Southeastern Brazilian Bight Research Articles

Brazilian sardine (Sardinella brasiliensis Steindachner, 1879) spawning and nursery habitats: spatial-scale partitioning and multiscale relationships with thermohaline descriptors

Abstract de Souza Moraes, L. E., Marcolino Gherardi, D. F., Katsuragawa, M., and Tavares Paes, E. 2012. Brazilian sardine (Sardinella brasiliensis Steindachner, 1879) spawning and nursery habitats: spatial-scale partitioning and multiscale relationships with thermohaline descriptors. – ICES Journal of Marine Science, 69: 939–952. We provide a detailed account of the spatial structure of the Brazilian sardine (Sardinella brasiliensis) spawning and nursery habitats, using ichthyoplankton data from nine surveys (1976–1993) covering the Southeastern Brazilian Bight (SBB). The spatial variability of sardine eggs and larvae was partitioned into predefined spatial-scale classes (broad scale, 200–500 km; medium scale, 50–100 km; and local scale, <50 km). The relationship between density distributions at both developmental stages and environmental descriptors (temperature and salinity) was also explored within these spatial scales. Spatial distributions of sardine eggs were mostly structured on medium and local scales, while larvae were characterized by broad- and medium-scale distributions. Broad- and medium-scale surface temperatures were positively correlated with sardine densities, for both developmental stages. Correlations with salinity were predominantly negative and concentrated on a medium scale. Broad-scale structuring might be explained by mesoscale processes, such as pulsing upwelling events and Brazil Current meandering at the northern portion of the SBB, while medium-scale relationships may be associated with local estuarine outflows. The results indicate that processes favouring vertical stability might regulate the spatial extensions of suitable spawning and nursery habitats for the Brazilian sardine.

Trophic model of the outer continental shelf and upper slope demersal community of the southeastern Brazilian Bight

It is increasingly recognized that demersal communities are important for the functioning of continental shelf and slope ecosystems around the world, including tropical regions. Demersal communities are most prominent in areas of high detritus production and transport, and they link benthic and pelagic biological communities. To understand the structure and role of the demersal community on the southeastern Brazilian Bight, we constructed a trophodynamic model with 37 functional groups to represent the demersal community of the outer continental shelf and upper slope of this area, using the Ecopath with Ecosim 6 (EwE) approach and software. The model indicates high production and biomass of detritus and benthic invertebrates, and strong linkages of these components to demersal and pelagic sub-webs. The level of omnivory indexes in this ecosystem was high, forming a highly connected trophic web reminiscent of tropical land areas. Although high levels of ascendency may indicate resistance and resilience to disturbance, recent and present fisheries trends are probably degrading the biological community and related ecosystem services.

Occurrence, distribution and abundance of Halobates micans Eschscholtz, 1822 (Heteroptera, Gerridae) along the southeastern Brazilian coast

Data collected during an oceanographic cruise along the southeastern Brazilian coast from Cape Frio (22 degrees 58' S) and Paraná (27 degrees 50' S) in March 1982 showed that the marine insect Halobates micans occurred along the Southeastern Brazilian Bight, but in lower abundance in low-temperature areas due to the intrusion and upwelling of South Atlantic Central Water, and in low-salinity areas in Coastal Water. Insect capture was higher at night and in the oligotrophic Tropical Water. The number of nymphs and adult females was higher, probably because of an active breeding season during the austral summer. Adult sex ratio was 1.3:1.0 (F:M). Floating gas vesicles of benthic Sargassum spp. and petroleum lumps were used by females for egg-laying.

Condition of the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879) larvae in the São Sebastião inner and middle continental shelf (São Paulo, Brazil)

Institut fur Meereskunde an der Universitat Kiel (Dusternbrooker Weg, 20, Kiel, Germany D-24105) Brazilian sardine is the most important target of purse seine fisheries along Southeastern Brazilian Bight. Fluctuations in the catch during the past 50 years have been noticeable (Matsuura, 1998; Cergole

Distribution, growth and mortality of young rough scad, Trachurus lathami , in the south-eastern Brazilian Bight

Distribution, growth and mortality of larval and juvenile rough scad Trachurus lathami Nichols, 1920, were studied, based on samples collected during December 1991 in the south-eastern Brazilian Bight. Young rough scad were widespread throughout the region surveyed, but spawning was more intensive in the northern area and tended to be greater in areas of low temperature and high salinity. The length class distribution of the rough scad larvae and juveniles ranged from 2.25 to 32.25 mm body length (BL), and the preflexion larvae of size categories from 2.25 to 3.25 mm BL were the most abundant. Net avoidance was detected for early larvae (2.25 mm length class) and for juveniles larger than 12.25 mm BL length class. Two models were applied to estimate growth and daily growth rate: a linear regression and a Gompertz curve. Both curves showed similar results and a good fit to the data. The mean growth rate estimated by linear regression was 0.44 mm per day (SD=0.008 mm). In small larvae up to 25 mm BL the linear and Gompertz curves showed similar estimated lengths. The hypothetical length at age zero (L0) was estimated as 1.5 mm. The instantaneous daily mortality coefficient estimated from the slope of the regression of log-transformed values of relative production rates (Pt/dt) against age (ti) was Z=0.1888 for larval and juvenile rough scad. This corresponds to a daily mortality rate of 17.2%.

