Oligotrophic water conditions associated with organic matter regeneration support life and indicate pollution on the western side of Fernando de Noronha Island - NE, Brazil (3°S)

Oligotrophy has its basis in low inorganic nutrient availability and it is generally known that in equatorial waters inorganic nutrient availability is insufficient to sustain the richness of life observed in some special places at this latitude. Thus, the understanding of the organic dissolved component role in N and P biogeochemical cycles could explain the support of the food chain in oligotrophic equatorial waters. This study was undertaken for the purpose of contributing to the knowledge of nutrient availability and the participation of dissolved organic components in the trophic conditions of an oceanic equatorial island in the South Atlantic. Water and phytoplankton were sampled on the western fringe of the Fernando de Noronha Archipelago in March 2015. Tropical oceanic conditions prevailed in this oceanic domain with high salinity (>;36.19) and temperatures (>;28.30°C). The oceanic conditions assured a high pH and dissolved oxygen levels (>;5.00 mL L-1). Alkalinity showed slight variations, its lowest values being associated with biological interaction. Suspended particulate matter was relatively low and its organic fraction was associated with the productive process and/or pollution contribution, which is confirmed mainly by high DON concentrations (~4.00 µmol L-1) with an association with high total chlorophyll in the primary production process and with urea in the pollution situation. The urea content attained 2.77 µmol L-1 at a waste disposal outlet when a contamination event was observed in the region. The available inorganic nutrients showed low concentrations with an N-ammonium average of 1.99±0.64 µmol L-1, nitrate with an average of 0.13±0.04 µmol L-1, and nitrite with an average of 0.19±0.13 µmol L-1. The DIN varied from 0.74 to 4.32 µmol L-1, principally represented by N-ammonium. DOC showed values of from 53 to 109 µmol L-1 and the DOC:DON ratio confirmed the organic source as being an inorganic N pool of oxidized organic matter and indicated that nitrogen-rich compounds are recycled faster than carbon-rich compounds. Total chlorophyll concentrations reached 0.81 mg m-3 and the noteworthy presence of filamentous cyanobacteria despite low inorganic nitrogen availability lead to a trophic chain initially supported with the contribution of a fixation process.A oligotrofia tem base na baixa disponibilidade de nutrientes inorgânicos, sendo que, normalmente, em águas equatoriais, o teor de nutrientes inorgânicos não é suficiente para sustentar a riqueza de vida observada em alguns lugares especiais nesta latitude. Assim, a compreensão do papel dos componentes orgânicos dissolvidos nos ciclos biogeoquímicos do N e do P poderia esclarecer o suporte da cadeia alimentar em águas equatoriais oligotróficas. Este estudo foi realizado com o objetivo de contribuir ao conhecimento da disponibilidade de nutrientes e participação de componentes orgânicos na condição trófica das águas do entorno de uma ilha equatorial oceânica no Atlântico Sul. A água e o fitoplâncton foram amostrados na franja ocidental do arquipélago Fernando de Noronha, em março de 2015. As condições tropicais oceânicas prevaleceram neste domínio oceânico com altas salinidade (>;36,19) e temperatura (>;28,30°C). As condições oceânicas garantiram os altos valores de pH (>;8,0) e oxigênio dissolvido (>;5,00 mL L-1). A alcalinidade mostrou ligeiras variações com menores valores associados à interação biológica. A matéria particulada em suspensão esteve relativamente baixa e a fração orgânica foi associada ao processo produtivo e/ou contribuição da poluição, o que é confirmado principalmente por altas concentrações de DON (~4,00 µmol L-1) associada aos maiores valores de clorofila total na situação de produção primária e, com a ureia em situação de poluição. O conteúdo de ureia atingiu 2,77 µmol L-1 em um ponto de disposição de efluentes quando um evento de contaminação foi observado na região. Os nutrientes inorgânicos disponíveis apresentaram baixas concentrações, com uma média de N-amoniacal de 1,99±0,64 µmol L-1, nitrato com média de 0,13±0,04 µmol L-1, nitrito com média de 0,19±0,13 µmol L-1. O DIN variou de 0,74 a 4,32 µmol L-1, principalmente representado por N-amoniacal. O DOC apresentou valores de 53 a 109 µmol L-1 e, a relação DOC:DON confirmou uma fonte orgânica para o reservatório de N inorgânico a partir da oxidação da matéria orgânica e indicou que os compostos ricos em nitrogênio são reciclados mais rapidamente do que os compostos ricos em carbono. As concentrações totais de clorofila atingiram 0,81 mg m-3 e a notável presença de cianobactérias filamentosas frente à baixa disponibilidade de nitrogênio inorgânico, conduzindo a uma cadeia trófica inicialmente suportada com contribuição do processo de fixação

Dissolved organic nutrients (C, N, P) in seawater on the continental shelf in the Southwestern South Atlantic with emphasis State Marine Park of Laje de Santos (SMPLS) - São Paulo - Brazil

