oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Influence of Water quality on the biodiversity of phytoplankton in Dhamra River Estuary of Odisha Coast, Bay of Bengal
S Palleyi, RN kAR, CR Panda
Journal of Applied Sciences and Environmental Management , 2010,
Abstract: Dhamra estuarine ecosystem is a hotspot of rich biological diversity which supports a patch of mangrove along with unique flora and fauna. In this study, the diversity of phytoplankton population and other factors that control their growth and biodiversity were investigated. The samples were collected monthly from Dhamra estuary of Bay of Bengal at 6 different stations (grouped under three regions) from March -2008 to February -2009. A total of 41 genera of phytoplankton species belonging to 4 classes of algae were identified. The maximum value of 9.3 X 104 cells l-1 was recorded in post monsoon season. Phytoplankton of Bacillariophyceae, appearing throughout the year, and represent majority of population (75-94%) at all the sampling stations, followed by Dinophyceae (3-14%), Cyanophyceae (3-8%) and Chlorophyceae (0-4%) classes. The Shannonweavers diversity index (H) remains between 0.22 and 2.49. Based on the correlation coefficient data, phytoplankton shows positive relationship with DO, salinity, nutrients and negative relationship with temperature and turbidity. Present study shows that the occurrence and diversity of these primary producers do not subscribe to a single dimensional phenomenon of a single factor, rather than, a consequence of a series of supported factors which will help to maintain and balance such type of fragile ecosystem
Guanabara bay sedimentation rates based on 210Pb dating: reviewing the existing data and adding new data
Godoy, Jose M.;Oliveira, Alessandra V.;Almeida, Ana C.;Godoy, Maria Luiza D. P.;Moreira, Isabel;Wagener, Angela R.;Figueiredo Junior, Alberto G. de;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012000700010
Abstract: three sediment cores were taken from guanabara bay. two of them yielded 210pb profiles that could be applied for dating purposes. actual sedimentation rates of approximately 1 cm year-1 (five times higher than the baseline values) were observed for both sediment cores, which agree with the reviewed existing data in the literature related to guanabara bay sedimentation rates based on 210pb. dating validation was carried out based on the chromium, copper and lead profiles, on the 210pb flux and on the historical record of the main physical interventions occurring in the last century, such as embankment, the channeling of main rivers and the construction of express roads. at the end of this process, only one sediment core dating could be adequately validated.
Sedimentary sterols as indicators of environmental conditions in Southeastern Guanabara Bay, Brazil
Santos, Elisamara Sabadini;Carreira, Renato da Silva;Knoppers, Bastiaan Adrian;
Brazilian Journal of Oceanography , 2008, DOI: 10.1590/S1679-87592008000200003
Abstract: the interconnected icaraí and jurujuba embayments, set within the lower south-eastern portion of guanabara bay, se-brazil, have been subject to the direct input of domestic effluents and other associated contaminants from human activities in their watersheds. this study addresses the composition of carbon, nitrogen and molecular steroid markers of surface sediments (n = 24) and a short core (l = 47 cm), in order to evaluate the impact by sewage, the contribution between allochthonous and autochthonous derived organic matter and eutrophication of the embayments. coprostanol concentrations revealed, when compared to other regions in guanabara bay, high contamination by sewage close to the point of sewage discharge in icaraí embayment. in contrast, the more enclosed and eutrophic jurujuba embayment exhibited a larger contribution of autochthonous organic matter, as shown by the combination of cholesterol, dinosterol and, partially, also brassicasterol. the presence of stigmasterol and b-sitosterol also indicated a minor contribution of organic matter from terrestrial plants, as revealed by principal component analysis. the sedimentary record of the jurujuba embayment exhibited highest concentrations of all sterol markers in the top layer, corroborating the recent increase in the accumulation of sewage, plankton derived organic carbon and also eutrophication. trend in degradation of organic matter was evidenced by sterol/stanol ratios and the behavior of dinosterol indicated that the embayment has been dominated by the accumulation of phytoplankton derived organic matter since earlier times.