Food and feeding ecology of Brazilian sardine (Sardinella brasiliensis) larvae from the southeastern Brazilian Bight

Results from depth integrated and vertically stratified plankton samples collected in the southeastern Brazilian Bight were used to study the feeding behavior of Brazilian sardine (Sardinella brasiliensis) larvae. Sampling of the ichthyoplankton was carried out with 60 cm Bongo nets in the Bight during the spawning seasons of 1991/92 and 1992/93. The sampling of microzooplankton was carried out in the coastal region off Ubatuba, using the closing-type plankton net, in December 1995. The feeding study was based on a total of 901 captured larvae. Gut content analysis of the sardine larvae showed a diurnal pattern of food intake. Copepod nauplii dominated the diet of the preflexion and flexion larvae, but they were the second in abundance for the postflexion larvae which fed preferentially on copepodites and adults of Oncaea spp. Averaged feeding incidence of the 901 larvae was 37.6%, but it increased to 58.5% for day-caught larvae. Seventy percent of the food particles were found in the mid-gut and food eaten showed a natural increase in digestion from fore-gut to hind-gut. Vertical distribution of microzooplankton revealed that copepod nauplii were present in densities of 10-20 ind. L-1, mainly in the upper mixed layer (0-20 m depth), but higher densities of copepodite and adult of Oncaea, Oithona and Paracalamis were found within and beneath the thermocline. These results show that Brazilian sardine larvae can successfully adapt their diet, feeding on the most abundant food particles in the upper mixed layer of the survey area.

Growth and mortality estimates of Sardinella brasiliensis in the southeastern Brazilian bight

Estudo sobre o crescimento e a mortalidade de Sardinella brasiliensis, da costa sudeste do Brasil, foi realizado para o periodo 1977 a 1987. As analises foram efetuadas a partir de dados existentes sobre distribuicoes de frequencia de comprimento de amostras da captura comercial. Chaves idade/comprimento, construidas a partir de leitura de aneis de crescimento em otolitos, dentro do Programa Integrado de Estudos Biologicos sobre a Sardinha - PIEBS, foram utilizadas para transformar as distribuices de comprimento em idade. Os parâmetros de crescimento da equacao de von Bertalanffy foram estimados, anualmente e para o periodo como um todo, a partir de metodos que utilizam dados de idade e comprimento. Os parâmetros medios encontrados para o periodo foram: L∞ = 271 mm e K= 0,59 ano-1. Os coeficientes instantâneos de mortalidade total (Z) anuais foram calculados pelas curvas de captura e por metodos baseados no comprimento medio dos individuos nas capturas. A mortalidade total para todo o periodo foi obtida pela media dos valores anuais. O coeficiente instantâneo de mortalidade natural (M) foi estimado pela equacao empirica de Pauly (1980a), usando um fator de correcao de 0,8 para clupeoides, e o coeficiente instantâneo de mortalidade por pesca (F), pela diferenca entre a mortalidade total e a natural. Os valores encontrados foram: Z= 3,6 ano-1, M = 0,96 ano-1 e F= 2,6 ano-1.

Growth and mortality estimates of Sardinella brasiliensis in the southeastern Brazilian Bight

Length frequency analisys were applied for sardine data collected from commercial catches throughout the southeastern Brazilian coast in 1977-1987. Age/length keys were obtained by otolith ring countings and utilized to transform length into age composition. Growth parameters were estimated by the von Bertalanffy growth equation using age and length data for each year and for all the period of investigation. The mean growth parameters for the entire period were estimated as L∞ = 271 mm and K= 0.59 year-1. Instantaneous total mortality (Z) coefficients per year were estimated using catch curves and methods based on the mean length of the fish caught. Total mortality rate for the entire period was obtained through the average of the annual values. Natural mortality (M) was estimated using the Paul/s empirical equation (1980a), and fishing mortality (F) by the difference between total and natural mortality values.The results were Z = 3.6 year-1; M = 0.96 year-1; and F= 2.6 year-1.

Distribution and abundance of carangid larvae in the southeastern Brazilian Bight during 1975-1981

Distribution and abundance of the carangid larvae collected during ten survey cruises in the southeastern Brazilian Bight were analyzed. Trachurus lathami was the most abundant species in the surveyed area with 58.54 % of total carangids taken, followed by Chloroscombrus chrysurus with 15.22 % and Decapteruspunctatus with 12.17 %. Larvae of T lathami and D. punctatus were found all over the continental shelf while the distribution of C. chrysurus larvae was limited to the coastal region. Most of the species occurred all year-around but remarkably during spring and summer. This intensive spawning period of most carangid species seems to be related to the seasonal variation of the hydrographie structure of the southeastern coast of Brazil.