O principal objetivo deste trabalho é avaliar distribuição sazonal e espacial do carbono orgânico dissolvido (COD), nitrogênio orgânico (NOD), fósforo orgânico dissolvido (POD) e ureia em 10 estações do Parque Estadual Marinho da Laje de Santos (PEMLS). As estações 1 a 4 (mais próximas do continente) e as estações de 5 a 10 (mais próximas do parque marinho), todas na plataforma continental. Os resultados mostram que não foram observadas variações sazonais estatisticamente significativas para o COD e POD, todavia, o COD e o NOD, no período de verão apresentaram um pequeno aumento mostrando o aumento da atividade biológica e a influencia continental. Por outro lado, o NOD apresentou valores elevados em junho (2014 - inverno) e janeiro de 2015, variando de 12.51 a 32.76 µmol L-1, segundo o método de análise ANOVA (p< 0,01). Foram observados baixos valores de NOD em janeiro de 2014 (0,32-8,98 µmol L-1), em um verão anormalmente seco, enquanto que os valores mais elevados foram observados em julho de 2014 (27.50 µmol L-1). Ureia apresentou valores baixos na região do PEMLS e zonas costeiras atingindo 4,00 µmol L-1. Muitas vezes, a concentração de ureia pode estar associada com atividade de mergulho no parque. COD, NOD e ureia apresentaram valores ou diferenças entre as estações no PEMLS (5-10) e aquelas mais costeiras (1-4). O COD nas estações costeiras atingiu 267 µmol L-1, enquanto que no PEMLS, o valor máximo foi de 100 µmol L-1. Nenhuma variação significativa foi observada quanto à distribuição espacial entre as estações costeiras e as do parque para o POD (ANOVA pThe main objective of this work is evaluate seasonal and spatial distribution of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphorus (DOP) and urea in 10 stations of the State Marine Park of Laje de Santos (SMPLS). Stations 1 to 4 (nearest the continent) and the stations 5 to 10 (nearest the marine park) all of them were on the continental shelf. The results show that no statistic significant seasonal variations were found for the DOC and DOP nevertheless DOC and DON in summer period were lightly above the winter period showing the increase in biological activities and continental influence. On the other hand, DON showed high values in June (2014 - winter) to January 2015, ranging from 12.51 to 32.76 µmol L-1 according to the ANOVA method (

Oligotrophic water conditions associated with organic matter regeneration support life and indicate pollution on the western side of Fernando de Noronha Island - NE, Brazil (3°S)

Abstract Oligotrophy has its basis in low inorganic nutrient availability and it is generally known that in equatorial waters inorganic nutrient availability is insufficient to sustain the richness of life observed in some special places at this latitude. Thus, the understanding of the organic dissolved component role in N and P biogeochemical cycles could explain the support of the food chain in oligotrophic equatorial waters. This study was undertaken for the purpose of contributing to the knowledge of nutrient availability and the participation of dissolved organic components in the trophic conditions of an oceanic equatorial island in the South Atlantic. Water and phytoplankton were sampled on the western fringe of the Fernando de Noronha Archipelago in March 2015. Tropical oceanic conditions prevailed in this oceanic domain with high salinity (>36.19) and temperatures (>28.30°C). The oceanic conditions assured a high pH and dissolved oxygen levels (>5.00 mL L-1). Alkalinity showed slight variations, its lowest values being associated with biological interaction. Suspended particulate matter was relatively low and its organic fraction was associated with the productive process and/or pollution contribution, which is confirmed mainly by high DON concentrations (~4.00 µmol L-1) with an association with high total chlorophyll in the primary production process and with urea in the pollution situation. The urea content attained 2.77 µmol L-1 at a waste disposal outlet when a contamination event was observed in the region. The available inorganic nutrients showed low concentrations with an N-ammonium average of 1.99±0.64 µmol L-1, nitrate with an average of 0.13±0.04 µmol L-1, and nitrite with an average of 0.19±0.13 µmol L-1. The DIN varied from 0.74 to 4.32 µmol L-1, principally represented by N-ammonium. DOC showed values of from 53 to 109 µmol L-1 and the DOC:DON ratio confirmed the organic source as being an inorganic N pool of oxidized organic matter and indicated that nitrogen-rich compounds are recycled faster than carbon-rich compounds. Total chlorophyll concentrations reached 0.81 mg m-3 and the noteworthy presence of filamentous cyanobacteria despite low inorganic nitrogen availability lead to a trophic chain initially supported with the contribution of a fixation process

Oligotrophic water conditions associated with organic matter regeneration support life and indicate pollution on the western side of Fernando de Noronha Island - NE, Brazil (3°S)