Dynamic of decapod crustacean larvae on the entrance of Guanabara bay
Fernandes, Lohengrin Dias de Almeida;Bonecker, Sérgio Luiz Costa;Valentin, Jean Louis;
Brazilian Archives of Biology and Technology , 2002, DOI: 10.1590/S1516-89132002000600013
Abstract: in the present study, we observed seasonal variations in the density of decapod larvae as well as changes in density related to diurnal and tidal cycles. among the decapod larvae collected, portunids and grapsids were the most abundant, especially during nocturnal ebb tides and near the surface. the same results were obtained in late winter (september) and late summer (march). these results demonstrated a flow of decapod larvae from guanabara bay to adjacent coastal waters. luciferid (lucifer faxoni) was the only group with high densities during flood tides and we suggest this is an evidence of l. faxoni larvae entering guanabara bay in late winter. probably these changes in distribution of lucifer faxoni among winter and summer were related to reproductive cycle in the bay. for the portunids, grapsids and ocypodids, a similar dispersion strategy was observed towards adjacent coastal waters in the surface during nocturnal ebb tides.
Dynamic of decapod crustacean larvae on the entrance of Guanabara bay  [cached]
Fernandes Lohengrin Dias de Almeida,Bonecker Sérgio Luiz Costa,Valentin Jean Louis
Brazilian Archives of Biology and Technology , 2002,
Abstract: In the present study, we observed seasonal variations in the density of decapod larvae as well as changes in density related to diurnal and tidal cycles. Among the decapod larvae collected, portunids and grapsids were the most abundant, especially during nocturnal ebb tides and near the surface. The same results were obtained in late winter (September) and late summer (March). These results demonstrated a flow of decapod larvae from Guanabara Bay to adjacent coastal waters. Luciferid (Lucifer faxoni) was the only group with high densities during flood tides and we suggest this is an evidence of L. faxoni larvae entering Guanabara Bay in late winter. Probably these changes in distribution of Lucifer faxoni among winter and summer were related to reproductive cycle in the bay. For the portunids, grapsids and ocypodids, a similar dispersion strategy was observed towards adjacent coastal waters in the surface during nocturnal ebb tides.
Small time scale plankton structure variations at the entrance of a tropical eutrophic bay (Guanabara Bay, Brazil)  [cached]
Mariana Guenther,Isabel Lima,Glenda Mugrabe,Denise Rivera Tenenbaum
Brazilian Journal of Oceanography , 2012,
Abstract: The dynamics of the plankton compartments at the entrance of Guanabara Bay (SE Brazil) were assessed during a short-term temporal survey to estimate their trophic correlations. Size-fractioned phytoplankton (picoplankton: < 2μm, nanoplankton: 2-20μm and microplankton: > 20μm) biomass and photosynthetic efficiency, composition and abundance of the auto-and heterotrophic nano-and microplankton, and mesozooplankton were evaluated at a fixed station for 3 consecutive days at 3-h intervals, in the surface and bottom (20m) layers. The variability of almost all plankton compartments in the surface layer was directly dependent on temperature, indicating the great influence of the circulation at the entrance of the bay on plankton structure. In the surface layer, the mesozooplankton seems to be sustained by both autotrophic nano-and picoplankton, this last being channeled through the microzooplankton. Near the bottom, both auto-and heterotrophic microplankton are probably supporting the mesozooplankton biomass. Our findings thus suggest that the entrance of Guanabara bay presents a multivorous food web, i.e., a combination of both grazing and microbial trophic pathways. A dinamica dos vários compartimentos do plancton foi avaliada durante uma série de curta dura o na entrada da baía de Guanabara (SE do Brasil), com o objetivo de estimar suas correla es tróficas. A biomassa e eficiência fotossíntética das três fra es do fitoplancton (picoplancton: < 2μm, nanoplancton: 2-20μm e microplancton: > 20μm), juntamente com a composi o e abundancia do nano-e microplancton auto-e heterótrofos e do mesozooplancton, foram determinadas em uma esta o fixa durante 3 dias consecutivos, a intervalos de 3h, nas camadas de superfície e de fundo (20m). A variabilidade de quase todos os compartimentos do plancton na superfície foi diretamente relacionada à temperatura, indicando forte influência da circula o da entrada da baía na estrutura planct nica. Na camada superficial, o mesozooplancton parece ser alimentado pelo nano-e picoplancton autótrofos, esse último sendo sustentado pelo microzooplancton. Próximo ao fundo, o microplancton auto-e heterótrofo est o possivelmente sustentando a biomassa mesozooplanct nica. Nossos resultados sugerem, portanto, que na entrada da baía de Guanabara esteja estabelecida uma rede trófica multívora, i.e., uma combina o entre as cadeias microbiana e de pastagem.
