Oceanologica Acta最新文献

{"title":"Food consumption of fish in a sub-tropical SW Atlantic ecosystem off Brazil: comparison of four Sciaenid species","authors":"Lucy Satiko Hashimoto Soares","doi":"10.1016/S0399-1784(03)00045-8","DOIUrl":"https://doi.org/10.1016/S0399-1784(03)00045-8","url":null,"abstract":"<div><p>The first evaluations of the daily ration and population food consumption of four Sciaenid fish, under natural conditions for the Brazilian south-western Atlantic shelf (23°35′S, 45°00′W) are presented. The average daily ration ranged from 4.38 to 12.92 % body mass (90% confidence interval) for the juvenile shortfin corvina (<em>Isopisthus parvipinnis</em>), from 0.41 to 5.52 % body mass (90% confidence interval) for the juvenile shorthead drum (<em>Larimus breviceps</em>) and from 3.14% to 3.15% body mass for the juvenile whitemouth croacker (<em>Micropogonias furnieri</em>). Juveniles of the banded croacker (<em>Paralonchurus brasiliensis</em>) showed higher estimates (2.58–2.60% body mass) than those for the adults (1.2–1.84% body mass). The mean food consumption rate of the population was estimated at about 11 and 8 year^–1, respectively, for the whitemouth croacker, and banded croacker, corresponding to a gross efficiency of 13 and 10%. The estimates of daily ration were related to the feeding habits as well as to size of the fish, and probably to their specific energy budget. Estimates of population food consumption are related to population structure.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00045-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92037232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal budgets of organic matter in the Ubatuba shelf system, SE Brazil. I. Planktonic and benthic components","authors":"Gecely R.A. Rocha ,&nbsp;Carmen L.D.B. Rossi-Wongtschowski ,&nbsp;Ana M.S. Pires-Vanin ,&nbsp;Astrid Jarre-Teichmann","doi":"10.1016/S0399-1784(03)00043-4","DOIUrl":"10.1016/S0399-1784(03)00043-4","url":null,"abstract":"<div><p>Planktonic and benthic productivity and consumption were estimated to assess the availability of food to higher trophic-level consumers in the Ubatuba ecosystem on the SE coast of Brazil. The study area included waters from 10 to 100 m deep and covered 3800 km²<span>. The trophic compartments of the system were established on ecologically or taxonomically related species, considering their relative abundance and similarity of diets and habits. The compartments are phytoplankton<span><span><span>, zooplankton, salps, bacterioplankton<span>, cnidaria<span>, polyplacophora<span>, mollusca, carnivorous </span></span></span></span>benthos<span>, detritivorous polychaetes, other detritivorous benthos, penaeidea-caridea, brachyura, and echinodermata. Biomass, production, and consumption were estimated in summer and winter. </span></span>Plankton biomass, production and consumption were higher in summer than in winter, mainly because of the presence of salps. Primary production was estimated as 1486 g wet weight m</span></span>^–2 3 months^–1 in summer and 704 g in winter. Total benthic biomass in summer (101 gww m^–2) was twice that in winter (53 gww m^–2), but its production and consumption were similar in both seasons.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00043-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80567193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uranium in the Arabian Sea: role of denitrification in controlling its distribution","authors":"R Rengarajan,&nbsp;M.M Sarin,&nbsp;S Krishnaswami","doi":"10.1016/j.oceact.2003.05.001","DOIUrl":"10.1016/j.oceact.2003.05.001","url":null,"abstract":"<div><p>A total of 61 samples, from six vertical profiles between surface and 1800 m from the Arabian Sea, have been analysed for uranium concentration to assess its behaviour in oxic and sub-oxic waters. These samples cover a wide range of dissolved oxygen concentration, from 0.14 to 230 μM. Uranium concentration in most of the samples fall in the range of 3.2 ± 0.2 μg l^–1. In general, uranium exhibits a conservative behaviour in the Arabian Sea water column and denitrification processes do not seem to influence its abundance. The mean uranium/salinity ratio in waters with dissolved oxygen &lt;2 μM is (9.17 ± 0.15) × 10^–8 g g^–1, nearly identical to the ratio (9.22 ± 0.27) × 10^–8 g g^–1 in waters with dissolved oxygen &gt;100 μM, and in waters from other oceanic regions (9.34 ± 0.56) × 10^–8 g g^–1. In one of the profiles (18°N, 64°E) collected during summer monsoon (SK115/6; August 1996), two samples from 300 and 600 m have uranium concentration ∼10–15% lower than that expected based on salinity. Further studies are needed to confirm these results and to characterize the process(es) contributing to depletion of uranium at these depths.