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Manuel Haimovici - One of the best experts on this subject based on the ideXlab platform.
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diet and feeding of the cutlassfish trichiurus lepturus in the Subtropical Convergence ecosystem of southern brazil
Journal of the Marine Biological Association of the United Kingdom, 2005Co-Authors: Agnaldo Silva Martins, Manuel Haimovici, Raul PalaciosAbstract:The diet and feeding of the cutlass¢sh Trichiurus lepturus were studied based on analyses of the stomach contents of larvae, juveniles, and adults collected along the continental shelf and shelf break oi southern Brazil, from the Cape of Santa Marta Grande (28836 0 S) to Chu|¤ (34845 0 S). The larvae and pre-juveniles with a total length of 55 cm were found to have fed almost exclusively on calanoid copepods, whereas juveniles (5 to 30 cm) fed on small zooplanktonic crustaceans such as Lucifer faxoni and Promysys atlantica. On the other hand, sub-adults (30 to 70 cm), fed on euphausiids, mainly Euphausia similis, and small ¢sh, mostly anchovy Engraulis anchoita. Adults (70 to 160 cm) fed on a wide range of larger prey, such as anchovy, sciaenid ¢sh, cephalopods and coastal shrimps, as well as euphausiids. The juveniles and sub-adults fed more intensively than adults during the warm-water season whereas adults fed more intensively during the cold-water season. Feeding activity was more intense at night, while cannibalism was more frequent during the warm season, when biological productivity was lower. Finally, diet diversity was higher in coastal waters, during the warm season. The abundance of cutlass¢sh oi southern Brazil may be explained by the fact that it is adapted to feed on a wide size-range of both pelagic and demersal prey.
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reproduction of the cutlassfish trichiurus lepturus in the southern brazil Subtropical Convergence ecosystem
Scientia Marina, 2000Co-Authors: Agnaldo Silva Martins, Manuel HaimoviciAbstract:The reproduction of the cutlassfish Trichiurus lepturus was studied from samples collected in bottom trawl surveys on the continental shelf and shelf break off southern Brazil. The mean total length (LT) at first gonadal maturity was 63.9 cm for males and 69.3 cm for females. Batch fecundity ranged from 3,917 in a specimen of 70 cm LT to 154,216 in a specimen of 141 cm but the number of spawning batches in each season was not established. Spawning occurs in late spring and summer in the continental shelf and probably year round over the shelf break. High surface temperatures and moderate stratification of the water column were associated with the final stages of gonadal maturation. Seasonal and spatial differences in sex ratios, sizes, maturity stages and feeding intensities suggest that adult female T. lepturus remain during the cold season in the continental shelf of southern Brazil to feed, while adult males move to warmer waters northward or offshore.
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Distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil Subtropical Convergence ecosystem
Fisheries Research, 1997Co-Authors: Agnaldo Silva Martins, Manuel HaimoviciAbstract:Abstract The distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil Subtropical Convergence ecosystem were studied from demersal trawl surveys conducted along the continental shelf and upper slope from Cape Santa Marta Grande (28 °36′S) to Chui (34 °45′S) between 1981 and 1987. Trichiurus lepturus was more abundant at bottom water temperatures of over 16 °C and in the 40–120 m depth range. From late spring to fall, juveniles of 5–30 cm total length ( TL ) were found in coastal waters, subadults ( TL 30–70 cm) mainly in inner shelf waters and adults ( TL > 70 cm) in coastal, inner and outer shelf waters. Higher catches of subadults and adults were found associated with thermal fronts in the western boundary of the Subtropical Convergence or with a shelf break upwelling observed in summer. The standing stock in a 58 000 km 2 shelf area estimated by the swept area method, ranged from 3066 t (±46% CI ) in September 1981 to 37814 t (±22% CI ) in January 1982. Correlation between occurrences of different size groups of cutlassfishes and other fishes caught in 250 bottom trawl hauls was analyzed. A positive correlation between cutlassfish and juvenile weakfish, Cynoscion guatucupa , was associated with similar spatial distribution but also indicated trophic competition.
