Central Coast Of Brazil Research Articles

Amaryllididae and Lysianassidae (Amphipoda: Lysianassoidea) from off the central coast of Brazil (11 ºS – 22 ºS), with descriptions of three new species

Amaryllididae and Lysianassidae (Amphipoda: Lysianassoidea) from off the central coast of Brazil (11 ºS – 22 ºS), with descriptions of three new species

Evidence of seasonal changes in community structure for a coastal ecosystem in the central coast of Brazil, south-west Atlantic

This study reports on the seasonal variations of the community structure of a coastal ecosystem, off the central coast of Brazil. Samples were collected on a monthly basis on board a bottom otter trawl vessel from October 2003 to September 2004. A total of 57 species belonging to 26 families and 10 orders were collected. Resident species, which presented a high proportion of juveniles throughout the year, were the most abundant. Among these, benthonic fish of the Sciaenidae family were the dominant species, followed by Tetraodontiformes, nektonic Sciaenidae and Clupeiformes. Benthonic fish were more abundant during the spring/summer months (October to February) and pelagic species dominated the autumn/winter months (May to September). However, these differences were not statistically significant. The spring/summer months were also characterized by reproduction activity, while the autumn/winter months saw high proportions of juveniles. Indicator species analyses showed that 5 species presented significant differences in their occurrence and abundance throughout the seasons of the year. This study shows that the coastal area is an important place for reproduction and a nursing ground of many species. It also shows evidence of community-level reproductive patterns for a tropical ecosystem. Future studies are necessary to identify the likely ecosystem forcings underlying these patterns.

Incidental catch of sea turtles by the Brazilian pelagic longline fishery

This paper presents data on the incidental catch of sea turtles in both the Brazilian exclusive economic zone and adjacent international waters (both areas are located mainly in the south-western Atlantic) by Brazilian commercial pelagic longliners targeting swordfish, tuna and sharks. Data were obtained by on-board observers for 311 trips carried out in 2001–2005, totalling 7385 sets and 11,348,069 hooks. A total of 1386 sea turtles were incidentally captured in the five years (some of them were considered dead at capture): 789 loggerheads (Caretta caretta), 341 leatherbacks (Dermochelys coriacea), 45 green turtles (Chelonia mydas), 81 olive ridleys (Lepidochelys olivacea) and 130 of unknown species. Taking into account the distribution of the fishing effort in the study area and the incidental catch of sea turtles, four regions were highlighted for the analyses: Zone 1 is located off the northern Brazilian coast; Zone 2 is located off the central Brazilian coast; Zone 3 is the region off the southern Brazilian coast; and Zone 4, located in the open sea almost totally within international waters, is the region around a chain of undersea mountains known as the Rio Grande Rise (Elevação do Rio Grande). There is no information on the origin (nesting areas) of the captured olive ridleys, but there is some evidence, obtained through genetic and demographic analyses, that loggerheads, leatherbacks and green turtles inhabiting the open ocean around Brazil originate from nesting areas in several countries. Together with the fact that the south-western Atlantic is fished by longliners again from several countries, this places the conservation of sea turtles in that part of the ocean in an international context. Some conservation actions carried out by Brazil concerning the interaction between pelagic longlines and sea turtles in the study area are described.

Amaryllididae and Lysianassidae (Amphipoda: Lysianassoidea) from off the central coast of Brazil (11<sup>o</sup>S-22<sup>o</sup>S), with descriptions of three new species

Material collected on the central Brazilian coast from the REVIZEE Benthos Program was analyzed and three new species were herein described. Knowledge about sexual dimorphism on Bonassa is improved. The hypothesis of endemism of the genus Amaryllis to Australia is contested with the discovery of a new species of Amaryllis in the Southwestern Atlantic Ocean. A new species of Lysianassa is described, and its differences to L. brasiliensis are commented too. Lysianopsis concavus Senna, 2007 is herein described with more details in description and figures. The distributions of the described species are given. Keys to identification of Brazilian Lysianassoidea families and Lysianassidae species are presented in this paper.Key-words: Amaryllis, Bonassa, Lysianassa, Lysianopsis, taxonomy, Brazilian province

