Sao Sebastiao Channel Research Articles

Toxicity of puffer fish: two species (Lagocephalus laevigatus, linaeus 1766 and Sphoeroides spengleri, Bloch 1785) from the Southeastern Brazilian coast

In Brazil, where puffer fish are considered poisonous, there are few documented cases on human consumption and consequent poisoning. In this study, toxicity of two puffer fish species from the Brazilian coast was examined. Specimens of Sphoeroides spengleri and Lagocephalus laevigatus were caught in Sao Sebastiao Channel (North coast of Sao Paulo State, Brazil) between January 1996 and May 1997. Acidic ethanol extracts from muscle and skin plus viscera were tested for mice acute toxicity using the standard method of Kawabata. Polar extracts of S. spengleri showed high toxicity up to 946 MU/g. Extracts from L. laevigatus showed very low levels of toxicity, never exceeding 1.7 MU/g. All extracts from both species blocked amielinic nerve fiber evoked impulses of crustacean legs; this effect reverted on washing similar to the standard tetrodotoxin TTX. The aqueous extract solutions were partially purified using an ionic exchange column (Amberlit GC-50) followed by treatment with activated charcoal (Norit-A). The presence of TTX and their analogs in the semi-purified extracts were confirmed by HPLC and mass spectrometry (MALDI-TOF).

In vivo study of microsclere formation in sponges of the genus Mycale (Demospongiae, Poecilosclerida)

The process of microsclere secretion was examined in vivo through glass coverslip implants in three species of the genus Mycale from Sao Sebastiao channel, southeastern Brazil: Mycale (Aegogropila) angulosa, Mycale (Arenochalina) laxissima, and Mycale (Carmia) microsigmatosa. All three species adhered well to coverslips and developed normally through at least 2 weeks. Similar experiments with different species (Cinachyrella alloclada, Amphimedon viridis, Haliclona melana, and Aplysina caissara) were also successful with one exception (the cartilaginous Chondrilla nucula), indicating that the method can be applied to most demosponges. Microsclerocyte size varied according to the type of microsclere secreted, but all were elongated to fusiform and had small, anucleolated nuclei. Spicules were transported by microsclerocytes alone, without any other cell type ("helper cells") involved. Secretion of a microsclere was performed by a single sclerocyte. Although some axial filaments were found free in the mesohyl, all microsclere secretion in these animals was fully intracellular. Normal axial filaments were observed in most types of microscleres of the Mycale species (sigmas, toxas, and microxeas). Timed observations of sclerocytes suggest that immature spicules with the aspect of short straight rods with thick ends might be the precursors of the anisochelae. Observed differences in the size versus number of toxa secreted may indicate either the presence of two distinct subpopulations of toxa-producing microsclerocytes or that the initial number of axial filaments at the beginning of silica deposition may determine the final size of the spicules. Although other microscleres such as sigmas and chelae are secreted in a one cell–one spicule basis, several toxas and microxeas can be secreted simultaneously in a single cell.

Brazilian Oil Spills Chemical Characterization—Case Studies

In the last decade, PETROBRAS has experienced some significant oil spills cases and the PETROBRAS Research Center has played an important role in the company emergency response program by characterizing the spilled oil, monitoring the affected ecosystem, determining the fate of the oil in the environment, and, subsequently, helping the company in assessing the environmental damage. This paper presents the use of advanced chemical analytical techniques (GC/FID, P&T/GC/PID and GC/MS) in some Brazilian oil spill studies in order to determine fractions and individual petroleum hydrocarbons in different matrices such as water, groundwater, sediment, sand, fish and the spilled oil itself. The spill studies encompassed crude and fuel oil releases on land and coastal ecosystems, related to the incidents in Guanabara Bay (Rio de Janeiro), Barigui and Iguassu Rivers (Parana) and Sao Sebastiao Channel (Sao Paulo). Total petroleum hydrocarbons (TPH), n -alkanes, isoprenoids, unresolved complex mixtures (UCM), volatile monoaromatic compounds—benzene, toluene, ethylbenzene and xylenes (BTEX), parent and alkylated homologues polycyclic aromatic hydrocarbons (PAH), and terpanes and steranes were characterized for determining correlation to the spilled oil and other known oil sources and environmental assessment. Some of the acute ecotoxicity data for water and sediment samples is also presented.