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demersal bony fish of the outer shelf and upper slope of the southern brazil Subtropical Convergence ecosystem
Marine Ecology Progress Series, 1994Co-Authors: Manuel Haimovici, Agnaldo Silva Martins, Jose Lima De Figueiredo, Pedro Jose Castelli VieiraAbstract:Ninety-three species of bony fishes were caught in 4 seasonal bottom-trawl surveys carried out between July 1986 and May 1987 on the outer shelf and upper slope (124 to 587 m depth) along the southern Brazilian coast (30°40' to 34"30' S). On the outer shelf (< 179 m), the demersalpelagic species Trichiurus lepturus, Trachurus lathami, Cynoscion guatucupa, Scomber japonicus, and Thyrsitops lepidopoides predominated and also to a lesser degree the demersal benthonic Umbrina canosai and Mullus argentinae. Antiyonia capros and Priacanthus arenatus were found associated with the relic coral hard bottoms of the shelf break (180 to 249 m). Further offshore, the demersal-pelagic species Ariomma bondi and Zenopsis conchifera and the demersal benthonic species Polyprion americanus and Helicolenus lahillei were abundant, both associated with rocky bottoms. The macrourids Coelorinchus marinii and Malacocephalus occidentalis characterized deep-water hauls p 4 5 0 m). Frequent and widespread, but less abundant in the catch, were Polymixia lowei, Urophycis mystacea and Merluccius hubbsi. Mean total catch (kg h-') decreased 6-fold and the number of species by more than half along the depth range, with a sharp step at 350 m. Both catch and number of species were slightly higher in the winter cruises. Most species occurred in both winter and summer-autumn cruises, but, with increasing depth, the relative abundance of species that occur year-round decreased, whereas fishes that occur mostly in winter increased. The catch of demersal-pelagic fish decreased sharply below 350 m and differed little among seasons; catches of demersal-benthonic fish were more evenly distributed across the depth range and were larger in winter and spring. The high number of species on the shelf break may be attributable to the higher variety of soft and consolidated substrates and the overlapping of different water masses along the water column. The north-south shift of the western boundary of the Subtropical Convergence appears to be mainly responsible for the seasonal changes in abundance of the species.
Veronique Garcon - One of the best experts on this subject based on the ideXlab platform.
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event scale blooms drive enhanced primary productivity at the Subtropical Convergence
Geophysical Research Letters, 2005Co-Authors: J Llido, Veronique Garcon, J R E Lutjeharms, Joel SudreAbstract:Frontal systems in the Southern Ocean are known for their enhanced biological activity, with some tantalising suggestions that this enhancement may be intermittent. We have used frequent satellite ocean colour observations to investigate the Subtropical Convergence south of Africa. We demonstrate that the biological enhancement takes place as episodic chlorophyll bloom events with limited spatial and temporal scales. Most of the events appear in austral spring-summer. Two typical lifetimes, 8-24 and 40-60 days, emerge unambiguously during these seasons. A similar analysis has been carried out on modelled chlorophyll fields to investigate the physical-biogeochemical causes for such events. Strong and swift stratification, alleviating the light limitation on growth of phytoplankton, causes the appearance of a bloom. A mixed layer depth expansion subsequently leads to a rapid disappearance of the simulated event. Phytoplankton horizontal transport, either zonal or meridional, also plays a key role on the lifetime of the bloom events.
