluccius merluccius by means of sagittal otolith analysis. Our results show the change in the otolith shape from a lenticular otolith in early larvae to an almond-shaped otolith in larger larvae. Otolith diameter showed a power relation with larval size, with no significant differences between seasons. In spite of the sea surface temperature differences between the three periods of larval collection, the early growth estimates showed no significant differences. This was explained by the similarity in the temperature at the depths at which the larvae are located. Absolute growth rates in length were estimated by relating daily growth increments in otoliths and larval size (standard length). When using the whole larval size range the values obtained were similar to those found for other Merluccius species. Nevertheless, the present data evidenced that growth for larvae younger than 12 days is very low, showing a significant increase thereafter. This indicates that length is probably not the best parameter for describing the growth of hake larvae in the first days of life, as allometric analysis suggested.
Reproductive aspects of Microchirus azevia (Risso, 1810) (Pisces: Soleidae) from the south coast of Portugal
Authors: Afonso-Dias Isabel , Reis Catarina , Pedro Andrade J.
Published: October 2008

Fresh fish obtained from commercial landings in the harbours of Olhão and Quarteira (south Portugal) in 1998 and 1999, were examined in order to study different aspects of the reproductive biology of Microchirus azevia (Risso, 1810): spawning season, ovary maturation, length/age at first maturity and sex ratio. A five-stage maturity scale, based on external appearance was used to classify the ovaries. M. azevia is a winter-spring batch spawner with a protracted spawning season. Females outnumbered males in length classes greater than 19 cm and in all age groups. The estimated mean size at first maturity (L50%) for females was 23 cm total length at 3 years of age (t50%).
Dynamics of the Namibian hake fleet and management connotations: application of the ideal free distribution
Authors: Voges Elizabeth , Gordoa Ana , Field John G.
Published: October 2008

In order to determine the factors governing the spatial distribution of effort, it is essential to better understand the relationship between CPUE and abundance. In this study the spatial distribution of effort of the Namibian hake trawl fleet is examined by looking at competitive abilities among vessels, spatial allocation of effort, competition between vessels and equalisation of catch per unit effort (CPUE). The Ideal Free Distribution (IFD) was used as the foundation for deriving the tests. The results show that interference competition does not occur among vessels. Nevertheless, the prediction of the IFD of the equalisation of CPUE was confirmed in this fishery and indicates that the number of vessels in a specific area reflects stock density. Since there is no interference competition among vessels, the catchability coefficient (q) is not affected by this factor. Moreover, we infer that the CPUE from the whole area is not distorted as an index of abundance by the way effort is allocated in this fishery.
The complete larval development of Eurypanopeus canalensis Abele and Kim, 1989 (Crustacea: Brachyura: Panopeidae) described from laboratory reared material
Authors: García-Guerrero Marcelo U. , Rodríguez Antonio , Cuesta José A. , Hendrickx Michel E.
Published: October 2008

The estuarine panopeid crab Eurypanopeus canalensis Abele and Kim, 1989, is an eastern tropical Pacific species with a known distribution from the southeastern Gulf of California, Mexico, to Panama. Its complete larval development is fully described and illustrated from laboratory-reared material. The four zoeal stages and the megalopa are compared with two congeneric species from the West Atlantic, E. abbreviatus (Stimpson, 1860) and E. depressus (Smith, 1869). The main differences between larvae of E. canalensis and those of these two species include telson setation and the presence/absence of a stout hook-like spine in the megalopae cheliped ischium.
Temporal modification in cardiac rhythmicity of Nephrops norvegicus (Crustacea: Decapoda) in relation to trawl capture stress
Authors: Aguzzi Jacopo , Chiesa Juan , Abelló Pere , Diez-Noguera Antoni
Published: October 2008

The effects of trawling on cardiac rhythmicity of Nephrops norvegicus (L.) are still mostly unknown. Ultradian rhythms reported in previous studies may result from trawling capture stress, thus disappearing following acclimatisation to laboratory conditions. To test this hypothesis, 34 time series of cardiac activity data recorded in constant darkness were studied by Fourier analysis. Spectral decomposition of time series was obtained by defining the fundamental or circadian harmonic (CH) in 24-h together with 9 submultiples of this period. The power content (PC) of each harmonic was estimated in data segments of 24-h duration (days), giving graphic matrices of PC values over consecutive days. Values of PC for 9 submultiples were summed and studied in a block named ultradian band (UB). The modification in the PC of the CH and of the UB was evaluated during laboratory acclimatisation. A significant increase in the PC of the circadian harmonic component (CH) over consecutive days of testing was observed. These findings suggest that, rather than being a product of dim light environmental fluctuations experienced by the animals from the deep waters of the continental slope, ultradian periodicity could well be caused by the stress of capture.
Aspects of female reproductive biology of the orange-back squid, Sthenoteuthis pteropus (Steenstup) (Oegopsina: Ommastrephidae) in the eastern tropical Atlantic
Authors: Laptikhovsky Vladimir V. , Nigmatullin Chingis M.
Published: October 2008

Orange-back squid females, Sthenoteuthis pteropus, were found to mature at two different sizes: 230-270 mm and 380-450 mm mantle length (ML). The systematic status of these groups remains unknown. The ML of mature females varied from 155 to 558 mm (body weight 150-5900 g, respectively). Protoplasmic oocytes of 0.1 mm predominated in the ovaries during the entire life cycle providing a resource for further yolk accumulation. The number of yolk oocytes present at any one time represented only a small part of the Potential Fecundity (PF). Ripe eggs were 0.73-0.87 mm, and egg weight was 0.19-0.26 mg. The PF was 0.6 million to 15.8 million in mature animals and 1.2 million to 17.9 million in immature and maturing females, respectively. In mature females, the total number of yolk oocytes was 20 000 to 1.9 million, including 10 000 to 1 million ripe eggs. Spawning was intermittent. Large females presumably released at least 30-50% of the total oocyte stock. Results indicate that S. pteropus is a typical representative of the epipelagic oceanic cephalopod reproductive strategy characterised by small eggs, high fecundity, long intermittent spawning, active feeding, and somatic growth during spawning.