Taxonomy of Aristeidae (Dendrobranchiata: Penaeoidea) from the central coast of Brazil, collected by the Revizee program, between 19 º and 22 ºS

Taxonomy of Aristeidae (Dendrobranchiata: Penaeoidea) from the central coast of Brazil, collected by the Revizee program, between 19 º and 22 ºS

Age, growth and mortality of white grunt (<i>Haemulon plumierii</i>) from the central coast of Brazil

White grunt ( Haemulon plumierii ) otoliths were collected from 1997 to 1999 off the central coast of Brazil. Analysis of the edges of otolith sections suggests that one translucent and one opaque zone are formed once a year. Observed size and age class ranges for H. plumierii were 218–378 mm total length (TL) and 2–28 years, respectively. The von Bertalanffy growth models estimated were significantly different between sexes. The growth models for females, males and all fish were L t = 298.0[1 – e – 0.59(t–0.08) ], L t = 331.8[1 – e – 0.35(t+1.08) ] and L t = 312.2[1 – e – 0.48(t+0.32) ], respectively. Growth is fast during the first 4 years of life, when the average fish size is already in excess of 80% of the asymptotic size. The maximum age observed in this study is greater than those previously reported for H. plumierii . The natural mortality rate (M) estimate based on the oldest observed fish was 0.15 year -1 , while total mortality (Z) from the age-based catch curve was 0.21 year -1 (95% confidence interval: 0.18–0.24 year -1 ). These estimates show that the stock was under low to moderate levels of exploitation in the late 1990s.

Taxonomy of Aristeidae (Dendrobranchiata:Penaeoidea) from the central coast of Brazil, collected by the Revizee program, between 19º and 22ºS

The Aristeidae is a predominantly deep-water family composed of 26 species in nine genera. Until now, only four species were recorded from off the Brazilian coast: Aristaeomorpha folicea, Aristaeopsis edwarsiana, Aristeus antillensis and Hepomadus tener. With the material examined herein, another five species were recorded and redescribed from off the Brazilian coast: Aristeus antennatus, Hemipenaeus carpenteri, Plesiopenaeus armatus and Plesiopenaeus coruscans. In this paper these eight species are fully redescribed. Comments on geographical distribution and a key with the eight species found in the Brazilian waters are provided.

Age and growth of coney (Cephalopholis fulva), from the central coast of Brazil

Coney (Cephalopholis fulva) otoliths were collected from 1997 to 1999 off the central coast of Brazil. Analysis of the edges of otoliths sections suggests that one translucent and one opaque zone are formed once a year. Coney age and size-ranges were 2–25 years and 172–428 mm total length (TL) respectively. The von Bertalanffy growth equation was TLt=316(1−e−0.138(t+5.301)). The maximum age observed in this study is well above that previously reported for coney.

Holocene sea-level history on the Rio Grande do Norte State coast, Brazil

The Rio Grande do Norte State coast, northeastern Brazil, lies in an intraplate region which displays elevated Holocene shorelines, abandoned tidal flats and other intertidal deposits. A field and chronological investigation, which used 48 radiocarbon dates on unaltered mollusk shells, peats, coral reefs, and vermetids in living position and death assemblages encrusted on beachrock, tidal flat and peat deposits, was carried out along two littoral zones, one trending east–west and the other north–south. The sea-level envelope curve for the region indicates at least one sea-level oscillation after the maximum Holocene highstand, which occurred at ∼5000 cal. yr BP. This curve shows notable deviations from the mean sea-level curve for the Central Brazilian coast in the early and mid Holocene. However, in general, this envelope curve fits a glacio-isostatic prediction for the area. A significant deviation from this prediction, related to a small sea-level oscillation, occurred from ∼2100 to ∼1100 cal. yr BP. The comparison between the glacio-isostatic prediction and the sea-level observation enables us to conclude that local events may have disturbed the sea-level record. Minor Holocene sea-level oscillations, which were mainly associated with climate changes or tectonics and superimposed on a major smooth pattern, were observed in South Africa and Australia. But in northeastern Brazil, neotectonic controlled crustal movements or variation in marine and wind currents could provide the answer. The data indicate that local events may have an important role in the history of coastal progradation and retreat.