Brazilian Oil Spills Chemical Characterization--Case Studies

In the last decade, PETROBRAS has experienced some significant oil spills cases and the PETROBRAS Research Center has played an important role in the company emergency response program by characterizing the spilled oil, monitoring the affected ecosystem, determining the fate of the oil in the environment, and, subsequently, helping the company in assessing the environmental damage. This paper presents the use of advanced chemical analytical techniques (GC/FID, P&T/GC/PID and GC/MS) in some Brazilian oil spill studies in order to determine fractions and individual petroleum hydrocarbons in different matrices such as water, groundwater, sediment, sand, fish and the spilled oil itself. The spill studies encompassed crude and fuel oil releases on land and coastal ecosystems, related to the incidents in Guanabara Bay (Rio de Janeiro), Barigui and Iguassu Rivers (Parana) and Sao Sebastiao Channel (Sao Paulo). Total petroleum hydrocarbons (TPH), n -alkanes, isoprenoids, unresolved complex mixtures (UCM), volatile monoaromatic compounds--benzene, toluene, ethylbenzene and xylenes (BTEX), parent and alkylated homologues polycyclic aromatic hydrocarbons (PAH), and terpanes and steranes were characterized for determining correlation to the spilled oil and other known oil sources and environmental assessment. Some of the acute ecotoxicity data for water and sediment samples is also presented.

Spatial distribution of annelids in the intertidal zone in Sao Sebastiao Channel, Brazil

2) in the intertidal zone of each study site: lower, intermediate, and upper. In general, species richness increased from upper towards lower levels. The distribution of species at Engenho d’Agua was more homogeneous than at Sao Francisco. Only some individual spatial patterns were recognised at Sao Francisco. The most abundant polychaete species at Engenho d’Agua (Nematonereis hebes, Timarete filigera, and Scyphoproctus djiboutiensis) occurred in the intermediate and lower levels. The upper level of Sao Francisco was characterised by a peak of opportunists, with a large number of individuals but few dominant species (Capitella sp., Scolelepis squamata, Laeonereis acuta, and the oligochaete Tubifex sp).

Shallow-water Aplysina Nardo (Aplysinidae, Verongida, Demospongiae) from the São Sebastião Channel and its environs (Tropical southwestern Atlantic), with the description of a new species and a literature review of other brazilian records of the genus

Two species of Aplysina Nardo, 1834 are described in this article, Aplysina caissara sp. n. and A. fulva (Pallas, 1766). Additionally, a possible third species was identified as A. aff. cauliformis. Collections were done in the Sao Sebastiao Channel area as an ongoing effort to assess the poriferan biodiversity of the northern sector of the Sao Paulo State coastline. Specimens were collected by scuba diving, and descriptions of external morphology are based on the observation of populations alive, and on extensive underwater photography. A literature review of other brazilian records of Aplysina was undertaken, and an ammended species list is offered.

Annual variation of the malacofauna on two intertidal sandy substrates with rock fragments in southeastern Brazil

The temporal variation in molluscan communities was studied in two intertidal substrates composed of sand and rock fragments <300 mm) in Sao Sebastiao Channel, Brazil. Samples were taken between August 1995 and July 1996 in Sao Francisco (mainland) and Engenho d'Agua (Sao Sebastiao Island) beaches. A pronounced decrease in abundance and diversity of molluscs was associated with changes in the structure of the environment, caused by sea storms in the beginning of the summer (December), and by the increase of waste water discharge in this same period. Areas not subjected to such events showed no evident modifications in mollusc fauna structure during the sampling period, and the small oscillations observed were attributed to population recruitment. Both natural and human factors may be acting together in determining the community organization in these environments, as is also in typical sandy beaches.