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rossby wave and ocean color the cells uplifting hypothesis in the south atlantic Subtropical Convergence zone
Geophysical Research Letters, 2003Co-Authors: Guillaume Charria, F Melin, Isabelle Dadou, Mariehelene Radenac, Veronique GarconAbstract:[1] Rossbywavessignaturesonfilteredoceancolordataare detected in the Subtropical Convergence zone of the South Atlantic ocean. We investigate whether these chlorophyll anomalies can be accounted for by the uplifting mechanism of phytoplanktonic cells associated with the passage of a Rossby wave. We consider vertical chlorophyll profiles exhibiting a subsurface chlorophyll maximum typical of the South Atlantic Subtropical Convergence Province. Chlorophyll remotely-sensed concentrations resulting from an academic uplifting of the three chlorophyll profiles are reconstructed with a radiative transfer model. Amplitude of the chlorophyll enrichments found with this hypothesis (0.06 mg chl.m 3 ) compares well with propagative ocean color anomalies detected in the SeaWiFS data. However, other processes such as the Rototiller effect [Siegel, 2001] or advection of chlorophyll gradients could also play a non negligible role. INDEX TERMS: 4560 Oceanography: Physical:Surface wavesandtides (1255);9325Information Related to Geographic Region: Atlantic Ocean; 4552 Oceanography:
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phytoplankton pigment distribution from seawifs data in the Subtropical Convergence zone south of africa a wavelet analysis
Geophysical Research Letters, 1999Co-Authors: Eric Machu, Bertrand Ferret, Veronique GarconAbstract:The Agulhas system (Agulhas Current, Retroflection, Agulhas Return Current (ARC)), south of Africa, constitutes a complex energetic system subject to high frequency mesoscale and low frequency variability. Using chlorophyll pigment concentration data collected by the SeaWiFS ocean color sensor and sea surface height satellite data, we demonstrate the utility of wavelet analysis in jointly analyzing ocean color and altimetric signals. Two distinct dynamical scenarios of the Agulhas system (October 1997 and January 1998) yield different dominant wavelengths (620 and 500 km) for the ARC Rossby wave. They are simultaneously retrieved from the chlorophyll and sea level anomaly signals. Longitudinal extension of the power, resulting from the wavelet analysis, also depends on the dynamical regime.
Eric D Barton - One of the best experts on this subject based on the ideXlab platform.
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water masses and larval fish habitats in the pacific tropical Subtropical Convergence off mexico
Continental Shelf Research, 2021Co-Authors: Fernando Contrerascatala, Emilio Beier, Laura Sanchezvelasco, Victor M Godinez, Elvia D Sanchezperez, Eric D BartonAbstract:Abstract In early summer (June 2010), we used zooplankton and hydrographic sampling to analyze relationships between larval fish habitats and converging water masses in the Pacific tropical-Subtropical region off Mexico. Results showed an equatorward jet parallel to the Baja California Peninsula (the Tropical Branch of California Current) which was located northward of 25oC surface isotherm. In this area, a larval fish habitat indicated by Triphoturus mexicanus larvae was identified. The habitat had low larval abundance (17 larvae per 10 m2) with major larval concentration below the thermocline (∼ 20 Co and oligotrophic conditions, 1 mg m-3) waters of the shallow thermocline (∼30 m depth). The other larval fish habitat occupied an area of anticyclonic circulation in the offshore California Current Water, where the thermocline was depressed ∼ 70 m depth. Oligotrophic conditions (0.3 mg m-3) corresponded with the lowest mean larval abundance (14 larvae per 10 m2) of the study. The distribution of the larval fish habitats and their indicator species correspond with the water masses distributions in the Tropical-Subtropical Convergence, which are modulated by mesoscale structures affecting the thermocline depth and the larval life-history.
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ommastrephid squid paralarvae distribution and transport under contrasting interannual conditions in the tropical Subtropical Convergence off mexico
Deep Sea Research Part I: Oceanographic Research Papers, 2020Co-Authors: Erick D Ruvalcabaaroche, Emilio Beier, Laura Sanchezvelasco, Victor M Godinez, Eric D Barton, David LanderostafollaAbstract:Abstract The distribution and transport of paralarvae of the complex Sthenoteuthis oualaniensis - Dosidicus gigas (SD complex, Cephalopoda: Ommastrephidae) in the tropical-Subtropical Convergence off Mexico were analyzed under contrasting interannual environmental conditions. Two El Nino years were sampled (2010 and 2016), in which the SST were up to 3 °C above the average throughout the study area, while during La Nina year (2012) the SST anomalies were up to 2 °C below the average. During El Nino years, a relative shallow thermocline ( 80 cycles h−1). In addition, a simple dispersion Lagrangian model based on observed satellite geostrophic currents, suggested association of the SD complex paralarvae with mesoscale structures, in which the eggs and hatched paralarvae had an appropriate habitat for a nursery, retaining the paralarvae until their recruitment in a ~100 km radius. But during warm extreme events, with less mesoscale activity, the paralarvae could be transported as far as 500 km southeast of the spawning zone. Even though the interannual ENSO conditions modulate the magnitude of the paralarvae abundance, the shallow and well developed thermocline could help paralarvae to increase their survival chances, while mesoscale activity retains them near the productive coastal waters.
