Mesophotic fishes of the Abrolhos Shelf, the largest reef ecosystem in the South Atlantic.

Fishes inhabiting rhodolith beds and reefs at mesophotic depths on the Abrolhos Shelf, which encompasses the largest and richest coral reef formation in the South Atlantic Ocean, were assessed through technical diving and remotely operated vehicles (ROVs). A total of 74 fish species were recorded, including at least one new species, one new record for the south-western Atlantic and six new records for the Abrolhos region. Overfishing, mining and port activities are already threatening many endangered and commercially important species recorded on the mesophotic reefs of Abrolhos Shelf, and the establishment of marine protected areas and off-reserve fisheries regulations are urgently needed.

Heavy metals in benthic organisms from Todos os Santos Bay, Brazil.

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae) in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.

Intra-cellular storage, transport and exocytosis of halogenated compounds in marine red alga Laurencia obtusa.

The production of secondary metabolites in seaweed have been related to a capability to partition compounds into cellular specialized storage structures, like gland cells and the corps en cerise (CC) or cherry bodies. The possible mechanisms that bring these compounds to the thallus surface remain poorly understood. Therefore, the aim of this work is perform a characterization of the CC and determine the intra-cellular dynamics of halogenated compounds in Laurencia obtusa. The dynamics of CC and the mechanisms related to the intra-cellular transport of halogenated compounds were evaluated by using optical tweezers and time-lapse video microscopy. The CC were isolated and its elemental composition was characterized using X-ray microanalysis. The cellular distribution of halogenated compounds was also demonstrated by fluorescence microscopy. Three-dimensional reconstruction technique was used to provide a visualization of the structures that connect CC to cell periphery. As main findings, we confirmed that the halogenated compounds are mainly found in CC and also in vesicles distributed along the cytoplasm and within the chloroplasts. We demonstrated that CC is mechanically fixed to cell periphery by a stalk-like connection. A vesicle transport though membranous tubular connections was seen occurring from CC to cell wall region. We also demonstrated a process of cortical cell death event, resulting in degradation of CC. We suggested that the vesicle transportation along membranous tubular connections and cell death events are related to the mechanisms of halogenated compounds exudation to the thallus surface and consequently with defensive role against herbivores and fouling.

Heavy metals in benthic organisms from Todos os Santos Bay, Brazil

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae) in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.

A Baía de Todos os Santos (TSB, Estado da Bahia, Brasil), vem sendo impactada pela presença, em seu entorno, de uma extensa área metropolitana e por atividades químicas e petroquímicas. Apesar de sua importância ecológica, existe pouca informação sobre a contaminação da biota marinha da TSB por metais pesados. Neste contexto, foram analisadas as concentrações de metais em quatro espécies de organismos bentônicos: duas algas, Padina gymnospora e Sargassum sp.; uma grama marinha, Halodule wrightii; e uma ostra, Crassostrea rhizophorae, em três locais das regiões da TSB mais afetadas pelas atividades industriais. As concentrações de Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn foram determinadas por espectrofotometria de absorção atômica. Os resultados obtidos indicaram que o cádmio e o cobre em algas, gramas marinhas e ostras, assim como o níquel em ostras estão, em concentrações de áreas contaminadas. Pelos resultados obtidos o cádmio e o cobre estão biodisponíveis a partir das partículas de sedimento em suspensão, fração dissolvida da coluna da água e da água intersticial do sedimento de fundo. Como ostras e outros moluscos são utilizados como fonte de alimento pelas populações locais, as concentrações de metais encontradas nas ostras da TSB podem constituir risco para as populações humanas locais. Os resultados obtidos sugerem a necessidade de implementação de um programa de monitoramento das concentrações de metais pesados em organismos dos ecossistemas marinhos da TSB.

Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas.

Amorphous phosphate granules are present in vertebrate and invertebrate organisms. The functions attributed to these structures depend on their mineral contents and organic matrix composition. In the present study we have determined zinc concentrations in the hepatopancreas of the crab Ucides cordatus from regions contaminated with zinc, and the elemental composition of hepatopancreal phosphate granules. Organisms were collected from the contaminated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-contaminated area, Ribeira Bay (RB). The first two sites are located near the metropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectroscopy (AAS) showed a significant difference (P<0.05) for zinc concentration in the hepatopancreas from organisms collected at the contaminated sites GB (210 +/- 20 microg/g dry weight) and SB (181 +/- 16 microg/g dry weight) compared to the non-contaminated site RB (76 +/- 14 microg/g dry weight). Phosphate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive X-ray analysis (EDX) and electron spectroscopic imaging (ESI). ED of granules presented no diffraction spots, indicating that these structures are in an amorphous state, while EDX of granules isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were colocalized in the mineralized layers of most granules observed. The correlation between the results obtained by AAS and those obtained by microanalytical techniques suggests that the hepatopancreatic granules of U. cordatus may be related to the phenomenon of heavy metal retention.

Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas

Amorphous phosphate granules are present in vertebrate and invertebrate organisms. The functions attributed to these structures depend on their mineral contents and organic matrix composition. In the present study we have determined zinc concentrations in the hepatopancreas of the crab Ucides cordatus from regions contaminated with zinc, and the elemental composition of hepatopancreal phosphate granules. Organisms were collected from the contaminated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-contaminated area, Ribeira Bay (RB). The first two sites are located near the metropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectroscopy (AAS) showed a significant difference (P<0.05) for zinc concentration in the hepatopancreas from organisms collected at the contaminated sites GB (210 + or - 20 µg/g dry weight) and SB (181 + or - 16 µg/g dry weight) compared to the non-contaminated site RB (76 + or - 14 µg/g dry weight). Phosphate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive X-ray analysis (EDX) and electron spectroscopic imaging (ESI). ED of granules presented no diffraction spots, indicating that these structures are in an amorphous state, while EDX of granules isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were colocalized in the mineralized layers of most granules observed. The correlation between the results obtained by AAS and those obtained by microanalytical techniques suggests that the hepatopancreatic granules of U. cordatus may be related to the phenomenon of heavy metal retention

Effects on growth and accumulation of zinc in six seaweed species.

Seaweed species from a coastal area contaminated by heavy metals (Sepetiba Bay) in Rio de Janeiro State (Brazil) presented different levels of Zn concentrations. In some species the levels were 20 times higher than that from a noncontaminated area. The present study was undertaken to investigate the capability of different species to tolerate and accumulate zinc. For this purpose six species, Ulva lactuca, Enteromorpha flexuosa, Padina gymnospora, Sargassum filipendula, Hypnea musciformis, and Spyridia filamentosa, were cultivated under laboratory semistatic conditions in five Zn concentrations in seawater, 10, 20, 100, 1000, and 5000 micrograms.liter-1 for a period of 21 days. All species died at 5000 micrograms.liter-1 of Zn, two species (U. lactuca and E. flexuosa) died at 1000 micrograms.liter-1, and one, H. musciformis, died with 100 micrograms.liter-1. The lowest concentration of Zn that presented growth inhibition in the six species was 20 micrograms.liter-1. The brown alga P. gymnospora presented the highest accumulation level of Zn, and H. musciformis the lowest level. The results of tolerance and accumulation under laboratory conditions, associated with field results, indicate the species of Padina and Sargassum as the best species for monitoring heavy metals in tropical coastal areas, and the potential use of their biomass to remove heavy metals from wastewaters.

[Metal concentrations in benthic marine algae in 3 regions of the state of Rio de Janeiro]. / Concentrações de metais em algas marinhas bentônicas de três regiões do estado do Rio de Janeiro.

The concentrations of zinc, cadmium and copper were determined in different benthic algal species from some sites located in Guanabara Bay, Sepetiba Bay and Ribeira Bay (State of Rio de Janeiro). The aim is to verify the possibility of using algae as indicators of metallic contamination in these areas. According to our results, the highest concentrations of Zn and Cd in algae were observed in Sepetiba Bay. In this region, the differences among the concentrations of the metals were analysed in three sampling sites. Padina gymnospora was the species recommended to monitor the contamination of Zn and Cd in Sepetiba Bay, for the following reasons: 1) its great abundance and distribution in the areas, and 2) its high ability to accumulate metals. More studies are suggested to evaluate the levels of metals in Guanabara Bay.

Trace metal accumulation by algae in Sepetiba Bay, Brazil.

Trace metal concentrations (Zn, Cd, Pb, Cr and Cu) were determined in some benthic algae from Sepetiba Bay, Brazil. This region has been modified by the increase of industrial activities during the last 30 years. Among species sampled the brown algae Padina gymnospora contained the greatest amount of Zn. The Bioconcentration Factor for Zn in P. gymnospora was found to be 10(4) under laboratory conditions. The absorption of (65)Zn depended on exposure time and increased with Zn concentrations in the medium. An insignificant amount of Zn desorbed from algae suggested a very high affinity with cellular binding sites. Zinc uptake by P. gymnospora is discussed by considering field and laboratory conditions.