Pollen record and paleoenvironment of a 4210 years B.P.old sediment in the Bay of Guanabara, Rio de Janeiro, Brazil
Barth, Ortrud M.;Barreto, Cíntia F.;Coelho, Luciane G.;Luz, Cynthia F.P.;
Anais da Academia Brasileira de Ciências , 2004, DOI: 10.1590/S0001-37652004000300009
Abstract: pollen analysis of a sediment sample obtained at 222 cm from the top of a drilling core collected in the bay of guanabara, rio de janeiro, was used as a tool to obtain more knowledge about pre-historical human living and environment. 14c datation revealed the age of 4210 years b.p. most frequent pollen grains came from plants like alchornea (euphorbiaceae), celtis (ulmaceae), lecythidaceae, meliaceae, ochnaceae and spores from forest pteridophyta. palynology and environmental studies revealed that agricultural activities could not be detected. the dense tropical rain forest was the dominant vegetation occurring in this region.
Pollen record and paleoenvironment of a 4210 years B.P.old sediment in the Bay of Guanabara, Rio de Janeiro, Brazil  [cached]
Barth Ortrud M.,Barreto Cíntia F.,Coelho Luciane G.,Luz Cynthia F.P.
Anais da Academia Brasileira de Ciências , 2004,
Abstract: Pollen analysis of a sediment sample obtained at 222 cm from the top of a drilling core collected in the Bay of Guanabara, Rio de Janeiro, was used as a tool to obtain more knowledge about pre-historical human living and environment. 14C datation revealed the age of 4210 years B.P. Most frequent pollen grains came from plants like Alchornea (Euphorbiaceae), Celtis (Ulmaceae), Lecythidaceae, Meliaceae, Ochnaceae and spores from forest Pteridophyta. Palynology and environmental studies revealed that agricultural activities could not be detected. The dense tropical rain forest was the dominant vegetation occurring in this region.
PHYTOPLANKTON ASSEMBLAGES AT FISH FARM IN MASLINOVA BAY (THE ISLAND OF BRA )  [PDF]
Sanda Skeji?,Ivona Marasovi?,?ivana Nin?evi? Gladan
Ribarstvo : Croatian Journal of Fisheries , 2012,
Abstract: The aim of this study was to establish phytoplankton composition at the sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) fish farm in the middle Adriatic Sea. The investigation was performed from September 2005 to September 2006 at a station located in Maslinova Bay at the island of Bra . Considering the whole research period, diatoms generally prevailed in terms of abundance while dinoflagellates were particularly abundant in June. Number of species of diatoms in comparison to dinoflagellates through the investigated period was similar. From 111 species of phytoplankton found, there were 55 species of Bacillariophyceae (diatoms), 47 species of Dinophyta (dinoflagellates), 5 species of Prymnesiophyceae, 3 Chrysophyceae and 1 Euglenophyta. Among the diatoms, the majority of species belonged to genus Chaetoceros. The most represented dinoflagellate genera were Oxytoxum and Gymnodinium. There were no considerable differences in phytoplankton composition with respect to different depths, but seasonal influence was significant. Biodiversity and abundance ranges of phytoplankton species indicated good water conditions and there were no evident alterations induced by the increased release of nutrients.
Biodiversity inventories and conservation of the marine fishes of Bootless Bay, Papua New Guinea  [cached]
Drew Joshua A,Buxman Charlene L,Holmes Darcae D,Mandecki Joanna L
BMC Ecology , 2012, DOI: 10.1186/1472-6785-12-15
Abstract: Background The effective management and conservation of biodiversity is predicated on clearly defined conservation targets. Species number is frequently used as a metric for conservation prioritization and monitoring changes in ecosystem health. We conducted a series of synoptic surveys focusing on the fishes of the Bootless Bay region of Papua New Guinea to generate a checklist of fishes of the region. Bootless Bay lies directly south of Port Moresby, the capital of Papua New Guinea, and experiences the highest human population density of any marine area in the country. Our checklist will set a baseline against which future environmental changes can be tracked. Results We generated a checklist of 488 fish species in 72 families found in Bootless Bay during a two-week sampling effort. Using incident-based methods of species estimation, we extrapolate there to be approximately 940 fish species in Bootless Bay, one of the lowest reported numbers in Papua New Guinea. Conclusions Our data suggest that the Bootless Bay ecosystem of Papua New Guinea, while diverse in absolute terms, has lower fish biodiversity compared to other shallow marine areas within the country. These differences in faunal diversity are most likely a combination of unequal sampling effort as well as biophysical factors within Bootless Bay compounded by historical and/or contemporary anthropogenic disturbances.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.