Trophic structure of polychaetes in the São Sebastião Channel (southeastern Brazil)

Between November 1993 and August 1994, the spatial and seasonal trophic structures of polychaete annelids were studied in the Sao Sebastiao Channel, southeastern Brazil, located between the mainland of Sao Paulo State and Sao Sebastiao Island. Four sampling surveys were carried out with a van Veen grab of 0.1 m2 at 15 stations. A total of 12 003 individuals (126 species) was recorded and separated into 14 feeding guilds. Data were analysed with univariate and multivariate techniques (cluster and canonical correspondence analysis). Results showed a strong correlation between trophic groups and sediment variables such as grain size and organic carbon content. The Channel was dominated by surface deposit-feeders, followed by carnivores. Suspension-feeders were confined to medium and coarse sandy sites, environments with high energy. Bottoms where silt, clay and organic carbon predominated showed low polychaete densities. In these places the pollution induced by the sewage discharge from Araca underwater emissions and by the oil terminal Dutos e Terminais Centro Sul was evident. There were no significant seasonal variations in the trophic structure over the study period, except in fall when densities were low. The polychaetes' relationships within the benthic system are discussed.

Evaluation of produced water toxicity from an oil maritime terminal through Skeletonema costatum toxicity tests

The liquid effluent from an oil maritime terminal, with produced water as the main component, had its toxicity evaluated through toxicity tests with the diatom Skeletonema costatum. Two previously treated effluent samples (effluents A and B), were provided by PETROBRAS for the experiments. Both samples presented high salinity (67‰ for effluent A and 62‰ for effluent B) and low pH values (6.2), whereas total sulphide, phenol and nutrient content, dissolved/dispersed petroleum hydrocarbon concentration, BOD and COD values were quite different from each other. During the toxicity experiment, three replicate flasks with samples for each treatment were exposed to a light radiation of 266µE m2 S-1 and maintained under a 10 h/14 h lightldark cycle, at a temperature of 24 :t 2oC. The EC50 values could not be accurately estimated for effluent A: 60 h and 132 h after starting the experiment they were below 3% and between 3-6% effluent concentration, respectively. Synergistic effects between effluent toxicity and salinity on the growth of S. costatum were detected. The effluent B showed higher toxicity: the EC5O values were 0.17% and 0.40% of effluent concentrations, after 48 h and 96 h, respectively. These results evidenced the deleterious effects of residual organic compounds contained in the aqueous effluents from the oil terminal under the present pretreatment on S. costatum. In the light of the present data, the direct disposal ofthese effluents into Sao Sebastiao Channel waters might be very hazardous to its indigenous biota.

Hydrographic properties in the São Sebastião Channel: daily variations observed in March 1980

A four-day quasi-synoptic survey of hydrographic properties sampled from March 4 to March 7, 1980 was used for a physical description of the daily variations in the thermohaline and mass structures in the Sao Sebastiao Channel. Temperature and salinity were sampled down the water column during events of non-tidal along channel current reversals. The observed temperature decrease and density increase in the southern channel bottom layer were mainly due to cold water transported northward by a subsurface current. The northward bottom current opposed the southward main flow in the upper layer. The low temperature and salinity of the water advected northward by the bottom current indicated influences of the South Atlantic Central Water (SACW), inducing a near bottom thermocline-like structure. By the end of the sampling period, the vertical temperature gradient intensified near the bottom and the salinity distribution reached almost uniform conditions.