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.oceact.2003.05.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90215510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Friction and mixing in the Faroe Bank Channel outflow","authors":"Louise M Duncan,&nbsp;Harry L Bryden,&nbsp;Stuart A Cunningham","doi":"10.1016/S0399-1784(03)00042-2","DOIUrl":"10.1016/S0399-1784(03)00042-2","url":null,"abstract":"<div><p>Three hydrographic sections made during RRS <em>Discovery</em> cruise 242, from 7 September to 6 October 1999, are used to study the Faroe Bank Channel overflow. Each section, made perpendicular to the plume direction, comprised 10–14 stations measuring the outflow properties and velocity. The overflow defined as water with potential temperatures below 3 °C has densities greater than 28.1 kg m^–3, salinities between 34.9 and 35.1, with velocities as high as 80 cm s^–1<span><span> approximately 20 km downstream from the sill. We use these measurements to describe the characteristics of the outflow and to estimate the amount of friction and mixing as the plume travels along the continental slope<span> into the Iceland Basin. From Lowered Acoustic Doppler Current Profiler (LADCP) measurements we estimate stress in the bottom </span></span>Ekman layer. Our stress results are best related to the overflow velocity with a drag coefficient of 0.5 × 10</span>^–3<span> and to the height of the bottom Ekman layer with a von Karman constant of 0.75. Below a potential temperature of 8 °C, the isotherms sink with distance downstream. Calculating transport below different isotherms, we make an estimate for the amount of entrainment. In the region downstream of the sill, entrainment is initially maximum near the 0 °C isotherm just above the cold dense outflow and turbulent diffusivities reach as high as 500 cm</span>² s^–1. Fifty kilometre downstream of the sill the depth of maximum entrainment has moved upwards to the 2 °C isotherm and turbulent diffusivity has decreased to 50 cm² s^–1<span><span>. Froude numbers are found to exceed one in the centre of the overflow on all three sections. Calculating </span>Richardson numbers we see evidence that mixing takes place above the fast flowing outflow core.</span></p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00042-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85636808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The demersal fish assemblage of the coastal area adjacent to the Tagus estuary (Portugal): relationships with environmental conditions","authors":"Nuno Prista ,&nbsp;Rita Pina Vasconcelos ,&nbsp;Maria José Costa ,&nbsp;Henrique Cabral","doi":"10.1016/S0399-1784(03)00047-1","DOIUrl":"10.1016/S0399-1784(03)00047-1","url":null,"abstract":"<div><p>The subtidal fish assemblage of Tagus estuary coastal area was sampled in order to infer about its relationship to environmental conditions and its possible nursery function for marine species. Fish sampling took place between May 2001 and February 2002 with an otter trawl. In addition to fish sampling, a physical, chemical and biological characterization of the water column and bottom sediment was performed. Density and biomass were determined and ecological and feeding guilds assigned to each fish species. Correspondence analysis (CA) was used to determine the spatio-temporal structure of the assemblage and its correlation to environmental variables. A total of 36 fish species were identified. The fish assemblage was dominated by few species, both in terms of density and biomass. The main fish species were <em>Callionymus lyra</em>, <em>Arnoglossus laterna</em>, <span><em>Diplodus</em><em> bellotti</em></span>, <span><em>Echiichthys </em><em>vipera</em></span> and <span><em>Raja</em><em> undulata</em></span>. Seasonally <span><em>Trachurus trachurus</em></span>, <span><em>Sardina pilchardus</em></span> and <span><em>Engraulis encrasicolus</em></span> were also abundant. Over 50% of the fish caught were juvenile stages. Benthic carnivorous species feeding on invertebrates dominated the assemblage. CA results indicated that distinct fish species occur in the northern and southern areas, although they distance only a few kilometres from each other. Depth and sediment type were the main structuring factors of the fish assemblage. Temperature and salinity showed reduced importance on overall assemblage structure although that may result from the particular climatic regime of the sampling year. The environmental preferences of the most important species are briefly discussed and the importance of integrating various spatial scales in multispecific studies of coastal fish assemblages emphasized. The presence of high densities of marine species juveniles indicates that this area may function as a spring–summer nursery for several species.