Roberto Sassi

Annual cycle of symbiotic dinoflagellates from three species of scleractinian corals from coastal reefs of northeastern Brazil

Predictable seasonal variation in densities of symbiotic dinoflagellates residing in scleractinian corals appears to be a characteristic of reef corals worldwide (Stimson 1997; Brown et al. 1999; Fagoonee et al. 1999; Fitt et al. 2000). Available light and temperature are thought to have a major influence on this variation (Brown et al. 2000; Warner et al. 2002), although the availability of dissolved nutrients in ocean waters may also play a role (Stimson 1997; Fagoonee et al. 1999). Despite their importance to the economy and health of reef ecosystems (Muller-Parker et al. 1988), few studies have focused on the association between symbiotic dinoflagellates and corals in Brazil, where almost half of the scleractinian species are endemic. Brazilian studies have reported on the utility of zooxanthellae for aiding coral taxonomy (Costa and Amaral 2002) and their possible role in coral bleaching (Costa et al. 2001). Nevertheless, the data obtained in Brazil are still insufficient to allow conclusions to be made on possible seasonal variations in the abundance of zooxanthellae and their photosynthetic pigment concentrations in the tissues of particular coral species. In this paper, we address this lack of data by documenting seasonal variation in the densities of zooxanthellae and their photosynthetic pigments from three species of corals endemic to Brazil: Mussismilia hartti, M. hispida, and Siderastrea stellata. Of these species, Mussismilia plays an important role in the construction of Brazilian reefs and in some areas, such as in Abrolhos region (Bahia State), it is the main constituent of reef foundations (Leão et al. 1988). Siderastrea is represented in Brazil solely by S. stellata and while it is one of the most conspicuous species, it is not prominent in the formation of Brazilian reefs.

Phytoplankton and environmental factors in the Paraíba do Norte River Estuary, northeastern Brazil: composition, distribution and quantitative remarks

This paper reports the results obtained from studies on the estuarine phytoplankton of the Paraiba do Norte River in northeastern Brazil. Surface and near-bottom samples were taken at four stations numbered seawards, during high and low tides from September 1978 to September 1979. A total of 139 phytoplankters were encountered. Diatoms and dinoflagellates showed highest diversity in most saline areas. Typical freshwater organisms were restricted to stations I and II where salinity was more reduced. Maximum cell densities were: 11,256,000 cells/1, 4,380,000 cells/1, 1,276,000 cells/1 and 1,035,000 cells/1, for stations I, II, III and IV, respectively. Sewage enrichments were probably responsible for the greatest values of the first two stations. However, in these stations the turbidity reduces light penetration, limiting phytoplankton growth particularly during the rainy season. The phytoflagellates (maximum of up to 4,874,000 cells/1) and the diatoms Thalassiosira spp (maximum of up to 9,262,000 cells/1) were dominant during the annual cycle. Other important taxa were Navicula spp, Cylindrotheca closterium, Paralia sulcata, Thalassionema nitzschioides and the dinoflagellate Protoperidinium spp. Seasonal variations of phytoplankton densities, dissolved oxygen, phosphate, water transparency, temperature, salinity and suspended material are also presented.

Studies on the decomposition of drift seaweed from the northeast Brazilian coastal reefs

Extensive beds of benthic, non-calcareous macroalgae are associated with reef formations in oligotrophic coastal waters of Northeastern Brazil. Large amounts of these algae constantly and naturally detach and decay. Part of them is deposited on the beach, remains exposed during low tides, and decomposes. Field experiments on decomposition were carried out in a tidal pool (temperatures fluctuating from 29 to 43°C salinity from 6 to 35 at Ponta do Seixas (Paraiba, Brazil), and laboratory studies were made in aerobic and anaerobic conditions. High values of NO3− (up to 148.92 μg at 1−1), NO2− (up to 3.14 μg at 1−1) and PO34− (up to 22.95 μg at 1−1) were released during algal degradation. Nitrogen values were higher in the tidal pool than in aerobic and anaerobic experiments, as opposed to phosphorus where the opposite phenomenon occurred. The diatom Phaeodactylum tricornutum inoculated in seawater enriched with decomposition products of algae showed intense growth, sometimes similar to that in complete algal culture medium. Inhibition and death of this diatom was observed in some other experiments. The importance of drift seaweed as a source of nutrients for the local ecosystem is stressed.