OCCURRENCE OF TETRODOTOXIN AND PARALYTIC SHELLFISH TOXINS IN Phallusia nigra (TUNICATA, ASCIDIACEA) FROM THE BRAZILIAN COAST

We have already shown the presence of guanidine neurotoxins in calcareous red algae and mussels collected in the Sao Sebastiao channel (State of Sao Paulo, Brazil). It is known that these neurotoxins comprise more than 25 analogues such as tetrodotoxin (TTX) and derivatives plus the paralytic shellfish toxins (PST) found in a variety of marine, freshwater and amphibious species. Filter feeding animals generally possess large amounts of these neurotoxins. The tunicates are sessil marine animals with a high rate of sea water filtration. The tunics and siphons of 50 specimens of Phallusia nigra were dissected and the visceral organs were immersed in methanol containing acetic acid 0.02 N pH 5.0. The extract was prepared by homogenization, filtration and the methanolic phase was concentrated under reduced pressure and defatted with chloroform. The polar phase was evaporated and the residue dissolved in deionized water for further purification in ionic-exchange resin column (Bio-Gel P-2) and HPLC analysis. The extract showed paralytic effects on mouse assay (26.9 MU/100mg) and on crustacean isolated nerve preparations. The chemical analysis for TTX and PST revealed toxins with retention times similar to gonyautoxins, saxitoxins and TTX. These findings are important to explain future toxin envenoming outbreaks on the Brazilian coast.

The janirid isopods (Crustacea, Isopoda, Asellota) living on the sea star Echinaster brasiliensis Müller &amp; Troschel at São Sebastião channel, Southeastern brazilian coast, with description of a new species

Three species of janirid isopods were found on the sea star Echinaster brasiliensis Muller & Troschel collected in Sao Sebastiao Channel, southeastern Brazil. Janaira gracilis Moreira & Pires and Carpias nereus (Pires) were previously known from the area and Carpias asterophilus, sp.n. is described. The three isopod species were found together on the dorsal surface of the sea star, and juveniles performed nearly 73% of the population. The janirids presented homeochromy with the sea stars, and food and shelter were the observed benefits that the crustaceans received from the association. A key to separate the species of Carpias with a spoon-like gnathopod is included.

Replacement of the compound ascidian species in a southeastern Brazilian fouling community

The replacement of compound ascidians on two series of ceramic plates (225 cm²) has been studied for nine months in the Sao Sebastiao Channel. One of the series was initiated in the summer and the other in the winter. Five species were the most abundant and frequent on the plates. Diplosoma listerianum (Milne-Edwards, 1841) and Symplegma brakenhielmi (Michaelsen, 1904) showed the higher percent values of cover in the beggining of succession. Although Didemnum speciosum (Herdman, 1886) recruited in high numbers, its cover was only important after some months because of its slow growth rate. Clavelina oblonga Herdman, 1880 was a typical late successional species with low recruitment intensity and slow growth rate, and Botryllus niger (Herdman, 1886) was characterized by its constant appearing and disappearing. The overgrowth between ascidian species was not seen and it seems probable that the replacement of species was related to the death of early colonizers that presented a shorter life span.

Seasonal variation in abundance of the developmental stages of Euterpina acutifrons (Copepoda: Harpacticoida) from the S�o Sebasti�o Channel, southern Brazil

The annual variation in abundance of all developmental stages of the harpacticoid copepod Euterpina acutifrons (Dana) was studied in plankton samples collected fortnightly from May 1971 to May 1972 in the Sao Sebastiao Channel, Brazil. The species occurred throughout the year, becoming scarce during the summer. Three distinct peaks of abundance were evident (July, December and April), the most pronounced being in July (winter). Generation time in the field (26°–27°C) was calculated as approximately two weeks. Small males were always more abundant that large males but densities peaked during the coldest months when the highest populational breeding peak occurred. Males usually outnumbered females, and young members (nauplii and copepodites) outnumbered adult forms. Results are compared with tropical, northern hemisphere and New Zealand data.

Mithrax (Mithrax) pleuracanthus Stimpson, 1871, a new decapod for the Brazilian fauna

Mithrax (M.) pleuracanthus Stimpson, 1871, was collected in the upper sublittoral on both sides of the Sao Sebastiao Channel (23o48'S, 45o23'W). The geographical distribution, ecological notes and main morphological characters of the species are given.