Holocene sea-level history along eastern-southeastern Brazil

Relative sea-level curves have been delineated for several sectors of the Brazilian coast. In order to have homogeneous and consistent curves, very short segments of the coastline with the same framework are considered. To minimize systematic errors tied to the particular nature of an indicator, we use the maximum number of different indicators available from former positions of relative sea level. These sea-level curves show that, during the last 7000 years, the central Brazilian coast has been subjected to a submergence phase which lasted until 5100 14C yr BP (5600 cal yr BP), followed by a drop in sea level. This drop in sea level was not continuous but was interrupted by two high-frequency oscillations. The Salvador curve, the most detailed, can be used as a reference for the central portion of the Brazilian coastline. It is now presented with corrections for isotopic fractionation and reservoir effects as well as calibrations for astronomical ages. Additional supporting evidence for the existence of high-frequency oscillations is provided. They are of the same magnitude as is predicted for the future under greenhouse conditions. These data will help us to understand how the coastal systems will respond to these sea-level changes.

Southern Oscillation Signal in South American Palaeoclimatic Data of the Last 7000 Years

During strong El Niño events, rainfall anomalies and changes in wind patterns are observed in different regions of South America. Along the central Brazilian coast, during the 1983 El Niño year, the frontal systems were blocked to the south, provoking a reversal of the longshore sand transport. Long-duration reversals of longshore transport were also recorded in Holocene beach-ridge terraces from the Rio Doce coastal plain. This led to the formulation of a model relating these reversals of longshore transport to El Niño-like conditions. El Niño-like conditions are past average climate situations that generate the same perturbations as the strong El Niño events observed during the last decade. They are likely to correspond to the long-duration low phase of the Southern Oscillation. To confirm this hypothesis we compared the Holocene beach-ridge record with other palaeoenvironmental records from regions where strong El Niño events would have a substancial signal as well: (1) water-level fluctuations of Lake Titicaca, (2) a pollen and sediment record in an eastern Amazonian lake, (3) changes of the Rio Xingu discharge in eastern Amazonia, and (4) variations of sand supply at the Rio Piura and Rio Chira outlets in the Sechura Desert. The occurrences of El Niño-like conditions were numerous before 3900-3600 yr B.P., absent between 39003600 and 2800-2500 yr B.P., and infrequent after 2800-2500 yr B.P.

The evolution of the continental and coastal environments during the last climatic cycle in Brazil (120 Ky. B.P. to Present)