Injuries caused by venomous animals and folk medicine in farmers from Cuité, State of Paraiba, Northeast of Brazil

Injuries caused by venomous animals reported by the agricultural workers from the municipality of Cuité, Curimataú region of Paraiba State, Northeast of Brazil, and the practices of folk medicine which they use to treat these cases were studied in this work from June to August 2010. The farmers studied aged from 11 to 90 years. The number of people who reported cases of injury by these animals in their families was high (89.3%). Scorpions, wasps, bees and snakes were the most cited and the extremities of the body (hands, feet, legs and head) were the most affected. The practice of folk medicine to treat these injuries includes various procedures ranging from ritualistic treatments, use of animals or parts of them, and some herbal preparations. The folk treatment was reported as effective by most of the workers injured (63.9%). Body parts of dead snakes are used in various zootherapic treatments. In the imaginary of the agricultural workers the venomous animals are considered hazardous (48.7%) or disgusting (11.3%), and several parts of such animals as the rattle, bee sting or snake leather are used as amulet. Several legends have also been reported about snakes, scorpions and bees. The need for educational activities that aim to clarify these workers about the dangers of such practices is urgent.

Biochemical compositions and fatty acid profiles in four species of microalgae cultivated on household sewage and agro-industrial residues

The potential of four regional microalgae species was evaluated in relation to their cell growth and biomass production when cultured in the following alternative media: bio-composts of fruit/horticultural wastes (HB), sugarcane waste and vinasse (VB) chicken excrements (BCE), raw chicken manure (RCM), and municipal domestic sewage (MDS). The cultures were maintained under controlled conditions and their growth responses, productivities, biochemical compositions, and the ester profiles of their biomasses were compared to the results obtained in the synthetic media. The MDS and HB media demonstrated promising results for cultivation, especially of Chlorella sp., Chlamydomonas sp., and Lagerheimia longiseta, which demonstrated productivities superior to those seen when grown on the control media. The highest lipid levels were obtained with the HB medium. The data obtained demonstrated the viability of cultivating microalgae and producing biomass in alternative media prepared from MDS and HB effluents to produce biodiesel.

Effects of cyanobacteria Synechocystis spp. in the host-parasite model Crassostrea gasar–Perkinsus marinus

Perkinsosis is a disease caused by protozoan parasites from the Perkinsus genus. In Brazil, two species, P. beihaiensis and P. marinus, are frequently found infecting native oysters (Crassostrea gasar and C. rhizophorae) from cultured and wild populations in several states of the Northeast region. The impacts of this disease in bivalves from Brazil, as well as the interactions with environmental factors, are poorly studied. In the present work, we evaluated the in vitro effects of the cyanobacteria Synechocystis spp. on trophozoites of P. marinus and haemocytes of C. gasar. Four cyanobacteria strains isolated from the Northeast Brazilian coast were used as whole cultures (WCs) and extracellular products (ECPs). Trophozoites of P. marinus were exposed for short (4h) and long (48h and 7days, the latter only for ECPs) periods, while haemocytes were exposed for a short period (4h). Cellular and immune parameters, i.e. cell viability, cell count, reactive oxygen species production (ROS) and phagocytosis of inert (latex beads) and biological particles (zymosan and trophozoites of P. marinus) were measured by flow cytometry. The viability of P. marinus trophozoites was improved in response to WCs of Synechocystis spp., which could be a beneficial effect of the cyanobacteria providing nutrients and reducing reactive oxygen species. Long-term exposure of trophozoites to ECPs of cyanobacteria did not modify in vitro cell proliferation nor viability. In contrast, C. gasar haemocytes showed a reduction in cell viability when exposed to WCs, but not to ECPs. However, ROS production was not altered. Haemocyte ability to engulf latex particles was reduced when exposed mainly to ECPs of cyanobacteria; while neither the WCs nor the ECPs modified phagocytosis of the biological particles, zymosan and P. marinus. Our results suggest a negative effect of cyanobacteria from the Synechocystis genus on host immune cells, in contrast to a more beneficial effect on the parasite cell, which could together disrupt the balance of the host-parasite interaction and make oysters more susceptible to P. marinus as well as opportunistic infections.

The Mangrove Forest at the Bucatu Lagoon, Northeast Brazil: Structural Characterization and Anthropic Impacts

We investigated the Bucatú microbasin in order to characterize the structure and composition of its surrounding mangrove area by recording the main anthropic interferences on the vegetation. This study was performed along 10 plots (1000 m2 in total), perpendicular to the estuarine canal. Deposition and accumulation of sediments on the plants root system were evaluated using auger holes and photographs. Four plant species, Laguncularia racemosa (L.) Gaertn. (White Mangrove), Rhizophora mangle L. (Red Mangrove), Conocarpus erectus L.(Silver-leaved Buttonwood), and Annona glabra L. (Pond-apple) were recorded. The structural parameters obtained were low, and a great number of dead plants were observe d, most of them of the species L. racemosa. Sediment deposition rates of 10-15 cm were recorded. Silting in the mangrove area and alterations of water flow in the drainage basin of the Bucatu River were the main anthropic effects observed, exerting a high negative impact on the mangrove ecosystem we investigated.