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distribution of calanoid copepods across the mesoscale frontal zone of tropical Subtropical Convergence off mexico
Deep-sea Research Part Ii-topical Studies in Oceanography, 2019Co-Authors: Javier Cruzhernandez, Emilio Beier, Laura Sanchezvelasco, Victor M Godinez, Eric D BartonAbstract:Abstract The distribution of calanoid copepods was investigated in the Convergence zone between the California Current Water and Transitional Tropical Water in June 2010 to understand how this zooplankton community responds to mesoscale environmental structure. Hydrographic conditions and zooplankton profiles were measured along two transects which crossed a mesoscale front and adjacent structures, visible in sea surface temperature and ocean color satellite images. The hydrographic structure showed strong temperature (~2 °C) and oxygen (50 μmol kg−1) gradients in the frontal zone (~90 km) associated with a sinking of the thermocline and oxycline, from ~30 m depth in the Transitional Tropical Water, to ~ 90 m depth in the California Current Water. The front was marked by a salinity minimum (
Agnaldo Silva Martins - One of the best experts on this subject based on the ideXlab platform.
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diet and feeding of the cutlassfish trichiurus lepturus in the Subtropical Convergence ecosystem of southern brazil
Journal of the Marine Biological Association of the United Kingdom, 2005Co-Authors: Agnaldo Silva Martins, Manuel Haimovici, Raul PalaciosAbstract:The diet and feeding of the cutlass¢sh Trichiurus lepturus were studied based on analyses of the stomach contents of larvae, juveniles, and adults collected along the continental shelf and shelf break oi southern Brazil, from the Cape of Santa Marta Grande (28836 0 S) to Chu|¤ (34845 0 S). The larvae and pre-juveniles with a total length of 55 cm were found to have fed almost exclusively on calanoid copepods, whereas juveniles (5 to 30 cm) fed on small zooplanktonic crustaceans such as Lucifer faxoni and Promysys atlantica. On the other hand, sub-adults (30 to 70 cm), fed on euphausiids, mainly Euphausia similis, and small ¢sh, mostly anchovy Engraulis anchoita. Adults (70 to 160 cm) fed on a wide range of larger prey, such as anchovy, sciaenid ¢sh, cephalopods and coastal shrimps, as well as euphausiids. The juveniles and sub-adults fed more intensively than adults during the warm-water season whereas adults fed more intensively during the cold-water season. Feeding activity was more intense at night, while cannibalism was more frequent during the warm season, when biological productivity was lower. Finally, diet diversity was higher in coastal waters, during the warm season. The abundance of cutlass¢sh oi southern Brazil may be explained by the fact that it is adapted to feed on a wide size-range of both pelagic and demersal prey.
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reproduction of the cutlassfish trichiurus lepturus in the southern brazil Subtropical Convergence ecosystem
Scientia Marina, 2000Co-Authors: Agnaldo Silva Martins, Manuel HaimoviciAbstract:The reproduction of the cutlassfish Trichiurus lepturus was studied from samples collected in bottom trawl surveys on the continental shelf and shelf break off southern Brazil. The mean total length (LT) at first gonadal maturity was 63.9 cm for males and 69.3 cm for females. Batch fecundity ranged from 3,917 in a specimen of 70 cm LT to 154,216 in a specimen of 141 cm but the number of spawning batches in each season was not established. Spawning occurs in late spring and summer in the continental shelf and probably year round over the shelf break. High surface temperatures and moderate stratification of the water column were associated with the final stages of gonadal maturation. Seasonal and spatial differences in sex ratios, sizes, maturity stages and feeding intensities suggest that adult female T. lepturus remain during the cold season in the continental shelf of southern Brazil to feed, while adult males move to warmer waters northward or offshore.