Studies done in Brazil, under the CNPq (Brazil) and ORSTOM (France) agreement, allowed us to envisage the general trend of climatic changes that occurred during the last 60,000 years. At first, examination of successive accumulation and erosion phases, recorded within Central Brazilian valley deposits, provided evidence of importam changes in slope vegetation cover and in the hydraulic regime of water courses, and hence characteristics of precipitation and climate regimes. Studies of Tamandua river valley deposits in the town of Sao Simao (State of Sao Paulo) showed that between 32 and 21 ky. B.P. the climate was humid, whereas between 17 and 11 ky. B.P. it was dry with very scarce and strong rains. From 10 ky to 8.5 ky. B.P. the climate was humid too. Finally, after 7.5 ky. B.P. the deposits revealed the existence of several dry episodes within a globally humid climate. Palynological and sedimentological analyses of lacustrine deposits sampled by vibrocorers in the Eastern Amazon (Carajas, State of Para) and in Central Brazil (Salitre, State of Minas Gerais) permitted us to outline the evolutionary history of the vegetation cover within these regions during the last 60,000 years for Carajas and 30,000 years for Salitre and thus to have a preliminary idea about their past climates. Then, it was possible to show that at Carajas regression of the evergreen rainforest occurred four times, at about 60, 40, between 23-11 and 7-4 ky. B.P. Moreover, apparently the last rainforest regression episode was quite different from the previous three episodes. At Salitre, the most characteristic is the indication of the existence of Araucaria forest between 12 and 8.5 ky. B.P. This Araucaria forest location is clearly much further north than at present, which suggests that during that time the climate was wetter and colder. Finally, studies developed along the central Brazilian coast allowed us to show evidence of wind-/driven change in littoral dynamics during the last 5 ky. A detailed examination of Doce river (State of Espirito Santo) mouth beach-ridge geometry has shown inversions in littoral drift direction as a consequence of change in wave and then in wind regimes, reflecting characteristics of atmospheric circulation during the last 5 ky.

Variation of coastal dynamics during the last 7000 years recorded in beach-ridge plains associated with river mouths: example from the central Brazilian coast

The reconstruction of relative sea-level changes, during the last 7000 years, has shown that the central Brazilian coast was been subjected to submergence until approximately 5100 yr. B.P. However, the emergence after 5100 yr. B.P. was interrupted by two important fluctuations with an amplitude of approximately 2–3 m and a duration of 200–300 yr. This evolutionary history, which is quite different from that of several other regions in the world, played an essential role in the development of the central Brazilian coastal plains, whether or not they are associated with important river mouths. The periods of submergence, characterized by erosional phases, introduced noticeable changes in the geometry of the coastal deposits. The periods of emergence gave rise to sandy terraces covered by beach-ridges whose orientation is determined by the longshore drift. Elsewhere on a low sandy coast, the direction of longshore sand transport depends on the orientation of the swell. In a coast subjected to various swell patterns the efficient swells are defined as those which determine the resulting longshore transport direction. Such swells are not necessarily the most prevalent. For instance, along the central Brazilian coast the southern sector waves, in spite of their infrequent occurrences, are much more powerful than the northern sector waves and therefore generate a longshore sand transport from south to north. When fossil beach-ridges are present, as is the case on the central Brazilian coast, their geometry reflects the past directions of longshore sand transport. This makes it possible to determine the provenance of past efficient swells and to establish the past wind patterns. A detailed study of the beach-ridge geometry of some sections of the central Brazilian coast, showed a sequence of reversals of the longshore drift during the last 5100 yr, with a duration ranging from 10 to 100 yr. These reversals represent changes in the direction of effective waves, which determine the longshore transportation of sediments, and, consequently, indicate changes in the wind pattern.

ON SEA-SURFACE TEMPERATURE, CLOUDINESS AND WIND VARIATIONS IN THE TROPICAL ATLANTIC

Abstract Records of sea-surface temperature, cloudiness and wind are investigated for eight ocean areas along the shipping lane between Europe and South America. There was a gradual increase in temperature over most of the tropical Atlantic between 1922 and 1938 (Bullig, 1954). The total warming over the 17-yr period varied between 0.6C and 0.9C and was strongest at latitude 7N. In the vicinity of the Cape Verde Islands, the strength of the northerly wind component decreased by about 0.8 m sec−1. Off the central Brazilian coast, the amount of cloud cover decreased by 5 to 7 per cent. The power spectra of temperature, cloudiness and wind anomalies are investigated for the frequency range between zero and six cycles per year. It is found that most of the power of temperature anomalies is concentrated at low frequencies and that there are no periodicities. A significant and inverse relation between temperature and wind anomalies is found in the NE trade-wind region. Along the Brazilian coast there is a direc...