Metabolites of interest for food technology produced by microalgae from the Northeast Brazil

There is an increasing demand for bioprospection focusing on microalgae isolated from the northeastern region of Brazil with potential importance for food industries. To attend that need, we evaluated the characteristics of 12 regional species of microalgae grown under controlled cultivation conditions (temperature = 24 ± 1 oC, illumination 150 µmol photons m-2 s-1, photoperiod of 12 h) in terms of their nutritional quality and lipid profiles. Significant differences in growth characteristics and chemical compositions were observed among the species investigated. High carbohydrate contents (> 25 g 100 g-1) were recorded in various strains of Chlorococcum and the marine microalga Amphidinium carterae; high protein contents (> 35 g 100 g-1) were observed in Scenedesmus acuminatus and Pediastrum tetras; and high lipid contents (> 25 g 100 g-1) in A. carterae and some strains of Chlorococcum sp. (cf. hypnosporum). Chlamydomonas sp. demonstrated the greatest production of carotenoids (64.92 mg g-1), chlorophyll-a (234.74 mg g-1), and chlorophyll-b (59.34 mg g-1). The lipid profiles of Chlorella cf. minutissima, four strains of Chlorococcum sp. (cf. hypnosporum), P. tetras, Planktothrix isothrix, and S. acuminatus indicated the presence of palmitic, oleic (ω-9), linoleic (ω-6) and α-linolenic (ω-3) acids, with more than 50% omegas in the total composition of their fatty acids. In terms of chemical nutrients, the microalgae cited were found to be potential sources of omegas, carotenoids, and chlorophylls that could be used in food industries.

Effectiveness of nutrient remotion and cell physiology of Amphora sp. cultured in shrimp farm effluents

Shrimp farm effluents are one of the principal causes of eutrophication in coastal environments. Integrated processes of bioremediation involving the culturing of purifying organisms have been suggested, but very few studies have focused on microalgae. For that purpose evaluated the growth potential of Amphora sp. in the residual waters of shrimp farm activity fulfilled on the Paraíba State, Brazil. The experiments were performed using Conway medium as the control and wastewaters from shrimp farm at 100% concentrations. Amphora sp. demonstrated good growth in the shrimp farm effluents under test conditions, although less than that observed in the control medium. This diatom was found to removed 73.357 and 72.572% of PO4− and NO3−, respectively, demonstrating a high mitigation potential for this type of effluent. Comparisons of the physiological responses measured by flow cytometry demonstrated higher cell densities of Amphora sp. in the control medium, but a higher lipid content was observed in Amphora cultured in shrimp farm effluents.

Estrutura da comunidade dos Tintinnina na região do Atol das Rocas (Rio Grande do Norte) e Arquipélago de Fernando de Noronha (Pernambuco)

Os Tintinnina que ocorrem em aguas proximas ao Atol das Rocas e Arquipelago de Fernando de Noronha (Nordeste do Brasil) foram estudados usando amostras de plâncton coletadas entre 13 e 30 de marco de 1999 em 27 estacoes oceânicas. O estudo procurou caracterizar a distribuicao espacial desses ciliados na area e examinar parâmetros como a diversidade e equitabilidade que definem a estrutura da comunidade. O material foi coletado por arrastos verticais desde 200 m de profundidade ate a superficie, usando uma rede de plâncton de 20 µm de abertura de malhas, preservado em formol neutro a 4%, e examinado em um microscopio invertido. A maior densidade de individuos foi encontrada na estacao 26 (122 ind.m-3), situada nas proximidades de Fernando de Noronha; mas altas densidades tambem foram registradas nas estacoes 1 (82,7 ind.m-3) e 2 (74,7 ind.m-3), situadas em areas mais distantes, bem como na estacao 5 (80,7 ind.m-3) proxima do Atol das Rocas. Eutintinnus fraknoi (Daday) Kofoid & Campbell, 1929 foi a especie mais abundante, atingindo 57,8% de dominância na estacao 4. O indice de diversidade especifica variou de alto (27% das amostras com valores maiores que 3 bits.ind-1) a medio (63% das amostras com valores maiores que 2 bits.ind-1), enquanto a equitabilidade variou entre 0,6 e 1,0. As baixas densidades de Tintinnina observadas no material coletado confirmam a condicao oligotrofica daquela regiao.