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Distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil Subtropical Convergence ecosystem
Fisheries Research, 1997Co-Authors: Agnaldo Silva Martins, Manuel HaimoviciAbstract:Abstract The distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil Subtropical Convergence ecosystem were studied from demersal trawl surveys conducted along the continental shelf and upper slope from Cape Santa Marta Grande (28 °36′S) to Chui (34 °45′S) between 1981 and 1987. Trichiurus lepturus was more abundant at bottom water temperatures of over 16 °C and in the 40–120 m depth range. From late spring to fall, juveniles of 5–30 cm total length ( TL ) were found in coastal waters, subadults ( TL 30–70 cm) mainly in inner shelf waters and adults ( TL > 70 cm) in coastal, inner and outer shelf waters. Higher catches of subadults and adults were found associated with thermal fronts in the western boundary of the Subtropical Convergence or with a shelf break upwelling observed in summer. The standing stock in a 58 000 km 2 shelf area estimated by the swept area method, ranged from 3066 t (±46% CI ) in September 1981 to 37814 t (±22% CI ) in January 1982. Correlation between occurrences of different size groups of cutlassfishes and other fishes caught in 250 bottom trawl hauls was analyzed. A positive correlation between cutlassfish and juvenile weakfish, Cynoscion guatucupa , was associated with similar spatial distribution but also indicated trophic competition.
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demersal bony fish of the outer shelf and upper slope of the southern brazil Subtropical Convergence ecosystem
Marine Ecology Progress Series, 1994Co-Authors: Manuel Haimovici, Agnaldo Silva Martins, Jose Lima De Figueiredo, Pedro Jose Castelli VieiraAbstract:Ninety-three species of bony fishes were caught in 4 seasonal bottom-trawl surveys carried out between July 1986 and May 1987 on the outer shelf and upper slope (124 to 587 m depth) along the southern Brazilian coast (30°40' to 34"30' S). On the outer shelf (< 179 m), the demersalpelagic species Trichiurus lepturus, Trachurus lathami, Cynoscion guatucupa, Scomber japonicus, and Thyrsitops lepidopoides predominated and also to a lesser degree the demersal benthonic Umbrina canosai and Mullus argentinae. Antiyonia capros and Priacanthus arenatus were found associated with the relic coral hard bottoms of the shelf break (180 to 249 m). Further offshore, the demersal-pelagic species Ariomma bondi and Zenopsis conchifera and the demersal benthonic species Polyprion americanus and Helicolenus lahillei were abundant, both associated with rocky bottoms. The macrourids Coelorinchus marinii and Malacocephalus occidentalis characterized deep-water hauls p 4 5 0 m). Frequent and widespread, but less abundant in the catch, were Polymixia lowei, Urophycis mystacea and Merluccius hubbsi. Mean total catch (kg h-') decreased 6-fold and the number of species by more than half along the depth range, with a sharp step at 350 m. Both catch and number of species were slightly higher in the winter cruises. Most species occurred in both winter and summer-autumn cruises, but, with increasing depth, the relative abundance of species that occur year-round decreased, whereas fishes that occur mostly in winter increased. The catch of demersal-pelagic fish decreased sharply below 350 m and differed little among seasons; catches of demersal-benthonic fish were more evenly distributed across the depth range and were larger in winter and spring. The high number of species on the shelf break may be attributable to the higher variety of soft and consolidated substrates and the overlapping of different water masses along the water column. The north-south shift of the western boundary of the Subtropical Convergence appears to be mainly responsible for the seasonal changes in abundance of the species.
Peter Munk - One of the best experts on this subject based on the ideXlab platform.
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species composition and diversity of fish larvae in the Subtropical Convergence zone of the sargasso sea from morphology and dna barcoding
Fisheries Oceanography, 2016Co-Authors: Lasse Riemann, Daniel Jiro Ayala, Peter MunkAbstract:Specific regions of otherwise oligotrophic oceans seem to attract fish spawning and sustain significant abundances of fish larvae. The Sargasso Sea in the North Atlantic Subtropical gyre is known as the spawning area of the Atlantic eels, but numerous other fish species also spawn in the area. In order to evaluate spatial variability of larval fish in the region, we examined species diversity, composition and abundances at eight stations in the Subtropical Convergence Zone (STCZ) using morphological identification and DNA barcoding. From a total of approximately 3500 specimens collected, at least 154 species from 50 families could be identified. The family Myctophidae had the highest species richness, with at least 32 species represented. The myctophids Lepidophanes gaussi, Bolinichthys indicus, Notolychnus valdiviae and Ceratoscopelus warmingii were the four most abundant species. Other common species included the three eels: Nemichthys scolopaceus, Ariosoma balearicum and Anguilla anguilla. Larval fish species composition differed substantially between the relatively closely spaced stations on either side of prominent hydrographic fronts in the study area, presumably because of the strong environmental gradients. Common eel species were concentrated between the fronts whereas common myctophids were of highest abundance at the outer edges of the fronts. The abundances of most species were generally enhanced in the vicinity of the fronts. The use of combined morphological and DNA-barcoding identification methods facilitated species identification, and we could document substantially higher levels and a larger degree of spatial variability in species diversity of fish larvae than previously shown for oligotrophic ocean areas.