Distribution and abundance of carangid larvae in the southeastern Brazilian Bight during 1975-1981

Distribution and abundance of the carangid larvae collected during ten survey cruises in the southeastern Brazilian Bight were analyzed. Trachurus lathami was the most abundant species in the surveyed area with 58.54 % of total carangids taken, followed by Chloroscombrus chrysurus with 15.22 % and Decapteruspunctatus with 12.17 %. Larvae of T lathami and D. punctatus were found all over the continental shelf while the distribution of C. chrysurus larvae was limited to the coastal region. Most of the species occurred all year-around but remarkably during spring and summer. This intensive spawning period of most carangid species seems to be related to the seasonal variation of the hydrographie structure of the southeastern coast of Brazil.

Comparison of spawning patterns of the Brazilian sardine (Sardinella brasiliensis) and anchoita (Engrautis anchoita) in Ubatuba region, southern Brazil during 1985 through 1988

The Brazilian sardine (Sardinella brasiliensis) and anchoita (Engrautis anchoita) inhabit the southeastern Brazilian Bight. The former spawns at night (21:00-03:00) in coastal region during late-spring and summer, meanwhile, the latter spawns all year-around, mainly in coastal region during summer and in neritic region during winter. The spawning time of E. anchoita was observed all day long, but more intensively at night. During summer there occurs a strong vertical stratification of water masses. The spawning of S. brasiliensis occurs in surface mixed layer, while that of E. anchoita occurs beneath the thermocline inside the cool South Atlantic Central Water which occupies the bottom layer during late spring and summer. However, the sardine and anchovy egss and larvae were found inside both the upper tropical and lower cold water masses, but predominantly above thermocline in this region

Comparison of spawning patterns of the Brazilian sardine (Sardinella brasiliensis) and anchoita (Engrautis anchoita) in Ubatuba region, southern Brazil during 1985 through 1988

The Brazilian sardine (Sardinella brasiliensis) and anchoita (Engrautis anchoita) inhabit the southeastern Brazilian Bight. The former spawns at night (21:00-03:00) in coastal region during late-spring and summer, meanwhile, the latter spawns all year-around, mainly in coastal region during summer and in neritic region during winter. The spawning time of E. anchoita was observed all day long, but more intensively at night. During summer there occurs a strong vertical stratification of water masses. The spawning of S. brasiliensis occurs in surface mixed layer, while that of E. anchoita occurs beneath the thermocline inside the cool South Atlantic Central Water which occupies the bottom layer during late spring and summer. However, the sardine and anchovy egss and larvae were found inside both the upper tropical and lower cold water masses, but predominantly above thermocline in this region

Comparison of the diel and spatial distribution patterns of ichthyoplankton and ichthyoneuston in the Southeastern Brazilian Bight

Fish larvae were collected by neuston and bongo nets, in the Southeastern Brazil, during four oceanographie cruises (January 1980; January 1981; October 1981; and March 1982). The results are compared and analyzed in order to study the patterns of diel vertical distributions of fish larvae and to detect sampling problems. Larvae collected with neuston net were quite different in types and size composition, when compared with those collected with bongo net in oblique tows. Clear tendency of stratification in size composition at the uppermost layer can be observed on juveniles ( > 19 mm) of Sardinella brasiliensis which also showed day time avoidance. Most of the neustonic taxa were also caught in the deeper layers, although some groups, e.g. Mugilidae, Mullidae, and Gerreidae, were more abundant at the surface. Density of ichthyoneuston is much higher than those observed in the Northwest Atlantic and number of fish larvae collected during the day by neuston net exceeded that of night samples.

Comparison of the diel and spatial distribution patterns of ichthyoplankton and ichthyoneuston in the Southeastern Brazilian Bight

Fish larvae were collected by neuston and bongo nets, in the Southeastern Brazil, during four océanographie cruises (January 1980; January 1981; October 1981; and March 1982). The results are compared and analyzed in order to study the patterns of diel vertical distributions of fish larvae and to detect sampling problems. Larvae collected with neuston net were quite different in types and size composition, when compared with those collected with bongo net in oblique tows. Clear tendency of stratification in size composition at the uppermost layer can be observed on juveniles ( > 19 mm) of Sardinella brasiliensis which also showed day time avoidance. Most of the neustonic taxa were also caught in the deeper layers, although some groups, e.g. Mugilidae, Mullidae, and Gerreidae, were more abundant at the surface. Density of ichthyoneuston is much higher than those observed in the Northwest Atlantic and number of fish larvae collected during the day by neuston net exceeded that of night samples.