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00047-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83426932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A semi-evolutive filter with partially local correction basis for data assimilation in oceanography","authors":"Ibrahim Hoteit ,&nbsp;Dinh-Tuan Pham ,&nbsp;Jacques Blum","doi":"10.1016/S0399-1784(03)00046-X","DOIUrl":"10.1016/S0399-1784(03)00046-X","url":null,"abstract":"<div><p>A new data assimilation scheme derived from the singular evolutive extended Kalman (Seek) filter is introduced. The novel feature of the new filter is its correction basis which is partially local in the sense that it consists of “global” and “local” vectors, the later obtained from a local empirical orthogonal functions (Eof) analysis. Such an analysis was introduced in order to better represent the local variability of the ocean. This not only significantly reduces the implementation cost but may also improve the representativeness of the correction basis of the filter. The performance of this scheme is evaluated through twin experiments conducted in a realistic setting of the OPA model over the tropical Pacific zone. The results are compared against those of the Seek filter. The new filter is shown to perform better while it is up to six times faster. Adaptive tuning of the forgetting factor was also used, which enhances performance and improves the stability of the filter during model unstable periods.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00046-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"56209367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial structure of coral reef fish communities in the Ryukyu Islands, southern Japan","authors":"David Lecchini ,&nbsp;Mehdi Adjeroud ,&nbsp;Morgan S Pratchett ,&nbsp;Laurence Cadoret ,&nbsp;René Galzin","doi":"10.1016/S0399-1784(03)00048-3","DOIUrl":"10.1016/S0399-1784(03)00048-3","url":null,"abstract":"<div><p><span>Coral reef fishes often exhibit a high degree of structure in their distribution and abundance, but the factors that influence their spatial arrangement are poorly understood. This study sought to explain the spatial structure of coral reef fish communities in the Ryukyu Archipelago, southern Japan. Visual surveys of coral reef fishes were conducted at multiple stations across the fringing reef (from the inner reef flat to the outer slope) at each of three different islands; Aka, Ishigaki and Sesoko. Spatial variation in fish communities (within and among reefs) was then compared to changes in environmental variables (water depth, distance from the shoreline, reef zone, coral abundance and coral richness). Despite being small islands, the total species richness of coral reef fishes in the Ryukyu Islands was very high (&gt;87 species per reef). Mean abundance of reef fishes was also very high (</span><em>x</em> = 2.26 ± 0.20 S.E. fishes per m²<span>), but more than 80% of all fishes were from the family Pomacentridae. The structure of fish communities was very consistent among reefs, but varied greatly among zones within each reef. On the reef flat, the fish community was dominated by the pomacentrid </span><em>Chrysiptera cyanea</em> and the acanthurid <span><em>Acanthurus</em><em> nigrofuscus</em></span>. In contrast, the reef slope community was characterised by high densities of the pomacentrids <span><em>Pomacentrus</em><em> lepidogenys</em></span> and <em>P. richardsoni</em>, as well as high densities of the acanthurid <span><em>Ctenochaetus</em><em> striatus</em></span>. Canonical correspondence analysis showed that the structure of the coral reef fish communities varied in relation to reef zone, water depth, and distance from the shoreline, but these changes were not related to spatial variation in either coral abundance or coral richness.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00048-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79261680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a coastal upwelling front driven by advection and topographic effects in the North Sea–Baltic Sea transition","authors":"Lars Chresten Lund-Hansen ,&nbsp;Torben Vang","doi":"10.1016/S0399-1784(03)00051-3","DOIUrl":"10.1016/S0399-1784(03)00051-3","url":null,"abstract":"<div><p><span>Upwelling of cold, saline, and nutrient rich water was observed in late September 1999 along an east–west transect in the SW Kattegat. The Kattegat forms part of the transitional zone between the high saline North Sea and the low saline Baltic Sea. The upwelling occurred after an extended period of northward flow and eastern winds in the Kattegat, that changed into a southward flow as wind ceased. The