<div><p>Abstract Oligotrophy has its basis in low inorganic nutrient availability and it is generally known that in equatorial waters inorganic nutrient availability is insufficient to sustain the richness of life observed in some special places at this latitude. Thus, the understanding of the organic dissolved component role in N and P biogeochemical cycles could explain the support of the food chain in oligotrophic equatorial waters. This study was undertaken for the purpose of contributing to the knowledge of nutrient availability and the participation of dissolved organic components in the trophic conditions of an oceanic equatorial island in the South Atlantic. Water and phytoplankton were sampled on the western fringe of the Fernando de Noronha Archipelago in March 2015. Tropical oceanic conditions prevailed in this oceanic domain with high salinity (>36.19) and temperatures (>28.30°C). The oceanic conditions assured a high pH and dissolved oxygen levels (>5.00 mL L-1). Alkalinity showed slight variations, its lowest values being associated with biological interaction. Suspended particulate matter was relatively low and its organic fraction was associated with the productive process and/or pollution contribution, which is confirmed mainly by high DON concentrations (~4.00 µmol L-1) with an association with high total chlorophyll in the primary production process and with urea in the pollution situation. The urea content attained 2.77 µmol L-1 at a waste disposal outlet when a contamination event was observed in the region. The available inorganic nutrients showed low concentrations with an N-ammonium average of 1.99±0.64 µmol L-1, nitrate with an average of 0.13±0.04 µmol L-1, and nitrite with an average of 0.19±0.13 µmol L-1. The DIN varied from 0.74 to 4.32 µmol L-1, principally represented by N-ammonium. DOC showed values of from 53 to 109 µmol L-1 and the DOC:DON ratio confirmed the organic source as being an inorganic N pool of oxidized organic matter and indicated that nitrogen-rich compounds are recycled faster than carbon-rich compounds. Total chlorophyll concentrations reached 0.81 mg m-3 and the noteworthy presence of filamentous cyanobacteria despite low inorganic nitrogen availability lead to a trophic chain initially supported with the contribution of a fixation process.</p></div

Dissolved organic nutrients (C, N, P) in seawater on the continental shelf in the Southwestern South Atlantic with emphasis State Marine Park of Laje de Santos (SMPLS) - São Paulo - Brazil

Abstract The main objective of this work is evaluate seasonal and spatial distribution of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphorus (DOP) and urea in 10 stations of the State Marine Park of Laje de Santos (SMPLS). Stations 1 to 4 (nearest the continent) and the stations 5 to 10 (nearest the marine park) all of them were on the continental shelf. The results show that no statistic significant seasonal variations were found for the DOC and DOP nevertheless DOC and DON in summer period were lightly above the winter period showing the increase in biological activities and continental influence. On the other hand, DON showed high values in June (2014 - winter) to January 2015, ranging from 12.51 to 32.76 µmol L-1 according to the ANOVA method (p <0.01). Low values of DON in January 2014 (0.32 to 8.98 µmol L-1) was observed in a summer unusually dry, while the highest values were observed in July 2014 (27.50 µmol L-1). Urea presented low values in SMPLS region and coastal areas reaching 4.00 µmol L-1. Sometimes, the urea concentration can be associated with diving activity in the park. DOC, DON and urea showed differences between SMPLS stations (5-10) and coastal stations (1-4). DOC coastal stations reached 267 µmol L-1, while the SMPLS the maximum value was 100 µmol L-1. No significant spatial variation between coastal stations and park were observed for the DOP (ANOVA p <0.01). Considering that dissolved organic compounds can also be monitored by means of the evaluation of C, N, P in their organic fraction, it was concluded that in the studied region the impact of eutrophic waters under continental and anthropic influence is minimal and these parameters could be monitored to support monitoring in the region

Diversions of the Ribeira River Flow and Their Influence on Sediment Supply in the Cananeia-Iguape Estuarine-Lagoonal System (SE Brazil)

The Cananéia-Iguape system is a combined estuarine-lagoonal sedimentary system, located along the SE coast of Brazil. It consists of a network of channels and islands oriented mainly parallel to the coast. About 165 years ago, an artificial channel, the Valo Grande, was opened in the northern part of this system to connect a major river of the region, the Ribeira River, to the estuarine-lagoon complex. The Valo Grande was closed with a dam and re-opened twice between 1978 and 1995, when it was finally left open. These openings and closures of the Valo Grande had a significant influence on the Cananéia-Iguape system. In this study we present mineralogical, chemical, palaeomagnetic, and geochronological data from a sediment core collected at the southern end of the 50 km long lagoonal system showing how the phases of the opening and closure of the channel through time are expressed in the sedimentary record. Despite the homogeneity of the grain size and magnetic properties throughout the core, significant variations in the mineralogical composition showed the influence of the opening of the channel on the sediment supply. Less mature sediment, with lower quartz and halite and higher kaolinite, brucite, and franklinite, corresponded to periods when the Valo Grande was open. On the other hand, higher abundance of quartz and halite, as well as the disappearance of other detrital minerals, corresponded with periods of absence or closure of the channel, indicating a more sea-influenced depositional setting. This work represented an example of anthropogenic influence in a lagoonal-estuarine sedimentary system, which is a common context along the coast of Brazil