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distribution and production of plankton communities in the Subtropical Convergence zone of the sargasso sea i phytoplankton and bacterioplankton
Marine Ecology Progress Series, 2011Co-Authors: Lasse Riemann, Torkel Gissel Nielsen, Theis Kragh, Katherine Richardson, Hjalte Parner, Hans Henrik Jakobsen, Peter MunkAbstract:Elevated levels of biomass and productivity are often associated with ocean frontal sys- tems. The Subtropical Convergence Zone (STCZ) in the southern Sargasso Sea shows pronounced and stable thermal fronts, but little is known about the ecological consequences of these hydrographic fea- tures. With the aim of improving the understanding of physical and lower trophic level processes in the area, we carried out field studies of physical, chemical and biological characteristics along 3 transects crossing thermal fronts associated with the STCZ in March to April 2007. Thermal and chemical strat- ification were evident at all stations within the STCZ, and a depletion of nitrate was measured in the upper ~150 m. The phytoplankton biomass was dominated by Prochlorococcus spp. with highest abundance, up to >400 000 cells ml -1 , at the chlorophyll a (chl a) maximum at 100 to 150 m depth. Syn- echococcus spp. were generally located higher in the water column. Picoalgae were less abundant, up to 8000 cells ml -1 , but explained most of the variation in chl a. Even though diatoms and dinoflagellates were few, the biomass of larger phytoplankton equalled or exceeded that of picoplankton at a few sta- tions. Bacterial biomass was roughly equal to half of the phytoplankton biomass. We did not find ele- vated levels of primary production or biomass of specific phytoplankton groups associated with the STCZ, probably due to a pronounced variability between stations along transects. Nevertheless, dis- tinct increases in chl a were associated with the zone and thermal fronts bordering the STCZ.
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distribution and production of plankton communities in the Subtropical Convergence zone of the sargasso sea ii protozooplankton and copepods
Marine Ecology Progress Series, 2011Co-Authors: Nikolaj Gedsted Andersen, Hans Henrik Jakobsen, Torkel Gissel Nielsen, Peter Munk, Lasse RiemannAbstract:The oligotrophic Sargasso Sea in the western part of the North Atlantic Ocean is influ- enced by a complex set of oceanographic features that might introduce nutrients and enhance pro- ductivity in certain areas. To increase our understanding of the variability in plankton communities and to determine the potential reasons why Atlantic eels Anguilla spp. use this area for spawning, we investigated the distribution and productivity of the zooplankton community across the Subtropical Convergence Zone (STCZ) in the Sargasso Sea in March and April 2007. The vertical and horizontal distributions of protozoans and metazooplankton were investigated at 33 stations along 3 north to south transects ranging from 64 to 70° W to a depth of 400 m. Copepods dominated the metazoo- plankton, while heterotrophic athecate dinoflagellates dominated the protozoan biomass. Other im - portant groups were appendicularians, gastropod larvae and ostracods. Most of the recorded meta- zoan groups responded numerically to the frontal features (i.e. the surfacing of the isotherms) with high abundance in the STCZ compared with areas north and south of this. Juvenile copepod growth and egg production peaked in the STCZ, with a weight-specific growth rate of juvenile copepods ranging from 0.09 to 0.21 d -1 , and a much lower specific egg production in the order of 0.01% d -1 . The Sargasso Sea is described as oligotrophic, but the availability of athecate dinoflagellates and ciliates in the STCZ potentially leads to an enhanced mesozooplankton secondary production, which may in turn be available to organisms at higher trophic levels such as larvae of Atlantic eels.