upwelling was the result of a combination of high current speeds and bottom topography whereby the high-speed inflow water was forced towards the surface at the slope. Nutrient data show that the upwelling brought nutrient rich bottom water to the light exposed surface and a related strong (1943.5 ml</span>^–1) bloom of <em>Pseudo-nitzschia pseudodelicatissima</em> was observed. Surface (1.0 m) chlorophyll-<em>a</em> values increased from 3.7 to 10.0 μg 1^–1 during upwelling. A frontal structure developed during the upwelling with raised fluorescence values at the front related to convergence. The present upwelling front was only indirectly related to the wind conditions and the front propagated off shore as compared to other upwelling fronts.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00051-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84067399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does phosphate adsorption onto Saharan dust explain the unusual N/P ratio in the Mediterranean Sea?","authors":"Céline Ridame ,&nbsp;Thierry Moutin ,&nbsp;Cécile Guieu","doi":"10.1016/S0399-1784(03)00061-6","DOIUrl":"10.1016/S0399-1784(03)00061-6","url":null,"abstract":"<div><p>A Saharan soil, considered as a proxy for Saharan aerosols, was used to perform radio-labelled phosphate adsorption experiments using ³³PO₄^3–: leached particles were exposed to poisoned western Mediterranean seawater for varying lengths of time. The measured adsorption capacity of Saharan dust for phosphate was 0.13 μmol g^–1. Considering this value and an annual Saharan dust deposition of 12.5 t km^–2 year^–1, we show that Saharan particles do not represent a significant sink for seawater phosphate in the western Mediterranean Sea. This result is in agreement with that determined from a similar approach conducted in the eastern basin. As a consequence, the unusual N/P ratio measured in the whole Mediterranean Sea (up to 29) cannot be explained by the adsorption process of seawater phosphate onto Saharan dust.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00061-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88820075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short-term variability of primary production and inorganic nitrogen uptake related to the environmental conditions in a shallow coastal area (Gulf of Trieste, N Adriatic Sea)","authors":"Carolina Cantoni ,&nbsp;Stefano Cozzi ,&nbsp;Irene Pecchiar ,&nbsp;Marina Cabrini ,&nbsp;Patricija Mozetič ,&nbsp;Giulio Catalano ,&nbsp;Serena Fonda Umani","doi":"10.1016/S0399-1784(03)00050-1","DOIUrl":"10.1016/S0399-1784(03)00050-1","url":null,"abstract":"<div><p>Primary production (PP) and nitrate (QNO₃) and ammonium (QNH₄<span>) uptakes were measured together with other environmental parameters from October 1999 to February 2001 in the Gulf of Trieste (N Adriatic Sea). Their trends showed a high variability because of the combined effects of meteorological conditions, water circulation and river discharges. PP ranged from 0.2 to 15.9 μmol C dm</span>^–3 d^–1, whereas QNO₃ varied from 0.8 to 442 nmol N dm^–3 d^–1, showing a trend similar to that of carbon basically ascribable to the autotrophic activity. QNH₄ ranged from 20 to 1308 nmol N dm^–3 d^–1<span> and it reached the highest values during the declining phases of phytoplankton<span> blooms, indicating that bacterial community can also be involved in its uptake. Regenerated PP generally prevailed over the new production (depth-integrated </span></span><em>f</em><span>-ratios from 0.05 to 0.50). C/N uptake ratios by planktonic community (annual average of 16 ± 11) showed the repetitive carbon overconsumption (23–33) during periods of high production, and lower values (2–13) during the post-bloom phases and in the months of scarce autotrophic activity. Residence time of freshwater in the area (1 d in November and January, up to 23 d in July) indicated the fast export of low salinity waters in winter and their longer permanence in summer. These values were closer to the ammonium turnover times (1–34 d) than to the nitrate ones (2–831 d). Riverine nitrate load (3–67 t N d</span>^–1) generally exceed the biological demand of this nutrient (uptakes from 0.2 to 8 t N d^–1), whereas the ammonium load (0.1–3.3 t N d^–1) was almost always insufficient (uptakes from 2.6 to 33 t N d^–1). These results evidenced the major role of physical transport and recycling processes to regulate, respectively, nitrate and ammonium availability in this shallow ecosystem.</p></div>","PeriodicalId":100980,"journal":{"name":"Oceanologica Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0399-1784(03)00050-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"56209379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}